tableam vs. TOAST

From 8f42139d1969ebdad21d28833080b684c58ead17 Mon Sep 17 00:00:00 2001
From: Robert Haas <rhaas@postgresql.org>
Date: Fri, 17 May 2019 09:23:45 -0400
Subject: [PATCH v2 3/3] Allow TOAST tables to be implemented using table AMs
 other than heap.

toast_fetch_datum, toast_save_datum, and toast_delete_datum are
adjusted to use tableam rather than heap-specific functions.  This
might have some performance impact, but this patch attempts to
mitigate that by restructuring things so that we don't open and close
the toast table and indexes multiple times per tuple.

tableam now exposes an integer value (not a callback) for the
maximum TOAST chunk size, and has a new callback allowing table
AMs to specify the AM that should be used to implement the TOAST
table. Previously, the toast AM was always the same as the table AM.
---
 src/backend/access/common/detoast.c         |  60 ++++-----
 src/backend/access/common/toast_internals.c | 127 +++++++-------------
 src/backend/access/heap/heapam.c            |   6 +-
 src/backend/access/heap/heapam_handler.c    |  16 ++-
 src/backend/access/heap/heaptoast.c         |  19 ++-
 src/backend/access/index/genam.c            |  20 +++
 src/backend/access/table/toast_helper.c     | 107 ++++++++++++++---
 src/backend/catalog/toasting.c              |   2 +-
 src/include/access/genam.h                  |   5 +-
 src/include/access/heapam.h                 |   3 +-
 src/include/access/heaptoast.h              |   3 +-
 src/include/access/tableam.h                |  31 +++++
 src/include/access/toast_helper.h           |  18 ++-
 src/include/access/toast_internals.h        |  13 +-
 14 files changed, 283 insertions(+), 147 deletions(-)

diff --git a/src/backend/access/common/detoast.c b/src/backend/access/common/detoast.c
index 57ca8afe2a..b89cf7d190 100644
--- a/src/backend/access/common/detoast.c
+++ b/src/backend/access/common/detoast.c
@@ -16,10 +16,11 @@
 
 #include "access/detoast.h"
 #include "access/genam.h"
-#include "access/heaptoast.h"
 #include "access/table.h"
 #include "access/toast_internals.h"
+#include "access/tableam.h"
 #include "common/pg_lzcompress.h"
+#include "executor/tuptable.h"
 #include "utils/expandeddatum.h"
 #include "utils/fmgroids.h"
 #include "utils/rel.h"
@@ -304,7 +305,7 @@ toast_fetch_datum(struct varlena *attr)
 	Relation   *toastidxs;
 	ScanKeyData toastkey;
 	SysScanDesc toastscan;
-	HeapTuple	ttup;
+	TupleTableSlot *slot;
 	TupleDesc	toasttupDesc;
 	struct varlena *result;
 	struct varatt_external toast_pointer;
@@ -313,11 +314,11 @@ toast_fetch_datum(struct varlena *attr)
 				nextidx;
 	int32		numchunks;
 	Pointer		chunk;
-	bool		isnull;
 	char	   *chunkdata;
 	int32		chunksize;
 	int			num_indexes;
 	int			validIndex;
+	int			max_chunk_size;
 	SnapshotData SnapshotToast;
 
 	if (!VARATT_IS_EXTERNAL_ONDISK(attr))
@@ -327,7 +328,6 @@ toast_fetch_datum(struct varlena *attr)
 	VARATT_EXTERNAL_GET_POINTER(toast_pointer, attr);
 
 	ressize = toast_pointer.va_extsize;
-	numchunks = ((ressize - 1) / TOAST_MAX_CHUNK_SIZE) + 1;
 
 	result = (struct varlena *) palloc(ressize + VARHDRSZ);
 
@@ -342,6 +342,9 @@ toast_fetch_datum(struct varlena *attr)
 	toastrel = table_open(toast_pointer.va_toastrelid, AccessShareLock);
 	toasttupDesc = toastrel->rd_att;
 
+	max_chunk_size = toastrel->rd_tableam->toast_max_chunk_size;
+	numchunks = ((ressize - 1) / max_chunk_size) + 1;
+
 	/* Look for the valid index of the toast relation */
 	validIndex = toast_open_indexes(toastrel,
 									AccessShareLock,
@@ -368,15 +371,15 @@ toast_fetch_datum(struct varlena *attr)
 	init_toast_snapshot(&SnapshotToast);
 	toastscan = systable_beginscan_ordered(toastrel, toastidxs[validIndex],
 										   &SnapshotToast, 1, &toastkey);
-	while ((ttup = systable_getnext_ordered(toastscan, ForwardScanDirection)) != NULL)
+	while ((slot = systable_getnextslot_ordered(toastscan, ForwardScanDirection)) != NULL)
 	{
 		/*
 		 * Have a chunk, extract the sequence number and the data
 		 */
-		residx = DatumGetInt32(fastgetattr(ttup, 2, toasttupDesc, &isnull));
-		Assert(!isnull);
-		chunk = DatumGetPointer(fastgetattr(ttup, 3, toasttupDesc, &isnull));
-		Assert(!isnull);
+		slot_getsomeattrs(slot, 3);
+		Assert(!slot->tts_isnull[1] && !slot->tts_isnull[2]);
+		residx = DatumGetInt32(slot->tts_values[1]);
+		chunk = DatumGetPointer(slot->tts_values[2]);
 		if (!VARATT_IS_EXTENDED(chunk))
 		{
 			chunksize = VARSIZE(chunk) - VARHDRSZ;
@@ -408,19 +411,19 @@ toast_fetch_datum(struct varlena *attr)
 				 RelationGetRelationName(toastrel));
 		if (residx < numchunks - 1)
 		{
-			if (chunksize != TOAST_MAX_CHUNK_SIZE)
+			if (chunksize != max_chunk_size)
 				elog(ERROR, "unexpected chunk size %d (expected %d) in chunk %d of %d for toast value %u in %s",
-					 chunksize, (int) TOAST_MAX_CHUNK_SIZE,
+					 chunksize, max_chunk_size,
 					 residx, numchunks,
 					 toast_pointer.va_valueid,
 					 RelationGetRelationName(toastrel));
 		}
 		else if (residx == numchunks - 1)
 		{
-			if ((residx * TOAST_MAX_CHUNK_SIZE + chunksize) != ressize)
+			if ((residx * max_chunk_size + chunksize) != ressize)
 				elog(ERROR, "unexpected chunk size %d (expected %d) in final chunk %d for toast value %u in %s",
 					 chunksize,
-					 (int) (ressize - residx * TOAST_MAX_CHUNK_SIZE),
+					 (int) (ressize - residx * max_chunk_size),
 					 residx,
 					 toast_pointer.va_valueid,
 					 RelationGetRelationName(toastrel));
@@ -435,7 +438,7 @@ toast_fetch_datum(struct varlena *attr)
 		/*
 		 * Copy the data into proper place in our result
 		 */
-		memcpy(VARDATA(result) + residx * TOAST_MAX_CHUNK_SIZE,
+		memcpy(VARDATA(result) + residx * max_chunk_size,
 			   chunkdata,
 			   chunksize);
 
@@ -499,6 +502,7 @@ toast_fetch_datum_slice(struct varlena *attr, int32 sliceoffset, int32 length)
 	int32		chcpyend;
 	int			num_indexes;
 	int			validIndex;
+	int			max_chunk_size;
 	SnapshotData SnapshotToast;
 
 	if (!VARATT_IS_EXTERNAL_ONDISK(attr))
@@ -514,7 +518,6 @@ toast_fetch_datum_slice(struct varlena *attr, int32 sliceoffset, int32 length)
 	Assert(!VARATT_EXTERNAL_IS_COMPRESSED(toast_pointer));
 
 	attrsize = toast_pointer.va_extsize;
-	totalchunks = ((attrsize - 1) / TOAST_MAX_CHUNK_SIZE) + 1;
 
 	if (sliceoffset >= attrsize)
 	{
@@ -532,19 +535,22 @@ toast_fetch_datum_slice(struct varlena *attr, int32 sliceoffset, int32 length)
 	if (length == 0)
 		return result;			/* Can save a lot of work at this point! */
 
-	startchunk = sliceoffset / TOAST_MAX_CHUNK_SIZE;
-	endchunk = (sliceoffset + length - 1) / TOAST_MAX_CHUNK_SIZE;
-	numchunks = (endchunk - startchunk) + 1;
-
-	startoffset = sliceoffset % TOAST_MAX_CHUNK_SIZE;
-	endoffset = (sliceoffset + length - 1) % TOAST_MAX_CHUNK_SIZE;
-
 	/*
 	 * Open the toast relation and its indexes
 	 */
 	toastrel = table_open(toast_pointer.va_toastrelid, AccessShareLock);
 	toasttupDesc = toastrel->rd_att;
 
+	max_chunk_size = toastrel->rd_tableam->toast_max_chunk_size;
+	totalchunks = ((attrsize - 1) / max_chunk_size) + 1;
+
+	startchunk = sliceoffset / max_chunk_size;
+	endchunk = (sliceoffset + length - 1) / max_chunk_size;
+	numchunks = (endchunk - startchunk) + 1;
+
+	startoffset = sliceoffset % max_chunk_size;
+	endoffset = (sliceoffset + length - 1) % max_chunk_size;
+
 	/* Look for the valid index of toast relation */
 	validIndex = toast_open_indexes(toastrel,
 									AccessShareLock,
@@ -633,19 +639,19 @@ toast_fetch_datum_slice(struct varlena *attr, int32 sliceoffset, int32 length)
 				 RelationGetRelationName(toastrel));
 		if (residx < totalchunks - 1)
 		{
-			if (chunksize != TOAST_MAX_CHUNK_SIZE)
+			if (chunksize != max_chunk_size)
 				elog(ERROR, "unexpected chunk size %d (expected %d) in chunk %d of %d for toast value %u in %s when fetching slice",
-					 chunksize, (int) TOAST_MAX_CHUNK_SIZE,
+					 chunksize, max_chunk_size,
 					 residx, totalchunks,
 					 toast_pointer.va_valueid,
 					 RelationGetRelationName(toastrel));
 		}
 		else if (residx == totalchunks - 1)
 		{
-			if ((residx * TOAST_MAX_CHUNK_SIZE + chunksize) != attrsize)
+			if ((residx * max_chunk_size + chunksize) != attrsize)
 				elog(ERROR, "unexpected chunk size %d (expected %d) in final chunk %d for toast value %u in %s when fetching slice",
 					 chunksize,
-					 (int) (attrsize - residx * TOAST_MAX_CHUNK_SIZE),
+					 (int) (attrsize - residx * max_chunk_size),
 					 residx,
 					 toast_pointer.va_valueid,
 					 RelationGetRelationName(toastrel));
@@ -668,7 +674,7 @@ toast_fetch_datum_slice(struct varlena *attr, int32 sliceoffset, int32 length)
 			chcpyend = endoffset;
 
 		memcpy(VARDATA(result) +
-			   (residx * TOAST_MAX_CHUNK_SIZE - sliceoffset) + chcpystrt,
+			   (residx * max_chunk_size - sliceoffset) + chcpystrt,
 			   chunkdata + chcpystrt,
 			   (chcpyend - chcpystrt) + 1);
 
diff --git a/src/backend/access/common/toast_internals.c b/src/backend/access/common/toast_internals.c
index a971242490..a1d7f3ed66 100644
--- a/src/backend/access/common/toast_internals.c
+++ b/src/backend/access/common/toast_internals.c
@@ -15,9 +15,8 @@
 
 #include "access/detoast.h"
 #include "access/genam.h"
-#include "access/heapam.h"
-#include "access/heaptoast.h"
 #include "access/table.h"
+#include "access/tableam.h"
 #include "access/toast_internals.h"
 #include "access/xact.h"
 #include "catalog/catalog.h"
@@ -100,22 +99,21 @@ toast_compress_datum(Datum value)
  *	Save one single datum into the secondary relation and return
  *	a Datum reference for it.
  *
- * rel: the main relation we're working with (not the toast rel!)
+ * toastrel: the TOAST relation we're working with (not the main rel!)
+ * toastslot: a slot corresponding to 'toastrel'
+ * num_indexes, toastidxs, validIndex: as returned by toast_open_indexes
+ * toastoid: the toast OID that should be inserted into the new TOAST pointer
  * value: datum to be pushed to toast storage
  * oldexternal: if not NULL, toast pointer previously representing the datum
- * options: options to be passed to heap_insert() for toast rows
+ * options: options to be passed to table_insert() for toast rows
  * ----------
  */
 Datum
-toast_save_datum(Relation rel, Datum value,
-				 struct varlena *oldexternal, int options)
+toast_save_datum(Relation toastrel, TupleTableSlot *toastslot,
+				 int num_indexes, Relation *toastidxs, int validIndex,
+				 Oid toastoid, Datum value, struct varlena *oldexternal,
+				 int options, int max_chunk_size)
 {
-	Relation	toastrel;
-	Relation   *toastidxs;
-	HeapTuple	toasttup;
-	TupleDesc	toasttupDesc;
-	Datum		t_values[3];
-	bool		t_isnull[3];
 	CommandId	mycid = GetCurrentCommandId(true);
 	struct varlena *result;
 	struct varatt_external toast_pointer;
@@ -123,7 +121,7 @@ toast_save_datum(Relation rel, Datum value,
 	{
 		struct varlena hdr;
 		/* this is to make the union big enough for a chunk: */
-		char		data[TOAST_MAX_CHUNK_SIZE + VARHDRSZ];
+		char		data[BLCKSZ + VARHDRSZ];
 		/* ensure union is aligned well enough: */
 		int32		align_it;
 	}			chunk_data;
@@ -132,24 +130,9 @@ toast_save_datum(Relation rel, Datum value,
 	char	   *data_p;
 	int32		data_todo;
 	Pointer		dval = DatumGetPointer(value);
-	int			num_indexes;
-	int			validIndex;
 
 	Assert(!VARATT_IS_EXTERNAL(value));
-
-	/*
-	 * Open the toast relation and its indexes.  We can use the index to check
-	 * uniqueness of the OID we assign to the toasted item, even though it has
-	 * additional columns besides OID.
-	 */
-	toastrel = table_open(rel->rd_rel->reltoastrelid, RowExclusiveLock);
-	toasttupDesc = toastrel->rd_att;
-
-	/* Open all the toast indexes and look for the valid one */
-	validIndex = toast_open_indexes(toastrel,
-									RowExclusiveLock,
-									&toastidxs,
-									&num_indexes);
+	Assert(max_chunk_size <= BLCKSZ);
 
 	/*
 	 * Get the data pointer and length, and compute va_rawsize and va_extsize.
@@ -189,11 +172,11 @@ toast_save_datum(Relation rel, Datum value,
 	 *
 	 * Normally this is the actual OID of the target toast table, but during
 	 * table-rewriting operations such as CLUSTER, we have to insert the OID
-	 * of the table's real permanent toast table instead.  rd_toastoid is set
+	 * of the table's real permanent toast table instead.  toastoid is set
 	 * if we have to substitute such an OID.
 	 */
-	if (OidIsValid(rel->rd_toastoid))
-		toast_pointer.va_toastrelid = rel->rd_toastoid;
+	if (OidIsValid(toastoid))
+		toast_pointer.va_toastrelid = toastoid;
 	else
 		toast_pointer.va_toastrelid = RelationGetRelid(toastrel);
 
@@ -209,7 +192,7 @@ toast_save_datum(Relation rel, Datum value,
 	 * options have been changed), we have to pick a value ID that doesn't
 	 * conflict with either new or existing toast value OIDs.
 	 */
-	if (!OidIsValid(rel->rd_toastoid))
+	if (!OidIsValid(toastoid))
 	{
 		/* normal case: just choose an unused OID */
 		toast_pointer.va_valueid =
@@ -228,7 +211,7 @@ toast_save_datum(Relation rel, Datum value,
 			Assert(VARATT_IS_EXTERNAL_ONDISK(oldexternal));
 			/* Must copy to access aligned fields */
 			VARATT_EXTERNAL_GET_POINTER(old_toast_pointer, oldexternal);
-			if (old_toast_pointer.va_toastrelid == rel->rd_toastoid)
+			if (old_toast_pointer.va_toastrelid == toastoid)
 			{
 				/* This value came from the old toast table; reuse its OID */
 				toast_pointer.va_valueid = old_toast_pointer.va_valueid;
@@ -270,20 +253,11 @@ toast_save_datum(Relation rel, Datum value,
 					GetNewOidWithIndex(toastrel,
 									   RelationGetRelid(toastidxs[validIndex]),
 									   (AttrNumber) 1);
-			} while (toastid_valueid_exists(rel->rd_toastoid,
+			} while (toastid_valueid_exists(toastoid,
 											toast_pointer.va_valueid));
 		}
 	}
 
-	/*
-	 * Initialize constant parts of the tuple data
-	 */
-	t_values[0] = ObjectIdGetDatum(toast_pointer.va_valueid);
-	t_values[2] = PointerGetDatum(&chunk_data);
-	t_isnull[0] = false;
-	t_isnull[1] = false;
-	t_isnull[2] = false;
-
 	/*
 	 * Split up the item into chunks
 	 */
@@ -296,17 +270,22 @@ toast_save_datum(Relation rel, Datum value,
 		/*
 		 * Calculate the size of this chunk
 		 */
-		chunk_size = Min(TOAST_MAX_CHUNK_SIZE, data_todo);
+		chunk_size = Min(max_chunk_size, data_todo);
 
 		/*
 		 * Build a tuple and store it
 		 */
-		t_values[1] = Int32GetDatum(chunk_seq++);
+		toastslot->tts_values[0] = ObjectIdGetDatum(toast_pointer.va_valueid);
+		toastslot->tts_values[1] = Int32GetDatum(chunk_seq++);
 		SET_VARSIZE(&chunk_data, chunk_size + VARHDRSZ);
 		memcpy(VARDATA(&chunk_data), data_p, chunk_size);
-		toasttup = heap_form_tuple(toasttupDesc, t_values, t_isnull);
+		toastslot->tts_values[2] = PointerGetDatum(&chunk_data);
+		toastslot->tts_isnull[0] = false;
+		toastslot->tts_isnull[1] = false;
+		toastslot->tts_isnull[2] = false;
+		ExecStoreVirtualTuple(toastslot);
 
-		heap_insert(toastrel, toasttup, mycid, options, NULL);
+		table_insert(toastrel, toastslot, mycid, options, NULL);
 
 		/*
 		 * Create the index entry.  We cheat a little here by not using
@@ -323,8 +302,9 @@ toast_save_datum(Relation rel, Datum value,
 		{
 			/* Only index relations marked as ready can be updated */
 			if (toastidxs[i]->rd_index->indisready)
-				index_insert(toastidxs[i], t_values, t_isnull,
-							 &(toasttup->t_self),
+				index_insert(toastidxs[i], toastslot->tts_values,
+							 toastslot->tts_isnull,
+							 &(toastslot->tts_tid),
 							 toastrel,
 							 toastidxs[i]->rd_index->indisunique ?
 							 UNIQUE_CHECK_YES : UNIQUE_CHECK_NO,
@@ -332,9 +312,9 @@ toast_save_datum(Relation rel, Datum value,
 		}
 
 		/*
-		 * Free memory
+		 * Clear slot
 		 */
-		heap_freetuple(toasttup);
+		ExecClearTuple(toastslot);
 
 		/*
 		 * Move on to next chunk
@@ -343,12 +323,6 @@ toast_save_datum(Relation rel, Datum value,
 		data_p += chunk_size;
 	}
 
-	/*
-	 * Done - close toast relation and its indexes
-	 */
-	toast_close_indexes(toastidxs, num_indexes, RowExclusiveLock);
-	table_close(toastrel, RowExclusiveLock);
-
 	/*
 	 * Create the TOAST pointer value that we'll return
 	 */
@@ -366,35 +340,24 @@ toast_save_datum(Relation rel, Datum value,
  * ----------
  */
 void
-toast_delete_datum(Relation rel, Datum value, bool is_speculative)
+toast_delete_datum(Relation toastrel, int num_indexes, Relation *toastidxs,
+				   int validIndex, Datum value, bool is_speculative,
+				   uint32 specToken)
 {
 	struct varlena *attr = (struct varlena *) DatumGetPointer(value);
 	struct varatt_external toast_pointer;
-	Relation	toastrel;
-	Relation   *toastidxs;
 	ScanKeyData toastkey;
 	SysScanDesc toastscan;
-	HeapTuple	toasttup;
-	int			num_indexes;
-	int			validIndex;
+	TupleTableSlot *slot;
 	SnapshotData SnapshotToast;
 
-	if (!VARATT_IS_EXTERNAL_ONDISK(attr))
-		return;
+	Assert(VARATT_IS_EXTERNAL_ONDISK(attr));
 
 	/* Must copy to access aligned fields */
 	VARATT_EXTERNAL_GET_POINTER(toast_pointer, attr);
 
-	/*
-	 * Open the toast relation and its indexes
-	 */
-	toastrel = table_open(toast_pointer.va_toastrelid, RowExclusiveLock);
-
-	/* Fetch valid relation used for process */
-	validIndex = toast_open_indexes(toastrel,
-									RowExclusiveLock,
-									&toastidxs,
-									&num_indexes);
+	/* Check that caller gave us the correct TOAST relation. */
+	Assert(toast_pointer.va_toastrelid == RelationGetRelid(toastrel));
 
 	/*
 	 * Setup a scan key to find chunks with matching va_valueid
@@ -412,23 +375,19 @@ toast_delete_datum(Relation rel, Datum value, bool is_speculative)
 	init_toast_snapshot(&SnapshotToast);
 	toastscan = systable_beginscan_ordered(toastrel, toastidxs[validIndex],
 										   &SnapshotToast, 1, &toastkey);
-	while ((toasttup = systable_getnext_ordered(toastscan, ForwardScanDirection)) != NULL)
+	while ((slot = systable_getnextslot_ordered(toastscan, ForwardScanDirection)) != NULL)
 	{
 		/*
 		 * Have a chunk, delete it
 		 */
 		if (is_speculative)
-			heap_abort_speculative(toastrel, &toasttup->t_self);
+			table_complete_speculative(toastrel, slot, specToken, false);
 		else
-			simple_heap_delete(toastrel, &toasttup->t_self);
+			simple_table_delete(toastrel, &slot->tts_tid, &SnapshotToast);
 	}
 
-	/*
-	 * End scan and close relations
-	 */
+	/* End scan */
 	systable_endscan_ordered(toastscan);
-	toast_close_indexes(toastidxs, num_indexes, RowExclusiveLock);
-	table_close(toastrel, RowExclusiveLock);
 }
 
 /* ----------
diff --git a/src/backend/access/heap/heapam.c b/src/backend/access/heap/heapam.c
index 469c27ce48..6655b92855 100644
--- a/src/backend/access/heap/heapam.c
+++ b/src/backend/access/heap/heapam.c
@@ -2818,7 +2818,7 @@ l1:
 		Assert(!HeapTupleHasExternal(&tp));
 	}
 	else if (HeapTupleHasExternal(&tp))
-		toast_delete(relation, &tp, false);
+		toast_delete(relation, &tp, false, 0);
 
 	/*
 	 * Mark tuple for invalidation from system caches at next command
@@ -5549,7 +5549,7 @@ heap_finish_speculative(Relation relation, ItemPointer tid)
  * confirmation records.
  */
 void
-heap_abort_speculative(Relation relation, ItemPointer tid)
+heap_abort_speculative(Relation relation, ItemPointer tid, uint32 specToken)
 {
 	TransactionId xid = GetCurrentTransactionId();
 	ItemId		lp;
@@ -5658,7 +5658,7 @@ heap_abort_speculative(Relation relation, ItemPointer tid)
 	if (HeapTupleHasExternal(&tp))
 	{
 		Assert(!IsToastRelation(relation));
-		toast_delete(relation, &tp, true);
+		toast_delete(relation, &tp, true, specToken);
 	}
 
 	/*
diff --git a/src/backend/access/heap/heapam_handler.c b/src/backend/access/heap/heapam_handler.c
index c7d5ff3850..c88442adee 100644
--- a/src/backend/access/heap/heapam_handler.c
+++ b/src/backend/access/heap/heapam_handler.c
@@ -30,6 +30,7 @@
 #include "access/rewriteheap.h"
 #include "access/tableam.h"
 #include "access/tsmapi.h"
+#include "access/heaptoast.h"
 #include "access/xact.h"
 #include "catalog/catalog.h"
 #include "catalog/index.h"
@@ -286,7 +287,7 @@ heapam_tuple_insert_speculative(Relation relation, TupleTableSlot *slot,
 
 static void
 heapam_tuple_complete_speculative(Relation relation, TupleTableSlot *slot,
-								  uint32 spekToken, bool succeeded)
+								  uint32 specToken, bool succeeded)
 {
 	bool		shouldFree = true;
 	HeapTuple	tuple = ExecFetchSlotHeapTuple(slot, true, &shouldFree);
@@ -295,7 +296,7 @@ heapam_tuple_complete_speculative(Relation relation, TupleTableSlot *slot,
 	if (succeeded)
 		heap_finish_speculative(relation, &slot->tts_tid);
 	else
-		heap_abort_speculative(relation, &slot->tts_tid);
+		heap_abort_speculative(relation, &slot->tts_tid, specToken);
 
 	if (shouldFree)
 		pfree(tuple);
@@ -2061,6 +2062,15 @@ heapam_relation_needs_toast_table(Relation rel)
 	return (tuple_length > TOAST_TUPLE_THRESHOLD);
 }
 
+/*
+ * TOAST tables for heap relations are just heap relations.
+ */
+static Oid
+heapam_relation_toast_am(Relation rel)
+{
+	return rel->rd_rel->relam;
+}
+
 
 /* ------------------------------------------------------------------------
  * Planner related callbacks for the heap AM
@@ -2645,6 +2655,8 @@ static const TableAmRoutine heapam_methods = {
 
 	.relation_size = heapam_relation_size,
 	.relation_needs_toast_table = heapam_relation_needs_toast_table,
+	.relation_toast_am = heapam_relation_toast_am,
+	.toast_max_chunk_size = TOAST_MAX_CHUNK_SIZE,
 
 	.relation_estimate_size = heapam_estimate_rel_size,
 
diff --git a/src/backend/access/heap/heaptoast.c b/src/backend/access/heap/heaptoast.c
index 3a2118e1d8..1d4ad5b336 100644
--- a/src/backend/access/heap/heaptoast.c
+++ b/src/backend/access/heap/heaptoast.c
@@ -38,7 +38,8 @@
  * ----------
  */
 void
-toast_delete(Relation rel, HeapTuple oldtup, bool is_speculative)
+toast_delete(Relation rel, HeapTuple oldtup, bool is_speculative,
+			 uint32 specToken)
 {
 	TupleDesc	tupleDesc;
 	Datum		toast_values[MaxHeapAttributeNumber];
@@ -68,7 +69,8 @@ toast_delete(Relation rel, HeapTuple oldtup, bool is_speculative)
 	heap_deform_tuple(oldtup, tupleDesc, toast_values, toast_isnull);
 
 	/* Do the real work. */
-	toast_delete_external(rel, toast_values, toast_isnull, is_speculative);
+	toast_delete_external(rel, toast_values, toast_isnull, is_speculative,
+						  specToken);
 }
 
 
@@ -151,6 +153,8 @@ toast_insert_or_update(Relation rel, HeapTuple newtup, HeapTuple oldtup,
 		ttc.ttc_oldvalues = toast_oldvalues;
 		ttc.ttc_oldisnull = toast_oldisnull;
 	}
+	ttc.ttc_toastrel = NULL;
+	ttc.ttc_toastslot = NULL;
 	ttc.ttc_attr = toast_attr;
 	toast_tuple_init(&ttc);
 
@@ -207,7 +211,8 @@ toast_insert_or_update(Relation rel, HeapTuple newtup, HeapTuple oldtup,
 		 */
 		if (toast_attr[biggest_attno].tai_size > maxDataLen &&
 			rel->rd_rel->reltoastrelid != InvalidOid)
-			toast_tuple_externalize(&ttc, biggest_attno, options);
+			toast_tuple_externalize(&ttc, biggest_attno, options,
+									TOAST_MAX_CHUNK_SIZE);
 	}
 
 	/*
@@ -224,7 +229,8 @@ toast_insert_or_update(Relation rel, HeapTuple newtup, HeapTuple oldtup,
 		biggest_attno = toast_tuple_find_biggest_attribute(&ttc, false, false);
 		if (biggest_attno < 0)
 			break;
-		toast_tuple_externalize(&ttc, biggest_attno, options);
+		toast_tuple_externalize(&ttc, biggest_attno, options,
+								TOAST_MAX_CHUNK_SIZE);
 	}
 
 	/*
@@ -260,7 +266,8 @@ toast_insert_or_update(Relation rel, HeapTuple newtup, HeapTuple oldtup,
 		if (biggest_attno < 0)
 			break;
 
-		toast_tuple_externalize(&ttc, biggest_attno, options);
+		toast_tuple_externalize(&ttc, biggest_attno, options,
+								TOAST_MAX_CHUNK_SIZE);
 	}
 
 	/*
@@ -323,7 +330,7 @@ toast_insert_or_update(Relation rel, HeapTuple newtup, HeapTuple oldtup,
 	else
 		result_tuple = newtup;
 
-	toast_tuple_cleanup(&ttc);
+	toast_tuple_cleanup(&ttc, true);
 
 	return result_tuple;
 }
diff --git a/src/backend/access/index/genam.c b/src/backend/access/index/genam.c
index 42aaa5bad6..4264bad4e7 100644
--- a/src/backend/access/index/genam.c
+++ b/src/backend/access/index/genam.c
@@ -642,6 +642,26 @@ systable_getnext_ordered(SysScanDesc sysscan, ScanDirection direction)
 	return htup;
 }
 
+/*
+ * systable_getnextslot_ordered
+ *
+ * Return a slot containing the next tuple from an ordered catalog scan,
+ * or NULL if there are no more tuples.
+ */
+TupleTableSlot *
+systable_getnextslot_ordered(SysScanDesc sysscan, ScanDirection direction)
+{
+	Assert(sysscan->irel);
+	if (!index_getnext_slot(sysscan->iscan, direction, sysscan->slot))
+		return NULL;
+
+	/* See notes in systable_getnext */
+	if (sysscan->iscan->xs_recheck)
+		elog(ERROR, "system catalog scans with lossy index conditions are not implemented");
+
+	return sysscan->slot;
+}
+
 /*
  * systable_endscan_ordered --- close scan, release resources
  */
diff --git a/src/backend/access/table/toast_helper.c b/src/backend/access/table/toast_helper.c
index ee119cea2d..91ea50616d 100644
--- a/src/backend/access/table/toast_helper.c
+++ b/src/backend/access/table/toast_helper.c
@@ -17,6 +17,7 @@
 #include "access/detoast.h"
 #include "access/table.h"
 #include "access/toast_helper.h"
+#include "access/tableam.h"
 #include "access/toast_internals.h"
 
 /*
@@ -247,26 +248,49 @@ toast_tuple_try_compression(ToastTupleContext *ttc, int attribute)
  * Move an attribute to external storage.
  */
 void
-toast_tuple_externalize(ToastTupleContext *ttc, int attribute, int options)
+toast_tuple_externalize(ToastTupleContext *ttc, int attribute, int options,
+						int max_chunk_size)
 {
 	Datum  *value = &ttc->ttc_values[attribute];
 	Datum	old_value = *value;
 	ToastAttrInfo  *attr = &ttc->ttc_attr[attribute];
 
-	attr->tai_colflags |= TOASTCOL_IGNORE;
-	*value = toast_save_datum(ttc->ttc_rel, old_value, attr->tai_oldexternal,
-							  options);
+	/* Initialize for TOAST table access, if not yet done. */
+	if (ttc->ttc_toastrel == NULL)
+	{
+		ttc->ttc_toastrel =
+			table_open(ttc->ttc_rel->rd_rel->reltoastrelid, RowExclusiveLock);
+		ttc->ttc_validtoastidx = toast_open_indexes(ttc->ttc_toastrel,
+													RowExclusiveLock,
+													&ttc->ttc_toastidxs,
+													&ttc->ttc_ntoastidxs);
+	}
+	if (ttc->ttc_toastslot == NULL)
+		ttc->ttc_toastslot = table_slot_create(ttc->ttc_toastrel, NULL);
+
+	/* Do the real work. */
+	*value = toast_save_datum(ttc->ttc_toastrel, ttc->ttc_toastslot,
+							  ttc->ttc_ntoastidxs, ttc->ttc_toastidxs,
+							  ttc->ttc_validtoastidx,
+							  ttc->ttc_rel->rd_toastoid,
+							  old_value, attr->tai_oldexternal,
+							  options, max_chunk_size);
+
+	/* Update bookkeeping information. */
 	if ((attr->tai_colflags & TOASTCOL_NEEDS_FREE) != 0)
 		pfree(DatumGetPointer(old_value));
-	attr->tai_colflags |= TOASTCOL_NEEDS_FREE;
+	attr->tai_colflags |= (TOASTCOL_NEEDS_FREE | TOASTCOL_IGNORE);
 	ttc->ttc_flags |= (TOAST_NEEDS_CHANGE | TOAST_NEEDS_FREE);
 }
 
 /*
  * Perform appropriate cleanup after one tuple has been subjected to TOAST.
+ *
+ * Pass cleanup_toastrel as true to destroy and clear ttc_toastrel and
+ * ttc_toastslot, or false if caller will do it.
  */
 void
-toast_tuple_cleanup(ToastTupleContext *ttc)
+toast_tuple_cleanup(ToastTupleContext *ttc, bool cleanup_toastrel)
 {
 	TupleDesc	tupleDesc = ttc->ttc_rel->rd_att;
 	int			numAttrs = tupleDesc->natts;
@@ -294,14 +318,46 @@ toast_tuple_cleanup(ToastTupleContext *ttc)
 	{
 		int		i;
 
+		/* Initialize for TOAST table access, if not yet done. */
+		if (ttc->ttc_toastrel == NULL)
+		{
+			ttc->ttc_toastrel =
+				table_open(ttc->ttc_rel->rd_rel->reltoastrelid,
+						   RowExclusiveLock);
+			ttc->ttc_validtoastidx = toast_open_indexes(ttc->ttc_toastrel,
+														RowExclusiveLock,
+														&ttc->ttc_toastidxs,
+														&ttc->ttc_ntoastidxs);
+		}
+
+		/* Delete those attributes which require it. */
 		for (i = 0; i < numAttrs; i++)
 		{
 			ToastAttrInfo  *attr = &ttc->ttc_attr[i];
 
 			if ((attr->tai_colflags & TOASTCOL_NEEDS_DELETE_OLD) != 0)
-				toast_delete_datum(ttc->ttc_rel, ttc->ttc_oldvalues[i], false);
+				toast_delete_datum(ttc->ttc_toastrel, ttc->ttc_ntoastidxs,
+								   ttc->ttc_toastidxs, ttc->ttc_validtoastidx,
+								   ttc->ttc_oldvalues[i], false, 0);
 		}
 	}
+
+	/*
+	 * Close toast table and indexes and drop slot, if previously done and
+	 * if caller requests it.
+	 */
+	if (cleanup_toastrel && ttc->ttc_toastrel != NULL)
+	{
+		if (ttc->ttc_toastslot != NULL)
+		{
+			ExecDropSingleTupleTableSlot(ttc->ttc_toastslot);
+			ttc->ttc_toastslot = NULL;
+		}
+		toast_close_indexes(ttc->ttc_toastidxs, ttc->ttc_ntoastidxs,
+							RowExclusiveLock);
+		table_close(ttc->ttc_toastrel, RowExclusiveLock);
+		ttc->ttc_toastrel = NULL;
+	}
 }
 
 /*
@@ -310,22 +366,43 @@ toast_tuple_cleanup(ToastTupleContext *ttc)
  */
 void
 toast_delete_external(Relation rel, Datum *values, bool *isnull,
-					  bool is_speculative)
+					  bool is_speculative, uint32 specToken)
 {
 	TupleDesc	tupleDesc = rel->rd_att;
 	int			numAttrs = tupleDesc->natts;
 	int			i;
+	Relation    toastrel = NULL;
+	Relation   *toastidxs;
+	int         num_indexes;
+	int         validIndex;
 
 	for (i = 0; i < numAttrs; i++)
 	{
-		if (TupleDescAttr(tupleDesc, i)->attlen == -1)
-		{
-			Datum		value = values[i];
+		Datum	value;
+
+		if (isnull[i] || TupleDescAttr(tupleDesc, i)->attlen != -1)
+			continue;
+
+		value = values[i];
+		if (!VARATT_IS_EXTERNAL_ONDISK(PointerGetDatum(value)))
+			continue;
 
-			if (isnull[i])
-				continue;
-			else if (VARATT_IS_EXTERNAL_ONDISK(PointerGetDatum(value)))
-				toast_delete_datum(rel, value, is_speculative);
+		/* Initialize for TOAST table access, if not yet done. */
+		if (toastrel == NULL)
+		{
+			toastrel = table_open(rel->rd_rel->reltoastrelid,
+								  RowExclusiveLock);
+			validIndex = toast_open_indexes(toastrel, RowExclusiveLock,
+											&toastidxs, &num_indexes);
 		}
+
+		toast_delete_datum(toastrel, num_indexes, toastidxs, validIndex,
+						   value, is_speculative, specToken);
+	}
+
+	if (toastrel != NULL)
+	{
+		toast_close_indexes(toastidxs, num_indexes, RowExclusiveLock);
+		table_close(toastrel, RowExclusiveLock);
 	}
 }
diff --git a/src/backend/catalog/toasting.c b/src/backend/catalog/toasting.c
index cf20ddb4e9..d6033331aa 100644
--- a/src/backend/catalog/toasting.c
+++ b/src/backend/catalog/toasting.c
@@ -258,7 +258,7 @@ create_toast_table(Relation rel, Oid toastOid, Oid toastIndexOid,
 										   toast_typid,
 										   InvalidOid,
 										   rel->rd_rel->relowner,
-										   rel->rd_rel->relam,
+										   table_relation_toast_am(rel),
 										   tupdesc,
 										   NIL,
 										   RELKIND_TOASTVALUE,
diff --git a/src/include/access/genam.h b/src/include/access/genam.h
index 9717183ef2..38327bf977 100644
--- a/src/include/access/genam.h
+++ b/src/include/access/genam.h
@@ -21,8 +21,9 @@
 #include "utils/relcache.h"
 #include "utils/snapshot.h"
 
-/* We don't want this file to depend on execnodes.h. */
+/* We don't want this file to depend on execnodes.h or tuptable.h. */
 struct IndexInfo;
+struct TupleTableSlot;
 
 /*
  * Struct for statistics returned by ambuild
@@ -212,6 +213,8 @@ extern SysScanDesc systable_beginscan_ordered(Relation heapRelation,
 						   int nkeys, ScanKey key);
 extern HeapTuple systable_getnext_ordered(SysScanDesc sysscan,
 						 ScanDirection direction);
+extern struct TupleTableSlot *systable_getnextslot_ordered(SysScanDesc sysscan,
+						 ScanDirection direction);
 extern void systable_endscan_ordered(SysScanDesc sysscan);
 
 #endif							/* GENAM_H */
diff --git a/src/include/access/heapam.h b/src/include/access/heapam.h
index 62aaa08eff..970a37e993 100644
--- a/src/include/access/heapam.h
+++ b/src/include/access/heapam.h
@@ -145,7 +145,8 @@ extern TM_Result heap_delete(Relation relation, ItemPointer tid,
 			CommandId cid, Snapshot crosscheck, bool wait,
 			struct TM_FailureData *tmfd, bool changingPart);
 extern void heap_finish_speculative(Relation relation, ItemPointer tid);
-extern void heap_abort_speculative(Relation relation, ItemPointer tid);
+extern void heap_abort_speculative(Relation relation, ItemPointer tid,
+					   uint32 specToken);
 extern TM_Result heap_update(Relation relation, ItemPointer otid,
 			HeapTuple newtup,
 			CommandId cid, Snapshot crosscheck, bool wait,
diff --git a/src/include/access/heaptoast.h b/src/include/access/heaptoast.h
index 046aac7620..600b226826 100644
--- a/src/include/access/heaptoast.h
+++ b/src/include/access/heaptoast.h
@@ -104,7 +104,8 @@ extern HeapTuple toast_insert_or_update(Relation rel,
  *	Called by heap_delete().
  * ----------
  */
-extern void toast_delete(Relation rel, HeapTuple oldtup, bool is_speculative);
+extern void toast_delete(Relation rel, HeapTuple oldtup,
+			 bool is_speculative, uint32 specToken);
 
 /* ----------
  * toast_flatten_tuple -
diff --git a/src/include/access/tableam.h b/src/include/access/tableam.h
index 53b58c51da..2835beb39f 100644
--- a/src/include/access/tableam.h
+++ b/src/include/access/tableam.h
@@ -582,6 +582,27 @@ typedef struct TableAmRoutine
 	 */
 	bool	    (*relation_needs_toast_table) (Relation rel);
 
+	/*
+	 * This callback should return the OID of the table AM that implements
+	 * TOAST tables for this AM.  If the relation_needs_toast_table callback
+	 * always returns false, this callback is not required.
+	 */
+	Oid		    (*relation_toast_am) (Relation rel);
+
+	/*
+	 * If this table AM can be used to implement a TOAST table, the following
+	 * field should be set to the maximum number of bytes that can be stored
+	 * in a single TOAST chunk.  It must not be set to a value greater than
+	 * BLCKSZ.  If this table AM is not used to implement a TOAST table, this
+	 * value is ignored.
+	 *
+	 * (Note that there is no requirement that the TOAST table be implemented
+	 * using the same AM as the table to which it is attached.  If this AM
+	 * has TOAST tables but uses some other AM to implement them, this value
+	 * is ignored; it is a property of the TOAST table, not the parent table.)
+	 */
+	int			toast_max_chunk_size;
+
 
 	/* ------------------------------------------------------------------------
 	 * Planner related functions.
@@ -1604,6 +1625,16 @@ table_relation_needs_toast_table(Relation rel)
 	return rel->rd_tableam->relation_needs_toast_table(rel);
 }
 
+/*
+ * Return the OID of the AM that should be used to implement the TOAST table
+ * for this relation.
+ */
+static inline Oid
+table_relation_toast_am(Relation rel)
+{
+	return rel->rd_tableam->relation_toast_am(rel);
+}
+
 
 /* ----------------------------------------------------------------------------
  * Planner related functionality
diff --git a/src/include/access/toast_helper.h b/src/include/access/toast_helper.h
index 0fac6cc772..5d223d36ea 100644
--- a/src/include/access/toast_helper.h
+++ b/src/include/access/toast_helper.h
@@ -14,6 +14,7 @@
 #ifndef TOAST_HELPER_H
 #define TOAST_HELPER_H
 
+#include "executor/tuptable.h"
 #include "utils/rel.h"
 
 /*
@@ -51,6 +52,17 @@ typedef struct
 	Datum	   *ttc_oldvalues;		/* values from previous tuple */
 	bool	   *ttc_oldisnull;		/* null flags from previous tuple */
 
+	/*
+	 * Before calling toast_tuple_init, the caller should either initialize
+	 * all of these fields or else set ttc_toastrel and ttc_toastslot to NULL.
+	 * In the latter case, all of the fields will be initialized as required.
+	 */
+	Relation	ttc_toastrel;		/* the toast table for the relation */
+	TupleTableSlot *ttc_toastslot;	/* a slot for the toast table */
+	int			ttc_ntoastidxs;		/* # of toast indexes for toast table */
+	Relation   *ttc_toastidxs;		/* array of those toast indexes */
+	int			ttc_validtoastidx;	/* the valid toast index */
+
 	/*
 	 * Before calling toast_tuple_init, the caller should set tts_attr to
 	 * point to an array of ToastAttrInfo structures of a length equal to
@@ -105,10 +117,10 @@ extern int toast_tuple_find_biggest_attribute(ToastTupleContext *ttc,
 								   bool for_compression, bool check_main);
 extern void toast_tuple_try_compression(ToastTupleContext *ttc, int attribute);
 extern void toast_tuple_externalize(ToastTupleContext *ttc, int attribute,
-						int options);
-extern void toast_tuple_cleanup(ToastTupleContext *ttc);
+						int options, int max_chunk_size);
+extern void toast_tuple_cleanup(ToastTupleContext *ttc, bool cleanup_toastrel);
 
 extern void toast_delete_external(Relation rel, Datum *values, bool *isnull,
-					  bool is_speculative);
+					  bool is_speculative, uint32 specToken);
 
 #endif
diff --git a/src/include/access/toast_internals.h b/src/include/access/toast_internals.h
index 8ac367fb9f..67ef5a134f 100644
--- a/src/include/access/toast_internals.h
+++ b/src/include/access/toast_internals.h
@@ -16,6 +16,8 @@
 #include "utils/relcache.h"
 #include "utils/snapshot.h"
 
+struct TupleTableSlot;
+
 /*
  *	The information at the start of the compressed toast data.
  */
@@ -39,9 +41,14 @@ typedef struct toast_compress_header
 extern Datum toast_compress_datum(Datum value);
 extern Oid	toast_get_valid_index(Oid toastoid, LOCKMODE lock);
 
-extern void toast_delete_datum(Relation rel, Datum value, bool is_speculative);
-extern Datum toast_save_datum(Relation rel, Datum value,
-				 struct varlena *oldexternal, int options);
+extern void toast_delete_datum(Relation toastrel, int num_indexes,
+				   Relation *toastidxs, int validIndex,
+				   Datum value, bool is_speculative, uint32 specToken);
+extern Datum toast_save_datum(Relation toastrel,
+				 struct TupleTableSlot *toastslot,
+				 int num_indexes, Relation *toastidxs, int validIndex,
+				 Oid toastoid, Datum value, struct varlena *oldexternal,
+				 int options, int max_chunk_size);
 
 extern int toast_open_indexes(Relation toastrel,
 				   LOCKMODE lock,
-- 
2.17.2 (Apple Git-113)

From 975b88d0018949805a4309d6af8820ab43620377 Mon Sep 17 00:00:00 2001
From: Robert Haas <rhaas@postgresql.org>
Date: Tue, 14 May 2019 17:11:28 -0400
Subject: [PATCH v2 2/3] Create an API for inserting and deleting rows in TOAST
 tables.

This moves much of the non-heap-specific logic from toast_delete and
toast_insert_or_update into a helper functions accessible via a new
header, toast_helper.h.  Using the functions in this module, a table
AM can implement creation and deletion of TOAST table rows with
much less code duplication than was possible heretofore.  Some
table AMs won't want to use the TOAST logic at all, but for those
that do this will make that easier.
---
 src/backend/access/heap/heaptoast.c     | 400 +++---------------------
 src/backend/access/table/Makefile       |   2 +-
 src/backend/access/table/toast_helper.c | 331 ++++++++++++++++++++
 src/include/access/toast_helper.h       | 114 +++++++
 4 files changed, 490 insertions(+), 357 deletions(-)
 create mode 100644 src/backend/access/table/toast_helper.c
 create mode 100644 src/include/access/toast_helper.h

diff --git a/src/backend/access/heap/heaptoast.c b/src/backend/access/heap/heaptoast.c
index 5d105e3517..3a2118e1d8 100644
--- a/src/backend/access/heap/heaptoast.c
+++ b/src/backend/access/heap/heaptoast.c
@@ -27,6 +27,7 @@
 #include "access/detoast.h"
 #include "access/heapam.h"
 #include "access/heaptoast.h"
+#include "access/toast_helper.h"
 #include "access/toast_internals.h"
 
 
@@ -40,8 +41,6 @@ void
 toast_delete(Relation rel, HeapTuple oldtup, bool is_speculative)
 {
 	TupleDesc	tupleDesc;
-	int			numAttrs;
-	int			i;
 	Datum		toast_values[MaxHeapAttributeNumber];
 	bool		toast_isnull[MaxHeapAttributeNumber];
 
@@ -64,27 +63,12 @@ toast_delete(Relation rel, HeapTuple oldtup, bool is_speculative)
 	 * least one varlena column, by the way.)
 	 */
 	tupleDesc = rel->rd_att;
-	numAttrs = tupleDesc->natts;
 
-	Assert(numAttrs <= MaxHeapAttributeNumber);
+	Assert(tupleDesc->natts <= MaxHeapAttributeNumber);
 	heap_deform_tuple(oldtup, tupleDesc, toast_values, toast_isnull);
 
-	/*
-	 * Check for external stored attributes and delete them from the secondary
-	 * relation.
-	 */
-	for (i = 0; i < numAttrs; i++)
-	{
-		if (TupleDescAttr(tupleDesc, i)->attlen == -1)
-		{
-			Datum		value = toast_values[i];
-
-			if (toast_isnull[i])
-				continue;
-			else if (VARATT_IS_EXTERNAL_ONDISK(PointerGetDatum(value)))
-				toast_delete_datum(rel, value, is_speculative);
-		}
-	}
+	/* Do the real work. */
+	toast_delete_external(rel, toast_values, toast_isnull, is_speculative);
 }
 
 
@@ -113,25 +97,16 @@ toast_insert_or_update(Relation rel, HeapTuple newtup, HeapTuple oldtup,
 	HeapTuple	result_tuple;
 	TupleDesc	tupleDesc;
 	int			numAttrs;
-	int			i;
-
-	bool		need_change = false;
-	bool		need_free = false;
-	bool		need_delold = false;
-	bool		has_nulls = false;
 
 	Size		maxDataLen;
 	Size		hoff;
 
-	char		toast_action[MaxHeapAttributeNumber];
 	bool		toast_isnull[MaxHeapAttributeNumber];
 	bool		toast_oldisnull[MaxHeapAttributeNumber];
 	Datum		toast_values[MaxHeapAttributeNumber];
 	Datum		toast_oldvalues[MaxHeapAttributeNumber];
-	struct varlena *toast_oldexternal[MaxHeapAttributeNumber];
-	int32		toast_sizes[MaxHeapAttributeNumber];
-	bool		toast_free[MaxHeapAttributeNumber];
-	bool		toast_delold[MaxHeapAttributeNumber];
+	ToastAttrInfo	toast_attr[MaxHeapAttributeNumber];
+	ToastTupleContext	ttc;
 
 	/*
 	 * Ignore the INSERT_SPECULATIVE option. Speculative insertions/super
@@ -160,129 +135,24 @@ toast_insert_or_update(Relation rel, HeapTuple newtup, HeapTuple oldtup,
 		heap_deform_tuple(oldtup, tupleDesc, toast_oldvalues, toast_oldisnull);
 
 	/* ----------
-	 * Then collect information about the values given
-	 *
-	 * NOTE: toast_action[i] can have these values:
-	 *		' '		default handling
-	 *		'p'		already processed --- don't touch it
-	 *		'x'		incompressible, but OK to move off
-	 *
-	 * NOTE: toast_sizes[i] is only made valid for varlena attributes with
-	 *		toast_action[i] different from 'p'.
+	 * Prepare for toasting
 	 * ----------
 	 */
-	memset(toast_action, ' ', numAttrs * sizeof(char));
-	memset(toast_oldexternal, 0, numAttrs * sizeof(struct varlena *));
-	memset(toast_free, 0, numAttrs * sizeof(bool));
-	memset(toast_delold, 0, numAttrs * sizeof(bool));
-
-	for (i = 0; i < numAttrs; i++)
+	ttc.ttc_rel = rel;
+	ttc.ttc_values = toast_values;
+	ttc.ttc_isnull = toast_isnull;
+	if (oldtup == NULL)
 	{
-		Form_pg_attribute att = TupleDescAttr(tupleDesc, i);
-		struct varlena *old_value;
-		struct varlena *new_value;
-
-		if (oldtup != NULL)
-		{
-			/*
-			 * For UPDATE get the old and new values of this attribute
-			 */
-			old_value = (struct varlena *) DatumGetPointer(toast_oldvalues[i]);
-			new_value = (struct varlena *) DatumGetPointer(toast_values[i]);
-
-			/*
-			 * If the old value is stored on disk, check if it has changed so
-			 * we have to delete it later.
-			 */
-			if (att->attlen == -1 && !toast_oldisnull[i] &&
-				VARATT_IS_EXTERNAL_ONDISK(old_value))
-			{
-				if (toast_isnull[i] || !VARATT_IS_EXTERNAL_ONDISK(new_value) ||
-					memcmp((char *) old_value, (char *) new_value,
-						   VARSIZE_EXTERNAL(old_value)) != 0)
-				{
-					/*
-					 * The old external stored value isn't needed any more
-					 * after the update
-					 */
-					toast_delold[i] = true;
-					need_delold = true;
-				}
-				else
-				{
-					/*
-					 * This attribute isn't changed by this update so we reuse
-					 * the original reference to the old value in the new
-					 * tuple.
-					 */
-					toast_action[i] = 'p';
-					continue;
-				}
-			}
-		}
-		else
-		{
-			/*
-			 * For INSERT simply get the new value
-			 */
-			new_value = (struct varlena *) DatumGetPointer(toast_values[i]);
-		}
-
-		/*
-		 * Handle NULL attributes
-		 */
-		if (toast_isnull[i])
-		{
-			toast_action[i] = 'p';
-			has_nulls = true;
-			continue;
-		}
-
-		/*
-		 * Now look at varlena attributes
-		 */
-		if (att->attlen == -1)
-		{
-			/*
-			 * If the table's attribute says PLAIN always, force it so.
-			 */
-			if (att->attstorage == 'p')
-				toast_action[i] = 'p';
-
-			/*
-			 * We took care of UPDATE above, so any external value we find
-			 * still in the tuple must be someone else's that we cannot reuse
-			 * (this includes the case of an out-of-line in-memory datum).
-			 * Fetch it back (without decompression, unless we are forcing
-			 * PLAIN storage).  If necessary, we'll push it out as a new
-			 * external value below.
-			 */
-			if (VARATT_IS_EXTERNAL(new_value))
-			{
-				toast_oldexternal[i] = new_value;
-				if (att->attstorage == 'p')
-					new_value = heap_tuple_untoast_attr(new_value);
-				else
-					new_value = heap_tuple_fetch_attr(new_value);
-				toast_values[i] = PointerGetDatum(new_value);
-				toast_free[i] = true;
-				need_change = true;
-				need_free = true;
-			}
-
-			/*
-			 * Remember the size of this attribute
-			 */
-			toast_sizes[i] = VARSIZE_ANY(new_value);
-		}
-		else
-		{
-			/*
-			 * Not a varlena attribute, plain storage always
-			 */
-			toast_action[i] = 'p';
-		}
+		ttc.ttc_oldvalues = NULL;
+		ttc.ttc_oldisnull = NULL;
 	}
+	else
+	{
+		ttc.ttc_oldvalues = toast_oldvalues;
+		ttc.ttc_oldisnull = toast_oldisnull;
+	}
+	ttc.ttc_attr = toast_attr;
+	toast_tuple_init(&ttc);
 
 	/* ----------
 	 * Compress and/or save external until data fits into target length
@@ -297,7 +167,7 @@ toast_insert_or_update(Relation rel, HeapTuple newtup, HeapTuple oldtup,
 
 	/* compute header overhead --- this should match heap_form_tuple() */
 	hoff = SizeofHeapTupleHeader;
-	if (has_nulls)
+	if ((ttc.ttc_flags & TOAST_HAS_NULLS) != 0)
 		hoff += BITMAPLEN(numAttrs);
 	hoff = MAXALIGN(hoff);
 	/* now convert to a limit on the tuple data size */
@@ -310,66 +180,21 @@ toast_insert_or_update(Relation rel, HeapTuple newtup, HeapTuple oldtup,
 	while (heap_compute_data_size(tupleDesc,
 								  toast_values, toast_isnull) > maxDataLen)
 	{
-		int			biggest_attno = -1;
-		int32		biggest_size = MAXALIGN(TOAST_POINTER_SIZE);
-		Datum		old_value;
-		Datum		new_value;
-
-		/*
-		 * Search for the biggest yet unprocessed internal attribute
-		 */
-		for (i = 0; i < numAttrs; i++)
-		{
-			Form_pg_attribute att = TupleDescAttr(tupleDesc, i);
-
-			if (toast_action[i] != ' ')
-				continue;
-			if (VARATT_IS_EXTERNAL(DatumGetPointer(toast_values[i])))
-				continue;		/* can't happen, toast_action would be 'p' */
-			if (VARATT_IS_COMPRESSED(DatumGetPointer(toast_values[i])))
-				continue;
-			if (att->attstorage != 'x' && att->attstorage != 'e')
-				continue;
-			if (toast_sizes[i] > biggest_size)
-			{
-				biggest_attno = i;
-				biggest_size = toast_sizes[i];
-			}
-		}
+		int			biggest_attno;
 
+		biggest_attno = toast_tuple_find_biggest_attribute(&ttc, true, false);
 		if (biggest_attno < 0)
 			break;
 
 		/*
 		 * Attempt to compress it inline, if it has attstorage 'x'
 		 */
-		i = biggest_attno;
-		if (TupleDescAttr(tupleDesc, i)->attstorage == 'x')
-		{
-			old_value = toast_values[i];
-			new_value = toast_compress_datum(old_value);
-
-			if (DatumGetPointer(new_value) != NULL)
-			{
-				/* successful compression */
-				if (toast_free[i])
-					pfree(DatumGetPointer(old_value));
-				toast_values[i] = new_value;
-				toast_free[i] = true;
-				toast_sizes[i] = VARSIZE(DatumGetPointer(toast_values[i]));
-				need_change = true;
-				need_free = true;
-			}
-			else
-			{
-				/* incompressible, ignore on subsequent compression passes */
-				toast_action[i] = 'x';
-			}
-		}
+		if (TupleDescAttr(tupleDesc, biggest_attno)->attstorage == 'x')
+			toast_tuple_try_compression(&ttc, biggest_attno);
 		else
 		{
 			/* has attstorage 'e', ignore on subsequent compression passes */
-			toast_action[i] = 'x';
+			toast_attr[biggest_attno].tai_colflags |= TOASTCOL_INCOMPRESSIBLE;
 		}
 
 		/*
@@ -380,72 +205,26 @@ toast_insert_or_update(Relation rel, HeapTuple newtup, HeapTuple oldtup,
 		 *
 		 * XXX maybe the threshold should be less than maxDataLen?
 		 */
-		if (toast_sizes[i] > maxDataLen &&
+		if (toast_attr[biggest_attno].tai_size > maxDataLen &&
 			rel->rd_rel->reltoastrelid != InvalidOid)
-		{
-			old_value = toast_values[i];
-			toast_action[i] = 'p';
-			toast_values[i] = toast_save_datum(rel, toast_values[i],
-											   toast_oldexternal[i], options);
-			if (toast_free[i])
-				pfree(DatumGetPointer(old_value));
-			toast_free[i] = true;
-			need_change = true;
-			need_free = true;
-		}
+			toast_tuple_externalize(&ttc, biggest_attno, options);
 	}
 
 	/*
 	 * Second we look for attributes of attstorage 'x' or 'e' that are still
-	 * inline.  But skip this if there's no toast table to push them to.
+	 * inline, and make them external.  But skip this if there's no toast table
+	 * to push them to.
 	 */
 	while (heap_compute_data_size(tupleDesc,
 								  toast_values, toast_isnull) > maxDataLen &&
 		   rel->rd_rel->reltoastrelid != InvalidOid)
 	{
-		int			biggest_attno = -1;
-		int32		biggest_size = MAXALIGN(TOAST_POINTER_SIZE);
-		Datum		old_value;
-
-		/*------
-		 * Search for the biggest yet inlined attribute with
-		 * attstorage equals 'x' or 'e'
-		 *------
-		 */
-		for (i = 0; i < numAttrs; i++)
-		{
-			Form_pg_attribute att = TupleDescAttr(tupleDesc, i);
-
-			if (toast_action[i] == 'p')
-				continue;
-			if (VARATT_IS_EXTERNAL(DatumGetPointer(toast_values[i])))
-				continue;		/* can't happen, toast_action would be 'p' */
-			if (att->attstorage != 'x' && att->attstorage != 'e')
-				continue;
-			if (toast_sizes[i] > biggest_size)
-			{
-				biggest_attno = i;
-				biggest_size = toast_sizes[i];
-			}
-		}
+		int			biggest_attno;
 
+		biggest_attno = toast_tuple_find_biggest_attribute(&ttc, false, false);
 		if (biggest_attno < 0)
 			break;
-
-		/*
-		 * Store this external
-		 */
-		i = biggest_attno;
-		old_value = toast_values[i];
-		toast_action[i] = 'p';
-		toast_values[i] = toast_save_datum(rel, toast_values[i],
-										   toast_oldexternal[i], options);
-		if (toast_free[i])
-			pfree(DatumGetPointer(old_value));
-		toast_free[i] = true;
-
-		need_change = true;
-		need_free = true;
+		toast_tuple_externalize(&ttc, biggest_attno, options);
 	}
 
 	/*
@@ -455,57 +234,13 @@ toast_insert_or_update(Relation rel, HeapTuple newtup, HeapTuple oldtup,
 	while (heap_compute_data_size(tupleDesc,
 								  toast_values, toast_isnull) > maxDataLen)
 	{
-		int			biggest_attno = -1;
-		int32		biggest_size = MAXALIGN(TOAST_POINTER_SIZE);
-		Datum		old_value;
-		Datum		new_value;
-
-		/*
-		 * Search for the biggest yet uncompressed internal attribute
-		 */
-		for (i = 0; i < numAttrs; i++)
-		{
-			if (toast_action[i] != ' ')
-				continue;
-			if (VARATT_IS_EXTERNAL(DatumGetPointer(toast_values[i])))
-				continue;		/* can't happen, toast_action would be 'p' */
-			if (VARATT_IS_COMPRESSED(DatumGetPointer(toast_values[i])))
-				continue;
-			if (TupleDescAttr(tupleDesc, i)->attstorage != 'm')
-				continue;
-			if (toast_sizes[i] > biggest_size)
-			{
-				biggest_attno = i;
-				biggest_size = toast_sizes[i];
-			}
-		}
+		int			biggest_attno;
 
+		biggest_attno = toast_tuple_find_biggest_attribute(&ttc, true, true);
 		if (biggest_attno < 0)
 			break;
 
-		/*
-		 * Attempt to compress it inline
-		 */
-		i = biggest_attno;
-		old_value = toast_values[i];
-		new_value = toast_compress_datum(old_value);
-
-		if (DatumGetPointer(new_value) != NULL)
-		{
-			/* successful compression */
-			if (toast_free[i])
-				pfree(DatumGetPointer(old_value));
-			toast_values[i] = new_value;
-			toast_free[i] = true;
-			toast_sizes[i] = VARSIZE(DatumGetPointer(toast_values[i]));
-			need_change = true;
-			need_free = true;
-		}
-		else
-		{
-			/* incompressible, ignore on subsequent compression passes */
-			toast_action[i] = 'x';
-		}
+		toast_tuple_try_compression(&ttc, biggest_attno);
 	}
 
 	/*
@@ -519,54 +254,20 @@ toast_insert_or_update(Relation rel, HeapTuple newtup, HeapTuple oldtup,
 								  toast_values, toast_isnull) > maxDataLen &&
 		   rel->rd_rel->reltoastrelid != InvalidOid)
 	{
-		int			biggest_attno = -1;
-		int32		biggest_size = MAXALIGN(TOAST_POINTER_SIZE);
-		Datum		old_value;
-
-		/*--------
-		 * Search for the biggest yet inlined attribute with
-		 * attstorage = 'm'
-		 *--------
-		 */
-		for (i = 0; i < numAttrs; i++)
-		{
-			if (toast_action[i] == 'p')
-				continue;
-			if (VARATT_IS_EXTERNAL(DatumGetPointer(toast_values[i])))
-				continue;		/* can't happen, toast_action would be 'p' */
-			if (TupleDescAttr(tupleDesc, i)->attstorage != 'm')
-				continue;
-			if (toast_sizes[i] > biggest_size)
-			{
-				biggest_attno = i;
-				biggest_size = toast_sizes[i];
-			}
-		}
+		int			biggest_attno;
 
+		biggest_attno = toast_tuple_find_biggest_attribute(&ttc, false, true);
 		if (biggest_attno < 0)
 			break;
 
-		/*
-		 * Store this external
-		 */
-		i = biggest_attno;
-		old_value = toast_values[i];
-		toast_action[i] = 'p';
-		toast_values[i] = toast_save_datum(rel, toast_values[i],
-										   toast_oldexternal[i], options);
-		if (toast_free[i])
-			pfree(DatumGetPointer(old_value));
-		toast_free[i] = true;
-
-		need_change = true;
-		need_free = true;
+		toast_tuple_externalize(&ttc, biggest_attno, options);
 	}
 
 	/*
 	 * In the case we toasted any values, we need to build a new heap tuple
 	 * with the changed values.
 	 */
-	if (need_change)
+	if ((ttc.ttc_flags & TOAST_NEEDS_CHANGE) != 0)
 	{
 		HeapTupleHeader olddata = newtup->t_data;
 		HeapTupleHeader new_data;
@@ -585,7 +286,7 @@ toast_insert_or_update(Relation rel, HeapTuple newtup, HeapTuple oldtup,
 		 * whether there needs to be one at all.
 		 */
 		new_header_len = SizeofHeapTupleHeader;
-		if (has_nulls)
+		if ((ttc.ttc_flags & TOAST_HAS_NULLS) != 0)
 			new_header_len += BITMAPLEN(numAttrs);
 		new_header_len = MAXALIGN(new_header_len);
 		new_data_len = heap_compute_data_size(tupleDesc,
@@ -616,26 +317,13 @@ toast_insert_or_update(Relation rel, HeapTuple newtup, HeapTuple oldtup,
 						(char *) new_data + new_header_len,
 						new_data_len,
 						&(new_data->t_infomask),
-						has_nulls ? new_data->t_bits : NULL);
+						((ttc.ttc_flags & TOAST_HAS_NULLS) != 0) ?
+						new_data->t_bits : NULL);
 	}
 	else
 		result_tuple = newtup;
 
-	/*
-	 * Free allocated temp values
-	 */
-	if (need_free)
-		for (i = 0; i < numAttrs; i++)
-			if (toast_free[i])
-				pfree(DatumGetPointer(toast_values[i]));
-
-	/*
-	 * Delete external values from the old tuple
-	 */
-	if (need_delold)
-		for (i = 0; i < numAttrs; i++)
-			if (toast_delold[i])
-				toast_delete_datum(rel, toast_oldvalues[i], false);
+	toast_tuple_cleanup(&ttc);
 
 	return result_tuple;
 }
diff --git a/src/backend/access/table/Makefile b/src/backend/access/table/Makefile
index 55a0e5efad..b29df3f333 100644
--- a/src/backend/access/table/Makefile
+++ b/src/backend/access/table/Makefile
@@ -12,6 +12,6 @@ subdir = src/backend/access/table
 top_builddir = ../../../..
 include $(top_builddir)/src/Makefile.global
 
-OBJS = table.o tableam.o tableamapi.o
+OBJS = table.o tableam.o tableamapi.o toast_helper.o
 
 include $(top_srcdir)/src/backend/common.mk
diff --git a/src/backend/access/table/toast_helper.c b/src/backend/access/table/toast_helper.c
new file mode 100644
index 0000000000..ee119cea2d
--- /dev/null
+++ b/src/backend/access/table/toast_helper.c
@@ -0,0 +1,331 @@
+/*-------------------------------------------------------------------------
+ *
+ * toast_helper.c
+ *	  Helper functions for table AMs implementing compressed or
+ *    out-of-line storage of varlena attributes.
+ *
+ * Copyright (c) 2000-2019, PostgreSQL Global Development Group
+ *
+ * IDENTIFICATION
+ *	  src/backend/access/common/toast_helper.c
+ *
+ *-------------------------------------------------------------------------
+ */
+
+#include "postgres.h"
+
+#include "access/detoast.h"
+#include "access/table.h"
+#include "access/toast_helper.h"
+#include "access/toast_internals.h"
+
+/*
+ * Prepare to TOAST a tuple.
+ *
+ * tupleDesc, toast_values, and toast_isnull are required parameters; they
+ * provide the necessary details about the tuple to be toasted.
+ *
+ * toast_oldvalues and toast_oldisnull should be NULL for a newly-inserted
+ * tuple; for an update, they should describe the existing tuple.
+ *
+ * All of these arrays should have a length equal to tupleDesc->natts.
+ *
+ * On return, toast_flags and toast_attr will have been initialized.
+ * toast_flags is just a single uint8, but toast_attr is an caller-provided
+ * array with a length equal to tupleDesc->natts.  The caller need not
+ * perform any initialization of the array before calling this function.
+ */
+void
+toast_tuple_init(ToastTupleContext *ttc)
+{
+	TupleDesc	tupleDesc = ttc->ttc_rel->rd_att;
+	int			numAttrs = tupleDesc->natts;
+	int		i;
+
+	ttc->ttc_flags = 0;
+
+	for (i = 0; i < numAttrs; i++)
+	{
+		Form_pg_attribute att = TupleDescAttr(tupleDesc, i);
+		struct varlena *old_value;
+		struct varlena *new_value;
+
+		ttc->ttc_attr[i].tai_colflags = 0;
+		ttc->ttc_attr[i].tai_oldexternal = NULL;
+
+		if (ttc->ttc_oldvalues != NULL)
+		{
+			/*
+			 * For UPDATE get the old and new values of this attribute
+			 */
+			old_value =
+				(struct varlena *) DatumGetPointer(ttc->ttc_oldvalues[i]);
+			new_value =
+				(struct varlena *) DatumGetPointer(ttc->ttc_values[i]);
+
+			/*
+			 * If the old value is stored on disk, check if it has changed so
+			 * we have to delete it later.
+			 */
+			if (att->attlen == -1 && !ttc->ttc_oldisnull[i] &&
+				VARATT_IS_EXTERNAL_ONDISK(old_value))
+			{
+				if (ttc->ttc_isnull[i] ||
+					!VARATT_IS_EXTERNAL_ONDISK(new_value) ||
+					memcmp((char *) old_value, (char *) new_value,
+						   VARSIZE_EXTERNAL(old_value)) != 0)
+				{
+					/*
+					 * The old external stored value isn't needed any more
+					 * after the update
+					 */
+					ttc->ttc_attr[i].tai_colflags |= TOASTCOL_NEEDS_DELETE_OLD;
+					ttc->ttc_flags |= TOAST_NEEDS_DELETE_OLD;
+				}
+				else
+				{
+					/*
+					 * This attribute isn't changed by this update so we reuse
+					 * the original reference to the old value in the new
+					 * tuple.
+					 */
+					ttc->ttc_attr[i].tai_colflags |= TOASTCOL_IGNORE;
+					continue;
+				}
+			}
+		}
+		else
+		{
+			/*
+			 * For INSERT simply get the new value
+			 */
+			new_value = (struct varlena *) DatumGetPointer(ttc->ttc_values[i]);
+		}
+
+		/*
+		 * Handle NULL attributes
+		 */
+		if (ttc->ttc_isnull[i])
+		{
+			ttc->ttc_attr[i].tai_colflags |= TOASTCOL_IGNORE;
+			ttc->ttc_flags |= TOAST_HAS_NULLS;
+			continue;
+		}
+
+		/*
+		 * Now look at varlena attributes
+		 */
+		if (att->attlen == -1)
+		{
+			/*
+			 * If the table's attribute says PLAIN always, force it so.
+			 */
+			if (att->attstorage == 'p')
+				ttc->ttc_attr[i].tai_colflags |= TOASTCOL_IGNORE;
+
+			/*
+			 * We took care of UPDATE above, so any external value we find
+			 * still in the tuple must be someone else's that we cannot reuse
+			 * (this includes the case of an out-of-line in-memory datum).
+			 * Fetch it back (without decompression, unless we are forcing
+			 * PLAIN storage).  If necessary, we'll push it out as a new
+			 * external value below.
+			 */
+			if (VARATT_IS_EXTERNAL(new_value))
+			{
+				ttc->ttc_attr[i].tai_oldexternal = new_value;
+				if (att->attstorage == 'p')
+					new_value = heap_tuple_untoast_attr(new_value);
+				else
+					new_value = heap_tuple_fetch_attr(new_value);
+				ttc->ttc_values[i] = PointerGetDatum(new_value);
+				ttc->ttc_attr[i].tai_colflags |= TOASTCOL_NEEDS_FREE;
+				ttc->ttc_flags |= (TOAST_NEEDS_CHANGE | TOAST_NEEDS_FREE);
+			}
+
+			/*
+			 * Remember the size of this attribute
+			 */
+			ttc->ttc_attr[i].tai_size = VARSIZE_ANY(new_value);
+		}
+		else
+		{
+			/*
+			 * Not a varlena attribute, plain storage always
+			 */
+			ttc->ttc_attr[i].tai_colflags |= TOASTCOL_IGNORE;
+		}
+	}
+}
+
+/*
+ * Find the largest varlena attribute that satisfies certain criteria.
+ *
+ * The relevant column must not be marked TOASTCOL_IGNORE, and if the
+ * for_compression flag is passed as true, it must also not be marked
+ * TOASTCOL_INCOMPRESSIBLE.
+ *
+ * The column must have attstorage 'e' or 'x' if check_main is false, and
+ * must have attstorage 'm' if check_main is true.
+ *
+ * The column must have a minimum size of MAXALIGN(TOAST_POINTER_SIZE);
+ * if not, no benefit is to be expected by compressing it.
+ *
+ * The return value is the index of the biggest suitable column, or
+ * -1 if there is none.
+ */
+int
+toast_tuple_find_biggest_attribute(ToastTupleContext *ttc,
+								   bool for_compression, bool check_main)
+{
+	TupleDesc	tupleDesc = ttc->ttc_rel->rd_att;
+	int			numAttrs = tupleDesc->natts;
+	int			biggest_attno = -1;
+	int32		biggest_size = MAXALIGN(TOAST_POINTER_SIZE);
+	int32		skip_colflags = TOASTCOL_IGNORE;
+	int			i;
+
+	if (for_compression)
+		skip_colflags |= TOASTCOL_INCOMPRESSIBLE;
+
+	for (i = 0; i < numAttrs; i++)
+	{
+		Form_pg_attribute att = TupleDescAttr(tupleDesc, i);
+
+		if ((ttc->ttc_attr[i].tai_colflags & skip_colflags) != 0)
+			continue;
+		if (VARATT_IS_EXTERNAL(DatumGetPointer(ttc->ttc_values[i])))
+			continue;		/* can't happen, toast_action would be 'p' */
+		if (for_compression &&
+			VARATT_IS_COMPRESSED(DatumGetPointer(ttc->ttc_values[i])))
+			continue;
+		if (check_main && att->attstorage != 'm')
+			continue;
+		if (!check_main && att->attstorage != 'x' && att->attstorage != 'e')
+			continue;
+
+		if (ttc->ttc_attr[i].tai_size > biggest_size)
+		{
+			biggest_attno = i;
+			biggest_size = ttc->ttc_attr[i].tai_size;
+		}
+	}
+
+	return biggest_attno;
+}
+
+/*
+ * Try compression for an attribute.
+ *
+ * If we find that the attribute is not compressible, mark it so.
+ */
+void
+toast_tuple_try_compression(ToastTupleContext *ttc, int attribute)
+{
+	Datum  *value = &ttc->ttc_values[attribute];
+	Datum	new_value = toast_compress_datum(*value);
+	ToastAttrInfo  *attr = &ttc->ttc_attr[attribute];
+
+	if (DatumGetPointer(new_value) != NULL)
+	{
+		/* successful compression */
+		if ((attr->tai_colflags & TOASTCOL_NEEDS_FREE) != 0)
+			pfree(DatumGetPointer(*value));
+		*value = new_value;
+		attr->tai_colflags |= TOASTCOL_NEEDS_FREE;
+		attr->tai_size = VARSIZE(DatumGetPointer(*value));
+		ttc->ttc_flags |= (TOAST_NEEDS_CHANGE | TOAST_NEEDS_FREE);
+	}
+	else
+	{
+		/* incompressible, ignore on subsequent compression passes */
+		attr->tai_colflags |= TOASTCOL_INCOMPRESSIBLE;
+	}
+}
+
+/*
+ * Move an attribute to external storage.
+ */
+void
+toast_tuple_externalize(ToastTupleContext *ttc, int attribute, int options)
+{
+	Datum  *value = &ttc->ttc_values[attribute];
+	Datum	old_value = *value;
+	ToastAttrInfo  *attr = &ttc->ttc_attr[attribute];
+
+	attr->tai_colflags |= TOASTCOL_IGNORE;
+	*value = toast_save_datum(ttc->ttc_rel, old_value, attr->tai_oldexternal,
+							  options);
+	if ((attr->tai_colflags & TOASTCOL_NEEDS_FREE) != 0)
+		pfree(DatumGetPointer(old_value));
+	attr->tai_colflags |= TOASTCOL_NEEDS_FREE;
+	ttc->ttc_flags |= (TOAST_NEEDS_CHANGE | TOAST_NEEDS_FREE);
+}
+
+/*
+ * Perform appropriate cleanup after one tuple has been subjected to TOAST.
+ */
+void
+toast_tuple_cleanup(ToastTupleContext *ttc)
+{
+	TupleDesc	tupleDesc = ttc->ttc_rel->rd_att;
+	int			numAttrs = tupleDesc->natts;
+
+	/*
+	 * Free allocated temp values
+	 */
+	if ((ttc->ttc_flags & TOAST_NEEDS_FREE) != 0)
+	{
+		int		i;
+
+		for (i = 0; i < numAttrs; i++)
+		{
+			ToastAttrInfo  *attr = &ttc->ttc_attr[i];
+
+			if ((attr->tai_colflags & TOASTCOL_NEEDS_FREE) != 0)
+				pfree(DatumGetPointer(ttc->ttc_values[i]));
+		}
+	}
+
+	/*
+	 * Delete external values from the old tuple
+	 */
+	if ((ttc->ttc_flags & TOAST_NEEDS_DELETE_OLD) != 0)
+	{
+		int		i;
+
+		for (i = 0; i < numAttrs; i++)
+		{
+			ToastAttrInfo  *attr = &ttc->ttc_attr[i];
+
+			if ((attr->tai_colflags & TOASTCOL_NEEDS_DELETE_OLD) != 0)
+				toast_delete_datum(ttc->ttc_rel, ttc->ttc_oldvalues[i], false);
+		}
+	}
+}
+
+/*
+ * Check for external stored attributes and delete them from the secondary
+ * relation.
+ */
+void
+toast_delete_external(Relation rel, Datum *values, bool *isnull,
+					  bool is_speculative)
+{
+	TupleDesc	tupleDesc = rel->rd_att;
+	int			numAttrs = tupleDesc->natts;
+	int			i;
+
+	for (i = 0; i < numAttrs; i++)
+	{
+		if (TupleDescAttr(tupleDesc, i)->attlen == -1)
+		{
+			Datum		value = values[i];
+
+			if (isnull[i])
+				continue;
+			else if (VARATT_IS_EXTERNAL_ONDISK(PointerGetDatum(value)))
+				toast_delete_datum(rel, value, is_speculative);
+		}
+	}
+}
diff --git a/src/include/access/toast_helper.h b/src/include/access/toast_helper.h
new file mode 100644
index 0000000000..0fac6cc772
--- /dev/null
+++ b/src/include/access/toast_helper.h
@@ -0,0 +1,114 @@
+/*-------------------------------------------------------------------------
+ *
+ * toast_helper.h
+ *	  Helper functions for table AMs implementing compressed or
+ *    out-of-line storage of varlena attributes.
+ *
+ * Copyright (c) 2000-2019, PostgreSQL Global Development Group
+ *
+ * src/include/access/toast_helper.h
+ *
+ *-------------------------------------------------------------------------
+ */
+
+#ifndef TOAST_HELPER_H
+#define TOAST_HELPER_H
+
+#include "utils/rel.h"
+
+/*
+ * Information about one column of a tuple being toasted.
+ *
+ * NOTE: toast_action[i] can have these values:
+ *		' '		default handling
+ *		'p'		already processed --- don't touch it
+ *		'x'		incompressible, but OK to move off
+ *
+ * NOTE: toast_attr[i].tai_size is only made valid for varlena attributes with
+ * toast_action[i] different from 'p'.
+ */
+typedef struct
+{
+	struct varlena *tai_oldexternal;
+	int32		tai_size;
+	uint8		tai_colflags;
+} ToastAttrInfo;
+
+/*
+ * Information about one tuple being toasted.
+ */
+typedef struct
+{
+	/*
+	 * Before calling toast_tuple_init, the caller must initialize the
+	 * following fields.  Each array must have a length equal to
+	 * ttc_rel->rd_att->natts.  The tts_oldvalues and tts_oldisnull fields
+	 * should be NULL in the case of an insert.
+	 */
+	Relation	ttc_rel;			/* the relation that contains the tuple */
+	Datum	   *ttc_values;			/* values from the tuple columns */
+	bool	   *ttc_isnull;			/* null flags for the tuple columns */
+	Datum	   *ttc_oldvalues;		/* values from previous tuple */
+	bool	   *ttc_oldisnull;		/* null flags from previous tuple */
+
+	/*
+	 * Before calling toast_tuple_init, the caller should set tts_attr to
+	 * point to an array of ToastAttrInfo structures of a length equal to
+	 * tts_rel->rd_att->natts.  The contents of the array need not be
+	 * initialized.  ttc_flags also does not need to be initialized.
+	 */
+	uint8		ttc_flags;
+	ToastAttrInfo	*ttc_attr;
+} ToastTupleContext;
+
+/*
+ * Flags indicating the overall state of a TOAST operation.
+ *
+ * TOAST_NEEDS_DELETE_OLD indicates that one or more old TOAST datums need
+ * to be deleted.
+ *
+ * TOAST_NEEDS_FREE indicates that one or more TOAST values need to be freed.
+ *
+ * TOAST_HAS_NULLS indicates that nulls were found in the tuple being toasted.
+ *
+ * TOAST_NEEDS_CHANGE indicates that a new tuple needs to built; in other
+ * words, the toaster did something.
+ */
+#define TOAST_NEEDS_DELETE_OLD				0x0001
+#define TOAST_NEEDS_FREE					0x0002
+#define TOAST_HAS_NULLS						0x0004
+#define TOAST_NEEDS_CHANGE					0x0008
+
+/*
+ * Flags indicating the status of a TOAST operation with respect to a
+ * particular column.
+ *
+ * TOASTCOL_NEEDS_DELETE_OLD indicates that the old TOAST datums for this
+ * column need to be deleted.
+ *
+ * TOASTCOL_NEEDS_FREE indicates that the value for this column needs to
+ * be freed.
+ *
+ * TOASTCOL_IGNORE indicates that the toaster should not further process
+ * this column.
+ *
+ * TOASTCOL_INCOMPRESSIBLE indicates that this column has been found to
+ * be incompressible, but could be moved out-of-line.
+ */
+#define TOASTCOL_NEEDS_DELETE_OLD			TOAST_NEEDS_DELETE_OLD
+#define TOASTCOL_NEEDS_FREE					TOAST_NEEDS_FREE
+#define TOASTCOL_IGNORE						0x0010
+#define TOASTCOL_INCOMPRESSIBLE				0x0020
+
+extern void toast_tuple_init(ToastTupleContext *ttc);
+extern int toast_tuple_find_biggest_attribute(ToastTupleContext *ttc,
+								   bool for_compression, bool check_main);
+extern void toast_tuple_try_compression(ToastTupleContext *ttc, int attribute);
+extern void toast_tuple_externalize(ToastTupleContext *ttc, int attribute,
+						int options);
+extern void toast_tuple_cleanup(ToastTupleContext *ttc);
+
+extern void toast_delete_external(Relation rel, Datum *values, bool *isnull,
+					  bool is_speculative);
+
+#endif
-- 
2.17.2 (Apple Git-113)

From 856c0a1040bc227e4afaa7a7a3372b6671473b75 Mon Sep 17 00:00:00 2001
From: Robert Haas <rhaas@postgresql.org>
Date: Wed, 15 May 2019 13:33:16 -0400
Subject: [PATCH v2 1/3] Split tuptoaster.c into three separate files.

detoast.c/h contain functions required to detoast a datum, partially
or completely, plus a few other utility functions for examining the
size of toasted datums.

toast_internals.c/h contain functions that are used internally to the
TOAST subsystem but which (mostly) do not need to be accessed from
outside.

heaptoast.c/h contains code that is intrinsically specific to the
heap AM, either because it operates on HeapTuples or is based on the
layout of a heap page.

detoast.c and toast_internals.c are placed in
src/backend/access/common rather than src/backend/access/heap.  At
present, both files still have dependencies on the heap, but that will
be improved in a future commit.
---
 doc/src/sgml/storage.sgml                     |    2 +-
 src/backend/access/common/Makefile            |    5 +-
 src/backend/access/common/detoast.c           |  860 ++++++
 src/backend/access/common/heaptuple.c         |    4 +-
 src/backend/access/common/indextuple.c        |    9 +-
 src/backend/access/common/reloptions.c        |    2 +-
 src/backend/access/common/toast_internals.c   |  632 +++++
 src/backend/access/heap/Makefile              |    2 +-
 src/backend/access/heap/heapam.c              |    2 +-
 src/backend/access/heap/heapam_handler.c      |    2 +-
 src/backend/access/heap/heaptoast.c           |  917 +++++++
 src/backend/access/heap/rewriteheap.c         |    2 +-
 src/backend/access/heap/tuptoaster.c          | 2411 -----------------
 src/backend/access/transam/xlog.c             |    2 +-
 src/backend/commands/analyze.c                |    2 +-
 src/backend/commands/cluster.c                |    2 +-
 src/backend/executor/execExprInterp.c         |    2 +-
 src/backend/executor/execTuples.c             |    2 +-
 src/backend/executor/tstoreReceiver.c         |    2 +-
 .../replication/logical/reorderbuffer.c       |    2 +-
 src/backend/statistics/extended_stats.c       |    2 +-
 src/backend/storage/large_object/inv_api.c    |    3 +-
 src/backend/utils/adt/array_typanalyze.c      |    2 +-
 src/backend/utils/adt/datum.c                 |    2 +-
 src/backend/utils/adt/expandedrecord.c        |    3 +-
 src/backend/utils/adt/rowtypes.c              |    2 +-
 src/backend/utils/adt/tsgistidx.c             |    2 +-
 src/backend/utils/adt/varchar.c               |    2 +-
 src/backend/utils/adt/varlena.c               |    2 +-
 src/backend/utils/cache/catcache.c            |    2 +-
 src/backend/utils/fmgr/fmgr.c                 |    2 +-
 src/bin/pg_resetwal/pg_resetwal.c             |    2 +-
 src/include/access/detoast.h                  |   92 +
 .../access/{tuptoaster.h => heaptoast.h}      |  112 +-
 src/include/access/toast_internals.h          |   54 +
 src/pl/plpgsql/src/pl_exec.c                  |    2 +-
 src/test/regress/regress.c                    |    2 +-
 37 files changed, 2603 insertions(+), 2549 deletions(-)
 create mode 100644 src/backend/access/common/detoast.c
 create mode 100644 src/backend/access/common/toast_internals.c
 create mode 100644 src/backend/access/heap/heaptoast.c
 delete mode 100644 src/backend/access/heap/tuptoaster.c
 create mode 100644 src/include/access/detoast.h
 rename src/include/access/{tuptoaster.h => heaptoast.h} (57%)
 create mode 100644 src/include/access/toast_internals.h

diff --git a/doc/src/sgml/storage.sgml b/doc/src/sgml/storage.sgml
index c4bac87e80..42411a5379 100644
--- a/doc/src/sgml/storage.sgml
+++ b/doc/src/sgml/storage.sgml
@@ -382,7 +382,7 @@ The oldest and most common type is a pointer to out-of-line data stored in
 a <firstterm><acronym>TOAST</acronym> table</firstterm> that is separate from, but
 associated with, the table containing the <acronym>TOAST</acronym> pointer datum
 itself.  These <firstterm>on-disk</firstterm> pointer datums are created by the
-<acronym>TOAST</acronym> management code (in <filename>access/heap/tuptoaster.c</filename>)
+<acronym>TOAST</acronym> management code (in <filename>access/common/toast_internals.c</filename>)
 when a tuple to be stored on disk is too large to be stored as-is.
 Further details appear in <xref linkend="storage-toast-ondisk"/>.
 Alternatively, a <acronym>TOAST</acronym> pointer datum can contain a pointer to
diff --git a/src/backend/access/common/Makefile b/src/backend/access/common/Makefile
index d469504337..9ac19d9f9e 100644
--- a/src/backend/access/common/Makefile
+++ b/src/backend/access/common/Makefile
@@ -12,7 +12,8 @@ subdir = src/backend/access/common
 top_builddir = ../../../..
 include $(top_builddir)/src/Makefile.global
 
-OBJS = bufmask.o heaptuple.o indextuple.o printsimple.o printtup.o \
-	relation.o reloptions.o scankey.o session.o tupconvert.o tupdesc.o
+OBJS = bufmask.o detoast.o heaptuple.o indextuple.o printsimple.o \
+	printtup.o relation.o reloptions.o scankey.o session.o toast_internals.o \
+	tupconvert.o tupdesc.o
 
 include $(top_srcdir)/src/backend/common.mk
diff --git a/src/backend/access/common/detoast.c b/src/backend/access/common/detoast.c
new file mode 100644
index 0000000000..57ca8afe2a
--- /dev/null
+++ b/src/backend/access/common/detoast.c
@@ -0,0 +1,860 @@
+/*-------------------------------------------------------------------------
+ *
+ * detoast.c
+ *	  Support routines for external and compressed storage of
+ *	  variable size attributes.
+ *
+ * Copyright (c) 2000-2019, PostgreSQL Global Development Group
+ *
+ * IDENTIFICATION
+ *	  src/backend/access/common/detoast.c
+ *
+ *-------------------------------------------------------------------------
+ */
+
+#include "postgres.h"
+
+#include "access/detoast.h"
+#include "access/genam.h"
+#include "access/heaptoast.h"
+#include "access/table.h"
+#include "access/toast_internals.h"
+#include "common/pg_lzcompress.h"
+#include "utils/expandeddatum.h"
+#include "utils/fmgroids.h"
+#include "utils/rel.h"
+
+static struct varlena *toast_fetch_datum(struct varlena *attr);
+static struct varlena *toast_fetch_datum_slice(struct varlena *attr,
+						int32 sliceoffset, int32 length);
+static struct varlena *toast_decompress_datum(struct varlena *attr);
+static struct varlena *toast_decompress_datum_slice(struct varlena *attr, int32 slicelength);
+
+/* ----------
+ * heap_tuple_fetch_attr -
+ *
+ *	Public entry point to get back a toasted value from
+ *	external source (possibly still in compressed format).
+ *
+ * This will return a datum that contains all the data internally, ie, not
+ * relying on external storage or memory, but it can still be compressed or
+ * have a short header.  Note some callers assume that if the input is an
+ * EXTERNAL datum, the result will be a pfree'able chunk.
+ * ----------
+ */
+struct varlena *
+heap_tuple_fetch_attr(struct varlena *attr)
+{
+	struct varlena *result;
+
+	if (VARATT_IS_EXTERNAL_ONDISK(attr))
+	{
+		/*
+		 * This is an external stored plain value
+		 */
+		result = toast_fetch_datum(attr);
+	}
+	else if (VARATT_IS_EXTERNAL_INDIRECT(attr))
+	{
+		/*
+		 * This is an indirect pointer --- dereference it
+		 */
+		struct varatt_indirect redirect;
+
+		VARATT_EXTERNAL_GET_POINTER(redirect, attr);
+		attr = (struct varlena *) redirect.pointer;
+
+		/* nested indirect Datums aren't allowed */
+		Assert(!VARATT_IS_EXTERNAL_INDIRECT(attr));
+
+		/* recurse if value is still external in some other way */
+		if (VARATT_IS_EXTERNAL(attr))
+			return heap_tuple_fetch_attr(attr);
+
+		/*
+		 * Copy into the caller's memory context, in case caller tries to
+		 * pfree the result.
+		 */
+		result = (struct varlena *) palloc(VARSIZE_ANY(attr));
+		memcpy(result, attr, VARSIZE_ANY(attr));
+	}
+	else if (VARATT_IS_EXTERNAL_EXPANDED(attr))
+	{
+		/*
+		 * This is an expanded-object pointer --- get flat format
+		 */
+		ExpandedObjectHeader *eoh;
+		Size		resultsize;
+
+		eoh = DatumGetEOHP(PointerGetDatum(attr));
+		resultsize = EOH_get_flat_size(eoh);
+		result = (struct varlena *) palloc(resultsize);
+		EOH_flatten_into(eoh, (void *) result, resultsize);
+	}
+	else
+	{
+		/*
+		 * This is a plain value inside of the main tuple - why am I called?
+		 */
+		result = attr;
+	}
+
+	return result;
+}
+
+
+/* ----------
+ * heap_tuple_untoast_attr -
+ *
+ *	Public entry point to get back a toasted value from compression
+ *	or external storage.  The result is always non-extended varlena form.
+ *
+ * Note some callers assume that if the input is an EXTERNAL or COMPRESSED
+ * datum, the result will be a pfree'able chunk.
+ * ----------
+ */
+struct varlena *
+heap_tuple_untoast_attr(struct varlena *attr)
+{
+	if (VARATT_IS_EXTERNAL_ONDISK(attr))
+	{
+		/*
+		 * This is an externally stored datum --- fetch it back from there
+		 */
+		attr = toast_fetch_datum(attr);
+		/* If it's compressed, decompress it */
+		if (VARATT_IS_COMPRESSED(attr))
+		{
+			struct varlena *tmp = attr;
+
+			attr = toast_decompress_datum(tmp);
+			pfree(tmp);
+		}
+	}
+	else if (VARATT_IS_EXTERNAL_INDIRECT(attr))
+	{
+		/*
+		 * This is an indirect pointer --- dereference it
+		 */
+		struct varatt_indirect redirect;
+
+		VARATT_EXTERNAL_GET_POINTER(redirect, attr);
+		attr = (struct varlena *) redirect.pointer;
+
+		/* nested indirect Datums aren't allowed */
+		Assert(!VARATT_IS_EXTERNAL_INDIRECT(attr));
+
+		/* recurse in case value is still extended in some other way */
+		attr = heap_tuple_untoast_attr(attr);
+
+		/* if it isn't, we'd better copy it */
+		if (attr == (struct varlena *) redirect.pointer)
+		{
+			struct varlena *result;
+
+			result = (struct varlena *) palloc(VARSIZE_ANY(attr));
+			memcpy(result, attr, VARSIZE_ANY(attr));
+			attr = result;
+		}
+	}
+	else if (VARATT_IS_EXTERNAL_EXPANDED(attr))
+	{
+		/*
+		 * This is an expanded-object pointer --- get flat format
+		 */
+		attr = heap_tuple_fetch_attr(attr);
+		/* flatteners are not allowed to produce compressed/short output */
+		Assert(!VARATT_IS_EXTENDED(attr));
+	}
+	else if (VARATT_IS_COMPRESSED(attr))
+	{
+		/*
+		 * This is a compressed value inside of the main tuple
+		 */
+		attr = toast_decompress_datum(attr);
+	}
+	else if (VARATT_IS_SHORT(attr))
+	{
+		/*
+		 * This is a short-header varlena --- convert to 4-byte header format
+		 */
+		Size		data_size = VARSIZE_SHORT(attr) - VARHDRSZ_SHORT;
+		Size		new_size = data_size + VARHDRSZ;
+		struct varlena *new_attr;
+
+		new_attr = (struct varlena *) palloc(new_size);
+		SET_VARSIZE(new_attr, new_size);
+		memcpy(VARDATA(new_attr), VARDATA_SHORT(attr), data_size);
+		attr = new_attr;
+	}
+
+	return attr;
+}
+
+
+/* ----------
+ * heap_tuple_untoast_attr_slice -
+ *
+ *		Public entry point to get back part of a toasted value
+ *		from compression or external storage.
+ * ----------
+ */
+struct varlena *
+heap_tuple_untoast_attr_slice(struct varlena *attr,
+							  int32 sliceoffset, int32 slicelength)
+{
+	struct varlena *preslice;
+	struct varlena *result;
+	char	   *attrdata;
+	int32		attrsize;
+
+	if (VARATT_IS_EXTERNAL_ONDISK(attr))
+	{
+		struct varatt_external toast_pointer;
+
+		VARATT_EXTERNAL_GET_POINTER(toast_pointer, attr);
+
+		/* fast path for non-compressed external datums */
+		if (!VARATT_EXTERNAL_IS_COMPRESSED(toast_pointer))
+			return toast_fetch_datum_slice(attr, sliceoffset, slicelength);
+
+		/* fetch it back (compressed marker will get set automatically) */
+		preslice = toast_fetch_datum(attr);
+	}
+	else if (VARATT_IS_EXTERNAL_INDIRECT(attr))
+	{
+		struct varatt_indirect redirect;
+
+		VARATT_EXTERNAL_GET_POINTER(redirect, attr);
+
+		/* nested indirect Datums aren't allowed */
+		Assert(!VARATT_IS_EXTERNAL_INDIRECT(redirect.pointer));
+
+		return heap_tuple_untoast_attr_slice(redirect.pointer,
+											 sliceoffset, slicelength);
+	}
+	else if (VARATT_IS_EXTERNAL_EXPANDED(attr))
+	{
+		/* pass it off to heap_tuple_fetch_attr to flatten */
+		preslice = heap_tuple_fetch_attr(attr);
+	}
+	else
+		preslice = attr;
+
+	Assert(!VARATT_IS_EXTERNAL(preslice));
+
+	if (VARATT_IS_COMPRESSED(preslice))
+	{
+		struct varlena *tmp = preslice;
+
+		/* Decompress enough to encompass the slice and the offset */
+		if (slicelength > 0 && sliceoffset >= 0)
+			preslice = toast_decompress_datum_slice(tmp, slicelength + sliceoffset);
+		else
+			preslice = toast_decompress_datum(tmp);
+
+		if (tmp != attr)
+			pfree(tmp);
+	}
+
+	if (VARATT_IS_SHORT(preslice))
+	{
+		attrdata = VARDATA_SHORT(preslice);
+		attrsize = VARSIZE_SHORT(preslice) - VARHDRSZ_SHORT;
+	}
+	else
+	{
+		attrdata = VARDATA(preslice);
+		attrsize = VARSIZE(preslice) - VARHDRSZ;
+	}
+
+	/* slicing of datum for compressed cases and plain value */
+
+	if (sliceoffset >= attrsize)
+	{
+		sliceoffset = 0;
+		slicelength = 0;
+	}
+
+	if (((sliceoffset + slicelength) > attrsize) || slicelength < 0)
+		slicelength = attrsize - sliceoffset;
+
+	result = (struct varlena *) palloc(slicelength + VARHDRSZ);
+	SET_VARSIZE(result, slicelength + VARHDRSZ);
+
+	memcpy(VARDATA(result), attrdata + sliceoffset, slicelength);
+
+	if (preslice != attr)
+		pfree(preslice);
+
+	return result;
+}
+
+/* ----------
+ * toast_fetch_datum -
+ *
+ *	Reconstruct an in memory Datum from the chunks saved
+ *	in the toast relation
+ * ----------
+ */
+static struct varlena *
+toast_fetch_datum(struct varlena *attr)
+{
+	Relation	toastrel;
+	Relation   *toastidxs;
+	ScanKeyData toastkey;
+	SysScanDesc toastscan;
+	HeapTuple	ttup;
+	TupleDesc	toasttupDesc;
+	struct varlena *result;
+	struct varatt_external toast_pointer;
+	int32		ressize;
+	int32		residx,
+				nextidx;
+	int32		numchunks;
+	Pointer		chunk;
+	bool		isnull;
+	char	   *chunkdata;
+	int32		chunksize;
+	int			num_indexes;
+	int			validIndex;
+	SnapshotData SnapshotToast;
+
+	if (!VARATT_IS_EXTERNAL_ONDISK(attr))
+		elog(ERROR, "toast_fetch_datum shouldn't be called for non-ondisk datums");
+
+	/* Must copy to access aligned fields */
+	VARATT_EXTERNAL_GET_POINTER(toast_pointer, attr);
+
+	ressize = toast_pointer.va_extsize;
+	numchunks = ((ressize - 1) / TOAST_MAX_CHUNK_SIZE) + 1;
+
+	result = (struct varlena *) palloc(ressize + VARHDRSZ);
+
+	if (VARATT_EXTERNAL_IS_COMPRESSED(toast_pointer))
+		SET_VARSIZE_COMPRESSED(result, ressize + VARHDRSZ);
+	else
+		SET_VARSIZE(result, ressize + VARHDRSZ);
+
+	/*
+	 * Open the toast relation and its indexes
+	 */
+	toastrel = table_open(toast_pointer.va_toastrelid, AccessShareLock);
+	toasttupDesc = toastrel->rd_att;
+
+	/* Look for the valid index of the toast relation */
+	validIndex = toast_open_indexes(toastrel,
+									AccessShareLock,
+									&toastidxs,
+									&num_indexes);
+
+	/*
+	 * Setup a scan key to fetch from the index by va_valueid
+	 */
+	ScanKeyInit(&toastkey,
+				(AttrNumber) 1,
+				BTEqualStrategyNumber, F_OIDEQ,
+				ObjectIdGetDatum(toast_pointer.va_valueid));
+
+	/*
+	 * Read the chunks by index
+	 *
+	 * Note that because the index is actually on (valueid, chunkidx) we will
+	 * see the chunks in chunkidx order, even though we didn't explicitly ask
+	 * for it.
+	 */
+	nextidx = 0;
+
+	init_toast_snapshot(&SnapshotToast);
+	toastscan = systable_beginscan_ordered(toastrel, toastidxs[validIndex],
+										   &SnapshotToast, 1, &toastkey);
+	while ((ttup = systable_getnext_ordered(toastscan, ForwardScanDirection)) != NULL)
+	{
+		/*
+		 * Have a chunk, extract the sequence number and the data
+		 */
+		residx = DatumGetInt32(fastgetattr(ttup, 2, toasttupDesc, &isnull));
+		Assert(!isnull);
+		chunk = DatumGetPointer(fastgetattr(ttup, 3, toasttupDesc, &isnull));
+		Assert(!isnull);
+		if (!VARATT_IS_EXTENDED(chunk))
+		{
+			chunksize = VARSIZE(chunk) - VARHDRSZ;
+			chunkdata = VARDATA(chunk);
+		}
+		else if (VARATT_IS_SHORT(chunk))
+		{
+			/* could happen due to heap_form_tuple doing its thing */
+			chunksize = VARSIZE_SHORT(chunk) - VARHDRSZ_SHORT;
+			chunkdata = VARDATA_SHORT(chunk);
+		}
+		else
+		{
+			/* should never happen */
+			elog(ERROR, "found toasted toast chunk for toast value %u in %s",
+				 toast_pointer.va_valueid,
+				 RelationGetRelationName(toastrel));
+			chunksize = 0;		/* keep compiler quiet */
+			chunkdata = NULL;
+		}
+
+		/*
+		 * Some checks on the data we've found
+		 */
+		if (residx != nextidx)
+			elog(ERROR, "unexpected chunk number %d (expected %d) for toast value %u in %s",
+				 residx, nextidx,
+				 toast_pointer.va_valueid,
+				 RelationGetRelationName(toastrel));
+		if (residx < numchunks - 1)
+		{
+			if (chunksize != TOAST_MAX_CHUNK_SIZE)
+				elog(ERROR, "unexpected chunk size %d (expected %d) in chunk %d of %d for toast value %u in %s",
+					 chunksize, (int) TOAST_MAX_CHUNK_SIZE,
+					 residx, numchunks,
+					 toast_pointer.va_valueid,
+					 RelationGetRelationName(toastrel));
+		}
+		else if (residx == numchunks - 1)
+		{
+			if ((residx * TOAST_MAX_CHUNK_SIZE + chunksize) != ressize)
+				elog(ERROR, "unexpected chunk size %d (expected %d) in final chunk %d for toast value %u in %s",
+					 chunksize,
+					 (int) (ressize - residx * TOAST_MAX_CHUNK_SIZE),
+					 residx,
+					 toast_pointer.va_valueid,
+					 RelationGetRelationName(toastrel));
+		}
+		else
+			elog(ERROR, "unexpected chunk number %d (out of range %d..%d) for toast value %u in %s",
+				 residx,
+				 0, numchunks - 1,
+				 toast_pointer.va_valueid,
+				 RelationGetRelationName(toastrel));
+
+		/*
+		 * Copy the data into proper place in our result
+		 */
+		memcpy(VARDATA(result) + residx * TOAST_MAX_CHUNK_SIZE,
+			   chunkdata,
+			   chunksize);
+
+		nextidx++;
+	}
+
+	/*
+	 * Final checks that we successfully fetched the datum
+	 */
+	if (nextidx != numchunks)
+		elog(ERROR, "missing chunk number %d for toast value %u in %s",
+			 nextidx,
+			 toast_pointer.va_valueid,
+			 RelationGetRelationName(toastrel));
+
+	/*
+	 * End scan and close relations
+	 */
+	systable_endscan_ordered(toastscan);
+	toast_close_indexes(toastidxs, num_indexes, AccessShareLock);
+	table_close(toastrel, AccessShareLock);
+
+	return result;
+}
+
+/* ----------
+ * toast_fetch_datum_slice -
+ *
+ *	Reconstruct a segment of a Datum from the chunks saved
+ *	in the toast relation
+ *
+ *	Note that this function only supports non-compressed external datums.
+ * ----------
+ */
+static struct varlena *
+toast_fetch_datum_slice(struct varlena *attr, int32 sliceoffset, int32 length)
+{
+	Relation	toastrel;
+	Relation   *toastidxs;
+	ScanKeyData toastkey[3];
+	int			nscankeys;
+	SysScanDesc toastscan;
+	HeapTuple	ttup;
+	TupleDesc	toasttupDesc;
+	struct varlena *result;
+	struct varatt_external toast_pointer;
+	int32		attrsize;
+	int32		residx;
+	int32		nextidx;
+	int			numchunks;
+	int			startchunk;
+	int			endchunk;
+	int32		startoffset;
+	int32		endoffset;
+	int			totalchunks;
+	Pointer		chunk;
+	bool		isnull;
+	char	   *chunkdata;
+	int32		chunksize;
+	int32		chcpystrt;
+	int32		chcpyend;
+	int			num_indexes;
+	int			validIndex;
+	SnapshotData SnapshotToast;
+
+	if (!VARATT_IS_EXTERNAL_ONDISK(attr))
+		elog(ERROR, "toast_fetch_datum_slice shouldn't be called for non-ondisk datums");
+
+	/* Must copy to access aligned fields */
+	VARATT_EXTERNAL_GET_POINTER(toast_pointer, attr);
+
+	/*
+	 * It's nonsense to fetch slices of a compressed datum -- this isn't lo_*
+	 * we can't return a compressed datum which is meaningful to toast later
+	 */
+	Assert(!VARATT_EXTERNAL_IS_COMPRESSED(toast_pointer));
+
+	attrsize = toast_pointer.va_extsize;
+	totalchunks = ((attrsize - 1) / TOAST_MAX_CHUNK_SIZE) + 1;
+
+	if (sliceoffset >= attrsize)
+	{
+		sliceoffset = 0;
+		length = 0;
+	}
+
+	if (((sliceoffset + length) > attrsize) || length < 0)
+		length = attrsize - sliceoffset;
+
+	result = (struct varlena *) palloc(length + VARHDRSZ);
+
+	SET_VARSIZE(result, length + VARHDRSZ);
+
+	if (length == 0)
+		return result;			/* Can save a lot of work at this point! */
+
+	startchunk = sliceoffset / TOAST_MAX_CHUNK_SIZE;
+	endchunk = (sliceoffset + length - 1) / TOAST_MAX_CHUNK_SIZE;
+	numchunks = (endchunk - startchunk) + 1;
+
+	startoffset = sliceoffset % TOAST_MAX_CHUNK_SIZE;
+	endoffset = (sliceoffset + length - 1) % TOAST_MAX_CHUNK_SIZE;
+
+	/*
+	 * Open the toast relation and its indexes
+	 */
+	toastrel = table_open(toast_pointer.va_toastrelid, AccessShareLock);
+	toasttupDesc = toastrel->rd_att;
+
+	/* Look for the valid index of toast relation */
+	validIndex = toast_open_indexes(toastrel,
+									AccessShareLock,
+									&toastidxs,
+									&num_indexes);
+
+	/*
+	 * Setup a scan key to fetch from the index. This is either two keys or
+	 * three depending on the number of chunks.
+	 */
+	ScanKeyInit(&toastkey[0],
+				(AttrNumber) 1,
+				BTEqualStrategyNumber, F_OIDEQ,
+				ObjectIdGetDatum(toast_pointer.va_valueid));
+
+	/*
+	 * Use equality condition for one chunk, a range condition otherwise:
+	 */
+	if (numchunks == 1)
+	{
+		ScanKeyInit(&toastkey[1],
+					(AttrNumber) 2,
+					BTEqualStrategyNumber, F_INT4EQ,
+					Int32GetDatum(startchunk));
+		nscankeys = 2;
+	}
+	else
+	{
+		ScanKeyInit(&toastkey[1],
+					(AttrNumber) 2,
+					BTGreaterEqualStrategyNumber, F_INT4GE,
+					Int32GetDatum(startchunk));
+		ScanKeyInit(&toastkey[2],
+					(AttrNumber) 2,
+					BTLessEqualStrategyNumber, F_INT4LE,
+					Int32GetDatum(endchunk));
+		nscankeys = 3;
+	}
+
+	/*
+	 * Read the chunks by index
+	 *
+	 * The index is on (valueid, chunkidx) so they will come in order
+	 */
+	init_toast_snapshot(&SnapshotToast);
+	nextidx = startchunk;
+	toastscan = systable_beginscan_ordered(toastrel, toastidxs[validIndex],
+										   &SnapshotToast, nscankeys, toastkey);
+	while ((ttup = systable_getnext_ordered(toastscan, ForwardScanDirection)) != NULL)
+	{
+		/*
+		 * Have a chunk, extract the sequence number and the data
+		 */
+		residx = DatumGetInt32(fastgetattr(ttup, 2, toasttupDesc, &isnull));
+		Assert(!isnull);
+		chunk = DatumGetPointer(fastgetattr(ttup, 3, toasttupDesc, &isnull));
+		Assert(!isnull);
+		if (!VARATT_IS_EXTENDED(chunk))
+		{
+			chunksize = VARSIZE(chunk) - VARHDRSZ;
+			chunkdata = VARDATA(chunk);
+		}
+		else if (VARATT_IS_SHORT(chunk))
+		{
+			/* could happen due to heap_form_tuple doing its thing */
+			chunksize = VARSIZE_SHORT(chunk) - VARHDRSZ_SHORT;
+			chunkdata = VARDATA_SHORT(chunk);
+		}
+		else
+		{
+			/* should never happen */
+			elog(ERROR, "found toasted toast chunk for toast value %u in %s",
+				 toast_pointer.va_valueid,
+				 RelationGetRelationName(toastrel));
+			chunksize = 0;		/* keep compiler quiet */
+			chunkdata = NULL;
+		}
+
+		/*
+		 * Some checks on the data we've found
+		 */
+		if ((residx != nextidx) || (residx > endchunk) || (residx < startchunk))
+			elog(ERROR, "unexpected chunk number %d (expected %d) for toast value %u in %s",
+				 residx, nextidx,
+				 toast_pointer.va_valueid,
+				 RelationGetRelationName(toastrel));
+		if (residx < totalchunks - 1)
+		{
+			if (chunksize != TOAST_MAX_CHUNK_SIZE)
+				elog(ERROR, "unexpected chunk size %d (expected %d) in chunk %d of %d for toast value %u in %s when fetching slice",
+					 chunksize, (int) TOAST_MAX_CHUNK_SIZE,
+					 residx, totalchunks,
+					 toast_pointer.va_valueid,
+					 RelationGetRelationName(toastrel));
+		}
+		else if (residx == totalchunks - 1)
+		{
+			if ((residx * TOAST_MAX_CHUNK_SIZE + chunksize) != attrsize)
+				elog(ERROR, "unexpected chunk size %d (expected %d) in final chunk %d for toast value %u in %s when fetching slice",
+					 chunksize,
+					 (int) (attrsize - residx * TOAST_MAX_CHUNK_SIZE),
+					 residx,
+					 toast_pointer.va_valueid,
+					 RelationGetRelationName(toastrel));
+		}
+		else
+			elog(ERROR, "unexpected chunk number %d (out of range %d..%d) for toast value %u in %s",
+				 residx,
+				 0, totalchunks - 1,
+				 toast_pointer.va_valueid,
+				 RelationGetRelationName(toastrel));
+
+		/*
+		 * Copy the data into proper place in our result
+		 */
+		chcpystrt = 0;
+		chcpyend = chunksize - 1;
+		if (residx == startchunk)
+			chcpystrt = startoffset;
+		if (residx == endchunk)
+			chcpyend = endoffset;
+
+		memcpy(VARDATA(result) +
+			   (residx * TOAST_MAX_CHUNK_SIZE - sliceoffset) + chcpystrt,
+			   chunkdata + chcpystrt,
+			   (chcpyend - chcpystrt) + 1);
+
+		nextidx++;
+	}
+
+	/*
+	 * Final checks that we successfully fetched the datum
+	 */
+	if (nextidx != (endchunk + 1))
+		elog(ERROR, "missing chunk number %d for toast value %u in %s",
+			 nextidx,
+			 toast_pointer.va_valueid,
+			 RelationGetRelationName(toastrel));
+
+	/*
+	 * End scan and close relations
+	 */
+	systable_endscan_ordered(toastscan);
+	toast_close_indexes(toastidxs, num_indexes, AccessShareLock);
+	table_close(toastrel, AccessShareLock);
+
+	return result;
+}
+
+/* ----------
+ * toast_decompress_datum -
+ *
+ * Decompress a compressed version of a varlena datum
+ */
+static struct varlena *
+toast_decompress_datum(struct varlena *attr)
+{
+	struct varlena *result;
+
+	Assert(VARATT_IS_COMPRESSED(attr));
+
+	result = (struct varlena *)
+		palloc(TOAST_COMPRESS_RAWSIZE(attr) + VARHDRSZ);
+	SET_VARSIZE(result, TOAST_COMPRESS_RAWSIZE(attr) + VARHDRSZ);
+
+	if (pglz_decompress(TOAST_COMPRESS_RAWDATA(attr),
+						VARSIZE(attr) - TOAST_COMPRESS_HDRSZ,
+						VARDATA(result),
+						TOAST_COMPRESS_RAWSIZE(attr), true) < 0)
+		elog(ERROR, "compressed data is corrupted");
+
+	return result;
+}
+
+
+/* ----------
+ * toast_decompress_datum_slice -
+ *
+ * Decompress the front of a compressed version of a varlena datum.
+ * offset handling happens in heap_tuple_untoast_attr_slice.
+ * Here we just decompress a slice from the front.
+ */
+static struct varlena *
+toast_decompress_datum_slice(struct varlena *attr, int32 slicelength)
+{
+	struct varlena *result;
+	int32 rawsize;
+
+	Assert(VARATT_IS_COMPRESSED(attr));
+
+	result = (struct varlena *) palloc(slicelength + VARHDRSZ);
+
+	rawsize = pglz_decompress(TOAST_COMPRESS_RAWDATA(attr),
+						VARSIZE(attr) - TOAST_COMPRESS_HDRSZ,
+						VARDATA(result),
+						slicelength, false);
+	if (rawsize < 0)
+		elog(ERROR, "compressed data is corrupted");
+
+	SET_VARSIZE(result, rawsize + VARHDRSZ);
+	return result;
+}
+
+/* ----------
+ * toast_raw_datum_size -
+ *
+ *	Return the raw (detoasted) size of a varlena datum
+ *	(including the VARHDRSZ header)
+ * ----------
+ */
+Size
+toast_raw_datum_size(Datum value)
+{
+	struct varlena *attr = (struct varlena *) DatumGetPointer(value);
+	Size		result;
+
+	if (VARATT_IS_EXTERNAL_ONDISK(attr))
+	{
+		/* va_rawsize is the size of the original datum -- including header */
+		struct varatt_external toast_pointer;
+
+		VARATT_EXTERNAL_GET_POINTER(toast_pointer, attr);
+		result = toast_pointer.va_rawsize;
+	}
+	else if (VARATT_IS_EXTERNAL_INDIRECT(attr))
+	{
+		struct varatt_indirect toast_pointer;
+
+		VARATT_EXTERNAL_GET_POINTER(toast_pointer, attr);
+
+		/* nested indirect Datums aren't allowed */
+		Assert(!VARATT_IS_EXTERNAL_INDIRECT(toast_pointer.pointer));
+
+		return toast_raw_datum_size(PointerGetDatum(toast_pointer.pointer));
+	}
+	else if (VARATT_IS_EXTERNAL_EXPANDED(attr))
+	{
+		result = EOH_get_flat_size(DatumGetEOHP(value));
+	}
+	else if (VARATT_IS_COMPRESSED(attr))
+	{
+		/* here, va_rawsize is just the payload size */
+		result = VARRAWSIZE_4B_C(attr) + VARHDRSZ;
+	}
+	else if (VARATT_IS_SHORT(attr))
+	{
+		/*
+		 * we have to normalize the header length to VARHDRSZ or else the
+		 * callers of this function will be confused.
+		 */
+		result = VARSIZE_SHORT(attr) - VARHDRSZ_SHORT + VARHDRSZ;
+	}
+	else
+	{
+		/* plain untoasted datum */
+		result = VARSIZE(attr);
+	}
+	return result;
+}
+
+/* ----------
+ * toast_datum_size
+ *
+ *	Return the physical storage size (possibly compressed) of a varlena datum
+ * ----------
+ */
+Size
+toast_datum_size(Datum value)
+{
+	struct varlena *attr = (struct varlena *) DatumGetPointer(value);
+	Size		result;
+
+	if (VARATT_IS_EXTERNAL_ONDISK(attr))
+	{
+		/*
+		 * Attribute is stored externally - return the extsize whether
+		 * compressed or not.  We do not count the size of the toast pointer
+		 * ... should we?
+		 */
+		struct varatt_external toast_pointer;
+
+		VARATT_EXTERNAL_GET_POINTER(toast_pointer, attr);
+		result = toast_pointer.va_extsize;
+	}
+	else if (VARATT_IS_EXTERNAL_INDIRECT(attr))
+	{
+		struct varatt_indirect toast_pointer;
+
+		VARATT_EXTERNAL_GET_POINTER(toast_pointer, attr);
+
+		/* nested indirect Datums aren't allowed */
+		Assert(!VARATT_IS_EXTERNAL_INDIRECT(attr));
+
+		return toast_datum_size(PointerGetDatum(toast_pointer.pointer));
+	}
+	else if (VARATT_IS_EXTERNAL_EXPANDED(attr))
+	{
+		result = EOH_get_flat_size(DatumGetEOHP(value));
+	}
+	else if (VARATT_IS_SHORT(attr))
+	{
+		result = VARSIZE_SHORT(attr);
+	}
+	else
+	{
+		/*
+		 * Attribute is stored inline either compressed or not, just calculate
+		 * the size of the datum in either case.
+		 */
+		result = VARSIZE(attr);
+	}
+	return result;
+}
diff --git a/src/backend/access/common/heaptuple.c b/src/backend/access/common/heaptuple.c
index 783b04a3cb..a2197a4b43 100644
--- a/src/backend/access/common/heaptuple.c
+++ b/src/backend/access/common/heaptuple.c
@@ -18,7 +18,7 @@
  * (In performance-critical code paths we can use pg_detoast_datum_packed
  * and the appropriate access macros to avoid that overhead.)  Note that this
  * conversion is performed directly in heap_form_tuple, without invoking
- * tuptoaster.c.
+ * heaptoast.c.
  *
  * This change will break any code that assumes it needn't detoast values
  * that have been put into a tuple but never sent to disk.  Hopefully there
@@ -57,9 +57,9 @@
 
 #include "postgres.h"
 
+#include "access/heaptoast.h"
 #include "access/sysattr.h"
 #include "access/tupdesc_details.h"
-#include "access/tuptoaster.h"
 #include "executor/tuptable.h"
 #include "utils/expandeddatum.h"
 
diff --git a/src/backend/access/common/indextuple.c b/src/backend/access/common/indextuple.c
index cb23be859d..07586201b9 100644
--- a/src/backend/access/common/indextuple.c
+++ b/src/backend/access/common/indextuple.c
@@ -16,10 +16,17 @@
 
 #include "postgres.h"
 
+#include "access/detoast.h"
+#include "access/heaptoast.h"
 #include "access/htup_details.h"
 #include "access/itup.h"
-#include "access/tuptoaster.h"
+#include "access/toast_internals.h"
 
+/*
+ * This enables de-toasting of index entries.  Needed until VACUUM is
+ * smart enough to rebuild indexes from scratch.
+ */
+#define TOAST_INDEX_HACK
 
 /* ----------------------------------------------------------------
  *				  index_ tuple interface routines
diff --git a/src/backend/access/common/reloptions.c b/src/backend/access/common/reloptions.c
index cfbabb5265..9d78d6ccc9 100644
--- a/src/backend/access/common/reloptions.c
+++ b/src/backend/access/common/reloptions.c
@@ -19,11 +19,11 @@
 
 #include "access/gist_private.h"
 #include "access/hash.h"
+#include "access/heaptoast.h"
 #include "access/htup_details.h"
 #include "access/nbtree.h"
 #include "access/reloptions.h"
 #include "access/spgist.h"
-#include "access/tuptoaster.h"
 #include "catalog/pg_type.h"
 #include "commands/defrem.h"
 #include "commands/tablespace.h"
diff --git a/src/backend/access/common/toast_internals.c b/src/backend/access/common/toast_internals.c
new file mode 100644
index 0000000000..a971242490
--- /dev/null
+++ b/src/backend/access/common/toast_internals.c
@@ -0,0 +1,632 @@
+/*-------------------------------------------------------------------------
+ *
+ * toast_internals.c
+ *	  Functions for internal use by the TOAST system.
+ *
+ * Copyright (c) 2000-2019, PostgreSQL Global Development Group
+ *
+ * IDENTIFICATION
+ *	  src/backend/access/common/toast_internals.c
+ *
+ *-------------------------------------------------------------------------
+ */
+
+#include "postgres.h"
+
+#include "access/detoast.h"
+#include "access/genam.h"
+#include "access/heapam.h"
+#include "access/heaptoast.h"
+#include "access/table.h"
+#include "access/toast_internals.h"
+#include "access/xact.h"
+#include "catalog/catalog.h"
+#include "common/pg_lzcompress.h"
+#include "miscadmin.h"
+#include "utils/fmgroids.h"
+#include "utils/rel.h"
+#include "utils/snapmgr.h"
+
+static bool toastrel_valueid_exists(Relation toastrel, Oid valueid);
+static bool toastid_valueid_exists(Oid toastrelid, Oid valueid);
+
+/* ----------
+ * toast_compress_datum -
+ *
+ *	Create a compressed version of a varlena datum
+ *
+ *	If we fail (ie, compressed result is actually bigger than original)
+ *	then return NULL.  We must not use compressed data if it'd expand
+ *	the tuple!
+ *
+ *	We use VAR{SIZE,DATA}_ANY so we can handle short varlenas here without
+ *	copying them.  But we can't handle external or compressed datums.
+ * ----------
+ */
+Datum
+toast_compress_datum(Datum value)
+{
+	struct varlena *tmp;
+	int32		valsize = VARSIZE_ANY_EXHDR(DatumGetPointer(value));
+	int32		len;
+
+	Assert(!VARATT_IS_EXTERNAL(DatumGetPointer(value)));
+	Assert(!VARATT_IS_COMPRESSED(DatumGetPointer(value)));
+
+	/*
+	 * No point in wasting a palloc cycle if value size is out of the allowed
+	 * range for compression
+	 */
+	if (valsize < PGLZ_strategy_default->min_input_size ||
+		valsize > PGLZ_strategy_default->max_input_size)
+		return PointerGetDatum(NULL);
+
+	tmp = (struct varlena *) palloc(PGLZ_MAX_OUTPUT(valsize) +
+									TOAST_COMPRESS_HDRSZ);
+
+	/*
+	 * We recheck the actual size even if pglz_compress() reports success,
+	 * because it might be satisfied with having saved as little as one byte
+	 * in the compressed data --- which could turn into a net loss once you
+	 * consider header and alignment padding.  Worst case, the compressed
+	 * format might require three padding bytes (plus header, which is
+	 * included in VARSIZE(tmp)), whereas the uncompressed format would take
+	 * only one header byte and no padding if the value is short enough.  So
+	 * we insist on a savings of more than 2 bytes to ensure we have a gain.
+	 */
+	len = pglz_compress(VARDATA_ANY(DatumGetPointer(value)),
+						valsize,
+						TOAST_COMPRESS_RAWDATA(tmp),
+						PGLZ_strategy_default);
+	if (len >= 0 &&
+		len + TOAST_COMPRESS_HDRSZ < valsize - 2)
+	{
+		TOAST_COMPRESS_SET_RAWSIZE(tmp, valsize);
+		SET_VARSIZE_COMPRESSED(tmp, len + TOAST_COMPRESS_HDRSZ);
+		/* successful compression */
+		return PointerGetDatum(tmp);
+	}
+	else
+	{
+		/* incompressible data */
+		pfree(tmp);
+		return PointerGetDatum(NULL);
+	}
+}
+
+/* ----------
+ * toast_save_datum -
+ *
+ *	Save one single datum into the secondary relation and return
+ *	a Datum reference for it.
+ *
+ * rel: the main relation we're working with (not the toast rel!)
+ * value: datum to be pushed to toast storage
+ * oldexternal: if not NULL, toast pointer previously representing the datum
+ * options: options to be passed to heap_insert() for toast rows
+ * ----------
+ */
+Datum
+toast_save_datum(Relation rel, Datum value,
+				 struct varlena *oldexternal, int options)
+{
+	Relation	toastrel;
+	Relation   *toastidxs;
+	HeapTuple	toasttup;
+	TupleDesc	toasttupDesc;
+	Datum		t_values[3];
+	bool		t_isnull[3];
+	CommandId	mycid = GetCurrentCommandId(true);
+	struct varlena *result;
+	struct varatt_external toast_pointer;
+	union
+	{
+		struct varlena hdr;
+		/* this is to make the union big enough for a chunk: */
+		char		data[TOAST_MAX_CHUNK_SIZE + VARHDRSZ];
+		/* ensure union is aligned well enough: */
+		int32		align_it;
+	}			chunk_data;
+	int32		chunk_size;
+	int32		chunk_seq = 0;
+	char	   *data_p;
+	int32		data_todo;
+	Pointer		dval = DatumGetPointer(value);
+	int			num_indexes;
+	int			validIndex;
+
+	Assert(!VARATT_IS_EXTERNAL(value));
+
+	/*
+	 * Open the toast relation and its indexes.  We can use the index to check
+	 * uniqueness of the OID we assign to the toasted item, even though it has
+	 * additional columns besides OID.
+	 */
+	toastrel = table_open(rel->rd_rel->reltoastrelid, RowExclusiveLock);
+	toasttupDesc = toastrel->rd_att;
+
+	/* Open all the toast indexes and look for the valid one */
+	validIndex = toast_open_indexes(toastrel,
+									RowExclusiveLock,
+									&toastidxs,
+									&num_indexes);
+
+	/*
+	 * Get the data pointer and length, and compute va_rawsize and va_extsize.
+	 *
+	 * va_rawsize is the size of the equivalent fully uncompressed datum, so
+	 * we have to adjust for short headers.
+	 *
+	 * va_extsize is the actual size of the data payload in the toast records.
+	 */
+	if (VARATT_IS_SHORT(dval))
+	{
+		data_p = VARDATA_SHORT(dval);
+		data_todo = VARSIZE_SHORT(dval) - VARHDRSZ_SHORT;
+		toast_pointer.va_rawsize = data_todo + VARHDRSZ;	/* as if not short */
+		toast_pointer.va_extsize = data_todo;
+	}
+	else if (VARATT_IS_COMPRESSED(dval))
+	{
+		data_p = VARDATA(dval);
+		data_todo = VARSIZE(dval) - VARHDRSZ;
+		/* rawsize in a compressed datum is just the size of the payload */
+		toast_pointer.va_rawsize = VARRAWSIZE_4B_C(dval) + VARHDRSZ;
+		toast_pointer.va_extsize = data_todo;
+		/* Assert that the numbers look like it's compressed */
+		Assert(VARATT_EXTERNAL_IS_COMPRESSED(toast_pointer));
+	}
+	else
+	{
+		data_p = VARDATA(dval);
+		data_todo = VARSIZE(dval) - VARHDRSZ;
+		toast_pointer.va_rawsize = VARSIZE(dval);
+		toast_pointer.va_extsize = data_todo;
+	}
+
+	/*
+	 * Insert the correct table OID into the result TOAST pointer.
+	 *
+	 * Normally this is the actual OID of the target toast table, but during
+	 * table-rewriting operations such as CLUSTER, we have to insert the OID
+	 * of the table's real permanent toast table instead.  rd_toastoid is set
+	 * if we have to substitute such an OID.
+	 */
+	if (OidIsValid(rel->rd_toastoid))
+		toast_pointer.va_toastrelid = rel->rd_toastoid;
+	else
+		toast_pointer.va_toastrelid = RelationGetRelid(toastrel);
+
+	/*
+	 * Choose an OID to use as the value ID for this toast value.
+	 *
+	 * Normally we just choose an unused OID within the toast table.  But
+	 * during table-rewriting operations where we are preserving an existing
+	 * toast table OID, we want to preserve toast value OIDs too.  So, if
+	 * rd_toastoid is set and we had a prior external value from that same
+	 * toast table, re-use its value ID.  If we didn't have a prior external
+	 * value (which is a corner case, but possible if the table's attstorage
+	 * options have been changed), we have to pick a value ID that doesn't
+	 * conflict with either new or existing toast value OIDs.
+	 */
+	if (!OidIsValid(rel->rd_toastoid))
+	{
+		/* normal case: just choose an unused OID */
+		toast_pointer.va_valueid =
+			GetNewOidWithIndex(toastrel,
+							   RelationGetRelid(toastidxs[validIndex]),
+							   (AttrNumber) 1);
+	}
+	else
+	{
+		/* rewrite case: check to see if value was in old toast table */
+		toast_pointer.va_valueid = InvalidOid;
+		if (oldexternal != NULL)
+		{
+			struct varatt_external old_toast_pointer;
+
+			Assert(VARATT_IS_EXTERNAL_ONDISK(oldexternal));
+			/* Must copy to access aligned fields */
+			VARATT_EXTERNAL_GET_POINTER(old_toast_pointer, oldexternal);
+			if (old_toast_pointer.va_toastrelid == rel->rd_toastoid)
+			{
+				/* This value came from the old toast table; reuse its OID */
+				toast_pointer.va_valueid = old_toast_pointer.va_valueid;
+
+				/*
+				 * There is a corner case here: the table rewrite might have
+				 * to copy both live and recently-dead versions of a row, and
+				 * those versions could easily reference the same toast value.
+				 * When we copy the second or later version of such a row,
+				 * reusing the OID will mean we select an OID that's already
+				 * in the new toast table.  Check for that, and if so, just
+				 * fall through without writing the data again.
+				 *
+				 * While annoying and ugly-looking, this is a good thing
+				 * because it ensures that we wind up with only one copy of
+				 * the toast value when there is only one copy in the old
+				 * toast table.  Before we detected this case, we'd have made
+				 * multiple copies, wasting space; and what's worse, the
+				 * copies belonging to already-deleted heap tuples would not
+				 * be reclaimed by VACUUM.
+				 */
+				if (toastrel_valueid_exists(toastrel,
+											toast_pointer.va_valueid))
+				{
+					/* Match, so short-circuit the data storage loop below */
+					data_todo = 0;
+				}
+			}
+		}
+		if (toast_pointer.va_valueid == InvalidOid)
+		{
+			/*
+			 * new value; must choose an OID that doesn't conflict in either
+			 * old or new toast table
+			 */
+			do
+			{
+				toast_pointer.va_valueid =
+					GetNewOidWithIndex(toastrel,
+									   RelationGetRelid(toastidxs[validIndex]),
+									   (AttrNumber) 1);
+			} while (toastid_valueid_exists(rel->rd_toastoid,
+											toast_pointer.va_valueid));
+		}
+	}
+
+	/*
+	 * Initialize constant parts of the tuple data
+	 */
+	t_values[0] = ObjectIdGetDatum(toast_pointer.va_valueid);
+	t_values[2] = PointerGetDatum(&chunk_data);
+	t_isnull[0] = false;
+	t_isnull[1] = false;
+	t_isnull[2] = false;
+
+	/*
+	 * Split up the item into chunks
+	 */
+	while (data_todo > 0)
+	{
+		int			i;
+
+		CHECK_FOR_INTERRUPTS();
+
+		/*
+		 * Calculate the size of this chunk
+		 */
+		chunk_size = Min(TOAST_MAX_CHUNK_SIZE, data_todo);
+
+		/*
+		 * Build a tuple and store it
+		 */
+		t_values[1] = Int32GetDatum(chunk_seq++);
+		SET_VARSIZE(&chunk_data, chunk_size + VARHDRSZ);
+		memcpy(VARDATA(&chunk_data), data_p, chunk_size);
+		toasttup = heap_form_tuple(toasttupDesc, t_values, t_isnull);
+
+		heap_insert(toastrel, toasttup, mycid, options, NULL);
+
+		/*
+		 * Create the index entry.  We cheat a little here by not using
+		 * FormIndexDatum: this relies on the knowledge that the index columns
+		 * are the same as the initial columns of the table for all the
+		 * indexes.  We also cheat by not providing an IndexInfo: this is okay
+		 * for now because btree doesn't need one, but we might have to be
+		 * more honest someday.
+		 *
+		 * Note also that there had better not be any user-created index on
+		 * the TOAST table, since we don't bother to update anything else.
+		 */
+		for (i = 0; i < num_indexes; i++)
+		{
+			/* Only index relations marked as ready can be updated */
+			if (toastidxs[i]->rd_index->indisready)
+				index_insert(toastidxs[i], t_values, t_isnull,
+							 &(toasttup->t_self),
+							 toastrel,
+							 toastidxs[i]->rd_index->indisunique ?
+							 UNIQUE_CHECK_YES : UNIQUE_CHECK_NO,
+							 NULL);
+		}
+
+		/*
+		 * Free memory
+		 */
+		heap_freetuple(toasttup);
+
+		/*
+		 * Move on to next chunk
+		 */
+		data_todo -= chunk_size;
+		data_p += chunk_size;
+	}
+
+	/*
+	 * Done - close toast relation and its indexes
+	 */
+	toast_close_indexes(toastidxs, num_indexes, RowExclusiveLock);
+	table_close(toastrel, RowExclusiveLock);
+
+	/*
+	 * Create the TOAST pointer value that we'll return
+	 */
+	result = (struct varlena *) palloc(TOAST_POINTER_SIZE);
+	SET_VARTAG_EXTERNAL(result, VARTAG_ONDISK);
+	memcpy(VARDATA_EXTERNAL(result), &toast_pointer, sizeof(toast_pointer));
+
+	return PointerGetDatum(result);
+}
+
+/* ----------
+ * toast_delete_datum -
+ *
+ *	Delete a single external stored value.
+ * ----------
+ */
+void
+toast_delete_datum(Relation rel, Datum value, bool is_speculative)
+{
+	struct varlena *attr = (struct varlena *) DatumGetPointer(value);
+	struct varatt_external toast_pointer;
+	Relation	toastrel;
+	Relation   *toastidxs;
+	ScanKeyData toastkey;
+	SysScanDesc toastscan;
+	HeapTuple	toasttup;
+	int			num_indexes;
+	int			validIndex;
+	SnapshotData SnapshotToast;
+
+	if (!VARATT_IS_EXTERNAL_ONDISK(attr))
+		return;
+
+	/* Must copy to access aligned fields */
+	VARATT_EXTERNAL_GET_POINTER(toast_pointer, attr);
+
+	/*
+	 * Open the toast relation and its indexes
+	 */
+	toastrel = table_open(toast_pointer.va_toastrelid, RowExclusiveLock);
+
+	/* Fetch valid relation used for process */
+	validIndex = toast_open_indexes(toastrel,
+									RowExclusiveLock,
+									&toastidxs,
+									&num_indexes);
+
+	/*
+	 * Setup a scan key to find chunks with matching va_valueid
+	 */
+	ScanKeyInit(&toastkey,
+				(AttrNumber) 1,
+				BTEqualStrategyNumber, F_OIDEQ,
+				ObjectIdGetDatum(toast_pointer.va_valueid));
+
+	/*
+	 * Find all the chunks.  (We don't actually care whether we see them in
+	 * sequence or not, but since we've already locked the index we might as
+	 * well use systable_beginscan_ordered.)
+	 */
+	init_toast_snapshot(&SnapshotToast);
+	toastscan = systable_beginscan_ordered(toastrel, toastidxs[validIndex],
+										   &SnapshotToast, 1, &toastkey);
+	while ((toasttup = systable_getnext_ordered(toastscan, ForwardScanDirection)) != NULL)
+	{
+		/*
+		 * Have a chunk, delete it
+		 */
+		if (is_speculative)
+			heap_abort_speculative(toastrel, &toasttup->t_self);
+		else
+			simple_heap_delete(toastrel, &toasttup->t_self);
+	}
+
+	/*
+	 * End scan and close relations
+	 */
+	systable_endscan_ordered(toastscan);
+	toast_close_indexes(toastidxs, num_indexes, RowExclusiveLock);
+	table_close(toastrel, RowExclusiveLock);
+}
+
+/* ----------
+ * toastrel_valueid_exists -
+ *
+ *	Test whether a toast value with the given ID exists in the toast relation.
+ *	For safety, we consider a value to exist if there are either live or dead
+ *	toast rows with that ID; see notes for GetNewOidWithIndex().
+ * ----------
+ */
+static bool
+toastrel_valueid_exists(Relation toastrel, Oid valueid)
+{
+	bool		result = false;
+	ScanKeyData toastkey;
+	SysScanDesc toastscan;
+	int			num_indexes;
+	int			validIndex;
+	Relation   *toastidxs;
+
+	/* Fetch a valid index relation */
+	validIndex = toast_open_indexes(toastrel,
+									RowExclusiveLock,
+									&toastidxs,
+									&num_indexes);
+
+	/*
+	 * Setup a scan key to find chunks with matching va_valueid
+	 */
+	ScanKeyInit(&toastkey,
+				(AttrNumber) 1,
+				BTEqualStrategyNumber, F_OIDEQ,
+				ObjectIdGetDatum(valueid));
+
+	/*
+	 * Is there any such chunk?
+	 */
+	toastscan = systable_beginscan(toastrel,
+								   RelationGetRelid(toastidxs[validIndex]),
+								   true, SnapshotAny, 1, &toastkey);
+
+	if (systable_getnext(toastscan) != NULL)
+		result = true;
+
+	systable_endscan(toastscan);
+
+	/* Clean up */
+	toast_close_indexes(toastidxs, num_indexes, RowExclusiveLock);
+
+	return result;
+}
+
+/* ----------
+ * toastid_valueid_exists -
+ *
+ *	As above, but work from toast rel's OID not an open relation
+ * ----------
+ */
+static bool
+toastid_valueid_exists(Oid toastrelid, Oid valueid)
+{
+	bool		result;
+	Relation	toastrel;
+
+	toastrel = table_open(toastrelid, AccessShareLock);
+
+	result = toastrel_valueid_exists(toastrel, valueid);
+
+	table_close(toastrel, AccessShareLock);
+
+	return result;
+}
+
+/* ----------
+ * toast_get_valid_index
+ *
+ *	Get OID of valid index associated to given toast relation. A toast
+ *	relation can have only one valid index at the same time.
+ */
+Oid
+toast_get_valid_index(Oid toastoid, LOCKMODE lock)
+{
+	int			num_indexes;
+	int			validIndex;
+	Oid			validIndexOid;
+	Relation   *toastidxs;
+	Relation	toastrel;
+
+	/* Open the toast relation */
+	toastrel = table_open(toastoid, lock);
+
+	/* Look for the valid index of the toast relation */
+	validIndex = toast_open_indexes(toastrel,
+									lock,
+									&toastidxs,
+									&num_indexes);
+	validIndexOid = RelationGetRelid(toastidxs[validIndex]);
+
+	/* Close the toast relation and all its indexes */
+	toast_close_indexes(toastidxs, num_indexes, lock);
+	table_close(toastrel, lock);
+
+	return validIndexOid;
+}
+
+/* ----------
+ * toast_open_indexes
+ *
+ *	Get an array of the indexes associated to the given toast relation
+ *	and return as well the position of the valid index used by the toast
+ *	relation in this array. It is the responsibility of the caller of this
+ *	function to close the indexes as well as free them.
+ */
+int
+toast_open_indexes(Relation toastrel,
+				   LOCKMODE lock,
+				   Relation **toastidxs,
+				   int *num_indexes)
+{
+	int			i = 0;
+	int			res = 0;
+	bool		found = false;
+	List	   *indexlist;
+	ListCell   *lc;
+
+	/* Get index list of the toast relation */
+	indexlist = RelationGetIndexList(toastrel);
+	Assert(indexlist != NIL);
+
+	*num_indexes = list_length(indexlist);
+
+	/* Open all the index relations */
+	*toastidxs = (Relation *) palloc(*num_indexes * sizeof(Relation));
+	foreach(lc, indexlist)
+		(*toastidxs)[i++] = index_open(lfirst_oid(lc), lock);
+
+	/* Fetch the first valid index in list */
+	for (i = 0; i < *num_indexes; i++)
+	{
+		Relation	toastidx = (*toastidxs)[i];
+
+		if (toastidx->rd_index->indisvalid)
+		{
+			res = i;
+			found = true;
+			break;
+		}
+	}
+
+	/*
+	 * Free index list, not necessary anymore as relations are opened and a
+	 * valid index has been found.
+	 */
+	list_free(indexlist);
+
+	/*
+	 * The toast relation should have one valid index, so something is going
+	 * wrong if there is nothing.
+	 */
+	if (!found)
+		elog(ERROR, "no valid index found for toast relation with Oid %u",
+			 RelationGetRelid(toastrel));
+
+	return res;
+}
+
+/* ----------
+ * toast_close_indexes
+ *
+ *	Close an array of indexes for a toast relation and free it. This should
+ *	be called for a set of indexes opened previously with toast_open_indexes.
+ */
+void
+toast_close_indexes(Relation *toastidxs, int num_indexes, LOCKMODE lock)
+{
+	int			i;
+
+	/* Close relations and clean up things */
+	for (i = 0; i < num_indexes; i++)
+		index_close(toastidxs[i], lock);
+	pfree(toastidxs);
+}
+
+/* ----------
+ * init_toast_snapshot
+ *
+ *	Initialize an appropriate TOAST snapshot.  We must use an MVCC snapshot
+ *	to initialize the TOAST snapshot; since we don't know which one to use,
+ *	just use the oldest one.  This is safe: at worst, we will get a "snapshot
+ *	too old" error that might have been avoided otherwise.
+ */
+void
+init_toast_snapshot(Snapshot toast_snapshot)
+{
+	Snapshot	snapshot = GetOldestSnapshot();
+
+	if (snapshot == NULL)
+		elog(ERROR, "no known snapshots");
+
+	InitToastSnapshot(*toast_snapshot, snapshot->lsn, snapshot->whenTaken);
+}
diff --git a/src/backend/access/heap/Makefile b/src/backend/access/heap/Makefile
index b2a017249b..38497b09c0 100644
--- a/src/backend/access/heap/Makefile
+++ b/src/backend/access/heap/Makefile
@@ -13,6 +13,6 @@ top_builddir = ../../../..
 include $(top_builddir)/src/Makefile.global
 
 OBJS = heapam.o heapam_handler.o heapam_visibility.o hio.o pruneheap.o rewriteheap.o \
-	syncscan.o tuptoaster.o vacuumlazy.o visibilitymap.o
+	syncscan.o heaptoast.o vacuumlazy.o visibilitymap.o
 
 include $(top_srcdir)/src/backend/common.mk
diff --git a/src/backend/access/heap/heapam.c b/src/backend/access/heap/heapam.c
index 19d2c529d8..469c27ce48 100644
--- a/src/backend/access/heap/heapam.c
+++ b/src/backend/access/heap/heapam.c
@@ -36,6 +36,7 @@
 #include "access/genam.h"
 #include "access/heapam.h"
 #include "access/heapam_xlog.h"
+#include "access/heaptoast.h"
 #include "access/hio.h"
 #include "access/multixact.h"
 #include "access/parallel.h"
@@ -43,7 +44,6 @@
 #include "access/sysattr.h"
 #include "access/tableam.h"
 #include "access/transam.h"
-#include "access/tuptoaster.h"
 #include "access/valid.h"
 #include "access/visibilitymap.h"
 #include "access/xact.h"
diff --git a/src/backend/access/heap/heapam_handler.c b/src/backend/access/heap/heapam_handler.c
index 56b2abda5f..c7d5ff3850 100644
--- a/src/backend/access/heap/heapam_handler.c
+++ b/src/backend/access/heap/heapam_handler.c
@@ -25,11 +25,11 @@
 
 #include "access/genam.h"
 #include "access/heapam.h"
+#include "access/heaptoast.h"
 #include "access/multixact.h"
 #include "access/rewriteheap.h"
 #include "access/tableam.h"
 #include "access/tsmapi.h"
-#include "access/tuptoaster.h"
 #include "access/xact.h"
 #include "catalog/catalog.h"
 #include "catalog/index.h"
diff --git a/src/backend/access/heap/heaptoast.c b/src/backend/access/heap/heaptoast.c
new file mode 100644
index 0000000000..5d105e3517
--- /dev/null
+++ b/src/backend/access/heap/heaptoast.c
@@ -0,0 +1,917 @@
+/*-------------------------------------------------------------------------
+ *
+ * heaptoast.c
+ *	  Heap-specific definitions for external and compressed storage
+ *	  of variable size attributes.
+ *
+ * Copyright (c) 2000-2019, PostgreSQL Global Development Group
+ *
+ *
+ * IDENTIFICATION
+ *	  src/backend/access/heap/heaptoast.c
+ *
+ *
+ * INTERFACE ROUTINES
+ *		toast_insert_or_update -
+ *			Try to make a given tuple fit into one page by compressing
+ *			or moving off attributes
+ *
+ *		toast_delete -
+ *			Reclaim toast storage when a tuple is deleted
+ *
+ *-------------------------------------------------------------------------
+ */
+
+#include "postgres.h"
+
+#include "access/detoast.h"
+#include "access/heapam.h"
+#include "access/heaptoast.h"
+#include "access/toast_internals.h"
+
+
+/* ----------
+ * toast_delete -
+ *
+ *	Cascaded delete toast-entries on DELETE
+ * ----------
+ */
+void
+toast_delete(Relation rel, HeapTuple oldtup, bool is_speculative)
+{
+	TupleDesc	tupleDesc;
+	int			numAttrs;
+	int			i;
+	Datum		toast_values[MaxHeapAttributeNumber];
+	bool		toast_isnull[MaxHeapAttributeNumber];
+
+	/*
+	 * We should only ever be called for tuples of plain relations or
+	 * materialized views --- recursing on a toast rel is bad news.
+	 */
+	Assert(rel->rd_rel->relkind == RELKIND_RELATION ||
+		   rel->rd_rel->relkind == RELKIND_MATVIEW);
+
+	/*
+	 * Get the tuple descriptor and break down the tuple into fields.
+	 *
+	 * NOTE: it's debatable whether to use heap_deform_tuple() here or just
+	 * heap_getattr() only the varlena columns.  The latter could win if there
+	 * are few varlena columns and many non-varlena ones. However,
+	 * heap_deform_tuple costs only O(N) while the heap_getattr way would cost
+	 * O(N^2) if there are many varlena columns, so it seems better to err on
+	 * the side of linear cost.  (We won't even be here unless there's at
+	 * least one varlena column, by the way.)
+	 */
+	tupleDesc = rel->rd_att;
+	numAttrs = tupleDesc->natts;
+
+	Assert(numAttrs <= MaxHeapAttributeNumber);
+	heap_deform_tuple(oldtup, tupleDesc, toast_values, toast_isnull);
+
+	/*
+	 * Check for external stored attributes and delete them from the secondary
+	 * relation.
+	 */
+	for (i = 0; i < numAttrs; i++)
+	{
+		if (TupleDescAttr(tupleDesc, i)->attlen == -1)
+		{
+			Datum		value = toast_values[i];
+
+			if (toast_isnull[i])
+				continue;
+			else if (VARATT_IS_EXTERNAL_ONDISK(PointerGetDatum(value)))
+				toast_delete_datum(rel, value, is_speculative);
+		}
+	}
+}
+
+
+/* ----------
+ * toast_insert_or_update -
+ *
+ *	Delete no-longer-used toast-entries and create new ones to
+ *	make the new tuple fit on INSERT or UPDATE
+ *
+ * Inputs:
+ *	newtup: the candidate new tuple to be inserted
+ *	oldtup: the old row version for UPDATE, or NULL for INSERT
+ *	options: options to be passed to heap_insert() for toast rows
+ * Result:
+ *	either newtup if no toasting is needed, or a palloc'd modified tuple
+ *	that is what should actually get stored
+ *
+ * NOTE: neither newtup nor oldtup will be modified.  This is a change
+ * from the pre-8.1 API of this routine.
+ * ----------
+ */
+HeapTuple
+toast_insert_or_update(Relation rel, HeapTuple newtup, HeapTuple oldtup,
+					   int options)
+{
+	HeapTuple	result_tuple;
+	TupleDesc	tupleDesc;
+	int			numAttrs;
+	int			i;
+
+	bool		need_change = false;
+	bool		need_free = false;
+	bool		need_delold = false;
+	bool		has_nulls = false;
+
+	Size		maxDataLen;
+	Size		hoff;
+
+	char		toast_action[MaxHeapAttributeNumber];
+	bool		toast_isnull[MaxHeapAttributeNumber];
+	bool		toast_oldisnull[MaxHeapAttributeNumber];
+	Datum		toast_values[MaxHeapAttributeNumber];
+	Datum		toast_oldvalues[MaxHeapAttributeNumber];
+	struct varlena *toast_oldexternal[MaxHeapAttributeNumber];
+	int32		toast_sizes[MaxHeapAttributeNumber];
+	bool		toast_free[MaxHeapAttributeNumber];
+	bool		toast_delold[MaxHeapAttributeNumber];
+
+	/*
+	 * Ignore the INSERT_SPECULATIVE option. Speculative insertions/super
+	 * deletions just normally insert/delete the toast values. It seems
+	 * easiest to deal with that here, instead on, potentially, multiple
+	 * callers.
+	 */
+	options &= ~HEAP_INSERT_SPECULATIVE;
+
+	/*
+	 * We should only ever be called for tuples of plain relations or
+	 * materialized views --- recursing on a toast rel is bad news.
+	 */
+	Assert(rel->rd_rel->relkind == RELKIND_RELATION ||
+		   rel->rd_rel->relkind == RELKIND_MATVIEW);
+
+	/*
+	 * Get the tuple descriptor and break down the tuple(s) into fields.
+	 */
+	tupleDesc = rel->rd_att;
+	numAttrs = tupleDesc->natts;
+
+	Assert(numAttrs <= MaxHeapAttributeNumber);
+	heap_deform_tuple(newtup, tupleDesc, toast_values, toast_isnull);
+	if (oldtup != NULL)
+		heap_deform_tuple(oldtup, tupleDesc, toast_oldvalues, toast_oldisnull);
+
+	/* ----------
+	 * Then collect information about the values given
+	 *
+	 * NOTE: toast_action[i] can have these values:
+	 *		' '		default handling
+	 *		'p'		already processed --- don't touch it
+	 *		'x'		incompressible, but OK to move off
+	 *
+	 * NOTE: toast_sizes[i] is only made valid for varlena attributes with
+	 *		toast_action[i] different from 'p'.
+	 * ----------
+	 */
+	memset(toast_action, ' ', numAttrs * sizeof(char));
+	memset(toast_oldexternal, 0, numAttrs * sizeof(struct varlena *));
+	memset(toast_free, 0, numAttrs * sizeof(bool));
+	memset(toast_delold, 0, numAttrs * sizeof(bool));
+
+	for (i = 0; i < numAttrs; i++)
+	{
+		Form_pg_attribute att = TupleDescAttr(tupleDesc, i);
+		struct varlena *old_value;
+		struct varlena *new_value;
+
+		if (oldtup != NULL)
+		{
+			/*
+			 * For UPDATE get the old and new values of this attribute
+			 */
+			old_value = (struct varlena *) DatumGetPointer(toast_oldvalues[i]);
+			new_value = (struct varlena *) DatumGetPointer(toast_values[i]);
+
+			/*
+			 * If the old value is stored on disk, check if it has changed so
+			 * we have to delete it later.
+			 */
+			if (att->attlen == -1 && !toast_oldisnull[i] &&
+				VARATT_IS_EXTERNAL_ONDISK(old_value))
+			{
+				if (toast_isnull[i] || !VARATT_IS_EXTERNAL_ONDISK(new_value) ||
+					memcmp((char *) old_value, (char *) new_value,
+						   VARSIZE_EXTERNAL(old_value)) != 0)
+				{
+					/*
+					 * The old external stored value isn't needed any more
+					 * after the update
+					 */
+					toast_delold[i] = true;
+					need_delold = true;
+				}
+				else
+				{
+					/*
+					 * This attribute isn't changed by this update so we reuse
+					 * the original reference to the old value in the new
+					 * tuple.
+					 */
+					toast_action[i] = 'p';
+					continue;
+				}
+			}
+		}
+		else
+		{
+			/*
+			 * For INSERT simply get the new value
+			 */
+			new_value = (struct varlena *) DatumGetPointer(toast_values[i]);
+		}
+
+		/*
+		 * Handle NULL attributes
+		 */
+		if (toast_isnull[i])
+		{
+			toast_action[i] = 'p';
+			has_nulls = true;
+			continue;
+		}
+
+		/*
+		 * Now look at varlena attributes
+		 */
+		if (att->attlen == -1)
+		{
+			/*
+			 * If the table's attribute says PLAIN always, force it so.
+			 */
+			if (att->attstorage == 'p')
+				toast_action[i] = 'p';
+
+			/*
+			 * We took care of UPDATE above, so any external value we find
+			 * still in the tuple must be someone else's that we cannot reuse
+			 * (this includes the case of an out-of-line in-memory datum).
+			 * Fetch it back (without decompression, unless we are forcing
+			 * PLAIN storage).  If necessary, we'll push it out as a new
+			 * external value below.
+			 */
+			if (VARATT_IS_EXTERNAL(new_value))
+			{
+				toast_oldexternal[i] = new_value;
+				if (att->attstorage == 'p')
+					new_value = heap_tuple_untoast_attr(new_value);
+				else
+					new_value = heap_tuple_fetch_attr(new_value);
+				toast_values[i] = PointerGetDatum(new_value);
+				toast_free[i] = true;
+				need_change = true;
+				need_free = true;
+			}
+
+			/*
+			 * Remember the size of this attribute
+			 */
+			toast_sizes[i] = VARSIZE_ANY(new_value);
+		}
+		else
+		{
+			/*
+			 * Not a varlena attribute, plain storage always
+			 */
+			toast_action[i] = 'p';
+		}
+	}
+
+	/* ----------
+	 * Compress and/or save external until data fits into target length
+	 *
+	 *	1: Inline compress attributes with attstorage 'x', and store very
+	 *	   large attributes with attstorage 'x' or 'e' external immediately
+	 *	2: Store attributes with attstorage 'x' or 'e' external
+	 *	3: Inline compress attributes with attstorage 'm'
+	 *	4: Store attributes with attstorage 'm' external
+	 * ----------
+	 */
+
+	/* compute header overhead --- this should match heap_form_tuple() */
+	hoff = SizeofHeapTupleHeader;
+	if (has_nulls)
+		hoff += BITMAPLEN(numAttrs);
+	hoff = MAXALIGN(hoff);
+	/* now convert to a limit on the tuple data size */
+	maxDataLen = RelationGetToastTupleTarget(rel, TOAST_TUPLE_TARGET) - hoff;
+
+	/*
+	 * Look for attributes with attstorage 'x' to compress.  Also find large
+	 * attributes with attstorage 'x' or 'e', and store them external.
+	 */
+	while (heap_compute_data_size(tupleDesc,
+								  toast_values, toast_isnull) > maxDataLen)
+	{
+		int			biggest_attno = -1;
+		int32		biggest_size = MAXALIGN(TOAST_POINTER_SIZE);
+		Datum		old_value;
+		Datum		new_value;
+
+		/*
+		 * Search for the biggest yet unprocessed internal attribute
+		 */
+		for (i = 0; i < numAttrs; i++)
+		{
+			Form_pg_attribute att = TupleDescAttr(tupleDesc, i);
+
+			if (toast_action[i] != ' ')
+				continue;
+			if (VARATT_IS_EXTERNAL(DatumGetPointer(toast_values[i])))
+				continue;		/* can't happen, toast_action would be 'p' */
+			if (VARATT_IS_COMPRESSED(DatumGetPointer(toast_values[i])))
+				continue;
+			if (att->attstorage != 'x' && att->attstorage != 'e')
+				continue;
+			if (toast_sizes[i] > biggest_size)
+			{
+				biggest_attno = i;
+				biggest_size = toast_sizes[i];
+			}
+		}
+
+		if (biggest_attno < 0)
+			break;
+
+		/*
+		 * Attempt to compress it inline, if it has attstorage 'x'
+		 */
+		i = biggest_attno;
+		if (TupleDescAttr(tupleDesc, i)->attstorage == 'x')
+		{
+			old_value = toast_values[i];
+			new_value = toast_compress_datum(old_value);
+
+			if (DatumGetPointer(new_value) != NULL)
+			{
+				/* successful compression */
+				if (toast_free[i])
+					pfree(DatumGetPointer(old_value));
+				toast_values[i] = new_value;
+				toast_free[i] = true;
+				toast_sizes[i] = VARSIZE(DatumGetPointer(toast_values[i]));
+				need_change = true;
+				need_free = true;
+			}
+			else
+			{
+				/* incompressible, ignore on subsequent compression passes */
+				toast_action[i] = 'x';
+			}
+		}
+		else
+		{
+			/* has attstorage 'e', ignore on subsequent compression passes */
+			toast_action[i] = 'x';
+		}
+
+		/*
+		 * If this value is by itself more than maxDataLen (after compression
+		 * if any), push it out to the toast table immediately, if possible.
+		 * This avoids uselessly compressing other fields in the common case
+		 * where we have one long field and several short ones.
+		 *
+		 * XXX maybe the threshold should be less than maxDataLen?
+		 */
+		if (toast_sizes[i] > maxDataLen &&
+			rel->rd_rel->reltoastrelid != InvalidOid)
+		{
+			old_value = toast_values[i];
+			toast_action[i] = 'p';
+			toast_values[i] = toast_save_datum(rel, toast_values[i],
+											   toast_oldexternal[i], options);
+			if (toast_free[i])
+				pfree(DatumGetPointer(old_value));
+			toast_free[i] = true;
+			need_change = true;
+			need_free = true;
+		}
+	}
+
+	/*
+	 * Second we look for attributes of attstorage 'x' or 'e' that are still
+	 * inline.  But skip this if there's no toast table to push them to.
+	 */
+	while (heap_compute_data_size(tupleDesc,
+								  toast_values, toast_isnull) > maxDataLen &&
+		   rel->rd_rel->reltoastrelid != InvalidOid)
+	{
+		int			biggest_attno = -1;
+		int32		biggest_size = MAXALIGN(TOAST_POINTER_SIZE);
+		Datum		old_value;
+
+		/*------
+		 * Search for the biggest yet inlined attribute with
+		 * attstorage equals 'x' or 'e'
+		 *------
+		 */
+		for (i = 0; i < numAttrs; i++)
+		{
+			Form_pg_attribute att = TupleDescAttr(tupleDesc, i);
+
+			if (toast_action[i] == 'p')
+				continue;
+			if (VARATT_IS_EXTERNAL(DatumGetPointer(toast_values[i])))
+				continue;		/* can't happen, toast_action would be 'p' */
+			if (att->attstorage != 'x' && att->attstorage != 'e')
+				continue;
+			if (toast_sizes[i] > biggest_size)
+			{
+				biggest_attno = i;
+				biggest_size = toast_sizes[i];
+			}
+		}
+
+		if (biggest_attno < 0)
+			break;
+
+		/*
+		 * Store this external
+		 */
+		i = biggest_attno;
+		old_value = toast_values[i];
+		toast_action[i] = 'p';
+		toast_values[i] = toast_save_datum(rel, toast_values[i],
+										   toast_oldexternal[i], options);
+		if (toast_free[i])
+			pfree(DatumGetPointer(old_value));
+		toast_free[i] = true;
+
+		need_change = true;
+		need_free = true;
+	}
+
+	/*
+	 * Round 3 - this time we take attributes with storage 'm' into
+	 * compression
+	 */
+	while (heap_compute_data_size(tupleDesc,
+								  toast_values, toast_isnull) > maxDataLen)
+	{
+		int			biggest_attno = -1;
+		int32		biggest_size = MAXALIGN(TOAST_POINTER_SIZE);
+		Datum		old_value;
+		Datum		new_value;
+
+		/*
+		 * Search for the biggest yet uncompressed internal attribute
+		 */
+		for (i = 0; i < numAttrs; i++)
+		{
+			if (toast_action[i] != ' ')
+				continue;
+			if (VARATT_IS_EXTERNAL(DatumGetPointer(toast_values[i])))
+				continue;		/* can't happen, toast_action would be 'p' */
+			if (VARATT_IS_COMPRESSED(DatumGetPointer(toast_values[i])))
+				continue;
+			if (TupleDescAttr(tupleDesc, i)->attstorage != 'm')
+				continue;
+			if (toast_sizes[i] > biggest_size)
+			{
+				biggest_attno = i;
+				biggest_size = toast_sizes[i];
+			}
+		}
+
+		if (biggest_attno < 0)
+			break;
+
+		/*
+		 * Attempt to compress it inline
+		 */
+		i = biggest_attno;
+		old_value = toast_values[i];
+		new_value = toast_compress_datum(old_value);
+
+		if (DatumGetPointer(new_value) != NULL)
+		{
+			/* successful compression */
+			if (toast_free[i])
+				pfree(DatumGetPointer(old_value));
+			toast_values[i] = new_value;
+			toast_free[i] = true;
+			toast_sizes[i] = VARSIZE(DatumGetPointer(toast_values[i]));
+			need_change = true;
+			need_free = true;
+		}
+		else
+		{
+			/* incompressible, ignore on subsequent compression passes */
+			toast_action[i] = 'x';
+		}
+	}
+
+	/*
+	 * Finally we store attributes of type 'm' externally.  At this point we
+	 * increase the target tuple size, so that 'm' attributes aren't stored
+	 * externally unless really necessary.
+	 */
+	maxDataLen = TOAST_TUPLE_TARGET_MAIN - hoff;
+
+	while (heap_compute_data_size(tupleDesc,
+								  toast_values, toast_isnull) > maxDataLen &&
+		   rel->rd_rel->reltoastrelid != InvalidOid)
+	{
+		int			biggest_attno = -1;
+		int32		biggest_size = MAXALIGN(TOAST_POINTER_SIZE);
+		Datum		old_value;
+
+		/*--------
+		 * Search for the biggest yet inlined attribute with
+		 * attstorage = 'm'
+		 *--------
+		 */
+		for (i = 0; i < numAttrs; i++)
+		{
+			if (toast_action[i] == 'p')
+				continue;
+			if (VARATT_IS_EXTERNAL(DatumGetPointer(toast_values[i])))
+				continue;		/* can't happen, toast_action would be 'p' */
+			if (TupleDescAttr(tupleDesc, i)->attstorage != 'm')
+				continue;
+			if (toast_sizes[i] > biggest_size)
+			{
+				biggest_attno = i;
+				biggest_size = toast_sizes[i];
+			}
+		}
+
+		if (biggest_attno < 0)
+			break;
+
+		/*
+		 * Store this external
+		 */
+		i = biggest_attno;
+		old_value = toast_values[i];
+		toast_action[i] = 'p';
+		toast_values[i] = toast_save_datum(rel, toast_values[i],
+										   toast_oldexternal[i], options);
+		if (toast_free[i])
+			pfree(DatumGetPointer(old_value));
+		toast_free[i] = true;
+
+		need_change = true;
+		need_free = true;
+	}
+
+	/*
+	 * In the case we toasted any values, we need to build a new heap tuple
+	 * with the changed values.
+	 */
+	if (need_change)
+	{
+		HeapTupleHeader olddata = newtup->t_data;
+		HeapTupleHeader new_data;
+		int32		new_header_len;
+		int32		new_data_len;
+		int32		new_tuple_len;
+
+		/*
+		 * Calculate the new size of the tuple.
+		 *
+		 * Note: we used to assume here that the old tuple's t_hoff must equal
+		 * the new_header_len value, but that was incorrect.  The old tuple
+		 * might have a smaller-than-current natts, if there's been an ALTER
+		 * TABLE ADD COLUMN since it was stored; and that would lead to a
+		 * different conclusion about the size of the null bitmap, or even
+		 * whether there needs to be one at all.
+		 */
+		new_header_len = SizeofHeapTupleHeader;
+		if (has_nulls)
+			new_header_len += BITMAPLEN(numAttrs);
+		new_header_len = MAXALIGN(new_header_len);
+		new_data_len = heap_compute_data_size(tupleDesc,
+											  toast_values, toast_isnull);
+		new_tuple_len = new_header_len + new_data_len;
+
+		/*
+		 * Allocate and zero the space needed, and fill HeapTupleData fields.
+		 */
+		result_tuple = (HeapTuple) palloc0(HEAPTUPLESIZE + new_tuple_len);
+		result_tuple->t_len = new_tuple_len;
+		result_tuple->t_self = newtup->t_self;
+		result_tuple->t_tableOid = newtup->t_tableOid;
+		new_data = (HeapTupleHeader) ((char *) result_tuple + HEAPTUPLESIZE);
+		result_tuple->t_data = new_data;
+
+		/*
+		 * Copy the existing tuple header, but adjust natts and t_hoff.
+		 */
+		memcpy(new_data, olddata, SizeofHeapTupleHeader);
+		HeapTupleHeaderSetNatts(new_data, numAttrs);
+		new_data->t_hoff = new_header_len;
+
+		/* Copy over the data, and fill the null bitmap if needed */
+		heap_fill_tuple(tupleDesc,
+						toast_values,
+						toast_isnull,
+						(char *) new_data + new_header_len,
+						new_data_len,
+						&(new_data->t_infomask),
+						has_nulls ? new_data->t_bits : NULL);
+	}
+	else
+		result_tuple = newtup;
+
+	/*
+	 * Free allocated temp values
+	 */
+	if (need_free)
+		for (i = 0; i < numAttrs; i++)
+			if (toast_free[i])
+				pfree(DatumGetPointer(toast_values[i]));
+
+	/*
+	 * Delete external values from the old tuple
+	 */
+	if (need_delold)
+		for (i = 0; i < numAttrs; i++)
+			if (toast_delold[i])
+				toast_delete_datum(rel, toast_oldvalues[i], false);
+
+	return result_tuple;
+}
+
+
+/* ----------
+ * toast_flatten_tuple -
+ *
+ *	"Flatten" a tuple to contain no out-of-line toasted fields.
+ *	(This does not eliminate compressed or short-header datums.)
+ *
+ *	Note: we expect the caller already checked HeapTupleHasExternal(tup),
+ *	so there is no need for a short-circuit path.
+ * ----------
+ */
+HeapTuple
+toast_flatten_tuple(HeapTuple tup, TupleDesc tupleDesc)
+{
+	HeapTuple	new_tuple;
+	int			numAttrs = tupleDesc->natts;
+	int			i;
+	Datum		toast_values[MaxTupleAttributeNumber];
+	bool		toast_isnull[MaxTupleAttributeNumber];
+	bool		toast_free[MaxTupleAttributeNumber];
+
+	/*
+	 * Break down the tuple into fields.
+	 */
+	Assert(numAttrs <= MaxTupleAttributeNumber);
+	heap_deform_tuple(tup, tupleDesc, toast_values, toast_isnull);
+
+	memset(toast_free, 0, numAttrs * sizeof(bool));
+
+	for (i = 0; i < numAttrs; i++)
+	{
+		/*
+		 * Look at non-null varlena attributes
+		 */
+		if (!toast_isnull[i] && TupleDescAttr(tupleDesc, i)->attlen == -1)
+		{
+			struct varlena *new_value;
+
+			new_value = (struct varlena *) DatumGetPointer(toast_values[i]);
+			if (VARATT_IS_EXTERNAL(new_value))
+			{
+				new_value = heap_tuple_fetch_attr(new_value);
+				toast_values[i] = PointerGetDatum(new_value);
+				toast_free[i] = true;
+			}
+		}
+	}
+
+	/*
+	 * Form the reconfigured tuple.
+	 */
+	new_tuple = heap_form_tuple(tupleDesc, toast_values, toast_isnull);
+
+	/*
+	 * Be sure to copy the tuple's identity fields.  We also make a point of
+	 * copying visibility info, just in case anybody looks at those fields in
+	 * a syscache entry.
+	 */
+	new_tuple->t_self = tup->t_self;
+	new_tuple->t_tableOid = tup->t_tableOid;
+
+	new_tuple->t_data->t_choice = tup->t_data->t_choice;
+	new_tuple->t_data->t_ctid = tup->t_data->t_ctid;
+	new_tuple->t_data->t_infomask &= ~HEAP_XACT_MASK;
+	new_tuple->t_data->t_infomask |=
+		tup->t_data->t_infomask & HEAP_XACT_MASK;
+	new_tuple->t_data->t_infomask2 &= ~HEAP2_XACT_MASK;
+	new_tuple->t_data->t_infomask2 |=
+		tup->t_data->t_infomask2 & HEAP2_XACT_MASK;
+
+	/*
+	 * Free allocated temp values
+	 */
+	for (i = 0; i < numAttrs; i++)
+		if (toast_free[i])
+			pfree(DatumGetPointer(toast_values[i]));
+
+	return new_tuple;
+}
+
+
+/* ----------
+ * toast_flatten_tuple_to_datum -
+ *
+ *	"Flatten" a tuple containing out-of-line toasted fields into a Datum.
+ *	The result is always palloc'd in the current memory context.
+ *
+ *	We have a general rule that Datums of container types (rows, arrays,
+ *	ranges, etc) must not contain any external TOAST pointers.  Without
+ *	this rule, we'd have to look inside each Datum when preparing a tuple
+ *	for storage, which would be expensive and would fail to extend cleanly
+ *	to new sorts of container types.
+ *
+ *	However, we don't want to say that tuples represented as HeapTuples
+ *	can't contain toasted fields, so instead this routine should be called
+ *	when such a HeapTuple is being converted into a Datum.
+ *
+ *	While we're at it, we decompress any compressed fields too.  This is not
+ *	necessary for correctness, but reflects an expectation that compression
+ *	will be more effective if applied to the whole tuple not individual
+ *	fields.  We are not so concerned about that that we want to deconstruct
+ *	and reconstruct tuples just to get rid of compressed fields, however.
+ *	So callers typically won't call this unless they see that the tuple has
+ *	at least one external field.
+ *
+ *	On the other hand, in-line short-header varlena fields are left alone.
+ *	If we "untoasted" them here, they'd just get changed back to short-header
+ *	format anyway within heap_fill_tuple.
+ * ----------
+ */
+Datum
+toast_flatten_tuple_to_datum(HeapTupleHeader tup,
+							 uint32 tup_len,
+							 TupleDesc tupleDesc)
+{
+	HeapTupleHeader new_data;
+	int32		new_header_len;
+	int32		new_data_len;
+	int32		new_tuple_len;
+	HeapTupleData tmptup;
+	int			numAttrs = tupleDesc->natts;
+	int			i;
+	bool		has_nulls = false;
+	Datum		toast_values[MaxTupleAttributeNumber];
+	bool		toast_isnull[MaxTupleAttributeNumber];
+	bool		toast_free[MaxTupleAttributeNumber];
+
+	/* Build a temporary HeapTuple control structure */
+	tmptup.t_len = tup_len;
+	ItemPointerSetInvalid(&(tmptup.t_self));
+	tmptup.t_tableOid = InvalidOid;
+	tmptup.t_data = tup;
+
+	/*
+	 * Break down the tuple into fields.
+	 */
+	Assert(numAttrs <= MaxTupleAttributeNumber);
+	heap_deform_tuple(&tmptup, tupleDesc, toast_values, toast_isnull);
+
+	memset(toast_free, 0, numAttrs * sizeof(bool));
+
+	for (i = 0; i < numAttrs; i++)
+	{
+		/*
+		 * Look at non-null varlena attributes
+		 */
+		if (toast_isnull[i])
+			has_nulls = true;
+		else if (TupleDescAttr(tupleDesc, i)->attlen == -1)
+		{
+			struct varlena *new_value;
+
+			new_value = (struct varlena *) DatumGetPointer(toast_values[i]);
+			if (VARATT_IS_EXTERNAL(new_value) ||
+				VARATT_IS_COMPRESSED(new_value))
+			{
+				new_value = heap_tuple_untoast_attr(new_value);
+				toast_values[i] = PointerGetDatum(new_value);
+				toast_free[i] = true;
+			}
+		}
+	}
+
+	/*
+	 * Calculate the new size of the tuple.
+	 *
+	 * This should match the reconstruction code in toast_insert_or_update.
+	 */
+	new_header_len = SizeofHeapTupleHeader;
+	if (has_nulls)
+		new_header_len += BITMAPLEN(numAttrs);
+	new_header_len = MAXALIGN(new_header_len);
+	new_data_len = heap_compute_data_size(tupleDesc,
+										  toast_values, toast_isnull);
+	new_tuple_len = new_header_len + new_data_len;
+
+	new_data = (HeapTupleHeader) palloc0(new_tuple_len);
+
+	/*
+	 * Copy the existing tuple header, but adjust natts and t_hoff.
+	 */
+	memcpy(new_data, tup, SizeofHeapTupleHeader);
+	HeapTupleHeaderSetNatts(new_data, numAttrs);
+	new_data->t_hoff = new_header_len;
+
+	/* Set the composite-Datum header fields correctly */
+	HeapTupleHeaderSetDatumLength(new_data, new_tuple_len);
+	HeapTupleHeaderSetTypeId(new_data, tupleDesc->tdtypeid);
+	HeapTupleHeaderSetTypMod(new_data, tupleDesc->tdtypmod);
+
+	/* Copy over the data, and fill the null bitmap if needed */
+	heap_fill_tuple(tupleDesc,
+					toast_values,
+					toast_isnull,
+					(char *) new_data + new_header_len,
+					new_data_len,
+					&(new_data->t_infomask),
+					has_nulls ? new_data->t_bits : NULL);
+
+	/*
+	 * Free allocated temp values
+	 */
+	for (i = 0; i < numAttrs; i++)
+		if (toast_free[i])
+			pfree(DatumGetPointer(toast_values[i]));
+
+	return PointerGetDatum(new_data);
+}
+
+
+/* ----------
+ * toast_build_flattened_tuple -
+ *
+ *	Build a tuple containing no out-of-line toasted fields.
+ *	(This does not eliminate compressed or short-header datums.)
+ *
+ *	This is essentially just like heap_form_tuple, except that it will
+ *	expand any external-data pointers beforehand.
+ *
+ *	It's not very clear whether it would be preferable to decompress
+ *	in-line compressed datums while at it.  For now, we don't.
+ * ----------
+ */
+HeapTuple
+toast_build_flattened_tuple(TupleDesc tupleDesc,
+							Datum *values,
+							bool *isnull)
+{
+	HeapTuple	new_tuple;
+	int			numAttrs = tupleDesc->natts;
+	int			num_to_free;
+	int			i;
+	Datum		new_values[MaxTupleAttributeNumber];
+	Pointer		freeable_values[MaxTupleAttributeNumber];
+
+	/*
+	 * We can pass the caller's isnull array directly to heap_form_tuple, but
+	 * we potentially need to modify the values array.
+	 */
+	Assert(numAttrs <= MaxTupleAttributeNumber);
+	memcpy(new_values, values, numAttrs * sizeof(Datum));
+
+	num_to_free = 0;
+	for (i = 0; i < numAttrs; i++)
+	{
+		/*
+		 * Look at non-null varlena attributes
+		 */
+		if (!isnull[i] && TupleDescAttr(tupleDesc, i)->attlen == -1)
+		{
+			struct varlena *new_value;
+
+			new_value = (struct varlena *) DatumGetPointer(new_values[i]);
+			if (VARATT_IS_EXTERNAL(new_value))
+			{
+				new_value = heap_tuple_fetch_attr(new_value);
+				new_values[i] = PointerGetDatum(new_value);
+				freeable_values[num_to_free++] = (Pointer) new_value;
+			}
+		}
+	}
+
+	/*
+	 * Form the reconfigured tuple.
+	 */
+	new_tuple = heap_form_tuple(tupleDesc, new_values, isnull);
+
+	/*
+	 * Free allocated temp values
+	 */
+	for (i = 0; i < num_to_free; i++)
+		pfree(freeable_values[i]);
+
+	return new_tuple;
+}
diff --git a/src/backend/access/heap/rewriteheap.c b/src/backend/access/heap/rewriteheap.c
index bce4274362..9f90830ad5 100644
--- a/src/backend/access/heap/rewriteheap.c
+++ b/src/backend/access/heap/rewriteheap.c
@@ -109,9 +109,9 @@
 
 #include "access/heapam.h"
 #include "access/heapam_xlog.h"
+#include "access/heaptoast.h"
 #include "access/rewriteheap.h"
 #include "access/transam.h"
-#include "access/tuptoaster.h"
 #include "access/xact.h"
 #include "access/xloginsert.h"
 
diff --git a/src/backend/access/heap/tuptoaster.c b/src/backend/access/heap/tuptoaster.c
deleted file mode 100644
index 74e957abb7..0000000000
--- a/src/backend/access/heap/tuptoaster.c
+++ /dev/null
@@ -1,2411 +0,0 @@
-/*-------------------------------------------------------------------------
- *
- * tuptoaster.c
- *	  Support routines for external and compressed storage of
- *	  variable size attributes.
- *
- * Copyright (c) 2000-2019, PostgreSQL Global Development Group
- *
- *
- * IDENTIFICATION
- *	  src/backend/access/heap/tuptoaster.c
- *
- *
- * INTERFACE ROUTINES
- *		toast_insert_or_update -
- *			Try to make a given tuple fit into one page by compressing
- *			or moving off attributes
- *
- *		toast_delete -
- *			Reclaim toast storage when a tuple is deleted
- *
- *		heap_tuple_untoast_attr -
- *			Fetch back a given value from the "secondary" relation
- *
- *-------------------------------------------------------------------------
- */
-
-#include "postgres.h"
-
-#include <unistd.h>
-#include <fcntl.h>
-
-#include "access/genam.h"
-#include "access/heapam.h"
-#include "access/tuptoaster.h"
-#include "access/xact.h"
-#include "catalog/catalog.h"
-#include "common/pg_lzcompress.h"
-#include "miscadmin.h"
-#include "utils/expandeddatum.h"
-#include "utils/fmgroids.h"
-#include "utils/rel.h"
-#include "utils/snapmgr.h"
-#include "utils/typcache.h"
-
-
-#undef TOAST_DEBUG
-
-/*
- *	The information at the start of the compressed toast data.
- */
-typedef struct toast_compress_header
-{
-	int32		vl_len_;		/* varlena header (do not touch directly!) */
-	int32		rawsize;
-} toast_compress_header;
-
-/*
- * Utilities for manipulation of header information for compressed
- * toast entries.
- */
-#define TOAST_COMPRESS_HDRSZ		((int32) sizeof(toast_compress_header))
-#define TOAST_COMPRESS_RAWSIZE(ptr) (((toast_compress_header *) (ptr))->rawsize)
-#define TOAST_COMPRESS_RAWDATA(ptr) \
-	(((char *) (ptr)) + TOAST_COMPRESS_HDRSZ)
-#define TOAST_COMPRESS_SET_RAWSIZE(ptr, len) \
-	(((toast_compress_header *) (ptr))->rawsize = (len))
-
-static void toast_delete_datum(Relation rel, Datum value, bool is_speculative);
-static Datum toast_save_datum(Relation rel, Datum value,
-				 struct varlena *oldexternal, int options);
-static bool toastrel_valueid_exists(Relation toastrel, Oid valueid);
-static bool toastid_valueid_exists(Oid toastrelid, Oid valueid);
-static struct varlena *toast_fetch_datum(struct varlena *attr);
-static struct varlena *toast_fetch_datum_slice(struct varlena *attr,
-						int32 sliceoffset, int32 length);
-static struct varlena *toast_decompress_datum(struct varlena *attr);
-static struct varlena *toast_decompress_datum_slice(struct varlena *attr, int32 slicelength);
-static int toast_open_indexes(Relation toastrel,
-				   LOCKMODE lock,
-				   Relation **toastidxs,
-				   int *num_indexes);
-static void toast_close_indexes(Relation *toastidxs, int num_indexes,
-					LOCKMODE lock);
-static void init_toast_snapshot(Snapshot toast_snapshot);
-
-
-/* ----------
- * heap_tuple_fetch_attr -
- *
- *	Public entry point to get back a toasted value from
- *	external source (possibly still in compressed format).
- *
- * This will return a datum that contains all the data internally, ie, not
- * relying on external storage or memory, but it can still be compressed or
- * have a short header.  Note some callers assume that if the input is an
- * EXTERNAL datum, the result will be a pfree'able chunk.
- * ----------
- */
-struct varlena *
-heap_tuple_fetch_attr(struct varlena *attr)
-{
-	struct varlena *result;
-
-	if (VARATT_IS_EXTERNAL_ONDISK(attr))
-	{
-		/*
-		 * This is an external stored plain value
-		 */
-		result = toast_fetch_datum(attr);
-	}
-	else if (VARATT_IS_EXTERNAL_INDIRECT(attr))
-	{
-		/*
-		 * This is an indirect pointer --- dereference it
-		 */
-		struct varatt_indirect redirect;
-
-		VARATT_EXTERNAL_GET_POINTER(redirect, attr);
-		attr = (struct varlena *) redirect.pointer;
-
-		/* nested indirect Datums aren't allowed */
-		Assert(!VARATT_IS_EXTERNAL_INDIRECT(attr));
-
-		/* recurse if value is still external in some other way */
-		if (VARATT_IS_EXTERNAL(attr))
-			return heap_tuple_fetch_attr(attr);
-
-		/*
-		 * Copy into the caller's memory context, in case caller tries to
-		 * pfree the result.
-		 */
-		result = (struct varlena *) palloc(VARSIZE_ANY(attr));
-		memcpy(result, attr, VARSIZE_ANY(attr));
-	}
-	else if (VARATT_IS_EXTERNAL_EXPANDED(attr))
-	{
-		/*
-		 * This is an expanded-object pointer --- get flat format
-		 */
-		ExpandedObjectHeader *eoh;
-		Size		resultsize;
-
-		eoh = DatumGetEOHP(PointerGetDatum(attr));
-		resultsize = EOH_get_flat_size(eoh);
-		result = (struct varlena *) palloc(resultsize);
-		EOH_flatten_into(eoh, (void *) result, resultsize);
-	}
-	else
-	{
-		/*
-		 * This is a plain value inside of the main tuple - why am I called?
-		 */
-		result = attr;
-	}
-
-	return result;
-}
-
-
-/* ----------
- * heap_tuple_untoast_attr -
- *
- *	Public entry point to get back a toasted value from compression
- *	or external storage.  The result is always non-extended varlena form.
- *
- * Note some callers assume that if the input is an EXTERNAL or COMPRESSED
- * datum, the result will be a pfree'able chunk.
- * ----------
- */
-struct varlena *
-heap_tuple_untoast_attr(struct varlena *attr)
-{
-	if (VARATT_IS_EXTERNAL_ONDISK(attr))
-	{
-		/*
-		 * This is an externally stored datum --- fetch it back from there
-		 */
-		attr = toast_fetch_datum(attr);
-		/* If it's compressed, decompress it */
-		if (VARATT_IS_COMPRESSED(attr))
-		{
-			struct varlena *tmp = attr;
-
-			attr = toast_decompress_datum(tmp);
-			pfree(tmp);
-		}
-	}
-	else if (VARATT_IS_EXTERNAL_INDIRECT(attr))
-	{
-		/*
-		 * This is an indirect pointer --- dereference it
-		 */
-		struct varatt_indirect redirect;
-
-		VARATT_EXTERNAL_GET_POINTER(redirect, attr);
-		attr = (struct varlena *) redirect.pointer;
-
-		/* nested indirect Datums aren't allowed */
-		Assert(!VARATT_IS_EXTERNAL_INDIRECT(attr));
-
-		/* recurse in case value is still extended in some other way */
-		attr = heap_tuple_untoast_attr(attr);
-
-		/* if it isn't, we'd better copy it */
-		if (attr == (struct varlena *) redirect.pointer)
-		{
-			struct varlena *result;
-
-			result = (struct varlena *) palloc(VARSIZE_ANY(attr));
-			memcpy(result, attr, VARSIZE_ANY(attr));
-			attr = result;
-		}
-	}
-	else if (VARATT_IS_EXTERNAL_EXPANDED(attr))
-	{
-		/*
-		 * This is an expanded-object pointer --- get flat format
-		 */
-		attr = heap_tuple_fetch_attr(attr);
-		/* flatteners are not allowed to produce compressed/short output */
-		Assert(!VARATT_IS_EXTENDED(attr));
-	}
-	else if (VARATT_IS_COMPRESSED(attr))
-	{
-		/*
-		 * This is a compressed value inside of the main tuple
-		 */
-		attr = toast_decompress_datum(attr);
-	}
-	else if (VARATT_IS_SHORT(attr))
-	{
-		/*
-		 * This is a short-header varlena --- convert to 4-byte header format
-		 */
-		Size		data_size = VARSIZE_SHORT(attr) - VARHDRSZ_SHORT;
-		Size		new_size = data_size + VARHDRSZ;
-		struct varlena *new_attr;
-
-		new_attr = (struct varlena *) palloc(new_size);
-		SET_VARSIZE(new_attr, new_size);
-		memcpy(VARDATA(new_attr), VARDATA_SHORT(attr), data_size);
-		attr = new_attr;
-	}
-
-	return attr;
-}
-
-
-/* ----------
- * heap_tuple_untoast_attr_slice -
- *
- *		Public entry point to get back part of a toasted value
- *		from compression or external storage.
- * ----------
- */
-struct varlena *
-heap_tuple_untoast_attr_slice(struct varlena *attr,
-							  int32 sliceoffset, int32 slicelength)
-{
-	struct varlena *preslice;
-	struct varlena *result;
-	char	   *attrdata;
-	int32		attrsize;
-
-	if (VARATT_IS_EXTERNAL_ONDISK(attr))
-	{
-		struct varatt_external toast_pointer;
-
-		VARATT_EXTERNAL_GET_POINTER(toast_pointer, attr);
-
-		/* fast path for non-compressed external datums */
-		if (!VARATT_EXTERNAL_IS_COMPRESSED(toast_pointer))
-			return toast_fetch_datum_slice(attr, sliceoffset, slicelength);
-
-		/* fetch it back (compressed marker will get set automatically) */
-		preslice = toast_fetch_datum(attr);
-	}
-	else if (VARATT_IS_EXTERNAL_INDIRECT(attr))
-	{
-		struct varatt_indirect redirect;
-
-		VARATT_EXTERNAL_GET_POINTER(redirect, attr);
-
-		/* nested indirect Datums aren't allowed */
-		Assert(!VARATT_IS_EXTERNAL_INDIRECT(redirect.pointer));
-
-		return heap_tuple_untoast_attr_slice(redirect.pointer,
-											 sliceoffset, slicelength);
-	}
-	else if (VARATT_IS_EXTERNAL_EXPANDED(attr))
-	{
-		/* pass it off to heap_tuple_fetch_attr to flatten */
-		preslice = heap_tuple_fetch_attr(attr);
-	}
-	else
-		preslice = attr;
-
-	Assert(!VARATT_IS_EXTERNAL(preslice));
-
-	if (VARATT_IS_COMPRESSED(preslice))
-	{
-		struct varlena *tmp = preslice;
-
-		/* Decompress enough to encompass the slice and the offset */
-		if (slicelength > 0 && sliceoffset >= 0)
-			preslice = toast_decompress_datum_slice(tmp, slicelength + sliceoffset);
-		else
-			preslice = toast_decompress_datum(tmp);
-
-		if (tmp != attr)
-			pfree(tmp);
-	}
-
-	if (VARATT_IS_SHORT(preslice))
-	{
-		attrdata = VARDATA_SHORT(preslice);
-		attrsize = VARSIZE_SHORT(preslice) - VARHDRSZ_SHORT;
-	}
-	else
-	{
-		attrdata = VARDATA(preslice);
-		attrsize = VARSIZE(preslice) - VARHDRSZ;
-	}
-
-	/* slicing of datum for compressed cases and plain value */
-
-	if (sliceoffset >= attrsize)
-	{
-		sliceoffset = 0;
-		slicelength = 0;
-	}
-
-	if (((sliceoffset + slicelength) > attrsize) || slicelength < 0)
-		slicelength = attrsize - sliceoffset;
-
-	result = (struct varlena *) palloc(slicelength + VARHDRSZ);
-	SET_VARSIZE(result, slicelength + VARHDRSZ);
-
-	memcpy(VARDATA(result), attrdata + sliceoffset, slicelength);
-
-	if (preslice != attr)
-		pfree(preslice);
-
-	return result;
-}
-
-
-/* ----------
- * toast_raw_datum_size -
- *
- *	Return the raw (detoasted) size of a varlena datum
- *	(including the VARHDRSZ header)
- * ----------
- */
-Size
-toast_raw_datum_size(Datum value)
-{
-	struct varlena *attr = (struct varlena *) DatumGetPointer(value);
-	Size		result;
-
-	if (VARATT_IS_EXTERNAL_ONDISK(attr))
-	{
-		/* va_rawsize is the size of the original datum -- including header */
-		struct varatt_external toast_pointer;
-
-		VARATT_EXTERNAL_GET_POINTER(toast_pointer, attr);
-		result = toast_pointer.va_rawsize;
-	}
-	else if (VARATT_IS_EXTERNAL_INDIRECT(attr))
-	{
-		struct varatt_indirect toast_pointer;
-
-		VARATT_EXTERNAL_GET_POINTER(toast_pointer, attr);
-
-		/* nested indirect Datums aren't allowed */
-		Assert(!VARATT_IS_EXTERNAL_INDIRECT(toast_pointer.pointer));
-
-		return toast_raw_datum_size(PointerGetDatum(toast_pointer.pointer));
-	}
-	else if (VARATT_IS_EXTERNAL_EXPANDED(attr))
-	{
-		result = EOH_get_flat_size(DatumGetEOHP(value));
-	}
-	else if (VARATT_IS_COMPRESSED(attr))
-	{
-		/* here, va_rawsize is just the payload size */
-		result = VARRAWSIZE_4B_C(attr) + VARHDRSZ;
-	}
-	else if (VARATT_IS_SHORT(attr))
-	{
-		/*
-		 * we have to normalize the header length to VARHDRSZ or else the
-		 * callers of this function will be confused.
-		 */
-		result = VARSIZE_SHORT(attr) - VARHDRSZ_SHORT + VARHDRSZ;
-	}
-	else
-	{
-		/* plain untoasted datum */
-		result = VARSIZE(attr);
-	}
-	return result;
-}
-
-/* ----------
- * toast_datum_size
- *
- *	Return the physical storage size (possibly compressed) of a varlena datum
- * ----------
- */
-Size
-toast_datum_size(Datum value)
-{
-	struct varlena *attr = (struct varlena *) DatumGetPointer(value);
-	Size		result;
-
-	if (VARATT_IS_EXTERNAL_ONDISK(attr))
-	{
-		/*
-		 * Attribute is stored externally - return the extsize whether
-		 * compressed or not.  We do not count the size of the toast pointer
-		 * ... should we?
-		 */
-		struct varatt_external toast_pointer;
-
-		VARATT_EXTERNAL_GET_POINTER(toast_pointer, attr);
-		result = toast_pointer.va_extsize;
-	}
-	else if (VARATT_IS_EXTERNAL_INDIRECT(attr))
-	{
-		struct varatt_indirect toast_pointer;
-
-		VARATT_EXTERNAL_GET_POINTER(toast_pointer, attr);
-
-		/* nested indirect Datums aren't allowed */
-		Assert(!VARATT_IS_EXTERNAL_INDIRECT(attr));
-
-		return toast_datum_size(PointerGetDatum(toast_pointer.pointer));
-	}
-	else if (VARATT_IS_EXTERNAL_EXPANDED(attr))
-	{
-		result = EOH_get_flat_size(DatumGetEOHP(value));
-	}
-	else if (VARATT_IS_SHORT(attr))
-	{
-		result = VARSIZE_SHORT(attr);
-	}
-	else
-	{
-		/*
-		 * Attribute is stored inline either compressed or not, just calculate
-		 * the size of the datum in either case.
-		 */
-		result = VARSIZE(attr);
-	}
-	return result;
-}
-
-
-/* ----------
- * toast_delete -
- *
- *	Cascaded delete toast-entries on DELETE
- * ----------
- */
-void
-toast_delete(Relation rel, HeapTuple oldtup, bool is_speculative)
-{
-	TupleDesc	tupleDesc;
-	int			numAttrs;
-	int			i;
-	Datum		toast_values[MaxHeapAttributeNumber];
-	bool		toast_isnull[MaxHeapAttributeNumber];
-
-	/*
-	 * We should only ever be called for tuples of plain relations or
-	 * materialized views --- recursing on a toast rel is bad news.
-	 */
-	Assert(rel->rd_rel->relkind == RELKIND_RELATION ||
-		   rel->rd_rel->relkind == RELKIND_MATVIEW);
-
-	/*
-	 * Get the tuple descriptor and break down the tuple into fields.
-	 *
-	 * NOTE: it's debatable whether to use heap_deform_tuple() here or just
-	 * heap_getattr() only the varlena columns.  The latter could win if there
-	 * are few varlena columns and many non-varlena ones. However,
-	 * heap_deform_tuple costs only O(N) while the heap_getattr way would cost
-	 * O(N^2) if there are many varlena columns, so it seems better to err on
-	 * the side of linear cost.  (We won't even be here unless there's at
-	 * least one varlena column, by the way.)
-	 */
-	tupleDesc = rel->rd_att;
-	numAttrs = tupleDesc->natts;
-
-	Assert(numAttrs <= MaxHeapAttributeNumber);
-	heap_deform_tuple(oldtup, tupleDesc, toast_values, toast_isnull);
-
-	/*
-	 * Check for external stored attributes and delete them from the secondary
-	 * relation.
-	 */
-	for (i = 0; i < numAttrs; i++)
-	{
-		if (TupleDescAttr(tupleDesc, i)->attlen == -1)
-		{
-			Datum		value = toast_values[i];
-
-			if (toast_isnull[i])
-				continue;
-			else if (VARATT_IS_EXTERNAL_ONDISK(PointerGetDatum(value)))
-				toast_delete_datum(rel, value, is_speculative);
-		}
-	}
-}
-
-
-/* ----------
- * toast_insert_or_update -
- *
- *	Delete no-longer-used toast-entries and create new ones to
- *	make the new tuple fit on INSERT or UPDATE
- *
- * Inputs:
- *	newtup: the candidate new tuple to be inserted
- *	oldtup: the old row version for UPDATE, or NULL for INSERT
- *	options: options to be passed to heap_insert() for toast rows
- * Result:
- *	either newtup if no toasting is needed, or a palloc'd modified tuple
- *	that is what should actually get stored
- *
- * NOTE: neither newtup nor oldtup will be modified.  This is a change
- * from the pre-8.1 API of this routine.
- * ----------
- */
-HeapTuple
-toast_insert_or_update(Relation rel, HeapTuple newtup, HeapTuple oldtup,
-					   int options)
-{
-	HeapTuple	result_tuple;
-	TupleDesc	tupleDesc;
-	int			numAttrs;
-	int			i;
-
-	bool		need_change = false;
-	bool		need_free = false;
-	bool		need_delold = false;
-	bool		has_nulls = false;
-
-	Size		maxDataLen;
-	Size		hoff;
-
-	char		toast_action[MaxHeapAttributeNumber];
-	bool		toast_isnull[MaxHeapAttributeNumber];
-	bool		toast_oldisnull[MaxHeapAttributeNumber];
-	Datum		toast_values[MaxHeapAttributeNumber];
-	Datum		toast_oldvalues[MaxHeapAttributeNumber];
-	struct varlena *toast_oldexternal[MaxHeapAttributeNumber];
-	int32		toast_sizes[MaxHeapAttributeNumber];
-	bool		toast_free[MaxHeapAttributeNumber];
-	bool		toast_delold[MaxHeapAttributeNumber];
-
-	/*
-	 * Ignore the INSERT_SPECULATIVE option. Speculative insertions/super
-	 * deletions just normally insert/delete the toast values. It seems
-	 * easiest to deal with that here, instead on, potentially, multiple
-	 * callers.
-	 */
-	options &= ~HEAP_INSERT_SPECULATIVE;
-
-	/*
-	 * We should only ever be called for tuples of plain relations or
-	 * materialized views --- recursing on a toast rel is bad news.
-	 */
-	Assert(rel->rd_rel->relkind == RELKIND_RELATION ||
-		   rel->rd_rel->relkind == RELKIND_MATVIEW);
-
-	/*
-	 * Get the tuple descriptor and break down the tuple(s) into fields.
-	 */
-	tupleDesc = rel->rd_att;
-	numAttrs = tupleDesc->natts;
-
-	Assert(numAttrs <= MaxHeapAttributeNumber);
-	heap_deform_tuple(newtup, tupleDesc, toast_values, toast_isnull);
-	if (oldtup != NULL)
-		heap_deform_tuple(oldtup, tupleDesc, toast_oldvalues, toast_oldisnull);
-
-	/* ----------
-	 * Then collect information about the values given
-	 *
-	 * NOTE: toast_action[i] can have these values:
-	 *		' '		default handling
-	 *		'p'		already processed --- don't touch it
-	 *		'x'		incompressible, but OK to move off
-	 *
-	 * NOTE: toast_sizes[i] is only made valid for varlena attributes with
-	 *		toast_action[i] different from 'p'.
-	 * ----------
-	 */
-	memset(toast_action, ' ', numAttrs * sizeof(char));
-	memset(toast_oldexternal, 0, numAttrs * sizeof(struct varlena *));
-	memset(toast_free, 0, numAttrs * sizeof(bool));
-	memset(toast_delold, 0, numAttrs * sizeof(bool));
-
-	for (i = 0; i < numAttrs; i++)
-	{
-		Form_pg_attribute att = TupleDescAttr(tupleDesc, i);
-		struct varlena *old_value;
-		struct varlena *new_value;
-
-		if (oldtup != NULL)
-		{
-			/*
-			 * For UPDATE get the old and new values of this attribute
-			 */
-			old_value = (struct varlena *) DatumGetPointer(toast_oldvalues[i]);
-			new_value = (struct varlena *) DatumGetPointer(toast_values[i]);
-
-			/*
-			 * If the old value is stored on disk, check if it has changed so
-			 * we have to delete it later.
-			 */
-			if (att->attlen == -1 && !toast_oldisnull[i] &&
-				VARATT_IS_EXTERNAL_ONDISK(old_value))
-			{
-				if (toast_isnull[i] || !VARATT_IS_EXTERNAL_ONDISK(new_value) ||
-					memcmp((char *) old_value, (char *) new_value,
-						   VARSIZE_EXTERNAL(old_value)) != 0)
-				{
-					/*
-					 * The old external stored value isn't needed any more
-					 * after the update
-					 */
-					toast_delold[i] = true;
-					need_delold = true;
-				}
-				else
-				{
-					/*
-					 * This attribute isn't changed by this update so we reuse
-					 * the original reference to the old value in the new
-					 * tuple.
-					 */
-					toast_action[i] = 'p';
-					continue;
-				}
-			}
-		}
-		else
-		{
-			/*
-			 * For INSERT simply get the new value
-			 */
-			new_value = (struct varlena *) DatumGetPointer(toast_values[i]);
-		}
-
-		/*
-		 * Handle NULL attributes
-		 */
-		if (toast_isnull[i])
-		{
-			toast_action[i] = 'p';
-			has_nulls = true;
-			continue;
-		}
-
-		/*
-		 * Now look at varlena attributes
-		 */
-		if (att->attlen == -1)
-		{
-			/*
-			 * If the table's attribute says PLAIN always, force it so.
-			 */
-			if (att->attstorage == 'p')
-				toast_action[i] = 'p';
-
-			/*
-			 * We took care of UPDATE above, so any external value we find
-			 * still in the tuple must be someone else's that we cannot reuse
-			 * (this includes the case of an out-of-line in-memory datum).
-			 * Fetch it back (without decompression, unless we are forcing
-			 * PLAIN storage).  If necessary, we'll push it out as a new
-			 * external value below.
-			 */
-			if (VARATT_IS_EXTERNAL(new_value))
-			{
-				toast_oldexternal[i] = new_value;
-				if (att->attstorage == 'p')
-					new_value = heap_tuple_untoast_attr(new_value);
-				else
-					new_value = heap_tuple_fetch_attr(new_value);
-				toast_values[i] = PointerGetDatum(new_value);
-				toast_free[i] = true;
-				need_change = true;
-				need_free = true;
-			}
-
-			/*
-			 * Remember the size of this attribute
-			 */
-			toast_sizes[i] = VARSIZE_ANY(new_value);
-		}
-		else
-		{
-			/*
-			 * Not a varlena attribute, plain storage always
-			 */
-			toast_action[i] = 'p';
-		}
-	}
-
-	/* ----------
-	 * Compress and/or save external until data fits into target length
-	 *
-	 *	1: Inline compress attributes with attstorage 'x', and store very
-	 *	   large attributes with attstorage 'x' or 'e' external immediately
-	 *	2: Store attributes with attstorage 'x' or 'e' external
-	 *	3: Inline compress attributes with attstorage 'm'
-	 *	4: Store attributes with attstorage 'm' external
-	 * ----------
-	 */
-
-	/* compute header overhead --- this should match heap_form_tuple() */
-	hoff = SizeofHeapTupleHeader;
-	if (has_nulls)
-		hoff += BITMAPLEN(numAttrs);
-	hoff = MAXALIGN(hoff);
-	/* now convert to a limit on the tuple data size */
-	maxDataLen = RelationGetToastTupleTarget(rel, TOAST_TUPLE_TARGET) - hoff;
-
-	/*
-	 * Look for attributes with attstorage 'x' to compress.  Also find large
-	 * attributes with attstorage 'x' or 'e', and store them external.
-	 */
-	while (heap_compute_data_size(tupleDesc,
-								  toast_values, toast_isnull) > maxDataLen)
-	{
-		int			biggest_attno = -1;
-		int32		biggest_size = MAXALIGN(TOAST_POINTER_SIZE);
-		Datum		old_value;
-		Datum		new_value;
-
-		/*
-		 * Search for the biggest yet unprocessed internal attribute
-		 */
-		for (i = 0; i < numAttrs; i++)
-		{
-			Form_pg_attribute att = TupleDescAttr(tupleDesc, i);
-
-			if (toast_action[i] != ' ')
-				continue;
-			if (VARATT_IS_EXTERNAL(DatumGetPointer(toast_values[i])))
-				continue;		/* can't happen, toast_action would be 'p' */
-			if (VARATT_IS_COMPRESSED(DatumGetPointer(toast_values[i])))
-				continue;
-			if (att->attstorage != 'x' && att->attstorage != 'e')
-				continue;
-			if (toast_sizes[i] > biggest_size)
-			{
-				biggest_attno = i;
-				biggest_size = toast_sizes[i];
-			}
-		}
-
-		if (biggest_attno < 0)
-			break;
-
-		/*
-		 * Attempt to compress it inline, if it has attstorage 'x'
-		 */
-		i = biggest_attno;
-		if (TupleDescAttr(tupleDesc, i)->attstorage == 'x')
-		{
-			old_value = toast_values[i];
-			new_value = toast_compress_datum(old_value);
-
-			if (DatumGetPointer(new_value) != NULL)
-			{
-				/* successful compression */
-				if (toast_free[i])
-					pfree(DatumGetPointer(old_value));
-				toast_values[i] = new_value;
-				toast_free[i] = true;
-				toast_sizes[i] = VARSIZE(DatumGetPointer(toast_values[i]));
-				need_change = true;
-				need_free = true;
-			}
-			else
-			{
-				/* incompressible, ignore on subsequent compression passes */
-				toast_action[i] = 'x';
-			}
-		}
-		else
-		{
-			/* has attstorage 'e', ignore on subsequent compression passes */
-			toast_action[i] = 'x';
-		}
-
-		/*
-		 * If this value is by itself more than maxDataLen (after compression
-		 * if any), push it out to the toast table immediately, if possible.
-		 * This avoids uselessly compressing other fields in the common case
-		 * where we have one long field and several short ones.
-		 *
-		 * XXX maybe the threshold should be less than maxDataLen?
-		 */
-		if (toast_sizes[i] > maxDataLen &&
-			rel->rd_rel->reltoastrelid != InvalidOid)
-		{
-			old_value = toast_values[i];
-			toast_action[i] = 'p';
-			toast_values[i] = toast_save_datum(rel, toast_values[i],
-											   toast_oldexternal[i], options);
-			if (toast_free[i])
-				pfree(DatumGetPointer(old_value));
-			toast_free[i] = true;
-			need_change = true;
-			need_free = true;
-		}
-	}
-
-	/*
-	 * Second we look for attributes of attstorage 'x' or 'e' that are still
-	 * inline.  But skip this if there's no toast table to push them to.
-	 */
-	while (heap_compute_data_size(tupleDesc,
-								  toast_values, toast_isnull) > maxDataLen &&
-		   rel->rd_rel->reltoastrelid != InvalidOid)
-	{
-		int			biggest_attno = -1;
-		int32		biggest_size = MAXALIGN(TOAST_POINTER_SIZE);
-		Datum		old_value;
-
-		/*------
-		 * Search for the biggest yet inlined attribute with
-		 * attstorage equals 'x' or 'e'
-		 *------
-		 */
-		for (i = 0; i < numAttrs; i++)
-		{
-			Form_pg_attribute att = TupleDescAttr(tupleDesc, i);
-
-			if (toast_action[i] == 'p')
-				continue;
-			if (VARATT_IS_EXTERNAL(DatumGetPointer(toast_values[i])))
-				continue;		/* can't happen, toast_action would be 'p' */
-			if (att->attstorage != 'x' && att->attstorage != 'e')
-				continue;
-			if (toast_sizes[i] > biggest_size)
-			{
-				biggest_attno = i;
-				biggest_size = toast_sizes[i];
-			}
-		}
-
-		if (biggest_attno < 0)
-			break;
-
-		/*
-		 * Store this external
-		 */
-		i = biggest_attno;
-		old_value = toast_values[i];
-		toast_action[i] = 'p';
-		toast_values[i] = toast_save_datum(rel, toast_values[i],
-										   toast_oldexternal[i], options);
-		if (toast_free[i])
-			pfree(DatumGetPointer(old_value));
-		toast_free[i] = true;
-
-		need_change = true;
-		need_free = true;
-	}
-
-	/*
-	 * Round 3 - this time we take attributes with storage 'm' into
-	 * compression
-	 */
-	while (heap_compute_data_size(tupleDesc,
-								  toast_values, toast_isnull) > maxDataLen)
-	{
-		int			biggest_attno = -1;
-		int32		biggest_size = MAXALIGN(TOAST_POINTER_SIZE);
-		Datum		old_value;
-		Datum		new_value;
-
-		/*
-		 * Search for the biggest yet uncompressed internal attribute
-		 */
-		for (i = 0; i < numAttrs; i++)
-		{
-			if (toast_action[i] != ' ')
-				continue;
-			if (VARATT_IS_EXTERNAL(DatumGetPointer(toast_values[i])))
-				continue;		/* can't happen, toast_action would be 'p' */
-			if (VARATT_IS_COMPRESSED(DatumGetPointer(toast_values[i])))
-				continue;
-			if (TupleDescAttr(tupleDesc, i)->attstorage != 'm')
-				continue;
-			if (toast_sizes[i] > biggest_size)
-			{
-				biggest_attno = i;
-				biggest_size = toast_sizes[i];
-			}
-		}
-
-		if (biggest_attno < 0)
-			break;
-
-		/*
-		 * Attempt to compress it inline
-		 */
-		i = biggest_attno;
-		old_value = toast_values[i];
-		new_value = toast_compress_datum(old_value);
-
-		if (DatumGetPointer(new_value) != NULL)
-		{
-			/* successful compression */
-			if (toast_free[i])
-				pfree(DatumGetPointer(old_value));
-			toast_values[i] = new_value;
-			toast_free[i] = true;
-			toast_sizes[i] = VARSIZE(DatumGetPointer(toast_values[i]));
-			need_change = true;
-			need_free = true;
-		}
-		else
-		{
-			/* incompressible, ignore on subsequent compression passes */
-			toast_action[i] = 'x';
-		}
-	}
-
-	/*
-	 * Finally we store attributes of type 'm' externally.  At this point we
-	 * increase the target tuple size, so that 'm' attributes aren't stored
-	 * externally unless really necessary.
-	 */
-	maxDataLen = TOAST_TUPLE_TARGET_MAIN - hoff;
-
-	while (heap_compute_data_size(tupleDesc,
-								  toast_values, toast_isnull) > maxDataLen &&
-		   rel->rd_rel->reltoastrelid != InvalidOid)
-	{
-		int			biggest_attno = -1;
-		int32		biggest_size = MAXALIGN(TOAST_POINTER_SIZE);
-		Datum		old_value;
-
-		/*--------
-		 * Search for the biggest yet inlined attribute with
-		 * attstorage = 'm'
-		 *--------
-		 */
-		for (i = 0; i < numAttrs; i++)
-		{
-			if (toast_action[i] == 'p')
-				continue;
-			if (VARATT_IS_EXTERNAL(DatumGetPointer(toast_values[i])))
-				continue;		/* can't happen, toast_action would be 'p' */
-			if (TupleDescAttr(tupleDesc, i)->attstorage != 'm')
-				continue;
-			if (toast_sizes[i] > biggest_size)
-			{
-				biggest_attno = i;
-				biggest_size = toast_sizes[i];
-			}
-		}
-
-		if (biggest_attno < 0)
-			break;
-
-		/*
-		 * Store this external
-		 */
-		i = biggest_attno;
-		old_value = toast_values[i];
-		toast_action[i] = 'p';
-		toast_values[i] = toast_save_datum(rel, toast_values[i],
-										   toast_oldexternal[i], options);
-		if (toast_free[i])
-			pfree(DatumGetPointer(old_value));
-		toast_free[i] = true;
-
-		need_change = true;
-		need_free = true;
-	}
-
-	/*
-	 * In the case we toasted any values, we need to build a new heap tuple
-	 * with the changed values.
-	 */
-	if (need_change)
-	{
-		HeapTupleHeader olddata = newtup->t_data;
-		HeapTupleHeader new_data;
-		int32		new_header_len;
-		int32		new_data_len;
-		int32		new_tuple_len;
-
-		/*
-		 * Calculate the new size of the tuple.
-		 *
-		 * Note: we used to assume here that the old tuple's t_hoff must equal
-		 * the new_header_len value, but that was incorrect.  The old tuple
-		 * might have a smaller-than-current natts, if there's been an ALTER
-		 * TABLE ADD COLUMN since it was stored; and that would lead to a
-		 * different conclusion about the size of the null bitmap, or even
-		 * whether there needs to be one at all.
-		 */
-		new_header_len = SizeofHeapTupleHeader;
-		if (has_nulls)
-			new_header_len += BITMAPLEN(numAttrs);
-		new_header_len = MAXALIGN(new_header_len);
-		new_data_len = heap_compute_data_size(tupleDesc,
-											  toast_values, toast_isnull);
-		new_tuple_len = new_header_len + new_data_len;
-
-		/*
-		 * Allocate and zero the space needed, and fill HeapTupleData fields.
-		 */
-		result_tuple = (HeapTuple) palloc0(HEAPTUPLESIZE + new_tuple_len);
-		result_tuple->t_len = new_tuple_len;
-		result_tuple->t_self = newtup->t_self;
-		result_tuple->t_tableOid = newtup->t_tableOid;
-		new_data = (HeapTupleHeader) ((char *) result_tuple + HEAPTUPLESIZE);
-		result_tuple->t_data = new_data;
-
-		/*
-		 * Copy the existing tuple header, but adjust natts and t_hoff.
-		 */
-		memcpy(new_data, olddata, SizeofHeapTupleHeader);
-		HeapTupleHeaderSetNatts(new_data, numAttrs);
-		new_data->t_hoff = new_header_len;
-
-		/* Copy over the data, and fill the null bitmap if needed */
-		heap_fill_tuple(tupleDesc,
-						toast_values,
-						toast_isnull,
-						(char *) new_data + new_header_len,
-						new_data_len,
-						&(new_data->t_infomask),
-						has_nulls ? new_data->t_bits : NULL);
-	}
-	else
-		result_tuple = newtup;
-
-	/*
-	 * Free allocated temp values
-	 */
-	if (need_free)
-		for (i = 0; i < numAttrs; i++)
-			if (toast_free[i])
-				pfree(DatumGetPointer(toast_values[i]));
-
-	/*
-	 * Delete external values from the old tuple
-	 */
-	if (need_delold)
-		for (i = 0; i < numAttrs; i++)
-			if (toast_delold[i])
-				toast_delete_datum(rel, toast_oldvalues[i], false);
-
-	return result_tuple;
-}
-
-
-/* ----------
- * toast_flatten_tuple -
- *
- *	"Flatten" a tuple to contain no out-of-line toasted fields.
- *	(This does not eliminate compressed or short-header datums.)
- *
- *	Note: we expect the caller already checked HeapTupleHasExternal(tup),
- *	so there is no need for a short-circuit path.
- * ----------
- */
-HeapTuple
-toast_flatten_tuple(HeapTuple tup, TupleDesc tupleDesc)
-{
-	HeapTuple	new_tuple;
-	int			numAttrs = tupleDesc->natts;
-	int			i;
-	Datum		toast_values[MaxTupleAttributeNumber];
-	bool		toast_isnull[MaxTupleAttributeNumber];
-	bool		toast_free[MaxTupleAttributeNumber];
-
-	/*
-	 * Break down the tuple into fields.
-	 */
-	Assert(numAttrs <= MaxTupleAttributeNumber);
-	heap_deform_tuple(tup, tupleDesc, toast_values, toast_isnull);
-
-	memset(toast_free, 0, numAttrs * sizeof(bool));
-
-	for (i = 0; i < numAttrs; i++)
-	{
-		/*
-		 * Look at non-null varlena attributes
-		 */
-		if (!toast_isnull[i] && TupleDescAttr(tupleDesc, i)->attlen == -1)
-		{
-			struct varlena *new_value;
-
-			new_value = (struct varlena *) DatumGetPointer(toast_values[i]);
-			if (VARATT_IS_EXTERNAL(new_value))
-			{
-				new_value = heap_tuple_fetch_attr(new_value);
-				toast_values[i] = PointerGetDatum(new_value);
-				toast_free[i] = true;
-			}
-		}
-	}
-
-	/*
-	 * Form the reconfigured tuple.
-	 */
-	new_tuple = heap_form_tuple(tupleDesc, toast_values, toast_isnull);
-
-	/*
-	 * Be sure to copy the tuple's identity fields.  We also make a point of
-	 * copying visibility info, just in case anybody looks at those fields in
-	 * a syscache entry.
-	 */
-	new_tuple->t_self = tup->t_self;
-	new_tuple->t_tableOid = tup->t_tableOid;
-
-	new_tuple->t_data->t_choice = tup->t_data->t_choice;
-	new_tuple->t_data->t_ctid = tup->t_data->t_ctid;
-	new_tuple->t_data->t_infomask &= ~HEAP_XACT_MASK;
-	new_tuple->t_data->t_infomask |=
-		tup->t_data->t_infomask & HEAP_XACT_MASK;
-	new_tuple->t_data->t_infomask2 &= ~HEAP2_XACT_MASK;
-	new_tuple->t_data->t_infomask2 |=
-		tup->t_data->t_infomask2 & HEAP2_XACT_MASK;
-
-	/*
-	 * Free allocated temp values
-	 */
-	for (i = 0; i < numAttrs; i++)
-		if (toast_free[i])
-			pfree(DatumGetPointer(toast_values[i]));
-
-	return new_tuple;
-}
-
-
-/* ----------
- * toast_flatten_tuple_to_datum -
- *
- *	"Flatten" a tuple containing out-of-line toasted fields into a Datum.
- *	The result is always palloc'd in the current memory context.
- *
- *	We have a general rule that Datums of container types (rows, arrays,
- *	ranges, etc) must not contain any external TOAST pointers.  Without
- *	this rule, we'd have to look inside each Datum when preparing a tuple
- *	for storage, which would be expensive and would fail to extend cleanly
- *	to new sorts of container types.
- *
- *	However, we don't want to say that tuples represented as HeapTuples
- *	can't contain toasted fields, so instead this routine should be called
- *	when such a HeapTuple is being converted into a Datum.
- *
- *	While we're at it, we decompress any compressed fields too.  This is not
- *	necessary for correctness, but reflects an expectation that compression
- *	will be more effective if applied to the whole tuple not individual
- *	fields.  We are not so concerned about that that we want to deconstruct
- *	and reconstruct tuples just to get rid of compressed fields, however.
- *	So callers typically won't call this unless they see that the tuple has
- *	at least one external field.
- *
- *	On the other hand, in-line short-header varlena fields are left alone.
- *	If we "untoasted" them here, they'd just get changed back to short-header
- *	format anyway within heap_fill_tuple.
- * ----------
- */
-Datum
-toast_flatten_tuple_to_datum(HeapTupleHeader tup,
-							 uint32 tup_len,
-							 TupleDesc tupleDesc)
-{
-	HeapTupleHeader new_data;
-	int32		new_header_len;
-	int32		new_data_len;
-	int32		new_tuple_len;
-	HeapTupleData tmptup;
-	int			numAttrs = tupleDesc->natts;
-	int			i;
-	bool		has_nulls = false;
-	Datum		toast_values[MaxTupleAttributeNumber];
-	bool		toast_isnull[MaxTupleAttributeNumber];
-	bool		toast_free[MaxTupleAttributeNumber];
-
-	/* Build a temporary HeapTuple control structure */
-	tmptup.t_len = tup_len;
-	ItemPointerSetInvalid(&(tmptup.t_self));
-	tmptup.t_tableOid = InvalidOid;
-	tmptup.t_data = tup;
-
-	/*
-	 * Break down the tuple into fields.
-	 */
-	Assert(numAttrs <= MaxTupleAttributeNumber);
-	heap_deform_tuple(&tmptup, tupleDesc, toast_values, toast_isnull);
-
-	memset(toast_free, 0, numAttrs * sizeof(bool));
-
-	for (i = 0; i < numAttrs; i++)
-	{
-		/*
-		 * Look at non-null varlena attributes
-		 */
-		if (toast_isnull[i])
-			has_nulls = true;
-		else if (TupleDescAttr(tupleDesc, i)->attlen == -1)
-		{
-			struct varlena *new_value;
-
-			new_value = (struct varlena *) DatumGetPointer(toast_values[i]);
-			if (VARATT_IS_EXTERNAL(new_value) ||
-				VARATT_IS_COMPRESSED(new_value))
-			{
-				new_value = heap_tuple_untoast_attr(new_value);
-				toast_values[i] = PointerGetDatum(new_value);
-				toast_free[i] = true;
-			}
-		}
-	}
-
-	/*
-	 * Calculate the new size of the tuple.
-	 *
-	 * This should match the reconstruction code in toast_insert_or_update.
-	 */
-	new_header_len = SizeofHeapTupleHeader;
-	if (has_nulls)
-		new_header_len += BITMAPLEN(numAttrs);
-	new_header_len = MAXALIGN(new_header_len);
-	new_data_len = heap_compute_data_size(tupleDesc,
-										  toast_values, toast_isnull);
-	new_tuple_len = new_header_len + new_data_len;
-
-	new_data = (HeapTupleHeader) palloc0(new_tuple_len);
-
-	/*
-	 * Copy the existing tuple header, but adjust natts and t_hoff.
-	 */
-	memcpy(new_data, tup, SizeofHeapTupleHeader);
-	HeapTupleHeaderSetNatts(new_data, numAttrs);
-	new_data->t_hoff = new_header_len;
-
-	/* Set the composite-Datum header fields correctly */
-	HeapTupleHeaderSetDatumLength(new_data, new_tuple_len);
-	HeapTupleHeaderSetTypeId(new_data, tupleDesc->tdtypeid);
-	HeapTupleHeaderSetTypMod(new_data, tupleDesc->tdtypmod);
-
-	/* Copy over the data, and fill the null bitmap if needed */
-	heap_fill_tuple(tupleDesc,
-					toast_values,
-					toast_isnull,
-					(char *) new_data + new_header_len,
-					new_data_len,
-					&(new_data->t_infomask),
-					has_nulls ? new_data->t_bits : NULL);
-
-	/*
-	 * Free allocated temp values
-	 */
-	for (i = 0; i < numAttrs; i++)
-		if (toast_free[i])
-			pfree(DatumGetPointer(toast_values[i]));
-
-	return PointerGetDatum(new_data);
-}
-
-
-/* ----------
- * toast_build_flattened_tuple -
- *
- *	Build a tuple containing no out-of-line toasted fields.
- *	(This does not eliminate compressed or short-header datums.)
- *
- *	This is essentially just like heap_form_tuple, except that it will
- *	expand any external-data pointers beforehand.
- *
- *	It's not very clear whether it would be preferable to decompress
- *	in-line compressed datums while at it.  For now, we don't.
- * ----------
- */
-HeapTuple
-toast_build_flattened_tuple(TupleDesc tupleDesc,
-							Datum *values,
-							bool *isnull)
-{
-	HeapTuple	new_tuple;
-	int			numAttrs = tupleDesc->natts;
-	int			num_to_free;
-	int			i;
-	Datum		new_values[MaxTupleAttributeNumber];
-	Pointer		freeable_values[MaxTupleAttributeNumber];
-
-	/*
-	 * We can pass the caller's isnull array directly to heap_form_tuple, but
-	 * we potentially need to modify the values array.
-	 */
-	Assert(numAttrs <= MaxTupleAttributeNumber);
-	memcpy(new_values, values, numAttrs * sizeof(Datum));
-
-	num_to_free = 0;
-	for (i = 0; i < numAttrs; i++)
-	{
-		/*
-		 * Look at non-null varlena attributes
-		 */
-		if (!isnull[i] && TupleDescAttr(tupleDesc, i)->attlen == -1)
-		{
-			struct varlena *new_value;
-
-			new_value = (struct varlena *) DatumGetPointer(new_values[i]);
-			if (VARATT_IS_EXTERNAL(new_value))
-			{
-				new_value = heap_tuple_fetch_attr(new_value);
-				new_values[i] = PointerGetDatum(new_value);
-				freeable_values[num_to_free++] = (Pointer) new_value;
-			}
-		}
-	}
-
-	/*
-	 * Form the reconfigured tuple.
-	 */
-	new_tuple = heap_form_tuple(tupleDesc, new_values, isnull);
-
-	/*
-	 * Free allocated temp values
-	 */
-	for (i = 0; i < num_to_free; i++)
-		pfree(freeable_values[i]);
-
-	return new_tuple;
-}
-
-
-/* ----------
- * toast_compress_datum -
- *
- *	Create a compressed version of a varlena datum
- *
- *	If we fail (ie, compressed result is actually bigger than original)
- *	then return NULL.  We must not use compressed data if it'd expand
- *	the tuple!
- *
- *	We use VAR{SIZE,DATA}_ANY so we can handle short varlenas here without
- *	copying them.  But we can't handle external or compressed datums.
- * ----------
- */
-Datum
-toast_compress_datum(Datum value)
-{
-	struct varlena *tmp;
-	int32		valsize = VARSIZE_ANY_EXHDR(DatumGetPointer(value));
-	int32		len;
-
-	Assert(!VARATT_IS_EXTERNAL(DatumGetPointer(value)));
-	Assert(!VARATT_IS_COMPRESSED(DatumGetPointer(value)));
-
-	/*
-	 * No point in wasting a palloc cycle if value size is out of the allowed
-	 * range for compression
-	 */
-	if (valsize < PGLZ_strategy_default->min_input_size ||
-		valsize > PGLZ_strategy_default->max_input_size)
-		return PointerGetDatum(NULL);
-
-	tmp = (struct varlena *) palloc(PGLZ_MAX_OUTPUT(valsize) +
-									TOAST_COMPRESS_HDRSZ);
-
-	/*
-	 * We recheck the actual size even if pglz_compress() reports success,
-	 * because it might be satisfied with having saved as little as one byte
-	 * in the compressed data --- which could turn into a net loss once you
-	 * consider header and alignment padding.  Worst case, the compressed
-	 * format might require three padding bytes (plus header, which is
-	 * included in VARSIZE(tmp)), whereas the uncompressed format would take
-	 * only one header byte and no padding if the value is short enough.  So
-	 * we insist on a savings of more than 2 bytes to ensure we have a gain.
-	 */
-	len = pglz_compress(VARDATA_ANY(DatumGetPointer(value)),
-						valsize,
-						TOAST_COMPRESS_RAWDATA(tmp),
-						PGLZ_strategy_default);
-	if (len >= 0 &&
-		len + TOAST_COMPRESS_HDRSZ < valsize - 2)
-	{
-		TOAST_COMPRESS_SET_RAWSIZE(tmp, valsize);
-		SET_VARSIZE_COMPRESSED(tmp, len + TOAST_COMPRESS_HDRSZ);
-		/* successful compression */
-		return PointerGetDatum(tmp);
-	}
-	else
-	{
-		/* incompressible data */
-		pfree(tmp);
-		return PointerGetDatum(NULL);
-	}
-}
-
-
-/* ----------
- * toast_get_valid_index
- *
- *	Get OID of valid index associated to given toast relation. A toast
- *	relation can have only one valid index at the same time.
- */
-Oid
-toast_get_valid_index(Oid toastoid, LOCKMODE lock)
-{
-	int			num_indexes;
-	int			validIndex;
-	Oid			validIndexOid;
-	Relation   *toastidxs;
-	Relation	toastrel;
-
-	/* Open the toast relation */
-	toastrel = table_open(toastoid, lock);
-
-	/* Look for the valid index of the toast relation */
-	validIndex = toast_open_indexes(toastrel,
-									lock,
-									&toastidxs,
-									&num_indexes);
-	validIndexOid = RelationGetRelid(toastidxs[validIndex]);
-
-	/* Close the toast relation and all its indexes */
-	toast_close_indexes(toastidxs, num_indexes, lock);
-	table_close(toastrel, lock);
-
-	return validIndexOid;
-}
-
-
-/* ----------
- * toast_save_datum -
- *
- *	Save one single datum into the secondary relation and return
- *	a Datum reference for it.
- *
- * rel: the main relation we're working with (not the toast rel!)
- * value: datum to be pushed to toast storage
- * oldexternal: if not NULL, toast pointer previously representing the datum
- * options: options to be passed to heap_insert() for toast rows
- * ----------
- */
-static Datum
-toast_save_datum(Relation rel, Datum value,
-				 struct varlena *oldexternal, int options)
-{
-	Relation	toastrel;
-	Relation   *toastidxs;
-	HeapTuple	toasttup;
-	TupleDesc	toasttupDesc;
-	Datum		t_values[3];
-	bool		t_isnull[3];
-	CommandId	mycid = GetCurrentCommandId(true);
-	struct varlena *result;
-	struct varatt_external toast_pointer;
-	union
-	{
-		struct varlena hdr;
-		/* this is to make the union big enough for a chunk: */
-		char		data[TOAST_MAX_CHUNK_SIZE + VARHDRSZ];
-		/* ensure union is aligned well enough: */
-		int32		align_it;
-	}			chunk_data;
-	int32		chunk_size;
-	int32		chunk_seq = 0;
-	char	   *data_p;
-	int32		data_todo;
-	Pointer		dval = DatumGetPointer(value);
-	int			num_indexes;
-	int			validIndex;
-
-	Assert(!VARATT_IS_EXTERNAL(value));
-
-	/*
-	 * Open the toast relation and its indexes.  We can use the index to check
-	 * uniqueness of the OID we assign to the toasted item, even though it has
-	 * additional columns besides OID.
-	 */
-	toastrel = table_open(rel->rd_rel->reltoastrelid, RowExclusiveLock);
-	toasttupDesc = toastrel->rd_att;
-
-	/* Open all the toast indexes and look for the valid one */
-	validIndex = toast_open_indexes(toastrel,
-									RowExclusiveLock,
-									&toastidxs,
-									&num_indexes);
-
-	/*
-	 * Get the data pointer and length, and compute va_rawsize and va_extsize.
-	 *
-	 * va_rawsize is the size of the equivalent fully uncompressed datum, so
-	 * we have to adjust for short headers.
-	 *
-	 * va_extsize is the actual size of the data payload in the toast records.
-	 */
-	if (VARATT_IS_SHORT(dval))
-	{
-		data_p = VARDATA_SHORT(dval);
-		data_todo = VARSIZE_SHORT(dval) - VARHDRSZ_SHORT;
-		toast_pointer.va_rawsize = data_todo + VARHDRSZ;	/* as if not short */
-		toast_pointer.va_extsize = data_todo;
-	}
-	else if (VARATT_IS_COMPRESSED(dval))
-	{
-		data_p = VARDATA(dval);
-		data_todo = VARSIZE(dval) - VARHDRSZ;
-		/* rawsize in a compressed datum is just the size of the payload */
-		toast_pointer.va_rawsize = VARRAWSIZE_4B_C(dval) + VARHDRSZ;
-		toast_pointer.va_extsize = data_todo;
-		/* Assert that the numbers look like it's compressed */
-		Assert(VARATT_EXTERNAL_IS_COMPRESSED(toast_pointer));
-	}
-	else
-	{
-		data_p = VARDATA(dval);
-		data_todo = VARSIZE(dval) - VARHDRSZ;
-		toast_pointer.va_rawsize = VARSIZE(dval);
-		toast_pointer.va_extsize = data_todo;
-	}
-
-	/*
-	 * Insert the correct table OID into the result TOAST pointer.
-	 *
-	 * Normally this is the actual OID of the target toast table, but during
-	 * table-rewriting operations such as CLUSTER, we have to insert the OID
-	 * of the table's real permanent toast table instead.  rd_toastoid is set
-	 * if we have to substitute such an OID.
-	 */
-	if (OidIsValid(rel->rd_toastoid))
-		toast_pointer.va_toastrelid = rel->rd_toastoid;
-	else
-		toast_pointer.va_toastrelid = RelationGetRelid(toastrel);
-
-	/*
-	 * Choose an OID to use as the value ID for this toast value.
-	 *
-	 * Normally we just choose an unused OID within the toast table.  But
-	 * during table-rewriting operations where we are preserving an existing
-	 * toast table OID, we want to preserve toast value OIDs too.  So, if
-	 * rd_toastoid is set and we had a prior external value from that same
-	 * toast table, re-use its value ID.  If we didn't have a prior external
-	 * value (which is a corner case, but possible if the table's attstorage
-	 * options have been changed), we have to pick a value ID that doesn't
-	 * conflict with either new or existing toast value OIDs.
-	 */
-	if (!OidIsValid(rel->rd_toastoid))
-	{
-		/* normal case: just choose an unused OID */
-		toast_pointer.va_valueid =
-			GetNewOidWithIndex(toastrel,
-							   RelationGetRelid(toastidxs[validIndex]),
-							   (AttrNumber) 1);
-	}
-	else
-	{
-		/* rewrite case: check to see if value was in old toast table */
-		toast_pointer.va_valueid = InvalidOid;
-		if (oldexternal != NULL)
-		{
-			struct varatt_external old_toast_pointer;
-
-			Assert(VARATT_IS_EXTERNAL_ONDISK(oldexternal));
-			/* Must copy to access aligned fields */
-			VARATT_EXTERNAL_GET_POINTER(old_toast_pointer, oldexternal);
-			if (old_toast_pointer.va_toastrelid == rel->rd_toastoid)
-			{
-				/* This value came from the old toast table; reuse its OID */
-				toast_pointer.va_valueid = old_toast_pointer.va_valueid;
-
-				/*
-				 * There is a corner case here: the table rewrite might have
-				 * to copy both live and recently-dead versions of a row, and
-				 * those versions could easily reference the same toast value.
-				 * When we copy the second or later version of such a row,
-				 * reusing the OID will mean we select an OID that's already
-				 * in the new toast table.  Check for that, and if so, just
-				 * fall through without writing the data again.
-				 *
-				 * While annoying and ugly-looking, this is a good thing
-				 * because it ensures that we wind up with only one copy of
-				 * the toast value when there is only one copy in the old
-				 * toast table.  Before we detected this case, we'd have made
-				 * multiple copies, wasting space; and what's worse, the
-				 * copies belonging to already-deleted heap tuples would not
-				 * be reclaimed by VACUUM.
-				 */
-				if (toastrel_valueid_exists(toastrel,
-											toast_pointer.va_valueid))
-				{
-					/* Match, so short-circuit the data storage loop below */
-					data_todo = 0;
-				}
-			}
-		}
-		if (toast_pointer.va_valueid == InvalidOid)
-		{
-			/*
-			 * new value; must choose an OID that doesn't conflict in either
-			 * old or new toast table
-			 */
-			do
-			{
-				toast_pointer.va_valueid =
-					GetNewOidWithIndex(toastrel,
-									   RelationGetRelid(toastidxs[validIndex]),
-									   (AttrNumber) 1);
-			} while (toastid_valueid_exists(rel->rd_toastoid,
-											toast_pointer.va_valueid));
-		}
-	}
-
-	/*
-	 * Initialize constant parts of the tuple data
-	 */
-	t_values[0] = ObjectIdGetDatum(toast_pointer.va_valueid);
-	t_values[2] = PointerGetDatum(&chunk_data);
-	t_isnull[0] = false;
-	t_isnull[1] = false;
-	t_isnull[2] = false;
-
-	/*
-	 * Split up the item into chunks
-	 */
-	while (data_todo > 0)
-	{
-		int			i;
-
-		CHECK_FOR_INTERRUPTS();
-
-		/*
-		 * Calculate the size of this chunk
-		 */
-		chunk_size = Min(TOAST_MAX_CHUNK_SIZE, data_todo);
-
-		/*
-		 * Build a tuple and store it
-		 */
-		t_values[1] = Int32GetDatum(chunk_seq++);
-		SET_VARSIZE(&chunk_data, chunk_size + VARHDRSZ);
-		memcpy(VARDATA(&chunk_data), data_p, chunk_size);
-		toasttup = heap_form_tuple(toasttupDesc, t_values, t_isnull);
-
-		heap_insert(toastrel, toasttup, mycid, options, NULL);
-
-		/*
-		 * Create the index entry.  We cheat a little here by not using
-		 * FormIndexDatum: this relies on the knowledge that the index columns
-		 * are the same as the initial columns of the table for all the
-		 * indexes.  We also cheat by not providing an IndexInfo: this is okay
-		 * for now because btree doesn't need one, but we might have to be
-		 * more honest someday.
-		 *
-		 * Note also that there had better not be any user-created index on
-		 * the TOAST table, since we don't bother to update anything else.
-		 */
-		for (i = 0; i < num_indexes; i++)
-		{
-			/* Only index relations marked as ready can be updated */
-			if (toastidxs[i]->rd_index->indisready)
-				index_insert(toastidxs[i], t_values, t_isnull,
-							 &(toasttup->t_self),
-							 toastrel,
-							 toastidxs[i]->rd_index->indisunique ?
-							 UNIQUE_CHECK_YES : UNIQUE_CHECK_NO,
-							 NULL);
-		}
-
-		/*
-		 * Free memory
-		 */
-		heap_freetuple(toasttup);
-
-		/*
-		 * Move on to next chunk
-		 */
-		data_todo -= chunk_size;
-		data_p += chunk_size;
-	}
-
-	/*
-	 * Done - close toast relation and its indexes
-	 */
-	toast_close_indexes(toastidxs, num_indexes, RowExclusiveLock);
-	table_close(toastrel, RowExclusiveLock);
-
-	/*
-	 * Create the TOAST pointer value that we'll return
-	 */
-	result = (struct varlena *) palloc(TOAST_POINTER_SIZE);
-	SET_VARTAG_EXTERNAL(result, VARTAG_ONDISK);
-	memcpy(VARDATA_EXTERNAL(result), &toast_pointer, sizeof(toast_pointer));
-
-	return PointerGetDatum(result);
-}
-
-
-/* ----------
- * toast_delete_datum -
- *
- *	Delete a single external stored value.
- * ----------
- */
-static void
-toast_delete_datum(Relation rel, Datum value, bool is_speculative)
-{
-	struct varlena *attr = (struct varlena *) DatumGetPointer(value);
-	struct varatt_external toast_pointer;
-	Relation	toastrel;
-	Relation   *toastidxs;
-	ScanKeyData toastkey;
-	SysScanDesc toastscan;
-	HeapTuple	toasttup;
-	int			num_indexes;
-	int			validIndex;
-	SnapshotData SnapshotToast;
-
-	if (!VARATT_IS_EXTERNAL_ONDISK(attr))
-		return;
-
-	/* Must copy to access aligned fields */
-	VARATT_EXTERNAL_GET_POINTER(toast_pointer, attr);
-
-	/*
-	 * Open the toast relation and its indexes
-	 */
-	toastrel = table_open(toast_pointer.va_toastrelid, RowExclusiveLock);
-
-	/* Fetch valid relation used for process */
-	validIndex = toast_open_indexes(toastrel,
-									RowExclusiveLock,
-									&toastidxs,
-									&num_indexes);
-
-	/*
-	 * Setup a scan key to find chunks with matching va_valueid
-	 */
-	ScanKeyInit(&toastkey,
-				(AttrNumber) 1,
-				BTEqualStrategyNumber, F_OIDEQ,
-				ObjectIdGetDatum(toast_pointer.va_valueid));
-
-	/*
-	 * Find all the chunks.  (We don't actually care whether we see them in
-	 * sequence or not, but since we've already locked the index we might as
-	 * well use systable_beginscan_ordered.)
-	 */
-	init_toast_snapshot(&SnapshotToast);
-	toastscan = systable_beginscan_ordered(toastrel, toastidxs[validIndex],
-										   &SnapshotToast, 1, &toastkey);
-	while ((toasttup = systable_getnext_ordered(toastscan, ForwardScanDirection)) != NULL)
-	{
-		/*
-		 * Have a chunk, delete it
-		 */
-		if (is_speculative)
-			heap_abort_speculative(toastrel, &toasttup->t_self);
-		else
-			simple_heap_delete(toastrel, &toasttup->t_self);
-	}
-
-	/*
-	 * End scan and close relations
-	 */
-	systable_endscan_ordered(toastscan);
-	toast_close_indexes(toastidxs, num_indexes, RowExclusiveLock);
-	table_close(toastrel, RowExclusiveLock);
-}
-
-
-/* ----------
- * toastrel_valueid_exists -
- *
- *	Test whether a toast value with the given ID exists in the toast relation.
- *	For safety, we consider a value to exist if there are either live or dead
- *	toast rows with that ID; see notes for GetNewOidWithIndex().
- * ----------
- */
-static bool
-toastrel_valueid_exists(Relation toastrel, Oid valueid)
-{
-	bool		result = false;
-	ScanKeyData toastkey;
-	SysScanDesc toastscan;
-	int			num_indexes;
-	int			validIndex;
-	Relation   *toastidxs;
-
-	/* Fetch a valid index relation */
-	validIndex = toast_open_indexes(toastrel,
-									RowExclusiveLock,
-									&toastidxs,
-									&num_indexes);
-
-	/*
-	 * Setup a scan key to find chunks with matching va_valueid
-	 */
-	ScanKeyInit(&toastkey,
-				(AttrNumber) 1,
-				BTEqualStrategyNumber, F_OIDEQ,
-				ObjectIdGetDatum(valueid));
-
-	/*
-	 * Is there any such chunk?
-	 */
-	toastscan = systable_beginscan(toastrel,
-								   RelationGetRelid(toastidxs[validIndex]),
-								   true, SnapshotAny, 1, &toastkey);
-
-	if (systable_getnext(toastscan) != NULL)
-		result = true;
-
-	systable_endscan(toastscan);
-
-	/* Clean up */
-	toast_close_indexes(toastidxs, num_indexes, RowExclusiveLock);
-
-	return result;
-}
-
-/* ----------
- * toastid_valueid_exists -
- *
- *	As above, but work from toast rel's OID not an open relation
- * ----------
- */
-static bool
-toastid_valueid_exists(Oid toastrelid, Oid valueid)
-{
-	bool		result;
-	Relation	toastrel;
-
-	toastrel = table_open(toastrelid, AccessShareLock);
-
-	result = toastrel_valueid_exists(toastrel, valueid);
-
-	table_close(toastrel, AccessShareLock);
-
-	return result;
-}
-
-
-/* ----------
- * toast_fetch_datum -
- *
- *	Reconstruct an in memory Datum from the chunks saved
- *	in the toast relation
- * ----------
- */
-static struct varlena *
-toast_fetch_datum(struct varlena *attr)
-{
-	Relation	toastrel;
-	Relation   *toastidxs;
-	ScanKeyData toastkey;
-	SysScanDesc toastscan;
-	HeapTuple	ttup;
-	TupleDesc	toasttupDesc;
-	struct varlena *result;
-	struct varatt_external toast_pointer;
-	int32		ressize;
-	int32		residx,
-				nextidx;
-	int32		numchunks;
-	Pointer		chunk;
-	bool		isnull;
-	char	   *chunkdata;
-	int32		chunksize;
-	int			num_indexes;
-	int			validIndex;
-	SnapshotData SnapshotToast;
-
-	if (!VARATT_IS_EXTERNAL_ONDISK(attr))
-		elog(ERROR, "toast_fetch_datum shouldn't be called for non-ondisk datums");
-
-	/* Must copy to access aligned fields */
-	VARATT_EXTERNAL_GET_POINTER(toast_pointer, attr);
-
-	ressize = toast_pointer.va_extsize;
-	numchunks = ((ressize - 1) / TOAST_MAX_CHUNK_SIZE) + 1;
-
-	result = (struct varlena *) palloc(ressize + VARHDRSZ);
-
-	if (VARATT_EXTERNAL_IS_COMPRESSED(toast_pointer))
-		SET_VARSIZE_COMPRESSED(result, ressize + VARHDRSZ);
-	else
-		SET_VARSIZE(result, ressize + VARHDRSZ);
-
-	/*
-	 * Open the toast relation and its indexes
-	 */
-	toastrel = table_open(toast_pointer.va_toastrelid, AccessShareLock);
-	toasttupDesc = toastrel->rd_att;
-
-	/* Look for the valid index of the toast relation */
-	validIndex = toast_open_indexes(toastrel,
-									AccessShareLock,
-									&toastidxs,
-									&num_indexes);
-
-	/*
-	 * Setup a scan key to fetch from the index by va_valueid
-	 */
-	ScanKeyInit(&toastkey,
-				(AttrNumber) 1,
-				BTEqualStrategyNumber, F_OIDEQ,
-				ObjectIdGetDatum(toast_pointer.va_valueid));
-
-	/*
-	 * Read the chunks by index
-	 *
-	 * Note that because the index is actually on (valueid, chunkidx) we will
-	 * see the chunks in chunkidx order, even though we didn't explicitly ask
-	 * for it.
-	 */
-	nextidx = 0;
-
-	init_toast_snapshot(&SnapshotToast);
-	toastscan = systable_beginscan_ordered(toastrel, toastidxs[validIndex],
-										   &SnapshotToast, 1, &toastkey);
-	while ((ttup = systable_getnext_ordered(toastscan, ForwardScanDirection)) != NULL)
-	{
-		/*
-		 * Have a chunk, extract the sequence number and the data
-		 */
-		residx = DatumGetInt32(fastgetattr(ttup, 2, toasttupDesc, &isnull));
-		Assert(!isnull);
-		chunk = DatumGetPointer(fastgetattr(ttup, 3, toasttupDesc, &isnull));
-		Assert(!isnull);
-		if (!VARATT_IS_EXTENDED(chunk))
-		{
-			chunksize = VARSIZE(chunk) - VARHDRSZ;
-			chunkdata = VARDATA(chunk);
-		}
-		else if (VARATT_IS_SHORT(chunk))
-		{
-			/* could happen due to heap_form_tuple doing its thing */
-			chunksize = VARSIZE_SHORT(chunk) - VARHDRSZ_SHORT;
-			chunkdata = VARDATA_SHORT(chunk);
-		}
-		else
-		{
-			/* should never happen */
-			elog(ERROR, "found toasted toast chunk for toast value %u in %s",
-				 toast_pointer.va_valueid,
-				 RelationGetRelationName(toastrel));
-			chunksize = 0;		/* keep compiler quiet */
-			chunkdata = NULL;
-		}
-
-		/*
-		 * Some checks on the data we've found
-		 */
-		if (residx != nextidx)
-			elog(ERROR, "unexpected chunk number %d (expected %d) for toast value %u in %s",
-				 residx, nextidx,
-				 toast_pointer.va_valueid,
-				 RelationGetRelationName(toastrel));
-		if (residx < numchunks - 1)
-		{
-			if (chunksize != TOAST_MAX_CHUNK_SIZE)
-				elog(ERROR, "unexpected chunk size %d (expected %d) in chunk %d of %d for toast value %u in %s",
-					 chunksize, (int) TOAST_MAX_CHUNK_SIZE,
-					 residx, numchunks,
-					 toast_pointer.va_valueid,
-					 RelationGetRelationName(toastrel));
-		}
-		else if (residx == numchunks - 1)
-		{
-			if ((residx * TOAST_MAX_CHUNK_SIZE + chunksize) != ressize)
-				elog(ERROR, "unexpected chunk size %d (expected %d) in final chunk %d for toast value %u in %s",
-					 chunksize,
-					 (int) (ressize - residx * TOAST_MAX_CHUNK_SIZE),
-					 residx,
-					 toast_pointer.va_valueid,
-					 RelationGetRelationName(toastrel));
-		}
-		else
-			elog(ERROR, "unexpected chunk number %d (out of range %d..%d) for toast value %u in %s",
-				 residx,
-				 0, numchunks - 1,
-				 toast_pointer.va_valueid,
-				 RelationGetRelationName(toastrel));
-
-		/*
-		 * Copy the data into proper place in our result
-		 */
-		memcpy(VARDATA(result) + residx * TOAST_MAX_CHUNK_SIZE,
-			   chunkdata,
-			   chunksize);
-
-		nextidx++;
-	}
-
-	/*
-	 * Final checks that we successfully fetched the datum
-	 */
-	if (nextidx != numchunks)
-		elog(ERROR, "missing chunk number %d for toast value %u in %s",
-			 nextidx,
-			 toast_pointer.va_valueid,
-			 RelationGetRelationName(toastrel));
-
-	/*
-	 * End scan and close relations
-	 */
-	systable_endscan_ordered(toastscan);
-	toast_close_indexes(toastidxs, num_indexes, AccessShareLock);
-	table_close(toastrel, AccessShareLock);
-
-	return result;
-}
-
-/* ----------
- * toast_fetch_datum_slice -
- *
- *	Reconstruct a segment of a Datum from the chunks saved
- *	in the toast relation
- *
- *	Note that this function only supports non-compressed external datums.
- * ----------
- */
-static struct varlena *
-toast_fetch_datum_slice(struct varlena *attr, int32 sliceoffset, int32 length)
-{
-	Relation	toastrel;
-	Relation   *toastidxs;
-	ScanKeyData toastkey[3];
-	int			nscankeys;
-	SysScanDesc toastscan;
-	HeapTuple	ttup;
-	TupleDesc	toasttupDesc;
-	struct varlena *result;
-	struct varatt_external toast_pointer;
-	int32		attrsize;
-	int32		residx;
-	int32		nextidx;
-	int			numchunks;
-	int			startchunk;
-	int			endchunk;
-	int32		startoffset;
-	int32		endoffset;
-	int			totalchunks;
-	Pointer		chunk;
-	bool		isnull;
-	char	   *chunkdata;
-	int32		chunksize;
-	int32		chcpystrt;
-	int32		chcpyend;
-	int			num_indexes;
-	int			validIndex;
-	SnapshotData SnapshotToast;
-
-	if (!VARATT_IS_EXTERNAL_ONDISK(attr))
-		elog(ERROR, "toast_fetch_datum_slice shouldn't be called for non-ondisk datums");
-
-	/* Must copy to access aligned fields */
-	VARATT_EXTERNAL_GET_POINTER(toast_pointer, attr);
-
-	/*
-	 * It's nonsense to fetch slices of a compressed datum -- this isn't lo_*
-	 * we can't return a compressed datum which is meaningful to toast later
-	 */
-	Assert(!VARATT_EXTERNAL_IS_COMPRESSED(toast_pointer));
-
-	attrsize = toast_pointer.va_extsize;
-	totalchunks = ((attrsize - 1) / TOAST_MAX_CHUNK_SIZE) + 1;
-
-	if (sliceoffset >= attrsize)
-	{
-		sliceoffset = 0;
-		length = 0;
-	}
-
-	if (((sliceoffset + length) > attrsize) || length < 0)
-		length = attrsize - sliceoffset;
-
-	result = (struct varlena *) palloc(length + VARHDRSZ);
-
-	SET_VARSIZE(result, length + VARHDRSZ);
-
-	if (length == 0)
-		return result;			/* Can save a lot of work at this point! */
-
-	startchunk = sliceoffset / TOAST_MAX_CHUNK_SIZE;
-	endchunk = (sliceoffset + length - 1) / TOAST_MAX_CHUNK_SIZE;
-	numchunks = (endchunk - startchunk) + 1;
-
-	startoffset = sliceoffset % TOAST_MAX_CHUNK_SIZE;
-	endoffset = (sliceoffset + length - 1) % TOAST_MAX_CHUNK_SIZE;
-
-	/*
-	 * Open the toast relation and its indexes
-	 */
-	toastrel = table_open(toast_pointer.va_toastrelid, AccessShareLock);
-	toasttupDesc = toastrel->rd_att;
-
-	/* Look for the valid index of toast relation */
-	validIndex = toast_open_indexes(toastrel,
-									AccessShareLock,
-									&toastidxs,
-									&num_indexes);
-
-	/*
-	 * Setup a scan key to fetch from the index. This is either two keys or
-	 * three depending on the number of chunks.
-	 */
-	ScanKeyInit(&toastkey[0],
-				(AttrNumber) 1,
-				BTEqualStrategyNumber, F_OIDEQ,
-				ObjectIdGetDatum(toast_pointer.va_valueid));
-
-	/*
-	 * Use equality condition for one chunk, a range condition otherwise:
-	 */
-	if (numchunks == 1)
-	{
-		ScanKeyInit(&toastkey[1],
-					(AttrNumber) 2,
-					BTEqualStrategyNumber, F_INT4EQ,
-					Int32GetDatum(startchunk));
-		nscankeys = 2;
-	}
-	else
-	{
-		ScanKeyInit(&toastkey[1],
-					(AttrNumber) 2,
-					BTGreaterEqualStrategyNumber, F_INT4GE,
-					Int32GetDatum(startchunk));
-		ScanKeyInit(&toastkey[2],
-					(AttrNumber) 2,
-					BTLessEqualStrategyNumber, F_INT4LE,
-					Int32GetDatum(endchunk));
-		nscankeys = 3;
-	}
-
-	/*
-	 * Read the chunks by index
-	 *
-	 * The index is on (valueid, chunkidx) so they will come in order
-	 */
-	init_toast_snapshot(&SnapshotToast);
-	nextidx = startchunk;
-	toastscan = systable_beginscan_ordered(toastrel, toastidxs[validIndex],
-										   &SnapshotToast, nscankeys, toastkey);
-	while ((ttup = systable_getnext_ordered(toastscan, ForwardScanDirection)) != NULL)
-	{
-		/*
-		 * Have a chunk, extract the sequence number and the data
-		 */
-		residx = DatumGetInt32(fastgetattr(ttup, 2, toasttupDesc, &isnull));
-		Assert(!isnull);
-		chunk = DatumGetPointer(fastgetattr(ttup, 3, toasttupDesc, &isnull));
-		Assert(!isnull);
-		if (!VARATT_IS_EXTENDED(chunk))
-		{
-			chunksize = VARSIZE(chunk) - VARHDRSZ;
-			chunkdata = VARDATA(chunk);
-		}
-		else if (VARATT_IS_SHORT(chunk))
-		{
-			/* could happen due to heap_form_tuple doing its thing */
-			chunksize = VARSIZE_SHORT(chunk) - VARHDRSZ_SHORT;
-			chunkdata = VARDATA_SHORT(chunk);
-		}
-		else
-		{
-			/* should never happen */
-			elog(ERROR, "found toasted toast chunk for toast value %u in %s",
-				 toast_pointer.va_valueid,
-				 RelationGetRelationName(toastrel));
-			chunksize = 0;		/* keep compiler quiet */
-			chunkdata = NULL;
-		}
-
-		/*
-		 * Some checks on the data we've found
-		 */
-		if ((residx != nextidx) || (residx > endchunk) || (residx < startchunk))
-			elog(ERROR, "unexpected chunk number %d (expected %d) for toast value %u in %s",
-				 residx, nextidx,
-				 toast_pointer.va_valueid,
-				 RelationGetRelationName(toastrel));
-		if (residx < totalchunks - 1)
-		{
-			if (chunksize != TOAST_MAX_CHUNK_SIZE)
-				elog(ERROR, "unexpected chunk size %d (expected %d) in chunk %d of %d for toast value %u in %s when fetching slice",
-					 chunksize, (int) TOAST_MAX_CHUNK_SIZE,
-					 residx, totalchunks,
-					 toast_pointer.va_valueid,
-					 RelationGetRelationName(toastrel));
-		}
-		else if (residx == totalchunks - 1)
-		{
-			if ((residx * TOAST_MAX_CHUNK_SIZE + chunksize) != attrsize)
-				elog(ERROR, "unexpected chunk size %d (expected %d) in final chunk %d for toast value %u in %s when fetching slice",
-					 chunksize,
-					 (int) (attrsize - residx * TOAST_MAX_CHUNK_SIZE),
-					 residx,
-					 toast_pointer.va_valueid,
-					 RelationGetRelationName(toastrel));
-		}
-		else
-			elog(ERROR, "unexpected chunk number %d (out of range %d..%d) for toast value %u in %s",
-				 residx,
-				 0, totalchunks - 1,
-				 toast_pointer.va_valueid,
-				 RelationGetRelationName(toastrel));
-
-		/*
-		 * Copy the data into proper place in our result
-		 */
-		chcpystrt = 0;
-		chcpyend = chunksize - 1;
-		if (residx == startchunk)
-			chcpystrt = startoffset;
-		if (residx == endchunk)
-			chcpyend = endoffset;
-
-		memcpy(VARDATA(result) +
-			   (residx * TOAST_MAX_CHUNK_SIZE - sliceoffset) + chcpystrt,
-			   chunkdata + chcpystrt,
-			   (chcpyend - chcpystrt) + 1);
-
-		nextidx++;
-	}
-
-	/*
-	 * Final checks that we successfully fetched the datum
-	 */
-	if (nextidx != (endchunk + 1))
-		elog(ERROR, "missing chunk number %d for toast value %u in %s",
-			 nextidx,
-			 toast_pointer.va_valueid,
-			 RelationGetRelationName(toastrel));
-
-	/*
-	 * End scan and close relations
-	 */
-	systable_endscan_ordered(toastscan);
-	toast_close_indexes(toastidxs, num_indexes, AccessShareLock);
-	table_close(toastrel, AccessShareLock);
-
-	return result;
-}
-
-/* ----------
- * toast_decompress_datum -
- *
- * Decompress a compressed version of a varlena datum
- */
-static struct varlena *
-toast_decompress_datum(struct varlena *attr)
-{
-	struct varlena *result;
-
-	Assert(VARATT_IS_COMPRESSED(attr));
-
-	result = (struct varlena *)
-		palloc(TOAST_COMPRESS_RAWSIZE(attr) + VARHDRSZ);
-	SET_VARSIZE(result, TOAST_COMPRESS_RAWSIZE(attr) + VARHDRSZ);
-
-	if (pglz_decompress(TOAST_COMPRESS_RAWDATA(attr),
-						VARSIZE(attr) - TOAST_COMPRESS_HDRSZ,
-						VARDATA(result),
-						TOAST_COMPRESS_RAWSIZE(attr), true) < 0)
-		elog(ERROR, "compressed data is corrupted");
-
-	return result;
-}
-
-
-/* ----------
- * toast_decompress_datum_slice -
- *
- * Decompress the front of a compressed version of a varlena datum.
- * offset handling happens in heap_tuple_untoast_attr_slice.
- * Here we just decompress a slice from the front.
- */
-static struct varlena *
-toast_decompress_datum_slice(struct varlena *attr, int32 slicelength)
-{
-	struct varlena *result;
-	int32 rawsize;
-
-	Assert(VARATT_IS_COMPRESSED(attr));
-
-	result = (struct varlena *) palloc(slicelength + VARHDRSZ);
-
-	rawsize = pglz_decompress(TOAST_COMPRESS_RAWDATA(attr),
-						VARSIZE(attr) - TOAST_COMPRESS_HDRSZ,
-						VARDATA(result),
-						slicelength, false);
-	if (rawsize < 0)
-		elog(ERROR, "compressed data is corrupted");
-
-	SET_VARSIZE(result, rawsize + VARHDRSZ);
-	return result;
-}
-
-
-/* ----------
- * toast_open_indexes
- *
- *	Get an array of the indexes associated to the given toast relation
- *	and return as well the position of the valid index used by the toast
- *	relation in this array. It is the responsibility of the caller of this
- *	function to close the indexes as well as free them.
- */
-static int
-toast_open_indexes(Relation toastrel,
-				   LOCKMODE lock,
-				   Relation **toastidxs,
-				   int *num_indexes)
-{
-	int			i = 0;
-	int			res = 0;
-	bool		found = false;
-	List	   *indexlist;
-	ListCell   *lc;
-
-	/* Get index list of the toast relation */
-	indexlist = RelationGetIndexList(toastrel);
-	Assert(indexlist != NIL);
-
-	*num_indexes = list_length(indexlist);
-
-	/* Open all the index relations */
-	*toastidxs = (Relation *) palloc(*num_indexes * sizeof(Relation));
-	foreach(lc, indexlist)
-		(*toastidxs)[i++] = index_open(lfirst_oid(lc), lock);
-
-	/* Fetch the first valid index in list */
-	for (i = 0; i < *num_indexes; i++)
-	{
-		Relation	toastidx = (*toastidxs)[i];
-
-		if (toastidx->rd_index->indisvalid)
-		{
-			res = i;
-			found = true;
-			break;
-		}
-	}
-
-	/*
-	 * Free index list, not necessary anymore as relations are opened and a
-	 * valid index has been found.
-	 */
-	list_free(indexlist);
-
-	/*
-	 * The toast relation should have one valid index, so something is going
-	 * wrong if there is nothing.
-	 */
-	if (!found)
-		elog(ERROR, "no valid index found for toast relation with Oid %u",
-			 RelationGetRelid(toastrel));
-
-	return res;
-}
-
-/* ----------
- * toast_close_indexes
- *
- *	Close an array of indexes for a toast relation and free it. This should
- *	be called for a set of indexes opened previously with toast_open_indexes.
- */
-static void
-toast_close_indexes(Relation *toastidxs, int num_indexes, LOCKMODE lock)
-{
-	int			i;
-
-	/* Close relations and clean up things */
-	for (i = 0; i < num_indexes; i++)
-		index_close(toastidxs[i], lock);
-	pfree(toastidxs);
-}
-
-/* ----------
- * init_toast_snapshot
- *
- *	Initialize an appropriate TOAST snapshot.  We must use an MVCC snapshot
- *	to initialize the TOAST snapshot; since we don't know which one to use,
- *	just use the oldest one.  This is safe: at worst, we will get a "snapshot
- *	too old" error that might have been avoided otherwise.
- */
-static void
-init_toast_snapshot(Snapshot toast_snapshot)
-{
-	Snapshot	snapshot = GetOldestSnapshot();
-
-	if (snapshot == NULL)
-		elog(ERROR, "no known snapshots");
-
-	InitToastSnapshot(*toast_snapshot, snapshot->lsn, snapshot->whenTaken);
-}
diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c
index 527522f165..dd57b78190 100644
--- a/src/backend/access/transam/xlog.c
+++ b/src/backend/access/transam/xlog.c
@@ -24,12 +24,12 @@
 
 #include "access/clog.h"
 #include "access/commit_ts.h"
+#include "access/heaptoast.h"
 #include "access/multixact.h"
 #include "access/rewriteheap.h"
 #include "access/subtrans.h"
 #include "access/timeline.h"
 #include "access/transam.h"
-#include "access/tuptoaster.h"
 #include "access/twophase.h"
 #include "access/xact.h"
 #include "access/xlog_internal.h"
diff --git a/src/backend/commands/analyze.c b/src/backend/commands/analyze.c
index e0ec62c88c..a16fc27cdc 100644
--- a/src/backend/commands/analyze.c
+++ b/src/backend/commands/analyze.c
@@ -16,6 +16,7 @@
 
 #include <math.h>
 
+#include "access/detoast.h"
 #include "access/genam.h"
 #include "access/multixact.h"
 #include "access/relation.h"
@@ -24,7 +25,6 @@
 #include "access/tableam.h"
 #include "access/transam.h"
 #include "access/tupconvert.h"
-#include "access/tuptoaster.h"
 #include "access/visibilitymap.h"
 #include "access/xact.h"
 #include "catalog/catalog.h"
diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c
index 3ee7056047..c79a300899 100644
--- a/src/backend/commands/cluster.c
+++ b/src/backend/commands/cluster.c
@@ -23,7 +23,7 @@
 #include "access/relscan.h"
 #include "access/tableam.h"
 #include "access/transam.h"
-#include "access/tuptoaster.h"
+#include "access/toast_internals.h"
 #include "access/xact.h"
 #include "access/xlog.h"
 #include "catalog/pg_am.h"
diff --git a/src/backend/executor/execExprInterp.c b/src/backend/executor/execExprInterp.c
index a018925d4e..7c35604ee2 100644
--- a/src/backend/executor/execExprInterp.c
+++ b/src/backend/executor/execExprInterp.c
@@ -56,7 +56,7 @@
  */
 #include "postgres.h"
 
-#include "access/tuptoaster.h"
+#include "access/heaptoast.h"
 #include "catalog/pg_type.h"
 #include "commands/sequence.h"
 #include "executor/execExpr.h"
diff --git a/src/backend/executor/execTuples.c b/src/backend/executor/execTuples.c
index 55d1669db0..41d6e9de18 100644
--- a/src/backend/executor/execTuples.c
+++ b/src/backend/executor/execTuples.c
@@ -57,9 +57,9 @@
  */
 #include "postgres.h"
 
+#include "access/heaptoast.h"
 #include "access/htup_details.h"
 #include "access/tupdesc_details.h"
-#include "access/tuptoaster.h"
 #include "funcapi.h"
 #include "catalog/pg_type.h"
 #include "nodes/nodeFuncs.h"
diff --git a/src/backend/executor/tstoreReceiver.c b/src/backend/executor/tstoreReceiver.c
index cf79feb6bd..c0c81c82da 100644
--- a/src/backend/executor/tstoreReceiver.c
+++ b/src/backend/executor/tstoreReceiver.c
@@ -20,7 +20,7 @@
 
 #include "postgres.h"
 
-#include "access/tuptoaster.h"
+#include "access/detoast.h"
 #include "executor/tstoreReceiver.h"
 
 
diff --git a/src/backend/replication/logical/reorderbuffer.c b/src/backend/replication/logical/reorderbuffer.c
index 65f86ad73d..7ad5b0610c 100644
--- a/src/backend/replication/logical/reorderbuffer.c
+++ b/src/backend/replication/logical/reorderbuffer.c
@@ -56,10 +56,10 @@
 #include <unistd.h>
 #include <sys/stat.h>
 
+#include "access/detoast.h"
 #include "access/heapam.h"
 #include "access/rewriteheap.h"
 #include "access/transam.h"
-#include "access/tuptoaster.h"
 #include "access/xact.h"
 #include "access/xlog_internal.h"
 #include "catalog/catalog.h"
diff --git a/src/backend/statistics/extended_stats.c b/src/backend/statistics/extended_stats.c
index ac0ae52ecf..d99a10e894 100644
--- a/src/backend/statistics/extended_stats.c
+++ b/src/backend/statistics/extended_stats.c
@@ -16,10 +16,10 @@
  */
 #include "postgres.h"
 
+#include "access/detoast.h"
 #include "access/genam.h"
 #include "access/htup_details.h"
 #include "access/table.h"
-#include "access/tuptoaster.h"
 #include "catalog/indexing.h"
 #include "catalog/pg_collation.h"
 #include "catalog/pg_statistic_ext.h"
diff --git a/src/backend/storage/large_object/inv_api.c b/src/backend/storage/large_object/inv_api.c
index a477cb9200..e591236343 100644
--- a/src/backend/storage/large_object/inv_api.c
+++ b/src/backend/storage/large_object/inv_api.c
@@ -32,10 +32,11 @@
 
 #include <limits.h>
 
+#include "access/detoast.h"
 #include "access/genam.h"
+#include "access/htup_details.h"
 #include "access/sysattr.h"
 #include "access/table.h"
-#include "access/tuptoaster.h"
 #include "access/xact.h"
 #include "catalog/dependency.h"
 #include "catalog/indexing.h"
diff --git a/src/backend/utils/adt/array_typanalyze.c b/src/backend/utils/adt/array_typanalyze.c
index a03b7f7860..c7f8bb4ef2 100644
--- a/src/backend/utils/adt/array_typanalyze.c
+++ b/src/backend/utils/adt/array_typanalyze.c
@@ -14,7 +14,7 @@
  */
 #include "postgres.h"
 
-#include "access/tuptoaster.h"
+#include "access/detoast.h"
 #include "commands/vacuum.h"
 #include "utils/array.h"
 #include "utils/builtins.h"
diff --git a/src/backend/utils/adt/datum.c b/src/backend/utils/adt/datum.c
index 81ea5a48e5..1568658bc9 100644
--- a/src/backend/utils/adt/datum.c
+++ b/src/backend/utils/adt/datum.c
@@ -42,7 +42,7 @@
 
 #include "postgres.h"
 
-#include "access/tuptoaster.h"
+#include "access/detoast.h"
 #include "fmgr.h"
 #include "utils/datum.h"
 #include "utils/expandeddatum.h"
diff --git a/src/backend/utils/adt/expandedrecord.c b/src/backend/utils/adt/expandedrecord.c
index 9971abd71f..4fdd4d489e 100644
--- a/src/backend/utils/adt/expandedrecord.c
+++ b/src/backend/utils/adt/expandedrecord.c
@@ -18,8 +18,9 @@
  */
 #include "postgres.h"
 
+#include "access/detoast.h"
+#include "access/heaptoast.h"
 #include "access/htup_details.h"
-#include "access/tuptoaster.h"
 #include "catalog/heap.h"
 #include "catalog/pg_type.h"
 #include "utils/builtins.h"
diff --git a/src/backend/utils/adt/rowtypes.c b/src/backend/utils/adt/rowtypes.c
index aa7ec8735c..ea3e40a369 100644
--- a/src/backend/utils/adt/rowtypes.c
+++ b/src/backend/utils/adt/rowtypes.c
@@ -16,8 +16,8 @@
 
 #include <ctype.h>
 
+#include "access/detoast.h"
 #include "access/htup_details.h"
-#include "access/tuptoaster.h"
 #include "catalog/pg_type.h"
 #include "funcapi.h"
 #include "libpq/pqformat.h"
diff --git a/src/backend/utils/adt/tsgistidx.c b/src/backend/utils/adt/tsgistidx.c
index 4f256260fd..6ff71a49b8 100644
--- a/src/backend/utils/adt/tsgistidx.c
+++ b/src/backend/utils/adt/tsgistidx.c
@@ -15,7 +15,7 @@
 #include "postgres.h"
 
 #include "access/gist.h"
-#include "access/tuptoaster.h"
+#include "access/heaptoast.h"
 #include "port/pg_bitutils.h"
 #include "tsearch/ts_utils.h"
 #include "utils/builtins.h"
diff --git a/src/backend/utils/adt/varchar.c b/src/backend/utils/adt/varchar.c
index 4003631d8f..cffb009b9e 100644
--- a/src/backend/utils/adt/varchar.c
+++ b/src/backend/utils/adt/varchar.c
@@ -14,7 +14,7 @@
  */
 #include "postgres.h"
 
-#include "access/tuptoaster.h"
+#include "access/detoast.h"
 #include "catalog/pg_collation.h"
 #include "catalog/pg_type.h"
 #include "libpq/pqformat.h"
diff --git a/src/backend/utils/adt/varlena.c b/src/backend/utils/adt/varlena.c
index f82ce92ce3..d190e5f956 100644
--- a/src/backend/utils/adt/varlena.c
+++ b/src/backend/utils/adt/varlena.c
@@ -17,7 +17,7 @@
 #include <ctype.h>
 #include <limits.h>
 
-#include "access/tuptoaster.h"
+#include "access/detoast.h"
 #include "catalog/pg_collation.h"
 #include "catalog/pg_type.h"
 #include "common/int.h"
diff --git a/src/backend/utils/cache/catcache.c b/src/backend/utils/cache/catcache.c
index d05930bc4c..1060a4f50d 100644
--- a/src/backend/utils/cache/catcache.c
+++ b/src/backend/utils/cache/catcache.c
@@ -15,10 +15,10 @@
 #include "postgres.h"
 
 #include "access/genam.h"
+#include "access/heaptoast.h"
 #include "access/relscan.h"
 #include "access/sysattr.h"
 #include "access/table.h"
-#include "access/tuptoaster.h"
 #include "access/valid.h"
 #include "access/xact.h"
 #include "catalog/pg_collation.h"
diff --git a/src/backend/utils/fmgr/fmgr.c b/src/backend/utils/fmgr/fmgr.c
index ead8b371a7..5d0ace0721 100644
--- a/src/backend/utils/fmgr/fmgr.c
+++ b/src/backend/utils/fmgr/fmgr.c
@@ -15,7 +15,7 @@
 
 #include "postgres.h"
 
-#include "access/tuptoaster.h"
+#include "access/detoast.h"
 #include "catalog/pg_language.h"
 #include "catalog/pg_proc.h"
 #include "executor/functions.h"
diff --git a/src/bin/pg_resetwal/pg_resetwal.c b/src/bin/pg_resetwal/pg_resetwal.c
index 2734f87318..43b41a9b17 100644
--- a/src/bin/pg_resetwal/pg_resetwal.c
+++ b/src/bin/pg_resetwal/pg_resetwal.c
@@ -45,7 +45,7 @@
 #include <unistd.h>
 
 #include "access/transam.h"
-#include "access/tuptoaster.h"
+#include "access/heaptoast.h"
 #include "access/multixact.h"
 #include "access/xlog.h"
 #include "access/xlog_internal.h"
diff --git a/src/include/access/detoast.h b/src/include/access/detoast.h
new file mode 100644
index 0000000000..582af147ea
--- /dev/null
+++ b/src/include/access/detoast.h
@@ -0,0 +1,92 @@
+/*-------------------------------------------------------------------------
+ *
+ * detoast.h
+ *	  Access to compressed and external varlena values.
+ *
+ * Copyright (c) 2000-2019, PostgreSQL Global Development Group
+ *
+ * src/include/access/detoast.h
+ *
+ *-------------------------------------------------------------------------
+ */
+#ifndef DETOAST_H 
+#define DETOAST_H
+
+/*
+ * Testing whether an externally-stored value is compressed now requires
+ * comparing extsize (the actual length of the external data) to rawsize
+ * (the original uncompressed datum's size).  The latter includes VARHDRSZ
+ * overhead, the former doesn't.  We never use compression unless it actually
+ * saves space, so we expect either equality or less-than.
+ */
+#define VARATT_EXTERNAL_IS_COMPRESSED(toast_pointer) \
+	((toast_pointer).va_extsize < (toast_pointer).va_rawsize - VARHDRSZ)
+
+/*
+ * Macro to fetch the possibly-unaligned contents of an EXTERNAL datum
+ * into a local "struct varatt_external" toast pointer.  This should be
+ * just a memcpy, but some versions of gcc seem to produce broken code
+ * that assumes the datum contents are aligned.  Introducing an explicit
+ * intermediate "varattrib_1b_e *" variable seems to fix it.
+ */
+#define VARATT_EXTERNAL_GET_POINTER(toast_pointer, attr) \
+do { \
+	varattrib_1b_e *attre = (varattrib_1b_e *) (attr); \
+	Assert(VARATT_IS_EXTERNAL(attre)); \
+	Assert(VARSIZE_EXTERNAL(attre) == sizeof(toast_pointer) + VARHDRSZ_EXTERNAL); \
+	memcpy(&(toast_pointer), VARDATA_EXTERNAL(attre), sizeof(toast_pointer)); \
+} while (0)
+
+/* Size of an EXTERNAL datum that contains a standard TOAST pointer */
+#define TOAST_POINTER_SIZE (VARHDRSZ_EXTERNAL + sizeof(varatt_external))
+
+/* Size of an EXTERNAL datum that contains an indirection pointer */
+#define INDIRECT_POINTER_SIZE (VARHDRSZ_EXTERNAL + sizeof(varatt_indirect))
+
+/* ----------
+ * heap_tuple_fetch_attr() -
+ *
+ *		Fetches an external stored attribute from the toast
+ *		relation. Does NOT decompress it, if stored external
+ *		in compressed format.
+ * ----------
+ */
+extern struct varlena *heap_tuple_fetch_attr(struct varlena *attr);
+
+/* ----------
+ * heap_tuple_untoast_attr() -
+ *
+ *		Fully detoasts one attribute, fetching and/or decompressing
+ *		it as needed.
+ * ----------
+ */
+extern struct varlena *heap_tuple_untoast_attr(struct varlena *attr);
+
+/* ----------
+ * heap_tuple_untoast_attr_slice() -
+ *
+ *		Fetches only the specified portion of an attribute.
+ *		(Handles all cases for attribute storage)
+ * ----------
+ */
+extern struct varlena *heap_tuple_untoast_attr_slice(struct varlena *attr,
+							  int32 sliceoffset,
+							  int32 slicelength);
+
+/* ----------
+ * toast_raw_datum_size -
+ *
+ *	Return the raw (detoasted) size of a varlena datum
+ * ----------
+ */
+extern Size toast_raw_datum_size(Datum value);
+
+/* ----------
+ * toast_datum_size -
+ *
+ *	Return the storage size of a varlena datum
+ * ----------
+ */
+extern Size toast_datum_size(Datum value);
+
+#endif							/* DETOAST_H */
diff --git a/src/include/access/tuptoaster.h b/src/include/access/heaptoast.h
similarity index 57%
rename from src/include/access/tuptoaster.h
rename to src/include/access/heaptoast.h
index 4bfefffbf3..046aac7620 100644
--- a/src/include/access/tuptoaster.h
+++ b/src/include/access/heaptoast.h
@@ -1,29 +1,22 @@
 /*-------------------------------------------------------------------------
  *
- * tuptoaster.h
- *	  POSTGRES definitions for external and compressed storage
+ * heaptoast.h
+ *	  Heap-specific definitions for external and compressed storage
  *	  of variable size attributes.
  *
  * Copyright (c) 2000-2019, PostgreSQL Global Development Group
  *
- * src/include/access/tuptoaster.h
+ * src/include/access/heaptoast.h
  *
  *-------------------------------------------------------------------------
  */
-#ifndef TUPTOASTER_H
-#define TUPTOASTER_H
+#ifndef HEAPTOAST_H
+#define HEAPTOAST_H
 
 #include "access/htup_details.h"
 #include "storage/lockdefs.h"
 #include "utils/relcache.h"
 
-/*
- * This enables de-toasting of index entries.  Needed until VACUUM is
- * smart enough to rebuild indexes from scratch.
- */
-#define TOAST_INDEX_HACK
-
-
 /*
  * Find the maximum size of a tuple if there are to be N tuples per page.
  */
@@ -95,37 +88,6 @@
 	 sizeof(int32) -									\
 	 VARHDRSZ)
 
-/* Size of an EXTERNAL datum that contains a standard TOAST pointer */
-#define TOAST_POINTER_SIZE (VARHDRSZ_EXTERNAL + sizeof(varatt_external))
-
-/* Size of an EXTERNAL datum that contains an indirection pointer */
-#define INDIRECT_POINTER_SIZE (VARHDRSZ_EXTERNAL + sizeof(varatt_indirect))
-
-/*
- * Testing whether an externally-stored value is compressed now requires
- * comparing extsize (the actual length of the external data) to rawsize
- * (the original uncompressed datum's size).  The latter includes VARHDRSZ
- * overhead, the former doesn't.  We never use compression unless it actually
- * saves space, so we expect either equality or less-than.
- */
-#define VARATT_EXTERNAL_IS_COMPRESSED(toast_pointer) \
-	((toast_pointer).va_extsize < (toast_pointer).va_rawsize - VARHDRSZ)
-
-/*
- * Macro to fetch the possibly-unaligned contents of an EXTERNAL datum
- * into a local "struct varatt_external" toast pointer.  This should be
- * just a memcpy, but some versions of gcc seem to produce broken code
- * that assumes the datum contents are aligned.  Introducing an explicit
- * intermediate "varattrib_1b_e *" variable seems to fix it.
- */
-#define VARATT_EXTERNAL_GET_POINTER(toast_pointer, attr) \
-do { \
-	varattrib_1b_e *attre = (varattrib_1b_e *) (attr); \
-	Assert(VARATT_IS_EXTERNAL(attre)); \
-	Assert(VARSIZE_EXTERNAL(attre) == sizeof(toast_pointer) + VARHDRSZ_EXTERNAL); \
-	memcpy(&(toast_pointer), VARDATA_EXTERNAL(attre), sizeof(toast_pointer)); \
-} while (0)
-
 /* ----------
  * toast_insert_or_update -
  *
@@ -144,36 +106,6 @@ extern HeapTuple toast_insert_or_update(Relation rel,
  */
 extern void toast_delete(Relation rel, HeapTuple oldtup, bool is_speculative);
 
-/* ----------
- * heap_tuple_fetch_attr() -
- *
- *		Fetches an external stored attribute from the toast
- *		relation. Does NOT decompress it, if stored external
- *		in compressed format.
- * ----------
- */
-extern struct varlena *heap_tuple_fetch_attr(struct varlena *attr);
-
-/* ----------
- * heap_tuple_untoast_attr() -
- *
- *		Fully detoasts one attribute, fetching and/or decompressing
- *		it as needed.
- * ----------
- */
-extern struct varlena *heap_tuple_untoast_attr(struct varlena *attr);
-
-/* ----------
- * heap_tuple_untoast_attr_slice() -
- *
- *		Fetches only the specified portion of an attribute.
- *		(Handles all cases for attribute storage)
- * ----------
- */
-extern struct varlena *heap_tuple_untoast_attr_slice(struct varlena *attr,
-							  int32 sliceoffset,
-							  int32 slicelength);
-
 /* ----------
  * toast_flatten_tuple -
  *
@@ -204,36 +136,4 @@ extern HeapTuple toast_build_flattened_tuple(TupleDesc tupleDesc,
 							Datum *values,
 							bool *isnull);
 
-/* ----------
- * toast_compress_datum -
- *
- *	Create a compressed version of a varlena datum, if possible
- * ----------
- */
-extern Datum toast_compress_datum(Datum value);
-
-/* ----------
- * toast_raw_datum_size -
- *
- *	Return the raw (detoasted) size of a varlena datum
- * ----------
- */
-extern Size toast_raw_datum_size(Datum value);
-
-/* ----------
- * toast_datum_size -
- *
- *	Return the storage size of a varlena datum
- * ----------
- */
-extern Size toast_datum_size(Datum value);
-
-/* ----------
- * toast_get_valid_index -
- *
- *	Return OID of valid index associated to a toast relation
- * ----------
- */
-extern Oid	toast_get_valid_index(Oid toastoid, LOCKMODE lock);
-
-#endif							/* TUPTOASTER_H */
+#endif							/* HEAPTOAST_H */
diff --git a/src/include/access/toast_internals.h b/src/include/access/toast_internals.h
new file mode 100644
index 0000000000..8ac367fb9f
--- /dev/null
+++ b/src/include/access/toast_internals.h
@@ -0,0 +1,54 @@
+/*-------------------------------------------------------------------------
+ *
+ * toast_internals.h
+ *	  Internal definitions for the TOAST system.
+ *
+ * Copyright (c) 2000-2019, PostgreSQL Global Development Group
+ *
+ * src/include/access/toast_internals.h
+ *
+ *-------------------------------------------------------------------------
+ */
+#ifndef TOAST_INTERNALS_H
+#define TOAST_INTERNALS_H
+
+#include "storage/lockdefs.h"
+#include "utils/relcache.h"
+#include "utils/snapshot.h"
+
+/*
+ *	The information at the start of the compressed toast data.
+ */
+typedef struct toast_compress_header
+{
+	int32		vl_len_;		/* varlena header (do not touch directly!) */
+	int32		rawsize;
+} toast_compress_header;
+
+/*
+ * Utilities for manipulation of header information for compressed
+ * toast entries.
+ */
+#define TOAST_COMPRESS_HDRSZ		((int32) sizeof(toast_compress_header))
+#define TOAST_COMPRESS_RAWSIZE(ptr) (((toast_compress_header *) (ptr))->rawsize)
+#define TOAST_COMPRESS_RAWDATA(ptr) \
+	(((char *) (ptr)) + TOAST_COMPRESS_HDRSZ)
+#define TOAST_COMPRESS_SET_RAWSIZE(ptr, len) \
+	(((toast_compress_header *) (ptr))->rawsize = (len))
+
+extern Datum toast_compress_datum(Datum value);
+extern Oid	toast_get_valid_index(Oid toastoid, LOCKMODE lock);
+
+extern void toast_delete_datum(Relation rel, Datum value, bool is_speculative);
+extern Datum toast_save_datum(Relation rel, Datum value,
+				 struct varlena *oldexternal, int options);
+
+extern int toast_open_indexes(Relation toastrel,
+				   LOCKMODE lock,
+				   Relation **toastidxs,
+				   int *num_indexes);
+extern void toast_close_indexes(Relation *toastidxs, int num_indexes,
+					LOCKMODE lock);
+extern void init_toast_snapshot(Snapshot toast_snapshot);
+
+#endif							/* TOAST_INTERNALS_H */
diff --git a/src/pl/plpgsql/src/pl_exec.c b/src/pl/plpgsql/src/pl_exec.c
index 1b1d87e59a..46ced56df0 100644
--- a/src/pl/plpgsql/src/pl_exec.c
+++ b/src/pl/plpgsql/src/pl_exec.c
@@ -17,10 +17,10 @@
 
 #include <ctype.h>
 
+#include "access/detoast.h"
 #include "access/htup_details.h"
 #include "access/transam.h"
 #include "access/tupconvert.h"
-#include "access/tuptoaster.h"
 #include "catalog/pg_proc.h"
 #include "catalog/pg_type.h"
 #include "commands/defrem.h"
diff --git a/src/test/regress/regress.c b/src/test/regress/regress.c
index ad3e803899..e364375da9 100644
--- a/src/test/regress/regress.c
+++ b/src/test/regress/regress.c
@@ -19,9 +19,9 @@
 #include <math.h>
 #include <signal.h>
 
+#include "access/detoast.h"
 #include "access/htup_details.h"
 #include "access/transam.h"
-#include "access/tuptoaster.h"
 #include "access/xact.h"
 #include "catalog/pg_operator.h"
 #include "catalog/pg_type.h"
-- 
2.17.2 (Apple Git-113)

From c4ec963a5a83c27dfd1e1a2787d88aa4fd01d95c Mon Sep 17 00:00:00 2001
From: Robert Haas <rhaas@postgresql.org>
Date: Tue, 11 Jun 2019 11:10:15 -0400
Subject: [PATCH v3 3/3] Allow TOAST tables to be implemented using table AMs
 other than heap.

toast_fetch_datum, toast_save_datum, and toast_delete_datum are
adjusted to use tableam rather than heap-specific functions.  This
might have some performance impact, but this patch attempts to
mitigate that by restructuring things so that we don't open and close
the toast table and indexes multiple times per tuple.

tableam now exposes an integer value (not a callback) for the
maximum TOAST chunk size, and has a new callback allowing table
AMs to specify the AM that should be used to implement the TOAST
table. Previously, the toast AM was always the same as the table AM.
---
 src/backend/access/common/detoast.c         |  60 ++++-----
 src/backend/access/common/toast_internals.c | 127 +++++++-------------
 src/backend/access/heap/heapam.c            |   6 +-
 src/backend/access/heap/heapam_handler.c    |  14 ++-
 src/backend/access/heap/heaptoast.c         |  19 ++-
 src/backend/access/index/genam.c            |  20 +++
 src/backend/access/table/toast_helper.c     | 107 ++++++++++++++---
 src/backend/catalog/toasting.c              |   2 +-
 src/include/access/genam.h                  |   5 +-
 src/include/access/heapam.h                 |   3 +-
 src/include/access/heaptoast.h              |   3 +-
 src/include/access/tableam.h                |  31 +++++
 src/include/access/toast_helper.h           |  18 ++-
 src/include/access/toast_internals.h        |  13 +-
 14 files changed, 282 insertions(+), 146 deletions(-)

diff --git a/src/backend/access/common/detoast.c b/src/backend/access/common/detoast.c
index 54727bdf2c..e3a25c55ae 100644
--- a/src/backend/access/common/detoast.c
+++ b/src/backend/access/common/detoast.c
@@ -15,10 +15,11 @@
 
 #include "access/detoast.h"
 #include "access/genam.h"
-#include "access/heaptoast.h"
 #include "access/table.h"
 #include "access/toast_internals.h"
+#include "access/tableam.h"
 #include "common/pg_lzcompress.h"
+#include "executor/tuptable.h"
 #include "utils/expandeddatum.h"
 #include "utils/fmgroids.h"
 #include "utils/rel.h"
@@ -303,7 +304,7 @@ toast_fetch_datum(struct varlena *attr)
 	Relation   *toastidxs;
 	ScanKeyData toastkey;
 	SysScanDesc toastscan;
-	HeapTuple	ttup;
+	TupleTableSlot *slot;
 	TupleDesc	toasttupDesc;
 	struct varlena *result;
 	struct varatt_external toast_pointer;
@@ -312,11 +313,11 @@ toast_fetch_datum(struct varlena *attr)
 				nextidx;
 	int32		numchunks;
 	Pointer		chunk;
-	bool		isnull;
 	char	   *chunkdata;
 	int32		chunksize;
 	int			num_indexes;
 	int			validIndex;
+	int			max_chunk_size;
 	SnapshotData SnapshotToast;
 
 	if (!VARATT_IS_EXTERNAL_ONDISK(attr))
@@ -326,7 +327,6 @@ toast_fetch_datum(struct varlena *attr)
 	VARATT_EXTERNAL_GET_POINTER(toast_pointer, attr);
 
 	ressize = toast_pointer.va_extsize;
-	numchunks = ((ressize - 1) / TOAST_MAX_CHUNK_SIZE) + 1;
 
 	result = (struct varlena *) palloc(ressize + VARHDRSZ);
 
@@ -341,6 +341,9 @@ toast_fetch_datum(struct varlena *attr)
 	toastrel = table_open(toast_pointer.va_toastrelid, AccessShareLock);
 	toasttupDesc = toastrel->rd_att;
 
+	max_chunk_size = toastrel->rd_tableam->toast_max_chunk_size;
+	numchunks = ((ressize - 1) / max_chunk_size) + 1;
+
 	/* Look for the valid index of the toast relation */
 	validIndex = toast_open_indexes(toastrel,
 									AccessShareLock,
@@ -367,15 +370,15 @@ toast_fetch_datum(struct varlena *attr)
 	init_toast_snapshot(&SnapshotToast);
 	toastscan = systable_beginscan_ordered(toastrel, toastidxs[validIndex],
 										   &SnapshotToast, 1, &toastkey);
-	while ((ttup = systable_getnext_ordered(toastscan, ForwardScanDirection)) != NULL)
+	while ((slot = systable_getnextslot_ordered(toastscan, ForwardScanDirection)) != NULL)
 	{
 		/*
 		 * Have a chunk, extract the sequence number and the data
 		 */
-		residx = DatumGetInt32(fastgetattr(ttup, 2, toasttupDesc, &isnull));
-		Assert(!isnull);
-		chunk = DatumGetPointer(fastgetattr(ttup, 3, toasttupDesc, &isnull));
-		Assert(!isnull);
+		slot_getsomeattrs(slot, 3);
+		Assert(!slot->tts_isnull[1] && !slot->tts_isnull[2]);
+		residx = DatumGetInt32(slot->tts_values[1]);
+		chunk = DatumGetPointer(slot->tts_values[2]);
 		if (!VARATT_IS_EXTENDED(chunk))
 		{
 			chunksize = VARSIZE(chunk) - VARHDRSZ;
@@ -407,19 +410,19 @@ toast_fetch_datum(struct varlena *attr)
 				 RelationGetRelationName(toastrel));
 		if (residx < numchunks - 1)
 		{
-			if (chunksize != TOAST_MAX_CHUNK_SIZE)
+			if (chunksize != max_chunk_size)
 				elog(ERROR, "unexpected chunk size %d (expected %d) in chunk %d of %d for toast value %u in %s",
-					 chunksize, (int) TOAST_MAX_CHUNK_SIZE,
+					 chunksize, max_chunk_size,
 					 residx, numchunks,
 					 toast_pointer.va_valueid,
 					 RelationGetRelationName(toastrel));
 		}
 		else if (residx == numchunks - 1)
 		{
-			if ((residx * TOAST_MAX_CHUNK_SIZE + chunksize) != ressize)
+			if ((residx * max_chunk_size + chunksize) != ressize)
 				elog(ERROR, "unexpected chunk size %d (expected %d) in final chunk %d for toast value %u in %s",
 					 chunksize,
-					 (int) (ressize - residx * TOAST_MAX_CHUNK_SIZE),
+					 (int) (ressize - residx * max_chunk_size),
 					 residx,
 					 toast_pointer.va_valueid,
 					 RelationGetRelationName(toastrel));
@@ -434,7 +437,7 @@ toast_fetch_datum(struct varlena *attr)
 		/*
 		 * Copy the data into proper place in our result
 		 */
-		memcpy(VARDATA(result) + residx * TOAST_MAX_CHUNK_SIZE,
+		memcpy(VARDATA(result) + residx * max_chunk_size,
 			   chunkdata,
 			   chunksize);
 
@@ -498,6 +501,7 @@ toast_fetch_datum_slice(struct varlena *attr, int32 sliceoffset, int32 length)
 	int32		chcpyend;
 	int			num_indexes;
 	int			validIndex;
+	int			max_chunk_size;
 	SnapshotData SnapshotToast;
 
 	if (!VARATT_IS_EXTERNAL_ONDISK(attr))
@@ -513,7 +517,6 @@ toast_fetch_datum_slice(struct varlena *attr, int32 sliceoffset, int32 length)
 	Assert(!VARATT_EXTERNAL_IS_COMPRESSED(toast_pointer));
 
 	attrsize = toast_pointer.va_extsize;
-	totalchunks = ((attrsize - 1) / TOAST_MAX_CHUNK_SIZE) + 1;
 
 	if (sliceoffset >= attrsize)
 	{
@@ -531,19 +534,22 @@ toast_fetch_datum_slice(struct varlena *attr, int32 sliceoffset, int32 length)
 	if (length == 0)
 		return result;			/* Can save a lot of work at this point! */
 
-	startchunk = sliceoffset / TOAST_MAX_CHUNK_SIZE;
-	endchunk = (sliceoffset + length - 1) / TOAST_MAX_CHUNK_SIZE;
-	numchunks = (endchunk - startchunk) + 1;
-
-	startoffset = sliceoffset % TOAST_MAX_CHUNK_SIZE;
-	endoffset = (sliceoffset + length - 1) % TOAST_MAX_CHUNK_SIZE;
-
 	/*
 	 * Open the toast relation and its indexes
 	 */
 	toastrel = table_open(toast_pointer.va_toastrelid, AccessShareLock);
 	toasttupDesc = toastrel->rd_att;
 
+	max_chunk_size = toastrel->rd_tableam->toast_max_chunk_size;
+	totalchunks = ((attrsize - 1) / max_chunk_size) + 1;
+
+	startchunk = sliceoffset / max_chunk_size;
+	endchunk = (sliceoffset + length - 1) / max_chunk_size;
+	numchunks = (endchunk - startchunk) + 1;
+
+	startoffset = sliceoffset % max_chunk_size;
+	endoffset = (sliceoffset + length - 1) % max_chunk_size;
+
 	/* Look for the valid index of toast relation */
 	validIndex = toast_open_indexes(toastrel,
 									AccessShareLock,
@@ -632,19 +638,19 @@ toast_fetch_datum_slice(struct varlena *attr, int32 sliceoffset, int32 length)
 				 RelationGetRelationName(toastrel));
 		if (residx < totalchunks - 1)
 		{
-			if (chunksize != TOAST_MAX_CHUNK_SIZE)
+			if (chunksize != max_chunk_size)
 				elog(ERROR, "unexpected chunk size %d (expected %d) in chunk %d of %d for toast value %u in %s when fetching slice",
-					 chunksize, (int) TOAST_MAX_CHUNK_SIZE,
+					 chunksize, max_chunk_size,
 					 residx, totalchunks,
 					 toast_pointer.va_valueid,
 					 RelationGetRelationName(toastrel));
 		}
 		else if (residx == totalchunks - 1)
 		{
-			if ((residx * TOAST_MAX_CHUNK_SIZE + chunksize) != attrsize)
+			if ((residx * max_chunk_size + chunksize) != attrsize)
 				elog(ERROR, "unexpected chunk size %d (expected %d) in final chunk %d for toast value %u in %s when fetching slice",
 					 chunksize,
-					 (int) (attrsize - residx * TOAST_MAX_CHUNK_SIZE),
+					 (int) (attrsize - residx * max_chunk_size),
 					 residx,
 					 toast_pointer.va_valueid,
 					 RelationGetRelationName(toastrel));
@@ -667,7 +673,7 @@ toast_fetch_datum_slice(struct varlena *attr, int32 sliceoffset, int32 length)
 			chcpyend = endoffset;
 
 		memcpy(VARDATA(result) +
-			   (residx * TOAST_MAX_CHUNK_SIZE - sliceoffset) + chcpystrt,
+			   (residx * max_chunk_size - sliceoffset) + chcpystrt,
 			   chunkdata + chcpystrt,
 			   (chcpyend - chcpystrt) + 1);
 
diff --git a/src/backend/access/common/toast_internals.c b/src/backend/access/common/toast_internals.c
index a971242490..beb303034d 100644
--- a/src/backend/access/common/toast_internals.c
+++ b/src/backend/access/common/toast_internals.c
@@ -15,9 +15,8 @@
 
 #include "access/detoast.h"
 #include "access/genam.h"
-#include "access/heapam.h"
-#include "access/heaptoast.h"
 #include "access/table.h"
+#include "access/tableam.h"
 #include "access/toast_internals.h"
 #include "access/xact.h"
 #include "catalog/catalog.h"
@@ -100,22 +99,21 @@ toast_compress_datum(Datum value)
  *	Save one single datum into the secondary relation and return
  *	a Datum reference for it.
  *
- * rel: the main relation we're working with (not the toast rel!)
+ * toastrel: the TOAST relation we're working with (not the main rel!)
+ * toastslot: a slot corresponding to 'toastrel'
+ * num_indexes, toastidxs, validIndex: as returned by toast_open_indexes
+ * toastoid: the toast OID that should be inserted into the new TOAST pointer
  * value: datum to be pushed to toast storage
  * oldexternal: if not NULL, toast pointer previously representing the datum
- * options: options to be passed to heap_insert() for toast rows
+ * options: options to be passed to table_tuple_insert() for toast rows
  * ----------
  */
 Datum
-toast_save_datum(Relation rel, Datum value,
-				 struct varlena *oldexternal, int options)
+toast_save_datum(Relation toastrel, TupleTableSlot *toastslot,
+				 int num_indexes, Relation *toastidxs, int validIndex,
+				 Oid toastoid, Datum value, struct varlena *oldexternal,
+				 int options, int max_chunk_size)
 {
-	Relation	toastrel;
-	Relation   *toastidxs;
-	HeapTuple	toasttup;
-	TupleDesc	toasttupDesc;
-	Datum		t_values[3];
-	bool		t_isnull[3];
 	CommandId	mycid = GetCurrentCommandId(true);
 	struct varlena *result;
 	struct varatt_external toast_pointer;
@@ -123,7 +121,7 @@ toast_save_datum(Relation rel, Datum value,
 	{
 		struct varlena hdr;
 		/* this is to make the union big enough for a chunk: */
-		char		data[TOAST_MAX_CHUNK_SIZE + VARHDRSZ];
+		char		data[BLCKSZ + VARHDRSZ];
 		/* ensure union is aligned well enough: */
 		int32		align_it;
 	}			chunk_data;
@@ -132,24 +130,9 @@ toast_save_datum(Relation rel, Datum value,
 	char	   *data_p;
 	int32		data_todo;
 	Pointer		dval = DatumGetPointer(value);
-	int			num_indexes;
-	int			validIndex;
 
 	Assert(!VARATT_IS_EXTERNAL(value));
-
-	/*
-	 * Open the toast relation and its indexes.  We can use the index to check
-	 * uniqueness of the OID we assign to the toasted item, even though it has
-	 * additional columns besides OID.
-	 */
-	toastrel = table_open(rel->rd_rel->reltoastrelid, RowExclusiveLock);
-	toasttupDesc = toastrel->rd_att;
-
-	/* Open all the toast indexes and look for the valid one */
-	validIndex = toast_open_indexes(toastrel,
-									RowExclusiveLock,
-									&toastidxs,
-									&num_indexes);
+	Assert(max_chunk_size <= BLCKSZ);
 
 	/*
 	 * Get the data pointer and length, and compute va_rawsize and va_extsize.
@@ -189,11 +172,11 @@ toast_save_datum(Relation rel, Datum value,
 	 *
 	 * Normally this is the actual OID of the target toast table, but during
 	 * table-rewriting operations such as CLUSTER, we have to insert the OID
-	 * of the table's real permanent toast table instead.  rd_toastoid is set
+	 * of the table's real permanent toast table instead.  toastoid is set
 	 * if we have to substitute such an OID.
 	 */
-	if (OidIsValid(rel->rd_toastoid))
-		toast_pointer.va_toastrelid = rel->rd_toastoid;
+	if (OidIsValid(toastoid))
+		toast_pointer.va_toastrelid = toastoid;
 	else
 		toast_pointer.va_toastrelid = RelationGetRelid(toastrel);
 
@@ -209,7 +192,7 @@ toast_save_datum(Relation rel, Datum value,
 	 * options have been changed), we have to pick a value ID that doesn't
 	 * conflict with either new or existing toast value OIDs.
 	 */
-	if (!OidIsValid(rel->rd_toastoid))
+	if (!OidIsValid(toastoid))
 	{
 		/* normal case: just choose an unused OID */
 		toast_pointer.va_valueid =
@@ -228,7 +211,7 @@ toast_save_datum(Relation rel, Datum value,
 			Assert(VARATT_IS_EXTERNAL_ONDISK(oldexternal));
 			/* Must copy to access aligned fields */
 			VARATT_EXTERNAL_GET_POINTER(old_toast_pointer, oldexternal);
-			if (old_toast_pointer.va_toastrelid == rel->rd_toastoid)
+			if (old_toast_pointer.va_toastrelid == toastoid)
 			{
 				/* This value came from the old toast table; reuse its OID */
 				toast_pointer.va_valueid = old_toast_pointer.va_valueid;
@@ -270,20 +253,11 @@ toast_save_datum(Relation rel, Datum value,
 					GetNewOidWithIndex(toastrel,
 									   RelationGetRelid(toastidxs[validIndex]),
 									   (AttrNumber) 1);
-			} while (toastid_valueid_exists(rel->rd_toastoid,
+			} while (toastid_valueid_exists(toastoid,
 											toast_pointer.va_valueid));
 		}
 	}
 
-	/*
-	 * Initialize constant parts of the tuple data
-	 */
-	t_values[0] = ObjectIdGetDatum(toast_pointer.va_valueid);
-	t_values[2] = PointerGetDatum(&chunk_data);
-	t_isnull[0] = false;
-	t_isnull[1] = false;
-	t_isnull[2] = false;
-
 	/*
 	 * Split up the item into chunks
 	 */
@@ -296,17 +270,22 @@ toast_save_datum(Relation rel, Datum value,
 		/*
 		 * Calculate the size of this chunk
 		 */
-		chunk_size = Min(TOAST_MAX_CHUNK_SIZE, data_todo);
+		chunk_size = Min(max_chunk_size, data_todo);
 
 		/*
 		 * Build a tuple and store it
 		 */
-		t_values[1] = Int32GetDatum(chunk_seq++);
+		toastslot->tts_values[0] = ObjectIdGetDatum(toast_pointer.va_valueid);
+		toastslot->tts_values[1] = Int32GetDatum(chunk_seq++);
 		SET_VARSIZE(&chunk_data, chunk_size + VARHDRSZ);
 		memcpy(VARDATA(&chunk_data), data_p, chunk_size);
-		toasttup = heap_form_tuple(toasttupDesc, t_values, t_isnull);
+		toastslot->tts_values[2] = PointerGetDatum(&chunk_data);
+		toastslot->tts_isnull[0] = false;
+		toastslot->tts_isnull[1] = false;
+		toastslot->tts_isnull[2] = false;
+		ExecStoreVirtualTuple(toastslot);
 
-		heap_insert(toastrel, toasttup, mycid, options, NULL);
+		table_tuple_insert(toastrel, toastslot, mycid, options, NULL);
 
 		/*
 		 * Create the index entry.  We cheat a little here by not using
@@ -323,8 +302,9 @@ toast_save_datum(Relation rel, Datum value,
 		{
 			/* Only index relations marked as ready can be updated */
 			if (toastidxs[i]->rd_index->indisready)
-				index_insert(toastidxs[i], t_values, t_isnull,
-							 &(toasttup->t_self),
+				index_insert(toastidxs[i], toastslot->tts_values,
+							 toastslot->tts_isnull,
+							 &(toastslot->tts_tid),
 							 toastrel,
 							 toastidxs[i]->rd_index->indisunique ?
 							 UNIQUE_CHECK_YES : UNIQUE_CHECK_NO,
@@ -332,9 +312,9 @@ toast_save_datum(Relation rel, Datum value,
 		}
 
 		/*
-		 * Free memory
+		 * Clear slot
 		 */
-		heap_freetuple(toasttup);
+		ExecClearTuple(toastslot);
 
 		/*
 		 * Move on to next chunk
@@ -343,12 +323,6 @@ toast_save_datum(Relation rel, Datum value,
 		data_p += chunk_size;
 	}
 
-	/*
-	 * Done - close toast relation and its indexes
-	 */
-	toast_close_indexes(toastidxs, num_indexes, RowExclusiveLock);
-	table_close(toastrel, RowExclusiveLock);
-
 	/*
 	 * Create the TOAST pointer value that we'll return
 	 */
@@ -366,35 +340,24 @@ toast_save_datum(Relation rel, Datum value,
  * ----------
  */
 void
-toast_delete_datum(Relation rel, Datum value, bool is_speculative)
+toast_delete_datum(Relation toastrel, int num_indexes, Relation *toastidxs,
+				   int validIndex, Datum value, bool is_speculative,
+				   uint32 specToken)
 {
 	struct varlena *attr = (struct varlena *) DatumGetPointer(value);
 	struct varatt_external toast_pointer;
-	Relation	toastrel;
-	Relation   *toastidxs;
 	ScanKeyData toastkey;
 	SysScanDesc toastscan;
-	HeapTuple	toasttup;
-	int			num_indexes;
-	int			validIndex;
+	TupleTableSlot *slot;
 	SnapshotData SnapshotToast;
 
-	if (!VARATT_IS_EXTERNAL_ONDISK(attr))
-		return;
+	Assert(VARATT_IS_EXTERNAL_ONDISK(attr));
 
 	/* Must copy to access aligned fields */
 	VARATT_EXTERNAL_GET_POINTER(toast_pointer, attr);
 
-	/*
-	 * Open the toast relation and its indexes
-	 */
-	toastrel = table_open(toast_pointer.va_toastrelid, RowExclusiveLock);
-
-	/* Fetch valid relation used for process */
-	validIndex = toast_open_indexes(toastrel,
-									RowExclusiveLock,
-									&toastidxs,
-									&num_indexes);
+	/* Check that caller gave us the correct TOAST relation. */
+	Assert(toast_pointer.va_toastrelid == RelationGetRelid(toastrel));
 
 	/*
 	 * Setup a scan key to find chunks with matching va_valueid
@@ -412,23 +375,19 @@ toast_delete_datum(Relation rel, Datum value, bool is_speculative)
 	init_toast_snapshot(&SnapshotToast);
 	toastscan = systable_beginscan_ordered(toastrel, toastidxs[validIndex],
 										   &SnapshotToast, 1, &toastkey);
-	while ((toasttup = systable_getnext_ordered(toastscan, ForwardScanDirection)) != NULL)
+	while ((slot = systable_getnextslot_ordered(toastscan, ForwardScanDirection)) != NULL)
 	{
 		/*
 		 * Have a chunk, delete it
 		 */
 		if (is_speculative)
-			heap_abort_speculative(toastrel, &toasttup->t_self);
+			table_tuple_complete_speculative(toastrel, slot, specToken, false);
 		else
-			simple_heap_delete(toastrel, &toasttup->t_self);
+			simple_table_tuple_delete(toastrel, &slot->tts_tid, &SnapshotToast);
 	}
 
-	/*
-	 * End scan and close relations
-	 */
+	/* End scan */
 	systable_endscan_ordered(toastscan);
-	toast_close_indexes(toastidxs, num_indexes, RowExclusiveLock);
-	table_close(toastrel, RowExclusiveLock);
 }
 
 /* ----------
diff --git a/src/backend/access/heap/heapam.c b/src/backend/access/heap/heapam.c
index d32b638dd9..a5038ff5ad 100644
--- a/src/backend/access/heap/heapam.c
+++ b/src/backend/access/heap/heapam.c
@@ -2809,7 +2809,7 @@ l1:
 		Assert(!HeapTupleHasExternal(&tp));
 	}
 	else if (HeapTupleHasExternal(&tp))
-		toast_delete(relation, &tp, false);
+		toast_delete(relation, &tp, false, 0);
 
 	/*
 	 * Mark tuple for invalidation from system caches at next command
@@ -5540,7 +5540,7 @@ heap_finish_speculative(Relation relation, ItemPointer tid)
  * confirmation records.
  */
 void
-heap_abort_speculative(Relation relation, ItemPointer tid)
+heap_abort_speculative(Relation relation, ItemPointer tid, uint32 specToken)
 {
 	TransactionId xid = GetCurrentTransactionId();
 	ItemId		lp;
@@ -5649,7 +5649,7 @@ heap_abort_speculative(Relation relation, ItemPointer tid)
 	if (HeapTupleHasExternal(&tp))
 	{
 		Assert(!IsToastRelation(relation));
-		toast_delete(relation, &tp, true);
+		toast_delete(relation, &tp, true, specToken);
 	}
 
 	/*
diff --git a/src/backend/access/heap/heapam_handler.c b/src/backend/access/heap/heapam_handler.c
index 468f045434..4cedcf683e 100644
--- a/src/backend/access/heap/heapam_handler.c
+++ b/src/backend/access/heap/heapam_handler.c
@@ -30,6 +30,7 @@
 #include "access/rewriteheap.h"
 #include "access/tableam.h"
 #include "access/tsmapi.h"
+#include "access/heaptoast.h"
 #include "access/xact.h"
 #include "catalog/catalog.h"
 #include "catalog/index.h"
@@ -295,7 +296,7 @@ heapam_tuple_complete_speculative(Relation relation, TupleTableSlot *slot,
 	if (succeeded)
 		heap_finish_speculative(relation, &slot->tts_tid);
 	else
-		heap_abort_speculative(relation, &slot->tts_tid);
+		heap_abort_speculative(relation, &slot->tts_tid, specToken);
 
 	if (shouldFree)
 		pfree(tuple);
@@ -2062,6 +2063,15 @@ heapam_relation_needs_toast_table(Relation rel)
 	return (tuple_length > TOAST_TUPLE_THRESHOLD);
 }
 
+/*
+ * TOAST tables for heap relations are just heap relations.
+ */
+static Oid
+heapam_relation_toast_am(Relation rel)
+{
+	return rel->rd_rel->relam;
+}
+
 
 /* ------------------------------------------------------------------------
  * Planner related callbacks for the heap AM
@@ -2646,6 +2656,8 @@ static const TableAmRoutine heapam_methods = {
 
 	.relation_size = heapam_relation_size,
 	.relation_needs_toast_table = heapam_relation_needs_toast_table,
+	.relation_toast_am = heapam_relation_toast_am,
+	.toast_max_chunk_size = TOAST_MAX_CHUNK_SIZE,
 
 	.relation_estimate_size = heapam_estimate_rel_size,
 
diff --git a/src/backend/access/heap/heaptoast.c b/src/backend/access/heap/heaptoast.c
index 3a2118e1d8..1d4ad5b336 100644
--- a/src/backend/access/heap/heaptoast.c
+++ b/src/backend/access/heap/heaptoast.c
@@ -38,7 +38,8 @@
  * ----------
  */
 void
-toast_delete(Relation rel, HeapTuple oldtup, bool is_speculative)
+toast_delete(Relation rel, HeapTuple oldtup, bool is_speculative,
+			 uint32 specToken)
 {
 	TupleDesc	tupleDesc;
 	Datum		toast_values[MaxHeapAttributeNumber];
@@ -68,7 +69,8 @@ toast_delete(Relation rel, HeapTuple oldtup, bool is_speculative)
 	heap_deform_tuple(oldtup, tupleDesc, toast_values, toast_isnull);
 
 	/* Do the real work. */
-	toast_delete_external(rel, toast_values, toast_isnull, is_speculative);
+	toast_delete_external(rel, toast_values, toast_isnull, is_speculative,
+						  specToken);
 }
 
 
@@ -151,6 +153,8 @@ toast_insert_or_update(Relation rel, HeapTuple newtup, HeapTuple oldtup,
 		ttc.ttc_oldvalues = toast_oldvalues;
 		ttc.ttc_oldisnull = toast_oldisnull;
 	}
+	ttc.ttc_toastrel = NULL;
+	ttc.ttc_toastslot = NULL;
 	ttc.ttc_attr = toast_attr;
 	toast_tuple_init(&ttc);
 
@@ -207,7 +211,8 @@ toast_insert_or_update(Relation rel, HeapTuple newtup, HeapTuple oldtup,
 		 */
 		if (toast_attr[biggest_attno].tai_size > maxDataLen &&
 			rel->rd_rel->reltoastrelid != InvalidOid)
-			toast_tuple_externalize(&ttc, biggest_attno, options);
+			toast_tuple_externalize(&ttc, biggest_attno, options,
+									TOAST_MAX_CHUNK_SIZE);
 	}
 
 	/*
@@ -224,7 +229,8 @@ toast_insert_or_update(Relation rel, HeapTuple newtup, HeapTuple oldtup,
 		biggest_attno = toast_tuple_find_biggest_attribute(&ttc, false, false);
 		if (biggest_attno < 0)
 			break;
-		toast_tuple_externalize(&ttc, biggest_attno, options);
+		toast_tuple_externalize(&ttc, biggest_attno, options,
+								TOAST_MAX_CHUNK_SIZE);
 	}
 
 	/*
@@ -260,7 +266,8 @@ toast_insert_or_update(Relation rel, HeapTuple newtup, HeapTuple oldtup,
 		if (biggest_attno < 0)
 			break;
 
-		toast_tuple_externalize(&ttc, biggest_attno, options);
+		toast_tuple_externalize(&ttc, biggest_attno, options,
+								TOAST_MAX_CHUNK_SIZE);
 	}
 
 	/*
@@ -323,7 +330,7 @@ toast_insert_or_update(Relation rel, HeapTuple newtup, HeapTuple oldtup,
 	else
 		result_tuple = newtup;
 
-	toast_tuple_cleanup(&ttc);
+	toast_tuple_cleanup(&ttc, true);
 
 	return result_tuple;
 }
diff --git a/src/backend/access/index/genam.c b/src/backend/access/index/genam.c
index 42aaa5bad6..4264bad4e7 100644
--- a/src/backend/access/index/genam.c
+++ b/src/backend/access/index/genam.c
@@ -642,6 +642,26 @@ systable_getnext_ordered(SysScanDesc sysscan, ScanDirection direction)
 	return htup;
 }
 
+/*
+ * systable_getnextslot_ordered
+ *
+ * Return a slot containing the next tuple from an ordered catalog scan,
+ * or NULL if there are no more tuples.
+ */
+TupleTableSlot *
+systable_getnextslot_ordered(SysScanDesc sysscan, ScanDirection direction)
+{
+	Assert(sysscan->irel);
+	if (!index_getnext_slot(sysscan->iscan, direction, sysscan->slot))
+		return NULL;
+
+	/* See notes in systable_getnext */
+	if (sysscan->iscan->xs_recheck)
+		elog(ERROR, "system catalog scans with lossy index conditions are not implemented");
+
+	return sysscan->slot;
+}
+
 /*
  * systable_endscan_ordered --- close scan, release resources
  */
diff --git a/src/backend/access/table/toast_helper.c b/src/backend/access/table/toast_helper.c
index ee119cea2d..91ea50616d 100644
--- a/src/backend/access/table/toast_helper.c
+++ b/src/backend/access/table/toast_helper.c
@@ -17,6 +17,7 @@
 #include "access/detoast.h"
 #include "access/table.h"
 #include "access/toast_helper.h"
+#include "access/tableam.h"
 #include "access/toast_internals.h"
 
 /*
@@ -247,26 +248,49 @@ toast_tuple_try_compression(ToastTupleContext *ttc, int attribute)
  * Move an attribute to external storage.
  */
 void
-toast_tuple_externalize(ToastTupleContext *ttc, int attribute, int options)
+toast_tuple_externalize(ToastTupleContext *ttc, int attribute, int options,
+						int max_chunk_size)
 {
 	Datum  *value = &ttc->ttc_values[attribute];
 	Datum	old_value = *value;
 	ToastAttrInfo  *attr = &ttc->ttc_attr[attribute];
 
-	attr->tai_colflags |= TOASTCOL_IGNORE;
-	*value = toast_save_datum(ttc->ttc_rel, old_value, attr->tai_oldexternal,
-							  options);
+	/* Initialize for TOAST table access, if not yet done. */
+	if (ttc->ttc_toastrel == NULL)
+	{
+		ttc->ttc_toastrel =
+			table_open(ttc->ttc_rel->rd_rel->reltoastrelid, RowExclusiveLock);
+		ttc->ttc_validtoastidx = toast_open_indexes(ttc->ttc_toastrel,
+													RowExclusiveLock,
+													&ttc->ttc_toastidxs,
+													&ttc->ttc_ntoastidxs);
+	}
+	if (ttc->ttc_toastslot == NULL)
+		ttc->ttc_toastslot = table_slot_create(ttc->ttc_toastrel, NULL);
+
+	/* Do the real work. */
+	*value = toast_save_datum(ttc->ttc_toastrel, ttc->ttc_toastslot,
+							  ttc->ttc_ntoastidxs, ttc->ttc_toastidxs,
+							  ttc->ttc_validtoastidx,
+							  ttc->ttc_rel->rd_toastoid,
+							  old_value, attr->tai_oldexternal,
+							  options, max_chunk_size);
+
+	/* Update bookkeeping information. */
 	if ((attr->tai_colflags & TOASTCOL_NEEDS_FREE) != 0)
 		pfree(DatumGetPointer(old_value));
-	attr->tai_colflags |= TOASTCOL_NEEDS_FREE;
+	attr->tai_colflags |= (TOASTCOL_NEEDS_FREE | TOASTCOL_IGNORE);
 	ttc->ttc_flags |= (TOAST_NEEDS_CHANGE | TOAST_NEEDS_FREE);
 }
 
 /*
  * Perform appropriate cleanup after one tuple has been subjected to TOAST.
+ *
+ * Pass cleanup_toastrel as true to destroy and clear ttc_toastrel and
+ * ttc_toastslot, or false if caller will do it.
  */
 void
-toast_tuple_cleanup(ToastTupleContext *ttc)
+toast_tuple_cleanup(ToastTupleContext *ttc, bool cleanup_toastrel)
 {
 	TupleDesc	tupleDesc = ttc->ttc_rel->rd_att;
 	int			numAttrs = tupleDesc->natts;
@@ -294,14 +318,46 @@ toast_tuple_cleanup(ToastTupleContext *ttc)
 	{
 		int		i;
 
+		/* Initialize for TOAST table access, if not yet done. */
+		if (ttc->ttc_toastrel == NULL)
+		{
+			ttc->ttc_toastrel =
+				table_open(ttc->ttc_rel->rd_rel->reltoastrelid,
+						   RowExclusiveLock);
+			ttc->ttc_validtoastidx = toast_open_indexes(ttc->ttc_toastrel,
+														RowExclusiveLock,
+														&ttc->ttc_toastidxs,
+														&ttc->ttc_ntoastidxs);
+		}
+
+		/* Delete those attributes which require it. */
 		for (i = 0; i < numAttrs; i++)
 		{
 			ToastAttrInfo  *attr = &ttc->ttc_attr[i];
 
 			if ((attr->tai_colflags & TOASTCOL_NEEDS_DELETE_OLD) != 0)
-				toast_delete_datum(ttc->ttc_rel, ttc->ttc_oldvalues[i], false);
+				toast_delete_datum(ttc->ttc_toastrel, ttc->ttc_ntoastidxs,
+								   ttc->ttc_toastidxs, ttc->ttc_validtoastidx,
+								   ttc->ttc_oldvalues[i], false, 0);
 		}
 	}
+
+	/*
+	 * Close toast table and indexes and drop slot, if previously done and
+	 * if caller requests it.
+	 */
+	if (cleanup_toastrel && ttc->ttc_toastrel != NULL)
+	{
+		if (ttc->ttc_toastslot != NULL)
+		{
+			ExecDropSingleTupleTableSlot(ttc->ttc_toastslot);
+			ttc->ttc_toastslot = NULL;
+		}
+		toast_close_indexes(ttc->ttc_toastidxs, ttc->ttc_ntoastidxs,
+							RowExclusiveLock);
+		table_close(ttc->ttc_toastrel, RowExclusiveLock);
+		ttc->ttc_toastrel = NULL;
+	}
 }
 
 /*
@@ -310,22 +366,43 @@ toast_tuple_cleanup(ToastTupleContext *ttc)
  */
 void
 toast_delete_external(Relation rel, Datum *values, bool *isnull,
-					  bool is_speculative)
+					  bool is_speculative, uint32 specToken)
 {
 	TupleDesc	tupleDesc = rel->rd_att;
 	int			numAttrs = tupleDesc->natts;
 	int			i;
+	Relation    toastrel = NULL;
+	Relation   *toastidxs;
+	int         num_indexes;
+	int         validIndex;
 
 	for (i = 0; i < numAttrs; i++)
 	{
-		if (TupleDescAttr(tupleDesc, i)->attlen == -1)
-		{
-			Datum		value = values[i];
+		Datum	value;
+
+		if (isnull[i] || TupleDescAttr(tupleDesc, i)->attlen != -1)
+			continue;
+
+		value = values[i];
+		if (!VARATT_IS_EXTERNAL_ONDISK(PointerGetDatum(value)))
+			continue;
 
-			if (isnull[i])
-				continue;
-			else if (VARATT_IS_EXTERNAL_ONDISK(PointerGetDatum(value)))
-				toast_delete_datum(rel, value, is_speculative);
+		/* Initialize for TOAST table access, if not yet done. */
+		if (toastrel == NULL)
+		{
+			toastrel = table_open(rel->rd_rel->reltoastrelid,
+								  RowExclusiveLock);
+			validIndex = toast_open_indexes(toastrel, RowExclusiveLock,
+											&toastidxs, &num_indexes);
 		}
+
+		toast_delete_datum(toastrel, num_indexes, toastidxs, validIndex,
+						   value, is_speculative, specToken);
+	}
+
+	if (toastrel != NULL)
+	{
+		toast_close_indexes(toastidxs, num_indexes, RowExclusiveLock);
+		table_close(toastrel, RowExclusiveLock);
 	}
 }
diff --git a/src/backend/catalog/toasting.c b/src/backend/catalog/toasting.c
index de6282a667..f082463bf6 100644
--- a/src/backend/catalog/toasting.c
+++ b/src/backend/catalog/toasting.c
@@ -258,7 +258,7 @@ create_toast_table(Relation rel, Oid toastOid, Oid toastIndexOid,
 										   toast_typid,
 										   InvalidOid,
 										   rel->rd_rel->relowner,
-										   rel->rd_rel->relam,
+										   table_relation_toast_am(rel),
 										   tupdesc,
 										   NIL,
 										   RELKIND_TOASTVALUE,
diff --git a/src/include/access/genam.h b/src/include/access/genam.h
index 8c053be2ca..a8f5076420 100644
--- a/src/include/access/genam.h
+++ b/src/include/access/genam.h
@@ -21,8 +21,9 @@
 #include "utils/relcache.h"
 #include "utils/snapshot.h"
 
-/* We don't want this file to depend on execnodes.h. */
+/* We don't want this file to depend on execnodes.h or tuptable.h. */
 struct IndexInfo;
+struct TupleTableSlot;
 
 /*
  * Struct for statistics returned by ambuild
@@ -212,6 +213,8 @@ extern SysScanDesc systable_beginscan_ordered(Relation heapRelation,
 											  int nkeys, ScanKey key);
 extern HeapTuple systable_getnext_ordered(SysScanDesc sysscan,
 										  ScanDirection direction);
+extern struct TupleTableSlot *systable_getnextslot_ordered(SysScanDesc sysscan,
+														   ScanDirection direction);
 extern void systable_endscan_ordered(SysScanDesc sysscan);
 
 #endif							/* GENAM_H */
diff --git a/src/include/access/heapam.h b/src/include/access/heapam.h
index dffb57bf11..256655952e 100644
--- a/src/include/access/heapam.h
+++ b/src/include/access/heapam.h
@@ -143,7 +143,8 @@ extern TM_Result heap_delete(Relation relation, ItemPointer tid,
 							 CommandId cid, Snapshot crosscheck, bool wait,
 							 struct TM_FailureData *tmfd, bool changingPart);
 extern void heap_finish_speculative(Relation relation, ItemPointer tid);
-extern void heap_abort_speculative(Relation relation, ItemPointer tid);
+extern void heap_abort_speculative(Relation relation, ItemPointer tid,
+					   uint32 specToken);
 extern TM_Result heap_update(Relation relation, ItemPointer otid,
 							 HeapTuple newtup,
 							 CommandId cid, Snapshot crosscheck, bool wait,
diff --git a/src/include/access/heaptoast.h b/src/include/access/heaptoast.h
index bf02d2c600..07d36ac968 100644
--- a/src/include/access/heaptoast.h
+++ b/src/include/access/heaptoast.h
@@ -104,7 +104,8 @@ extern HeapTuple toast_insert_or_update(Relation rel,
  *	Called by heap_delete().
  * ----------
  */
-extern void toast_delete(Relation rel, HeapTuple oldtup, bool is_speculative);
+extern void toast_delete(Relation rel, HeapTuple oldtup,
+			 bool is_speculative, uint32 specToken);
 
 /* ----------
  * toast_flatten_tuple -
diff --git a/src/include/access/tableam.h b/src/include/access/tableam.h
index fd07773b74..bf0192f976 100644
--- a/src/include/access/tableam.h
+++ b/src/include/access/tableam.h
@@ -581,6 +581,27 @@ typedef struct TableAmRoutine
 	 */
 	bool		(*relation_needs_toast_table) (Relation rel);
 
+	/*
+	 * This callback should return the OID of the table AM that implements
+	 * TOAST tables for this AM.  If the relation_needs_toast_table callback
+	 * always returns false, this callback is not required.
+	 */
+	Oid		    (*relation_toast_am) (Relation rel);
+
+	/*
+	 * If this table AM can be used to implement a TOAST table, the following
+	 * field should be set to the maximum number of bytes that can be stored
+	 * in a single TOAST chunk.  It must not be set to a value greater than
+	 * BLCKSZ.  If this table AM is not used to implement a TOAST table, this
+	 * value is ignored.
+	 *
+	 * (Note that there is no requirement that the TOAST table be implemented
+	 * using the same AM as the table to which it is attached.  If this AM
+	 * has TOAST tables but uses some other AM to implement them, this value
+	 * is ignored; it is a property of the TOAST table, not the parent table.)
+	 */
+	int			toast_max_chunk_size;
+
 
 	/* ------------------------------------------------------------------------
 	 * Planner related functions.
@@ -1604,6 +1625,16 @@ table_relation_needs_toast_table(Relation rel)
 	return rel->rd_tableam->relation_needs_toast_table(rel);
 }
 
+/*
+ * Return the OID of the AM that should be used to implement the TOAST table
+ * for this relation.
+ */
+static inline Oid
+table_relation_toast_am(Relation rel)
+{
+	return rel->rd_tableam->relation_toast_am(rel);
+}
+
 
 /* ----------------------------------------------------------------------------
  * Planner related functionality
diff --git a/src/include/access/toast_helper.h b/src/include/access/toast_helper.h
index 0fac6cc772..5d223d36ea 100644
--- a/src/include/access/toast_helper.h
+++ b/src/include/access/toast_helper.h
@@ -14,6 +14,7 @@
 #ifndef TOAST_HELPER_H
 #define TOAST_HELPER_H
 
+#include "executor/tuptable.h"
 #include "utils/rel.h"
 
 /*
@@ -51,6 +52,17 @@ typedef struct
 	Datum	   *ttc_oldvalues;		/* values from previous tuple */
 	bool	   *ttc_oldisnull;		/* null flags from previous tuple */
 
+	/*
+	 * Before calling toast_tuple_init, the caller should either initialize
+	 * all of these fields or else set ttc_toastrel and ttc_toastslot to NULL.
+	 * In the latter case, all of the fields will be initialized as required.
+	 */
+	Relation	ttc_toastrel;		/* the toast table for the relation */
+	TupleTableSlot *ttc_toastslot;	/* a slot for the toast table */
+	int			ttc_ntoastidxs;		/* # of toast indexes for toast table */
+	Relation   *ttc_toastidxs;		/* array of those toast indexes */
+	int			ttc_validtoastidx;	/* the valid toast index */
+
 	/*
 	 * Before calling toast_tuple_init, the caller should set tts_attr to
 	 * point to an array of ToastAttrInfo structures of a length equal to
@@ -105,10 +117,10 @@ extern int toast_tuple_find_biggest_attribute(ToastTupleContext *ttc,
 								   bool for_compression, bool check_main);
 extern void toast_tuple_try_compression(ToastTupleContext *ttc, int attribute);
 extern void toast_tuple_externalize(ToastTupleContext *ttc, int attribute,
-						int options);
-extern void toast_tuple_cleanup(ToastTupleContext *ttc);
+						int options, int max_chunk_size);
+extern void toast_tuple_cleanup(ToastTupleContext *ttc, bool cleanup_toastrel);
 
 extern void toast_delete_external(Relation rel, Datum *values, bool *isnull,
-					  bool is_speculative);
+					  bool is_speculative, uint32 specToken);
 
 #endif
diff --git a/src/include/access/toast_internals.h b/src/include/access/toast_internals.h
index 8ac367fb9f..67ef5a134f 100644
--- a/src/include/access/toast_internals.h
+++ b/src/include/access/toast_internals.h
@@ -16,6 +16,8 @@
 #include "utils/relcache.h"
 #include "utils/snapshot.h"
 
+struct TupleTableSlot;
+
 /*
  *	The information at the start of the compressed toast data.
  */
@@ -39,9 +41,14 @@ typedef struct toast_compress_header
 extern Datum toast_compress_datum(Datum value);
 extern Oid	toast_get_valid_index(Oid toastoid, LOCKMODE lock);
 
-extern void toast_delete_datum(Relation rel, Datum value, bool is_speculative);
-extern Datum toast_save_datum(Relation rel, Datum value,
-				 struct varlena *oldexternal, int options);
+extern void toast_delete_datum(Relation toastrel, int num_indexes,
+				   Relation *toastidxs, int validIndex,
+				   Datum value, bool is_speculative, uint32 specToken);
+extern Datum toast_save_datum(Relation toastrel,
+				 struct TupleTableSlot *toastslot,
+				 int num_indexes, Relation *toastidxs, int validIndex,
+				 Oid toastoid, Datum value, struct varlena *oldexternal,
+				 int options, int max_chunk_size);
 
 extern int toast_open_indexes(Relation toastrel,
 				   LOCKMODE lock,
-- 
2.17.2 (Apple Git-113)

From 1541ef5bc81b22025320a7fb6b1b8412900f3528 Mon Sep 17 00:00:00 2001
From: Robert Haas <rhaas@postgresql.org>
Date: Wed, 15 May 2019 13:33:16 -0400
Subject: [PATCH v3 1/3] Split tuptoaster.c into three separate files.

detoast.c/h contain functions required to detoast a datum, partially
or completely, plus a few other utility functions for examining the
size of toasted datums.

toast_internals.c/h contain functions that are used internally to the
TOAST subsystem but which (mostly) do not need to be accessed from
outside.

heaptoast.c/h contains code that is intrinsically specific to the
heap AM, either because it operates on HeapTuples or is based on the
layout of a heap page.

detoast.c and toast_internals.c are placed in
src/backend/access/common rather than src/backend/access/heap.  At
present, both files still have dependencies on the heap, but that will
be improved in a future commit.
---
 doc/src/sgml/storage.sgml                     |    2 +-
 src/backend/access/common/Makefile            |    5 +-
 src/backend/access/common/detoast.c           |  859 ++++++
 src/backend/access/common/heaptuple.c         |    4 +-
 src/backend/access/common/indextuple.c        |    9 +-
 src/backend/access/common/reloptions.c        |    2 +-
 src/backend/access/common/toast_internals.c   |  632 +++++
 src/backend/access/heap/Makefile              |    2 +-
 src/backend/access/heap/heapam.c              |    2 +-
 src/backend/access/heap/heapam_handler.c      |    2 +-
 src/backend/access/heap/heaptoast.c           |  917 +++++++
 src/backend/access/heap/rewriteheap.c         |    2 +-
 src/backend/access/heap/tuptoaster.c          | 2411 -----------------
 src/backend/access/transam/xlog.c             |    2 +-
 src/backend/commands/analyze.c                |    2 +-
 src/backend/commands/cluster.c                |    2 +-
 src/backend/executor/execExprInterp.c         |    2 +-
 src/backend/executor/execTuples.c             |    2 +-
 src/backend/executor/tstoreReceiver.c         |    2 +-
 .../replication/logical/reorderbuffer.c       |    2 +-
 src/backend/statistics/extended_stats.c       |    2 +-
 src/backend/storage/large_object/inv_api.c    |    3 +-
 src/backend/utils/adt/array_typanalyze.c      |    2 +-
 src/backend/utils/adt/datum.c                 |    2 +-
 src/backend/utils/adt/expandedrecord.c        |    3 +-
 src/backend/utils/adt/rowtypes.c              |    2 +-
 src/backend/utils/adt/tsgistidx.c             |    2 +-
 src/backend/utils/adt/varchar.c               |    2 +-
 src/backend/utils/adt/varlena.c               |    2 +-
 src/backend/utils/cache/catcache.c            |    2 +-
 src/backend/utils/fmgr/fmgr.c                 |    2 +-
 src/bin/pg_resetwal/pg_resetwal.c             |    2 +-
 src/include/access/detoast.h                  |   92 +
 .../access/{tuptoaster.h => heaptoast.h}      |  112 +-
 src/include/access/toast_internals.h          |   54 +
 src/pl/plpgsql/src/pl_exec.c                  |    2 +-
 src/test/regress/regress.c                    |    2 +-
 37 files changed, 2602 insertions(+), 2549 deletions(-)
 create mode 100644 src/backend/access/common/detoast.c
 create mode 100644 src/backend/access/common/toast_internals.c
 create mode 100644 src/backend/access/heap/heaptoast.c
 delete mode 100644 src/backend/access/heap/tuptoaster.c
 create mode 100644 src/include/access/detoast.h
 rename src/include/access/{tuptoaster.h => heaptoast.h} (57%)
 create mode 100644 src/include/access/toast_internals.h

diff --git a/doc/src/sgml/storage.sgml b/doc/src/sgml/storage.sgml
index 1047c77a63..78bd030346 100644
--- a/doc/src/sgml/storage.sgml
+++ b/doc/src/sgml/storage.sgml
@@ -382,7 +382,7 @@ The oldest and most common type is a pointer to out-of-line data stored in
 a <firstterm><acronym>TOAST</acronym> table</firstterm> that is separate from, but
 associated with, the table containing the <acronym>TOAST</acronym> pointer datum
 itself.  These <firstterm>on-disk</firstterm> pointer datums are created by the
-<acronym>TOAST</acronym> management code (in <filename>access/heap/tuptoaster.c</filename>)
+<acronym>TOAST</acronym> management code (in <filename>access/common/toast_internals.c</filename>)
 when a tuple to be stored on disk is too large to be stored as-is.
 Further details appear in <xref linkend="storage-toast-ondisk"/>.
 Alternatively, a <acronym>TOAST</acronym> pointer datum can contain a pointer to
diff --git a/src/backend/access/common/Makefile b/src/backend/access/common/Makefile
index d469504337..9ac19d9f9e 100644
--- a/src/backend/access/common/Makefile
+++ b/src/backend/access/common/Makefile
@@ -12,7 +12,8 @@ subdir = src/backend/access/common
 top_builddir = ../../../..
 include $(top_builddir)/src/Makefile.global
 
-OBJS = bufmask.o heaptuple.o indextuple.o printsimple.o printtup.o \
-	relation.o reloptions.o scankey.o session.o tupconvert.o tupdesc.o
+OBJS = bufmask.o detoast.o heaptuple.o indextuple.o printsimple.o \
+	printtup.o relation.o reloptions.o scankey.o session.o toast_internals.o \
+	tupconvert.o tupdesc.o
 
 include $(top_srcdir)/src/backend/common.mk
diff --git a/src/backend/access/common/detoast.c b/src/backend/access/common/detoast.c
new file mode 100644
index 0000000000..54727bdf2c
--- /dev/null
+++ b/src/backend/access/common/detoast.c
@@ -0,0 +1,859 @@
+/*-------------------------------------------------------------------------
+ *
+ * detoast.c
+ *	  Retrieve compressed or external variable size attributes.
+ *
+ * Copyright (c) 2000-2019, PostgreSQL Global Development Group
+ *
+ * IDENTIFICATION
+ *	  src/backend/access/common/detoast.c
+ *
+ *-------------------------------------------------------------------------
+ */
+
+#include "postgres.h"
+
+#include "access/detoast.h"
+#include "access/genam.h"
+#include "access/heaptoast.h"
+#include "access/table.h"
+#include "access/toast_internals.h"
+#include "common/pg_lzcompress.h"
+#include "utils/expandeddatum.h"
+#include "utils/fmgroids.h"
+#include "utils/rel.h"
+
+static struct varlena *toast_fetch_datum(struct varlena *attr);
+static struct varlena *toast_fetch_datum_slice(struct varlena *attr,
+						int32 sliceoffset, int32 length);
+static struct varlena *toast_decompress_datum(struct varlena *attr);
+static struct varlena *toast_decompress_datum_slice(struct varlena *attr, int32 slicelength);
+
+/* ----------
+ * heap_tuple_fetch_attr -
+ *
+ *	Public entry point to get back a toasted value from
+ *	external source (possibly still in compressed format).
+ *
+ * This will return a datum that contains all the data internally, ie, not
+ * relying on external storage or memory, but it can still be compressed or
+ * have a short header.  Note some callers assume that if the input is an
+ * EXTERNAL datum, the result will be a pfree'able chunk.
+ * ----------
+ */
+struct varlena *
+heap_tuple_fetch_attr(struct varlena *attr)
+{
+	struct varlena *result;
+
+	if (VARATT_IS_EXTERNAL_ONDISK(attr))
+	{
+		/*
+		 * This is an external stored plain value
+		 */
+		result = toast_fetch_datum(attr);
+	}
+	else if (VARATT_IS_EXTERNAL_INDIRECT(attr))
+	{
+		/*
+		 * This is an indirect pointer --- dereference it
+		 */
+		struct varatt_indirect redirect;
+
+		VARATT_EXTERNAL_GET_POINTER(redirect, attr);
+		attr = (struct varlena *) redirect.pointer;
+
+		/* nested indirect Datums aren't allowed */
+		Assert(!VARATT_IS_EXTERNAL_INDIRECT(attr));
+
+		/* recurse if value is still external in some other way */
+		if (VARATT_IS_EXTERNAL(attr))
+			return heap_tuple_fetch_attr(attr);
+
+		/*
+		 * Copy into the caller's memory context, in case caller tries to
+		 * pfree the result.
+		 */
+		result = (struct varlena *) palloc(VARSIZE_ANY(attr));
+		memcpy(result, attr, VARSIZE_ANY(attr));
+	}
+	else if (VARATT_IS_EXTERNAL_EXPANDED(attr))
+	{
+		/*
+		 * This is an expanded-object pointer --- get flat format
+		 */
+		ExpandedObjectHeader *eoh;
+		Size		resultsize;
+
+		eoh = DatumGetEOHP(PointerGetDatum(attr));
+		resultsize = EOH_get_flat_size(eoh);
+		result = (struct varlena *) palloc(resultsize);
+		EOH_flatten_into(eoh, (void *) result, resultsize);
+	}
+	else
+	{
+		/*
+		 * This is a plain value inside of the main tuple - why am I called?
+		 */
+		result = attr;
+	}
+
+	return result;
+}
+
+
+/* ----------
+ * heap_tuple_untoast_attr -
+ *
+ *	Public entry point to get back a toasted value from compression
+ *	or external storage.  The result is always non-extended varlena form.
+ *
+ * Note some callers assume that if the input is an EXTERNAL or COMPRESSED
+ * datum, the result will be a pfree'able chunk.
+ * ----------
+ */
+struct varlena *
+heap_tuple_untoast_attr(struct varlena *attr)
+{
+	if (VARATT_IS_EXTERNAL_ONDISK(attr))
+	{
+		/*
+		 * This is an externally stored datum --- fetch it back from there
+		 */
+		attr = toast_fetch_datum(attr);
+		/* If it's compressed, decompress it */
+		if (VARATT_IS_COMPRESSED(attr))
+		{
+			struct varlena *tmp = attr;
+
+			attr = toast_decompress_datum(tmp);
+			pfree(tmp);
+		}
+	}
+	else if (VARATT_IS_EXTERNAL_INDIRECT(attr))
+	{
+		/*
+		 * This is an indirect pointer --- dereference it
+		 */
+		struct varatt_indirect redirect;
+
+		VARATT_EXTERNAL_GET_POINTER(redirect, attr);
+		attr = (struct varlena *) redirect.pointer;
+
+		/* nested indirect Datums aren't allowed */
+		Assert(!VARATT_IS_EXTERNAL_INDIRECT(attr));
+
+		/* recurse in case value is still extended in some other way */
+		attr = heap_tuple_untoast_attr(attr);
+
+		/* if it isn't, we'd better copy it */
+		if (attr == (struct varlena *) redirect.pointer)
+		{
+			struct varlena *result;
+
+			result = (struct varlena *) palloc(VARSIZE_ANY(attr));
+			memcpy(result, attr, VARSIZE_ANY(attr));
+			attr = result;
+		}
+	}
+	else if (VARATT_IS_EXTERNAL_EXPANDED(attr))
+	{
+		/*
+		 * This is an expanded-object pointer --- get flat format
+		 */
+		attr = heap_tuple_fetch_attr(attr);
+		/* flatteners are not allowed to produce compressed/short output */
+		Assert(!VARATT_IS_EXTENDED(attr));
+	}
+	else if (VARATT_IS_COMPRESSED(attr))
+	{
+		/*
+		 * This is a compressed value inside of the main tuple
+		 */
+		attr = toast_decompress_datum(attr);
+	}
+	else if (VARATT_IS_SHORT(attr))
+	{
+		/*
+		 * This is a short-header varlena --- convert to 4-byte header format
+		 */
+		Size		data_size = VARSIZE_SHORT(attr) - VARHDRSZ_SHORT;
+		Size		new_size = data_size + VARHDRSZ;
+		struct varlena *new_attr;
+
+		new_attr = (struct varlena *) palloc(new_size);
+		SET_VARSIZE(new_attr, new_size);
+		memcpy(VARDATA(new_attr), VARDATA_SHORT(attr), data_size);
+		attr = new_attr;
+	}
+
+	return attr;
+}
+
+
+/* ----------
+ * heap_tuple_untoast_attr_slice -
+ *
+ *		Public entry point to get back part of a toasted value
+ *		from compression or external storage.
+ * ----------
+ */
+struct varlena *
+heap_tuple_untoast_attr_slice(struct varlena *attr,
+							  int32 sliceoffset, int32 slicelength)
+{
+	struct varlena *preslice;
+	struct varlena *result;
+	char	   *attrdata;
+	int32		attrsize;
+
+	if (VARATT_IS_EXTERNAL_ONDISK(attr))
+	{
+		struct varatt_external toast_pointer;
+
+		VARATT_EXTERNAL_GET_POINTER(toast_pointer, attr);
+
+		/* fast path for non-compressed external datums */
+		if (!VARATT_EXTERNAL_IS_COMPRESSED(toast_pointer))
+			return toast_fetch_datum_slice(attr, sliceoffset, slicelength);
+
+		/* fetch it back (compressed marker will get set automatically) */
+		preslice = toast_fetch_datum(attr);
+	}
+	else if (VARATT_IS_EXTERNAL_INDIRECT(attr))
+	{
+		struct varatt_indirect redirect;
+
+		VARATT_EXTERNAL_GET_POINTER(redirect, attr);
+
+		/* nested indirect Datums aren't allowed */
+		Assert(!VARATT_IS_EXTERNAL_INDIRECT(redirect.pointer));
+
+		return heap_tuple_untoast_attr_slice(redirect.pointer,
+											 sliceoffset, slicelength);
+	}
+	else if (VARATT_IS_EXTERNAL_EXPANDED(attr))
+	{
+		/* pass it off to heap_tuple_fetch_attr to flatten */
+		preslice = heap_tuple_fetch_attr(attr);
+	}
+	else
+		preslice = attr;
+
+	Assert(!VARATT_IS_EXTERNAL(preslice));
+
+	if (VARATT_IS_COMPRESSED(preslice))
+	{
+		struct varlena *tmp = preslice;
+
+		/* Decompress enough to encompass the slice and the offset */
+		if (slicelength > 0 && sliceoffset >= 0)
+			preslice = toast_decompress_datum_slice(tmp, slicelength + sliceoffset);
+		else
+			preslice = toast_decompress_datum(tmp);
+
+		if (tmp != attr)
+			pfree(tmp);
+	}
+
+	if (VARATT_IS_SHORT(preslice))
+	{
+		attrdata = VARDATA_SHORT(preslice);
+		attrsize = VARSIZE_SHORT(preslice) - VARHDRSZ_SHORT;
+	}
+	else
+	{
+		attrdata = VARDATA(preslice);
+		attrsize = VARSIZE(preslice) - VARHDRSZ;
+	}
+
+	/* slicing of datum for compressed cases and plain value */
+
+	if (sliceoffset >= attrsize)
+	{
+		sliceoffset = 0;
+		slicelength = 0;
+	}
+
+	if (((sliceoffset + slicelength) > attrsize) || slicelength < 0)
+		slicelength = attrsize - sliceoffset;
+
+	result = (struct varlena *) palloc(slicelength + VARHDRSZ);
+	SET_VARSIZE(result, slicelength + VARHDRSZ);
+
+	memcpy(VARDATA(result), attrdata + sliceoffset, slicelength);
+
+	if (preslice != attr)
+		pfree(preslice);
+
+	return result;
+}
+
+/* ----------
+ * toast_fetch_datum -
+ *
+ *	Reconstruct an in memory Datum from the chunks saved
+ *	in the toast relation
+ * ----------
+ */
+static struct varlena *
+toast_fetch_datum(struct varlena *attr)
+{
+	Relation	toastrel;
+	Relation   *toastidxs;
+	ScanKeyData toastkey;
+	SysScanDesc toastscan;
+	HeapTuple	ttup;
+	TupleDesc	toasttupDesc;
+	struct varlena *result;
+	struct varatt_external toast_pointer;
+	int32		ressize;
+	int32		residx,
+				nextidx;
+	int32		numchunks;
+	Pointer		chunk;
+	bool		isnull;
+	char	   *chunkdata;
+	int32		chunksize;
+	int			num_indexes;
+	int			validIndex;
+	SnapshotData SnapshotToast;
+
+	if (!VARATT_IS_EXTERNAL_ONDISK(attr))
+		elog(ERROR, "toast_fetch_datum shouldn't be called for non-ondisk datums");
+
+	/* Must copy to access aligned fields */
+	VARATT_EXTERNAL_GET_POINTER(toast_pointer, attr);
+
+	ressize = toast_pointer.va_extsize;
+	numchunks = ((ressize - 1) / TOAST_MAX_CHUNK_SIZE) + 1;
+
+	result = (struct varlena *) palloc(ressize + VARHDRSZ);
+
+	if (VARATT_EXTERNAL_IS_COMPRESSED(toast_pointer))
+		SET_VARSIZE_COMPRESSED(result, ressize + VARHDRSZ);
+	else
+		SET_VARSIZE(result, ressize + VARHDRSZ);
+
+	/*
+	 * Open the toast relation and its indexes
+	 */
+	toastrel = table_open(toast_pointer.va_toastrelid, AccessShareLock);
+	toasttupDesc = toastrel->rd_att;
+
+	/* Look for the valid index of the toast relation */
+	validIndex = toast_open_indexes(toastrel,
+									AccessShareLock,
+									&toastidxs,
+									&num_indexes);
+
+	/*
+	 * Setup a scan key to fetch from the index by va_valueid
+	 */
+	ScanKeyInit(&toastkey,
+				(AttrNumber) 1,
+				BTEqualStrategyNumber, F_OIDEQ,
+				ObjectIdGetDatum(toast_pointer.va_valueid));
+
+	/*
+	 * Read the chunks by index
+	 *
+	 * Note that because the index is actually on (valueid, chunkidx) we will
+	 * see the chunks in chunkidx order, even though we didn't explicitly ask
+	 * for it.
+	 */
+	nextidx = 0;
+
+	init_toast_snapshot(&SnapshotToast);
+	toastscan = systable_beginscan_ordered(toastrel, toastidxs[validIndex],
+										   &SnapshotToast, 1, &toastkey);
+	while ((ttup = systable_getnext_ordered(toastscan, ForwardScanDirection)) != NULL)
+	{
+		/*
+		 * Have a chunk, extract the sequence number and the data
+		 */
+		residx = DatumGetInt32(fastgetattr(ttup, 2, toasttupDesc, &isnull));
+		Assert(!isnull);
+		chunk = DatumGetPointer(fastgetattr(ttup, 3, toasttupDesc, &isnull));
+		Assert(!isnull);
+		if (!VARATT_IS_EXTENDED(chunk))
+		{
+			chunksize = VARSIZE(chunk) - VARHDRSZ;
+			chunkdata = VARDATA(chunk);
+		}
+		else if (VARATT_IS_SHORT(chunk))
+		{
+			/* could happen due to heap_form_tuple doing its thing */
+			chunksize = VARSIZE_SHORT(chunk) - VARHDRSZ_SHORT;
+			chunkdata = VARDATA_SHORT(chunk);
+		}
+		else
+		{
+			/* should never happen */
+			elog(ERROR, "found toasted toast chunk for toast value %u in %s",
+				 toast_pointer.va_valueid,
+				 RelationGetRelationName(toastrel));
+			chunksize = 0;		/* keep compiler quiet */
+			chunkdata = NULL;
+		}
+
+		/*
+		 * Some checks on the data we've found
+		 */
+		if (residx != nextidx)
+			elog(ERROR, "unexpected chunk number %d (expected %d) for toast value %u in %s",
+				 residx, nextidx,
+				 toast_pointer.va_valueid,
+				 RelationGetRelationName(toastrel));
+		if (residx < numchunks - 1)
+		{
+			if (chunksize != TOAST_MAX_CHUNK_SIZE)
+				elog(ERROR, "unexpected chunk size %d (expected %d) in chunk %d of %d for toast value %u in %s",
+					 chunksize, (int) TOAST_MAX_CHUNK_SIZE,
+					 residx, numchunks,
+					 toast_pointer.va_valueid,
+					 RelationGetRelationName(toastrel));
+		}
+		else if (residx == numchunks - 1)
+		{
+			if ((residx * TOAST_MAX_CHUNK_SIZE + chunksize) != ressize)
+				elog(ERROR, "unexpected chunk size %d (expected %d) in final chunk %d for toast value %u in %s",
+					 chunksize,
+					 (int) (ressize - residx * TOAST_MAX_CHUNK_SIZE),
+					 residx,
+					 toast_pointer.va_valueid,
+					 RelationGetRelationName(toastrel));
+		}
+		else
+			elog(ERROR, "unexpected chunk number %d (out of range %d..%d) for toast value %u in %s",
+				 residx,
+				 0, numchunks - 1,
+				 toast_pointer.va_valueid,
+				 RelationGetRelationName(toastrel));
+
+		/*
+		 * Copy the data into proper place in our result
+		 */
+		memcpy(VARDATA(result) + residx * TOAST_MAX_CHUNK_SIZE,
+			   chunkdata,
+			   chunksize);
+
+		nextidx++;
+	}
+
+	/*
+	 * Final checks that we successfully fetched the datum
+	 */
+	if (nextidx != numchunks)
+		elog(ERROR, "missing chunk number %d for toast value %u in %s",
+			 nextidx,
+			 toast_pointer.va_valueid,
+			 RelationGetRelationName(toastrel));
+
+	/*
+	 * End scan and close relations
+	 */
+	systable_endscan_ordered(toastscan);
+	toast_close_indexes(toastidxs, num_indexes, AccessShareLock);
+	table_close(toastrel, AccessShareLock);
+
+	return result;
+}
+
+/* ----------
+ * toast_fetch_datum_slice -
+ *
+ *	Reconstruct a segment of a Datum from the chunks saved
+ *	in the toast relation
+ *
+ *	Note that this function only supports non-compressed external datums.
+ * ----------
+ */
+static struct varlena *
+toast_fetch_datum_slice(struct varlena *attr, int32 sliceoffset, int32 length)
+{
+	Relation	toastrel;
+	Relation   *toastidxs;
+	ScanKeyData toastkey[3];
+	int			nscankeys;
+	SysScanDesc toastscan;
+	HeapTuple	ttup;
+	TupleDesc	toasttupDesc;
+	struct varlena *result;
+	struct varatt_external toast_pointer;
+	int32		attrsize;
+	int32		residx;
+	int32		nextidx;
+	int			numchunks;
+	int			startchunk;
+	int			endchunk;
+	int32		startoffset;
+	int32		endoffset;
+	int			totalchunks;
+	Pointer		chunk;
+	bool		isnull;
+	char	   *chunkdata;
+	int32		chunksize;
+	int32		chcpystrt;
+	int32		chcpyend;
+	int			num_indexes;
+	int			validIndex;
+	SnapshotData SnapshotToast;
+
+	if (!VARATT_IS_EXTERNAL_ONDISK(attr))
+		elog(ERROR, "toast_fetch_datum_slice shouldn't be called for non-ondisk datums");
+
+	/* Must copy to access aligned fields */
+	VARATT_EXTERNAL_GET_POINTER(toast_pointer, attr);
+
+	/*
+	 * It's nonsense to fetch slices of a compressed datum -- this isn't lo_*
+	 * we can't return a compressed datum which is meaningful to toast later
+	 */
+	Assert(!VARATT_EXTERNAL_IS_COMPRESSED(toast_pointer));
+
+	attrsize = toast_pointer.va_extsize;
+	totalchunks = ((attrsize - 1) / TOAST_MAX_CHUNK_SIZE) + 1;
+
+	if (sliceoffset >= attrsize)
+	{
+		sliceoffset = 0;
+		length = 0;
+	}
+
+	if (((sliceoffset + length) > attrsize) || length < 0)
+		length = attrsize - sliceoffset;
+
+	result = (struct varlena *) palloc(length + VARHDRSZ);
+
+	SET_VARSIZE(result, length + VARHDRSZ);
+
+	if (length == 0)
+		return result;			/* Can save a lot of work at this point! */
+
+	startchunk = sliceoffset / TOAST_MAX_CHUNK_SIZE;
+	endchunk = (sliceoffset + length - 1) / TOAST_MAX_CHUNK_SIZE;
+	numchunks = (endchunk - startchunk) + 1;
+
+	startoffset = sliceoffset % TOAST_MAX_CHUNK_SIZE;
+	endoffset = (sliceoffset + length - 1) % TOAST_MAX_CHUNK_SIZE;
+
+	/*
+	 * Open the toast relation and its indexes
+	 */
+	toastrel = table_open(toast_pointer.va_toastrelid, AccessShareLock);
+	toasttupDesc = toastrel->rd_att;
+
+	/* Look for the valid index of toast relation */
+	validIndex = toast_open_indexes(toastrel,
+									AccessShareLock,
+									&toastidxs,
+									&num_indexes);
+
+	/*
+	 * Setup a scan key to fetch from the index. This is either two keys or
+	 * three depending on the number of chunks.
+	 */
+	ScanKeyInit(&toastkey[0],
+				(AttrNumber) 1,
+				BTEqualStrategyNumber, F_OIDEQ,
+				ObjectIdGetDatum(toast_pointer.va_valueid));
+
+	/*
+	 * Use equality condition for one chunk, a range condition otherwise:
+	 */
+	if (numchunks == 1)
+	{
+		ScanKeyInit(&toastkey[1],
+					(AttrNumber) 2,
+					BTEqualStrategyNumber, F_INT4EQ,
+					Int32GetDatum(startchunk));
+		nscankeys = 2;
+	}
+	else
+	{
+		ScanKeyInit(&toastkey[1],
+					(AttrNumber) 2,
+					BTGreaterEqualStrategyNumber, F_INT4GE,
+					Int32GetDatum(startchunk));
+		ScanKeyInit(&toastkey[2],
+					(AttrNumber) 2,
+					BTLessEqualStrategyNumber, F_INT4LE,
+					Int32GetDatum(endchunk));
+		nscankeys = 3;
+	}
+
+	/*
+	 * Read the chunks by index
+	 *
+	 * The index is on (valueid, chunkidx) so they will come in order
+	 */
+	init_toast_snapshot(&SnapshotToast);
+	nextidx = startchunk;
+	toastscan = systable_beginscan_ordered(toastrel, toastidxs[validIndex],
+										   &SnapshotToast, nscankeys, toastkey);
+	while ((ttup = systable_getnext_ordered(toastscan, ForwardScanDirection)) != NULL)
+	{
+		/*
+		 * Have a chunk, extract the sequence number and the data
+		 */
+		residx = DatumGetInt32(fastgetattr(ttup, 2, toasttupDesc, &isnull));
+		Assert(!isnull);
+		chunk = DatumGetPointer(fastgetattr(ttup, 3, toasttupDesc, &isnull));
+		Assert(!isnull);
+		if (!VARATT_IS_EXTENDED(chunk))
+		{
+			chunksize = VARSIZE(chunk) - VARHDRSZ;
+			chunkdata = VARDATA(chunk);
+		}
+		else if (VARATT_IS_SHORT(chunk))
+		{
+			/* could happen due to heap_form_tuple doing its thing */
+			chunksize = VARSIZE_SHORT(chunk) - VARHDRSZ_SHORT;
+			chunkdata = VARDATA_SHORT(chunk);
+		}
+		else
+		{
+			/* should never happen */
+			elog(ERROR, "found toasted toast chunk for toast value %u in %s",
+				 toast_pointer.va_valueid,
+				 RelationGetRelationName(toastrel));
+			chunksize = 0;		/* keep compiler quiet */
+			chunkdata = NULL;
+		}
+
+		/*
+		 * Some checks on the data we've found
+		 */
+		if ((residx != nextidx) || (residx > endchunk) || (residx < startchunk))
+			elog(ERROR, "unexpected chunk number %d (expected %d) for toast value %u in %s",
+				 residx, nextidx,
+				 toast_pointer.va_valueid,
+				 RelationGetRelationName(toastrel));
+		if (residx < totalchunks - 1)
+		{
+			if (chunksize != TOAST_MAX_CHUNK_SIZE)
+				elog(ERROR, "unexpected chunk size %d (expected %d) in chunk %d of %d for toast value %u in %s when fetching slice",
+					 chunksize, (int) TOAST_MAX_CHUNK_SIZE,
+					 residx, totalchunks,
+					 toast_pointer.va_valueid,
+					 RelationGetRelationName(toastrel));
+		}
+		else if (residx == totalchunks - 1)
+		{
+			if ((residx * TOAST_MAX_CHUNK_SIZE + chunksize) != attrsize)
+				elog(ERROR, "unexpected chunk size %d (expected %d) in final chunk %d for toast value %u in %s when fetching slice",
+					 chunksize,
+					 (int) (attrsize - residx * TOAST_MAX_CHUNK_SIZE),
+					 residx,
+					 toast_pointer.va_valueid,
+					 RelationGetRelationName(toastrel));
+		}
+		else
+			elog(ERROR, "unexpected chunk number %d (out of range %d..%d) for toast value %u in %s",
+				 residx,
+				 0, totalchunks - 1,
+				 toast_pointer.va_valueid,
+				 RelationGetRelationName(toastrel));
+
+		/*
+		 * Copy the data into proper place in our result
+		 */
+		chcpystrt = 0;
+		chcpyend = chunksize - 1;
+		if (residx == startchunk)
+			chcpystrt = startoffset;
+		if (residx == endchunk)
+			chcpyend = endoffset;
+
+		memcpy(VARDATA(result) +
+			   (residx * TOAST_MAX_CHUNK_SIZE - sliceoffset) + chcpystrt,
+			   chunkdata + chcpystrt,
+			   (chcpyend - chcpystrt) + 1);
+
+		nextidx++;
+	}
+
+	/*
+	 * Final checks that we successfully fetched the datum
+	 */
+	if (nextidx != (endchunk + 1))
+		elog(ERROR, "missing chunk number %d for toast value %u in %s",
+			 nextidx,
+			 toast_pointer.va_valueid,
+			 RelationGetRelationName(toastrel));
+
+	/*
+	 * End scan and close relations
+	 */
+	systable_endscan_ordered(toastscan);
+	toast_close_indexes(toastidxs, num_indexes, AccessShareLock);
+	table_close(toastrel, AccessShareLock);
+
+	return result;
+}
+
+/* ----------
+ * toast_decompress_datum -
+ *
+ * Decompress a compressed version of a varlena datum
+ */
+static struct varlena *
+toast_decompress_datum(struct varlena *attr)
+{
+	struct varlena *result;
+
+	Assert(VARATT_IS_COMPRESSED(attr));
+
+	result = (struct varlena *)
+		palloc(TOAST_COMPRESS_RAWSIZE(attr) + VARHDRSZ);
+	SET_VARSIZE(result, TOAST_COMPRESS_RAWSIZE(attr) + VARHDRSZ);
+
+	if (pglz_decompress(TOAST_COMPRESS_RAWDATA(attr),
+						VARSIZE(attr) - TOAST_COMPRESS_HDRSZ,
+						VARDATA(result),
+						TOAST_COMPRESS_RAWSIZE(attr), true) < 0)
+		elog(ERROR, "compressed data is corrupted");
+
+	return result;
+}
+
+
+/* ----------
+ * toast_decompress_datum_slice -
+ *
+ * Decompress the front of a compressed version of a varlena datum.
+ * offset handling happens in heap_tuple_untoast_attr_slice.
+ * Here we just decompress a slice from the front.
+ */
+static struct varlena *
+toast_decompress_datum_slice(struct varlena *attr, int32 slicelength)
+{
+	struct varlena *result;
+	int32 rawsize;
+
+	Assert(VARATT_IS_COMPRESSED(attr));
+
+	result = (struct varlena *) palloc(slicelength + VARHDRSZ);
+
+	rawsize = pglz_decompress(TOAST_COMPRESS_RAWDATA(attr),
+						VARSIZE(attr) - TOAST_COMPRESS_HDRSZ,
+						VARDATA(result),
+						slicelength, false);
+	if (rawsize < 0)
+		elog(ERROR, "compressed data is corrupted");
+
+	SET_VARSIZE(result, rawsize + VARHDRSZ);
+	return result;
+}
+
+/* ----------
+ * toast_raw_datum_size -
+ *
+ *	Return the raw (detoasted) size of a varlena datum
+ *	(including the VARHDRSZ header)
+ * ----------
+ */
+Size
+toast_raw_datum_size(Datum value)
+{
+	struct varlena *attr = (struct varlena *) DatumGetPointer(value);
+	Size		result;
+
+	if (VARATT_IS_EXTERNAL_ONDISK(attr))
+	{
+		/* va_rawsize is the size of the original datum -- including header */
+		struct varatt_external toast_pointer;
+
+		VARATT_EXTERNAL_GET_POINTER(toast_pointer, attr);
+		result = toast_pointer.va_rawsize;
+	}
+	else if (VARATT_IS_EXTERNAL_INDIRECT(attr))
+	{
+		struct varatt_indirect toast_pointer;
+
+		VARATT_EXTERNAL_GET_POINTER(toast_pointer, attr);
+
+		/* nested indirect Datums aren't allowed */
+		Assert(!VARATT_IS_EXTERNAL_INDIRECT(toast_pointer.pointer));
+
+		return toast_raw_datum_size(PointerGetDatum(toast_pointer.pointer));
+	}
+	else if (VARATT_IS_EXTERNAL_EXPANDED(attr))
+	{
+		result = EOH_get_flat_size(DatumGetEOHP(value));
+	}
+	else if (VARATT_IS_COMPRESSED(attr))
+	{
+		/* here, va_rawsize is just the payload size */
+		result = VARRAWSIZE_4B_C(attr) + VARHDRSZ;
+	}
+	else if (VARATT_IS_SHORT(attr))
+	{
+		/*
+		 * we have to normalize the header length to VARHDRSZ or else the
+		 * callers of this function will be confused.
+		 */
+		result = VARSIZE_SHORT(attr) - VARHDRSZ_SHORT + VARHDRSZ;
+	}
+	else
+	{
+		/* plain untoasted datum */
+		result = VARSIZE(attr);
+	}
+	return result;
+}
+
+/* ----------
+ * toast_datum_size
+ *
+ *	Return the physical storage size (possibly compressed) of a varlena datum
+ * ----------
+ */
+Size
+toast_datum_size(Datum value)
+{
+	struct varlena *attr = (struct varlena *) DatumGetPointer(value);
+	Size		result;
+
+	if (VARATT_IS_EXTERNAL_ONDISK(attr))
+	{
+		/*
+		 * Attribute is stored externally - return the extsize whether
+		 * compressed or not.  We do not count the size of the toast pointer
+		 * ... should we?
+		 */
+		struct varatt_external toast_pointer;
+
+		VARATT_EXTERNAL_GET_POINTER(toast_pointer, attr);
+		result = toast_pointer.va_extsize;
+	}
+	else if (VARATT_IS_EXTERNAL_INDIRECT(attr))
+	{
+		struct varatt_indirect toast_pointer;
+
+		VARATT_EXTERNAL_GET_POINTER(toast_pointer, attr);
+
+		/* nested indirect Datums aren't allowed */
+		Assert(!VARATT_IS_EXTERNAL_INDIRECT(attr));
+
+		return toast_datum_size(PointerGetDatum(toast_pointer.pointer));
+	}
+	else if (VARATT_IS_EXTERNAL_EXPANDED(attr))
+	{
+		result = EOH_get_flat_size(DatumGetEOHP(value));
+	}
+	else if (VARATT_IS_SHORT(attr))
+	{
+		result = VARSIZE_SHORT(attr);
+	}
+	else
+	{
+		/*
+		 * Attribute is stored inline either compressed or not, just calculate
+		 * the size of the datum in either case.
+		 */
+		result = VARSIZE(attr);
+	}
+	return result;
+}
diff --git a/src/backend/access/common/heaptuple.c b/src/backend/access/common/heaptuple.c
index a48a6cd757..cc948958d7 100644
--- a/src/backend/access/common/heaptuple.c
+++ b/src/backend/access/common/heaptuple.c
@@ -18,7 +18,7 @@
  * (In performance-critical code paths we can use pg_detoast_datum_packed
  * and the appropriate access macros to avoid that overhead.)  Note that this
  * conversion is performed directly in heap_form_tuple, without invoking
- * tuptoaster.c.
+ * heaptoast.c.
  *
  * This change will break any code that assumes it needn't detoast values
  * that have been put into a tuple but never sent to disk.  Hopefully there
@@ -57,9 +57,9 @@
 
 #include "postgres.h"
 
+#include "access/heaptoast.h"
 #include "access/sysattr.h"
 #include "access/tupdesc_details.h"
-#include "access/tuptoaster.h"
 #include "executor/tuptable.h"
 #include "utils/expandeddatum.h"
 
diff --git a/src/backend/access/common/indextuple.c b/src/backend/access/common/indextuple.c
index cb23be859d..07586201b9 100644
--- a/src/backend/access/common/indextuple.c
+++ b/src/backend/access/common/indextuple.c
@@ -16,10 +16,17 @@
 
 #include "postgres.h"
 
+#include "access/detoast.h"
+#include "access/heaptoast.h"
 #include "access/htup_details.h"
 #include "access/itup.h"
-#include "access/tuptoaster.h"
+#include "access/toast_internals.h"
 
+/*
+ * This enables de-toasting of index entries.  Needed until VACUUM is
+ * smart enough to rebuild indexes from scratch.
+ */
+#define TOAST_INDEX_HACK
 
 /* ----------------------------------------------------------------
  *				  index_ tuple interface routines
diff --git a/src/backend/access/common/reloptions.c b/src/backend/access/common/reloptions.c
index de06c92574..42f793158f 100644
--- a/src/backend/access/common/reloptions.c
+++ b/src/backend/access/common/reloptions.c
@@ -19,11 +19,11 @@
 
 #include "access/gist_private.h"
 #include "access/hash.h"
+#include "access/heaptoast.h"
 #include "access/htup_details.h"
 #include "access/nbtree.h"
 #include "access/reloptions.h"
 #include "access/spgist.h"
-#include "access/tuptoaster.h"
 #include "catalog/pg_type.h"
 #include "commands/defrem.h"
 #include "commands/tablespace.h"
diff --git a/src/backend/access/common/toast_internals.c b/src/backend/access/common/toast_internals.c
new file mode 100644
index 0000000000..a971242490
--- /dev/null
+++ b/src/backend/access/common/toast_internals.c
@@ -0,0 +1,632 @@
+/*-------------------------------------------------------------------------
+ *
+ * toast_internals.c
+ *	  Functions for internal use by the TOAST system.
+ *
+ * Copyright (c) 2000-2019, PostgreSQL Global Development Group
+ *
+ * IDENTIFICATION
+ *	  src/backend/access/common/toast_internals.c
+ *
+ *-------------------------------------------------------------------------
+ */
+
+#include "postgres.h"
+
+#include "access/detoast.h"
+#include "access/genam.h"
+#include "access/heapam.h"
+#include "access/heaptoast.h"
+#include "access/table.h"
+#include "access/toast_internals.h"
+#include "access/xact.h"
+#include "catalog/catalog.h"
+#include "common/pg_lzcompress.h"
+#include "miscadmin.h"
+#include "utils/fmgroids.h"
+#include "utils/rel.h"
+#include "utils/snapmgr.h"
+
+static bool toastrel_valueid_exists(Relation toastrel, Oid valueid);
+static bool toastid_valueid_exists(Oid toastrelid, Oid valueid);
+
+/* ----------
+ * toast_compress_datum -
+ *
+ *	Create a compressed version of a varlena datum
+ *
+ *	If we fail (ie, compressed result is actually bigger than original)
+ *	then return NULL.  We must not use compressed data if it'd expand
+ *	the tuple!
+ *
+ *	We use VAR{SIZE,DATA}_ANY so we can handle short varlenas here without
+ *	copying them.  But we can't handle external or compressed datums.
+ * ----------
+ */
+Datum
+toast_compress_datum(Datum value)
+{
+	struct varlena *tmp;
+	int32		valsize = VARSIZE_ANY_EXHDR(DatumGetPointer(value));
+	int32		len;
+
+	Assert(!VARATT_IS_EXTERNAL(DatumGetPointer(value)));
+	Assert(!VARATT_IS_COMPRESSED(DatumGetPointer(value)));
+
+	/*
+	 * No point in wasting a palloc cycle if value size is out of the allowed
+	 * range for compression
+	 */
+	if (valsize < PGLZ_strategy_default->min_input_size ||
+		valsize > PGLZ_strategy_default->max_input_size)
+		return PointerGetDatum(NULL);
+
+	tmp = (struct varlena *) palloc(PGLZ_MAX_OUTPUT(valsize) +
+									TOAST_COMPRESS_HDRSZ);
+
+	/*
+	 * We recheck the actual size even if pglz_compress() reports success,
+	 * because it might be satisfied with having saved as little as one byte
+	 * in the compressed data --- which could turn into a net loss once you
+	 * consider header and alignment padding.  Worst case, the compressed
+	 * format might require three padding bytes (plus header, which is
+	 * included in VARSIZE(tmp)), whereas the uncompressed format would take
+	 * only one header byte and no padding if the value is short enough.  So
+	 * we insist on a savings of more than 2 bytes to ensure we have a gain.
+	 */
+	len = pglz_compress(VARDATA_ANY(DatumGetPointer(value)),
+						valsize,
+						TOAST_COMPRESS_RAWDATA(tmp),
+						PGLZ_strategy_default);
+	if (len >= 0 &&
+		len + TOAST_COMPRESS_HDRSZ < valsize - 2)
+	{
+		TOAST_COMPRESS_SET_RAWSIZE(tmp, valsize);
+		SET_VARSIZE_COMPRESSED(tmp, len + TOAST_COMPRESS_HDRSZ);
+		/* successful compression */
+		return PointerGetDatum(tmp);
+	}
+	else
+	{
+		/* incompressible data */
+		pfree(tmp);
+		return PointerGetDatum(NULL);
+	}
+}
+
+/* ----------
+ * toast_save_datum -
+ *
+ *	Save one single datum into the secondary relation and return
+ *	a Datum reference for it.
+ *
+ * rel: the main relation we're working with (not the toast rel!)
+ * value: datum to be pushed to toast storage
+ * oldexternal: if not NULL, toast pointer previously representing the datum
+ * options: options to be passed to heap_insert() for toast rows
+ * ----------
+ */
+Datum
+toast_save_datum(Relation rel, Datum value,
+				 struct varlena *oldexternal, int options)
+{
+	Relation	toastrel;
+	Relation   *toastidxs;
+	HeapTuple	toasttup;
+	TupleDesc	toasttupDesc;
+	Datum		t_values[3];
+	bool		t_isnull[3];
+	CommandId	mycid = GetCurrentCommandId(true);
+	struct varlena *result;
+	struct varatt_external toast_pointer;
+	union
+	{
+		struct varlena hdr;
+		/* this is to make the union big enough for a chunk: */
+		char		data[TOAST_MAX_CHUNK_SIZE + VARHDRSZ];
+		/* ensure union is aligned well enough: */
+		int32		align_it;
+	}			chunk_data;
+	int32		chunk_size;
+	int32		chunk_seq = 0;
+	char	   *data_p;
+	int32		data_todo;
+	Pointer		dval = DatumGetPointer(value);
+	int			num_indexes;
+	int			validIndex;
+
+	Assert(!VARATT_IS_EXTERNAL(value));
+
+	/*
+	 * Open the toast relation and its indexes.  We can use the index to check
+	 * uniqueness of the OID we assign to the toasted item, even though it has
+	 * additional columns besides OID.
+	 */
+	toastrel = table_open(rel->rd_rel->reltoastrelid, RowExclusiveLock);
+	toasttupDesc = toastrel->rd_att;
+
+	/* Open all the toast indexes and look for the valid one */
+	validIndex = toast_open_indexes(toastrel,
+									RowExclusiveLock,
+									&toastidxs,
+									&num_indexes);
+
+	/*
+	 * Get the data pointer and length, and compute va_rawsize and va_extsize.
+	 *
+	 * va_rawsize is the size of the equivalent fully uncompressed datum, so
+	 * we have to adjust for short headers.
+	 *
+	 * va_extsize is the actual size of the data payload in the toast records.
+	 */
+	if (VARATT_IS_SHORT(dval))
+	{
+		data_p = VARDATA_SHORT(dval);
+		data_todo = VARSIZE_SHORT(dval) - VARHDRSZ_SHORT;
+		toast_pointer.va_rawsize = data_todo + VARHDRSZ;	/* as if not short */
+		toast_pointer.va_extsize = data_todo;
+	}
+	else if (VARATT_IS_COMPRESSED(dval))
+	{
+		data_p = VARDATA(dval);
+		data_todo = VARSIZE(dval) - VARHDRSZ;
+		/* rawsize in a compressed datum is just the size of the payload */
+		toast_pointer.va_rawsize = VARRAWSIZE_4B_C(dval) + VARHDRSZ;
+		toast_pointer.va_extsize = data_todo;
+		/* Assert that the numbers look like it's compressed */
+		Assert(VARATT_EXTERNAL_IS_COMPRESSED(toast_pointer));
+	}
+	else
+	{
+		data_p = VARDATA(dval);
+		data_todo = VARSIZE(dval) - VARHDRSZ;
+		toast_pointer.va_rawsize = VARSIZE(dval);
+		toast_pointer.va_extsize = data_todo;
+	}
+
+	/*
+	 * Insert the correct table OID into the result TOAST pointer.
+	 *
+	 * Normally this is the actual OID of the target toast table, but during
+	 * table-rewriting operations such as CLUSTER, we have to insert the OID
+	 * of the table's real permanent toast table instead.  rd_toastoid is set
+	 * if we have to substitute such an OID.
+	 */
+	if (OidIsValid(rel->rd_toastoid))
+		toast_pointer.va_toastrelid = rel->rd_toastoid;
+	else
+		toast_pointer.va_toastrelid = RelationGetRelid(toastrel);
+
+	/*
+	 * Choose an OID to use as the value ID for this toast value.
+	 *
+	 * Normally we just choose an unused OID within the toast table.  But
+	 * during table-rewriting operations where we are preserving an existing
+	 * toast table OID, we want to preserve toast value OIDs too.  So, if
+	 * rd_toastoid is set and we had a prior external value from that same
+	 * toast table, re-use its value ID.  If we didn't have a prior external
+	 * value (which is a corner case, but possible if the table's attstorage
+	 * options have been changed), we have to pick a value ID that doesn't
+	 * conflict with either new or existing toast value OIDs.
+	 */
+	if (!OidIsValid(rel->rd_toastoid))
+	{
+		/* normal case: just choose an unused OID */
+		toast_pointer.va_valueid =
+			GetNewOidWithIndex(toastrel,
+							   RelationGetRelid(toastidxs[validIndex]),
+							   (AttrNumber) 1);
+	}
+	else
+	{
+		/* rewrite case: check to see if value was in old toast table */
+		toast_pointer.va_valueid = InvalidOid;
+		if (oldexternal != NULL)
+		{
+			struct varatt_external old_toast_pointer;
+
+			Assert(VARATT_IS_EXTERNAL_ONDISK(oldexternal));
+			/* Must copy to access aligned fields */
+			VARATT_EXTERNAL_GET_POINTER(old_toast_pointer, oldexternal);
+			if (old_toast_pointer.va_toastrelid == rel->rd_toastoid)
+			{
+				/* This value came from the old toast table; reuse its OID */
+				toast_pointer.va_valueid = old_toast_pointer.va_valueid;
+
+				/*
+				 * There is a corner case here: the table rewrite might have
+				 * to copy both live and recently-dead versions of a row, and
+				 * those versions could easily reference the same toast value.
+				 * When we copy the second or later version of such a row,
+				 * reusing the OID will mean we select an OID that's already
+				 * in the new toast table.  Check for that, and if so, just
+				 * fall through without writing the data again.
+				 *
+				 * While annoying and ugly-looking, this is a good thing
+				 * because it ensures that we wind up with only one copy of
+				 * the toast value when there is only one copy in the old
+				 * toast table.  Before we detected this case, we'd have made
+				 * multiple copies, wasting space; and what's worse, the
+				 * copies belonging to already-deleted heap tuples would not
+				 * be reclaimed by VACUUM.
+				 */
+				if (toastrel_valueid_exists(toastrel,
+											toast_pointer.va_valueid))
+				{
+					/* Match, so short-circuit the data storage loop below */
+					data_todo = 0;
+				}
+			}
+		}
+		if (toast_pointer.va_valueid == InvalidOid)
+		{
+			/*
+			 * new value; must choose an OID that doesn't conflict in either
+			 * old or new toast table
+			 */
+			do
+			{
+				toast_pointer.va_valueid =
+					GetNewOidWithIndex(toastrel,
+									   RelationGetRelid(toastidxs[validIndex]),
+									   (AttrNumber) 1);
+			} while (toastid_valueid_exists(rel->rd_toastoid,
+											toast_pointer.va_valueid));
+		}
+	}
+
+	/*
+	 * Initialize constant parts of the tuple data
+	 */
+	t_values[0] = ObjectIdGetDatum(toast_pointer.va_valueid);
+	t_values[2] = PointerGetDatum(&chunk_data);
+	t_isnull[0] = false;
+	t_isnull[1] = false;
+	t_isnull[2] = false;
+
+	/*
+	 * Split up the item into chunks
+	 */
+	while (data_todo > 0)
+	{
+		int			i;
+
+		CHECK_FOR_INTERRUPTS();
+
+		/*
+		 * Calculate the size of this chunk
+		 */
+		chunk_size = Min(TOAST_MAX_CHUNK_SIZE, data_todo);
+
+		/*
+		 * Build a tuple and store it
+		 */
+		t_values[1] = Int32GetDatum(chunk_seq++);
+		SET_VARSIZE(&chunk_data, chunk_size + VARHDRSZ);
+		memcpy(VARDATA(&chunk_data), data_p, chunk_size);
+		toasttup = heap_form_tuple(toasttupDesc, t_values, t_isnull);
+
+		heap_insert(toastrel, toasttup, mycid, options, NULL);
+
+		/*
+		 * Create the index entry.  We cheat a little here by not using
+		 * FormIndexDatum: this relies on the knowledge that the index columns
+		 * are the same as the initial columns of the table for all the
+		 * indexes.  We also cheat by not providing an IndexInfo: this is okay
+		 * for now because btree doesn't need one, but we might have to be
+		 * more honest someday.
+		 *
+		 * Note also that there had better not be any user-created index on
+		 * the TOAST table, since we don't bother to update anything else.
+		 */
+		for (i = 0; i < num_indexes; i++)
+		{
+			/* Only index relations marked as ready can be updated */
+			if (toastidxs[i]->rd_index->indisready)
+				index_insert(toastidxs[i], t_values, t_isnull,
+							 &(toasttup->t_self),
+							 toastrel,
+							 toastidxs[i]->rd_index->indisunique ?
+							 UNIQUE_CHECK_YES : UNIQUE_CHECK_NO,
+							 NULL);
+		}
+
+		/*
+		 * Free memory
+		 */
+		heap_freetuple(toasttup);
+
+		/*
+		 * Move on to next chunk
+		 */
+		data_todo -= chunk_size;
+		data_p += chunk_size;
+	}
+
+	/*
+	 * Done - close toast relation and its indexes
+	 */
+	toast_close_indexes(toastidxs, num_indexes, RowExclusiveLock);
+	table_close(toastrel, RowExclusiveLock);
+
+	/*
+	 * Create the TOAST pointer value that we'll return
+	 */
+	result = (struct varlena *) palloc(TOAST_POINTER_SIZE);
+	SET_VARTAG_EXTERNAL(result, VARTAG_ONDISK);
+	memcpy(VARDATA_EXTERNAL(result), &toast_pointer, sizeof(toast_pointer));
+
+	return PointerGetDatum(result);
+}
+
+/* ----------
+ * toast_delete_datum -
+ *
+ *	Delete a single external stored value.
+ * ----------
+ */
+void
+toast_delete_datum(Relation rel, Datum value, bool is_speculative)
+{
+	struct varlena *attr = (struct varlena *) DatumGetPointer(value);
+	struct varatt_external toast_pointer;
+	Relation	toastrel;
+	Relation   *toastidxs;
+	ScanKeyData toastkey;
+	SysScanDesc toastscan;
+	HeapTuple	toasttup;
+	int			num_indexes;
+	int			validIndex;
+	SnapshotData SnapshotToast;
+
+	if (!VARATT_IS_EXTERNAL_ONDISK(attr))
+		return;
+
+	/* Must copy to access aligned fields */
+	VARATT_EXTERNAL_GET_POINTER(toast_pointer, attr);
+
+	/*
+	 * Open the toast relation and its indexes
+	 */
+	toastrel = table_open(toast_pointer.va_toastrelid, RowExclusiveLock);
+
+	/* Fetch valid relation used for process */
+	validIndex = toast_open_indexes(toastrel,
+									RowExclusiveLock,
+									&toastidxs,
+									&num_indexes);
+
+	/*
+	 * Setup a scan key to find chunks with matching va_valueid
+	 */
+	ScanKeyInit(&toastkey,
+				(AttrNumber) 1,
+				BTEqualStrategyNumber, F_OIDEQ,
+				ObjectIdGetDatum(toast_pointer.va_valueid));
+
+	/*
+	 * Find all the chunks.  (We don't actually care whether we see them in
+	 * sequence or not, but since we've already locked the index we might as
+	 * well use systable_beginscan_ordered.)
+	 */
+	init_toast_snapshot(&SnapshotToast);
+	toastscan = systable_beginscan_ordered(toastrel, toastidxs[validIndex],
+										   &SnapshotToast, 1, &toastkey);
+	while ((toasttup = systable_getnext_ordered(toastscan, ForwardScanDirection)) != NULL)
+	{
+		/*
+		 * Have a chunk, delete it
+		 */
+		if (is_speculative)
+			heap_abort_speculative(toastrel, &toasttup->t_self);
+		else
+			simple_heap_delete(toastrel, &toasttup->t_self);
+	}
+
+	/*
+	 * End scan and close relations
+	 */
+	systable_endscan_ordered(toastscan);
+	toast_close_indexes(toastidxs, num_indexes, RowExclusiveLock);
+	table_close(toastrel, RowExclusiveLock);
+}
+
+/* ----------
+ * toastrel_valueid_exists -
+ *
+ *	Test whether a toast value with the given ID exists in the toast relation.
+ *	For safety, we consider a value to exist if there are either live or dead
+ *	toast rows with that ID; see notes for GetNewOidWithIndex().
+ * ----------
+ */
+static bool
+toastrel_valueid_exists(Relation toastrel, Oid valueid)
+{
+	bool		result = false;
+	ScanKeyData toastkey;
+	SysScanDesc toastscan;
+	int			num_indexes;
+	int			validIndex;
+	Relation   *toastidxs;
+
+	/* Fetch a valid index relation */
+	validIndex = toast_open_indexes(toastrel,
+									RowExclusiveLock,
+									&toastidxs,
+									&num_indexes);
+
+	/*
+	 * Setup a scan key to find chunks with matching va_valueid
+	 */
+	ScanKeyInit(&toastkey,
+				(AttrNumber) 1,
+				BTEqualStrategyNumber, F_OIDEQ,
+				ObjectIdGetDatum(valueid));
+
+	/*
+	 * Is there any such chunk?
+	 */
+	toastscan = systable_beginscan(toastrel,
+								   RelationGetRelid(toastidxs[validIndex]),
+								   true, SnapshotAny, 1, &toastkey);
+
+	if (systable_getnext(toastscan) != NULL)
+		result = true;
+
+	systable_endscan(toastscan);
+
+	/* Clean up */
+	toast_close_indexes(toastidxs, num_indexes, RowExclusiveLock);
+
+	return result;
+}
+
+/* ----------
+ * toastid_valueid_exists -
+ *
+ *	As above, but work from toast rel's OID not an open relation
+ * ----------
+ */
+static bool
+toastid_valueid_exists(Oid toastrelid, Oid valueid)
+{
+	bool		result;
+	Relation	toastrel;
+
+	toastrel = table_open(toastrelid, AccessShareLock);
+
+	result = toastrel_valueid_exists(toastrel, valueid);
+
+	table_close(toastrel, AccessShareLock);
+
+	return result;
+}
+
+/* ----------
+ * toast_get_valid_index
+ *
+ *	Get OID of valid index associated to given toast relation. A toast
+ *	relation can have only one valid index at the same time.
+ */
+Oid
+toast_get_valid_index(Oid toastoid, LOCKMODE lock)
+{
+	int			num_indexes;
+	int			validIndex;
+	Oid			validIndexOid;
+	Relation   *toastidxs;
+	Relation	toastrel;
+
+	/* Open the toast relation */
+	toastrel = table_open(toastoid, lock);
+
+	/* Look for the valid index of the toast relation */
+	validIndex = toast_open_indexes(toastrel,
+									lock,
+									&toastidxs,
+									&num_indexes);
+	validIndexOid = RelationGetRelid(toastidxs[validIndex]);
+
+	/* Close the toast relation and all its indexes */
+	toast_close_indexes(toastidxs, num_indexes, lock);
+	table_close(toastrel, lock);
+
+	return validIndexOid;
+}
+
+/* ----------
+ * toast_open_indexes
+ *
+ *	Get an array of the indexes associated to the given toast relation
+ *	and return as well the position of the valid index used by the toast
+ *	relation in this array. It is the responsibility of the caller of this
+ *	function to close the indexes as well as free them.
+ */
+int
+toast_open_indexes(Relation toastrel,
+				   LOCKMODE lock,
+				   Relation **toastidxs,
+				   int *num_indexes)
+{
+	int			i = 0;
+	int			res = 0;
+	bool		found = false;
+	List	   *indexlist;
+	ListCell   *lc;
+
+	/* Get index list of the toast relation */
+	indexlist = RelationGetIndexList(toastrel);
+	Assert(indexlist != NIL);
+
+	*num_indexes = list_length(indexlist);
+
+	/* Open all the index relations */
+	*toastidxs = (Relation *) palloc(*num_indexes * sizeof(Relation));
+	foreach(lc, indexlist)
+		(*toastidxs)[i++] = index_open(lfirst_oid(lc), lock);
+
+	/* Fetch the first valid index in list */
+	for (i = 0; i < *num_indexes; i++)
+	{
+		Relation	toastidx = (*toastidxs)[i];
+
+		if (toastidx->rd_index->indisvalid)
+		{
+			res = i;
+			found = true;
+			break;
+		}
+	}
+
+	/*
+	 * Free index list, not necessary anymore as relations are opened and a
+	 * valid index has been found.
+	 */
+	list_free(indexlist);
+
+	/*
+	 * The toast relation should have one valid index, so something is going
+	 * wrong if there is nothing.
+	 */
+	if (!found)
+		elog(ERROR, "no valid index found for toast relation with Oid %u",
+			 RelationGetRelid(toastrel));
+
+	return res;
+}
+
+/* ----------
+ * toast_close_indexes
+ *
+ *	Close an array of indexes for a toast relation and free it. This should
+ *	be called for a set of indexes opened previously with toast_open_indexes.
+ */
+void
+toast_close_indexes(Relation *toastidxs, int num_indexes, LOCKMODE lock)
+{
+	int			i;
+
+	/* Close relations and clean up things */
+	for (i = 0; i < num_indexes; i++)
+		index_close(toastidxs[i], lock);
+	pfree(toastidxs);
+}
+
+/* ----------
+ * init_toast_snapshot
+ *
+ *	Initialize an appropriate TOAST snapshot.  We must use an MVCC snapshot
+ *	to initialize the TOAST snapshot; since we don't know which one to use,
+ *	just use the oldest one.  This is safe: at worst, we will get a "snapshot
+ *	too old" error that might have been avoided otherwise.
+ */
+void
+init_toast_snapshot(Snapshot toast_snapshot)
+{
+	Snapshot	snapshot = GetOldestSnapshot();
+
+	if (snapshot == NULL)
+		elog(ERROR, "no known snapshots");
+
+	InitToastSnapshot(*toast_snapshot, snapshot->lsn, snapshot->whenTaken);
+}
diff --git a/src/backend/access/heap/Makefile b/src/backend/access/heap/Makefile
index b2a017249b..38497b09c0 100644
--- a/src/backend/access/heap/Makefile
+++ b/src/backend/access/heap/Makefile
@@ -13,6 +13,6 @@ top_builddir = ../../../..
 include $(top_builddir)/src/Makefile.global
 
 OBJS = heapam.o heapam_handler.o heapam_visibility.o hio.o pruneheap.o rewriteheap.o \
-	syncscan.o tuptoaster.o vacuumlazy.o visibilitymap.o
+	syncscan.o heaptoast.o vacuumlazy.o visibilitymap.o
 
 include $(top_srcdir)/src/backend/common.mk
diff --git a/src/backend/access/heap/heapam.c b/src/backend/access/heap/heapam.c
index 8ac0f8a513..d32b638dd9 100644
--- a/src/backend/access/heap/heapam.c
+++ b/src/backend/access/heap/heapam.c
@@ -36,6 +36,7 @@
 #include "access/genam.h"
 #include "access/heapam.h"
 #include "access/heapam_xlog.h"
+#include "access/heaptoast.h"
 #include "access/hio.h"
 #include "access/multixact.h"
 #include "access/parallel.h"
@@ -43,7 +44,6 @@
 #include "access/sysattr.h"
 #include "access/tableam.h"
 #include "access/transam.h"
-#include "access/tuptoaster.h"
 #include "access/valid.h"
 #include "access/visibilitymap.h"
 #include "access/xact.h"
diff --git a/src/backend/access/heap/heapam_handler.c b/src/backend/access/heap/heapam_handler.c
index b7d2ddbbdc..468f045434 100644
--- a/src/backend/access/heap/heapam_handler.c
+++ b/src/backend/access/heap/heapam_handler.c
@@ -25,11 +25,11 @@
 
 #include "access/genam.h"
 #include "access/heapam.h"
+#include "access/heaptoast.h"
 #include "access/multixact.h"
 #include "access/rewriteheap.h"
 #include "access/tableam.h"
 #include "access/tsmapi.h"
-#include "access/tuptoaster.h"
 #include "access/xact.h"
 #include "catalog/catalog.h"
 #include "catalog/index.h"
diff --git a/src/backend/access/heap/heaptoast.c b/src/backend/access/heap/heaptoast.c
new file mode 100644
index 0000000000..5d105e3517
--- /dev/null
+++ b/src/backend/access/heap/heaptoast.c
@@ -0,0 +1,917 @@
+/*-------------------------------------------------------------------------
+ *
+ * heaptoast.c
+ *	  Heap-specific definitions for external and compressed storage
+ *	  of variable size attributes.
+ *
+ * Copyright (c) 2000-2019, PostgreSQL Global Development Group
+ *
+ *
+ * IDENTIFICATION
+ *	  src/backend/access/heap/heaptoast.c
+ *
+ *
+ * INTERFACE ROUTINES
+ *		toast_insert_or_update -
+ *			Try to make a given tuple fit into one page by compressing
+ *			or moving off attributes
+ *
+ *		toast_delete -
+ *			Reclaim toast storage when a tuple is deleted
+ *
+ *-------------------------------------------------------------------------
+ */
+
+#include "postgres.h"
+
+#include "access/detoast.h"
+#include "access/heapam.h"
+#include "access/heaptoast.h"
+#include "access/toast_internals.h"
+
+
+/* ----------
+ * toast_delete -
+ *
+ *	Cascaded delete toast-entries on DELETE
+ * ----------
+ */
+void
+toast_delete(Relation rel, HeapTuple oldtup, bool is_speculative)
+{
+	TupleDesc	tupleDesc;
+	int			numAttrs;
+	int			i;
+	Datum		toast_values[MaxHeapAttributeNumber];
+	bool		toast_isnull[MaxHeapAttributeNumber];
+
+	/*
+	 * We should only ever be called for tuples of plain relations or
+	 * materialized views --- recursing on a toast rel is bad news.
+	 */
+	Assert(rel->rd_rel->relkind == RELKIND_RELATION ||
+		   rel->rd_rel->relkind == RELKIND_MATVIEW);
+
+	/*
+	 * Get the tuple descriptor and break down the tuple into fields.
+	 *
+	 * NOTE: it's debatable whether to use heap_deform_tuple() here or just
+	 * heap_getattr() only the varlena columns.  The latter could win if there
+	 * are few varlena columns and many non-varlena ones. However,
+	 * heap_deform_tuple costs only O(N) while the heap_getattr way would cost
+	 * O(N^2) if there are many varlena columns, so it seems better to err on
+	 * the side of linear cost.  (We won't even be here unless there's at
+	 * least one varlena column, by the way.)
+	 */
+	tupleDesc = rel->rd_att;
+	numAttrs = tupleDesc->natts;
+
+	Assert(numAttrs <= MaxHeapAttributeNumber);
+	heap_deform_tuple(oldtup, tupleDesc, toast_values, toast_isnull);
+
+	/*
+	 * Check for external stored attributes and delete them from the secondary
+	 * relation.
+	 */
+	for (i = 0; i < numAttrs; i++)
+	{
+		if (TupleDescAttr(tupleDesc, i)->attlen == -1)
+		{
+			Datum		value = toast_values[i];
+
+			if (toast_isnull[i])
+				continue;
+			else if (VARATT_IS_EXTERNAL_ONDISK(PointerGetDatum(value)))
+				toast_delete_datum(rel, value, is_speculative);
+		}
+	}
+}
+
+
+/* ----------
+ * toast_insert_or_update -
+ *
+ *	Delete no-longer-used toast-entries and create new ones to
+ *	make the new tuple fit on INSERT or UPDATE
+ *
+ * Inputs:
+ *	newtup: the candidate new tuple to be inserted
+ *	oldtup: the old row version for UPDATE, or NULL for INSERT
+ *	options: options to be passed to heap_insert() for toast rows
+ * Result:
+ *	either newtup if no toasting is needed, or a palloc'd modified tuple
+ *	that is what should actually get stored
+ *
+ * NOTE: neither newtup nor oldtup will be modified.  This is a change
+ * from the pre-8.1 API of this routine.
+ * ----------
+ */
+HeapTuple
+toast_insert_or_update(Relation rel, HeapTuple newtup, HeapTuple oldtup,
+					   int options)
+{
+	HeapTuple	result_tuple;
+	TupleDesc	tupleDesc;
+	int			numAttrs;
+	int			i;
+
+	bool		need_change = false;
+	bool		need_free = false;
+	bool		need_delold = false;
+	bool		has_nulls = false;
+
+	Size		maxDataLen;
+	Size		hoff;
+
+	char		toast_action[MaxHeapAttributeNumber];
+	bool		toast_isnull[MaxHeapAttributeNumber];
+	bool		toast_oldisnull[MaxHeapAttributeNumber];
+	Datum		toast_values[MaxHeapAttributeNumber];
+	Datum		toast_oldvalues[MaxHeapAttributeNumber];
+	struct varlena *toast_oldexternal[MaxHeapAttributeNumber];
+	int32		toast_sizes[MaxHeapAttributeNumber];
+	bool		toast_free[MaxHeapAttributeNumber];
+	bool		toast_delold[MaxHeapAttributeNumber];
+
+	/*
+	 * Ignore the INSERT_SPECULATIVE option. Speculative insertions/super
+	 * deletions just normally insert/delete the toast values. It seems
+	 * easiest to deal with that here, instead on, potentially, multiple
+	 * callers.
+	 */
+	options &= ~HEAP_INSERT_SPECULATIVE;
+
+	/*
+	 * We should only ever be called for tuples of plain relations or
+	 * materialized views --- recursing on a toast rel is bad news.
+	 */
+	Assert(rel->rd_rel->relkind == RELKIND_RELATION ||
+		   rel->rd_rel->relkind == RELKIND_MATVIEW);
+
+	/*
+	 * Get the tuple descriptor and break down the tuple(s) into fields.
+	 */
+	tupleDesc = rel->rd_att;
+	numAttrs = tupleDesc->natts;
+
+	Assert(numAttrs <= MaxHeapAttributeNumber);
+	heap_deform_tuple(newtup, tupleDesc, toast_values, toast_isnull);
+	if (oldtup != NULL)
+		heap_deform_tuple(oldtup, tupleDesc, toast_oldvalues, toast_oldisnull);
+
+	/* ----------
+	 * Then collect information about the values given
+	 *
+	 * NOTE: toast_action[i] can have these values:
+	 *		' '		default handling
+	 *		'p'		already processed --- don't touch it
+	 *		'x'		incompressible, but OK to move off
+	 *
+	 * NOTE: toast_sizes[i] is only made valid for varlena attributes with
+	 *		toast_action[i] different from 'p'.
+	 * ----------
+	 */
+	memset(toast_action, ' ', numAttrs * sizeof(char));
+	memset(toast_oldexternal, 0, numAttrs * sizeof(struct varlena *));
+	memset(toast_free, 0, numAttrs * sizeof(bool));
+	memset(toast_delold, 0, numAttrs * sizeof(bool));
+
+	for (i = 0; i < numAttrs; i++)
+	{
+		Form_pg_attribute att = TupleDescAttr(tupleDesc, i);
+		struct varlena *old_value;
+		struct varlena *new_value;
+
+		if (oldtup != NULL)
+		{
+			/*
+			 * For UPDATE get the old and new values of this attribute
+			 */
+			old_value = (struct varlena *) DatumGetPointer(toast_oldvalues[i]);
+			new_value = (struct varlena *) DatumGetPointer(toast_values[i]);
+
+			/*
+			 * If the old value is stored on disk, check if it has changed so
+			 * we have to delete it later.
+			 */
+			if (att->attlen == -1 && !toast_oldisnull[i] &&
+				VARATT_IS_EXTERNAL_ONDISK(old_value))
+			{
+				if (toast_isnull[i] || !VARATT_IS_EXTERNAL_ONDISK(new_value) ||
+					memcmp((char *) old_value, (char *) new_value,
+						   VARSIZE_EXTERNAL(old_value)) != 0)
+				{
+					/*
+					 * The old external stored value isn't needed any more
+					 * after the update
+					 */
+					toast_delold[i] = true;
+					need_delold = true;
+				}
+				else
+				{
+					/*
+					 * This attribute isn't changed by this update so we reuse
+					 * the original reference to the old value in the new
+					 * tuple.
+					 */
+					toast_action[i] = 'p';
+					continue;
+				}
+			}
+		}
+		else
+		{
+			/*
+			 * For INSERT simply get the new value
+			 */
+			new_value = (struct varlena *) DatumGetPointer(toast_values[i]);
+		}
+
+		/*
+		 * Handle NULL attributes
+		 */
+		if (toast_isnull[i])
+		{
+			toast_action[i] = 'p';
+			has_nulls = true;
+			continue;
+		}
+
+		/*
+		 * Now look at varlena attributes
+		 */
+		if (att->attlen == -1)
+		{
+			/*
+			 * If the table's attribute says PLAIN always, force it so.
+			 */
+			if (att->attstorage == 'p')
+				toast_action[i] = 'p';
+
+			/*
+			 * We took care of UPDATE above, so any external value we find
+			 * still in the tuple must be someone else's that we cannot reuse
+			 * (this includes the case of an out-of-line in-memory datum).
+			 * Fetch it back (without decompression, unless we are forcing
+			 * PLAIN storage).  If necessary, we'll push it out as a new
+			 * external value below.
+			 */
+			if (VARATT_IS_EXTERNAL(new_value))
+			{
+				toast_oldexternal[i] = new_value;
+				if (att->attstorage == 'p')
+					new_value = heap_tuple_untoast_attr(new_value);
+				else
+					new_value = heap_tuple_fetch_attr(new_value);
+				toast_values[i] = PointerGetDatum(new_value);
+				toast_free[i] = true;
+				need_change = true;
+				need_free = true;
+			}
+
+			/*
+			 * Remember the size of this attribute
+			 */
+			toast_sizes[i] = VARSIZE_ANY(new_value);
+		}
+		else
+		{
+			/*
+			 * Not a varlena attribute, plain storage always
+			 */
+			toast_action[i] = 'p';
+		}
+	}
+
+	/* ----------
+	 * Compress and/or save external until data fits into target length
+	 *
+	 *	1: Inline compress attributes with attstorage 'x', and store very
+	 *	   large attributes with attstorage 'x' or 'e' external immediately
+	 *	2: Store attributes with attstorage 'x' or 'e' external
+	 *	3: Inline compress attributes with attstorage 'm'
+	 *	4: Store attributes with attstorage 'm' external
+	 * ----------
+	 */
+
+	/* compute header overhead --- this should match heap_form_tuple() */
+	hoff = SizeofHeapTupleHeader;
+	if (has_nulls)
+		hoff += BITMAPLEN(numAttrs);
+	hoff = MAXALIGN(hoff);
+	/* now convert to a limit on the tuple data size */
+	maxDataLen = RelationGetToastTupleTarget(rel, TOAST_TUPLE_TARGET) - hoff;
+
+	/*
+	 * Look for attributes with attstorage 'x' to compress.  Also find large
+	 * attributes with attstorage 'x' or 'e', and store them external.
+	 */
+	while (heap_compute_data_size(tupleDesc,
+								  toast_values, toast_isnull) > maxDataLen)
+	{
+		int			biggest_attno = -1;
+		int32		biggest_size = MAXALIGN(TOAST_POINTER_SIZE);
+		Datum		old_value;
+		Datum		new_value;
+
+		/*
+		 * Search for the biggest yet unprocessed internal attribute
+		 */
+		for (i = 0; i < numAttrs; i++)
+		{
+			Form_pg_attribute att = TupleDescAttr(tupleDesc, i);
+
+			if (toast_action[i] != ' ')
+				continue;
+			if (VARATT_IS_EXTERNAL(DatumGetPointer(toast_values[i])))
+				continue;		/* can't happen, toast_action would be 'p' */
+			if (VARATT_IS_COMPRESSED(DatumGetPointer(toast_values[i])))
+				continue;
+			if (att->attstorage != 'x' && att->attstorage != 'e')
+				continue;
+			if (toast_sizes[i] > biggest_size)
+			{
+				biggest_attno = i;
+				biggest_size = toast_sizes[i];
+			}
+		}
+
+		if (biggest_attno < 0)
+			break;
+
+		/*
+		 * Attempt to compress it inline, if it has attstorage 'x'
+		 */
+		i = biggest_attno;
+		if (TupleDescAttr(tupleDesc, i)->attstorage == 'x')
+		{
+			old_value = toast_values[i];
+			new_value = toast_compress_datum(old_value);
+
+			if (DatumGetPointer(new_value) != NULL)
+			{
+				/* successful compression */
+				if (toast_free[i])
+					pfree(DatumGetPointer(old_value));
+				toast_values[i] = new_value;
+				toast_free[i] = true;
+				toast_sizes[i] = VARSIZE(DatumGetPointer(toast_values[i]));
+				need_change = true;
+				need_free = true;
+			}
+			else
+			{
+				/* incompressible, ignore on subsequent compression passes */
+				toast_action[i] = 'x';
+			}
+		}
+		else
+		{
+			/* has attstorage 'e', ignore on subsequent compression passes */
+			toast_action[i] = 'x';
+		}
+
+		/*
+		 * If this value is by itself more than maxDataLen (after compression
+		 * if any), push it out to the toast table immediately, if possible.
+		 * This avoids uselessly compressing other fields in the common case
+		 * where we have one long field and several short ones.
+		 *
+		 * XXX maybe the threshold should be less than maxDataLen?
+		 */
+		if (toast_sizes[i] > maxDataLen &&
+			rel->rd_rel->reltoastrelid != InvalidOid)
+		{
+			old_value = toast_values[i];
+			toast_action[i] = 'p';
+			toast_values[i] = toast_save_datum(rel, toast_values[i],
+											   toast_oldexternal[i], options);
+			if (toast_free[i])
+				pfree(DatumGetPointer(old_value));
+			toast_free[i] = true;
+			need_change = true;
+			need_free = true;
+		}
+	}
+
+	/*
+	 * Second we look for attributes of attstorage 'x' or 'e' that are still
+	 * inline.  But skip this if there's no toast table to push them to.
+	 */
+	while (heap_compute_data_size(tupleDesc,
+								  toast_values, toast_isnull) > maxDataLen &&
+		   rel->rd_rel->reltoastrelid != InvalidOid)
+	{
+		int			biggest_attno = -1;
+		int32		biggest_size = MAXALIGN(TOAST_POINTER_SIZE);
+		Datum		old_value;
+
+		/*------
+		 * Search for the biggest yet inlined attribute with
+		 * attstorage equals 'x' or 'e'
+		 *------
+		 */
+		for (i = 0; i < numAttrs; i++)
+		{
+			Form_pg_attribute att = TupleDescAttr(tupleDesc, i);
+
+			if (toast_action[i] == 'p')
+				continue;
+			if (VARATT_IS_EXTERNAL(DatumGetPointer(toast_values[i])))
+				continue;		/* can't happen, toast_action would be 'p' */
+			if (att->attstorage != 'x' && att->attstorage != 'e')
+				continue;
+			if (toast_sizes[i] > biggest_size)
+			{
+				biggest_attno = i;
+				biggest_size = toast_sizes[i];
+			}
+		}
+
+		if (biggest_attno < 0)
+			break;
+
+		/*
+		 * Store this external
+		 */
+		i = biggest_attno;
+		old_value = toast_values[i];
+		toast_action[i] = 'p';
+		toast_values[i] = toast_save_datum(rel, toast_values[i],
+										   toast_oldexternal[i], options);
+		if (toast_free[i])
+			pfree(DatumGetPointer(old_value));
+		toast_free[i] = true;
+
+		need_change = true;
+		need_free = true;
+	}
+
+	/*
+	 * Round 3 - this time we take attributes with storage 'm' into
+	 * compression
+	 */
+	while (heap_compute_data_size(tupleDesc,
+								  toast_values, toast_isnull) > maxDataLen)
+	{
+		int			biggest_attno = -1;
+		int32		biggest_size = MAXALIGN(TOAST_POINTER_SIZE);
+		Datum		old_value;
+		Datum		new_value;
+
+		/*
+		 * Search for the biggest yet uncompressed internal attribute
+		 */
+		for (i = 0; i < numAttrs; i++)
+		{
+			if (toast_action[i] != ' ')
+				continue;
+			if (VARATT_IS_EXTERNAL(DatumGetPointer(toast_values[i])))
+				continue;		/* can't happen, toast_action would be 'p' */
+			if (VARATT_IS_COMPRESSED(DatumGetPointer(toast_values[i])))
+				continue;
+			if (TupleDescAttr(tupleDesc, i)->attstorage != 'm')
+				continue;
+			if (toast_sizes[i] > biggest_size)
+			{
+				biggest_attno = i;
+				biggest_size = toast_sizes[i];
+			}
+		}
+
+		if (biggest_attno < 0)
+			break;
+
+		/*
+		 * Attempt to compress it inline
+		 */
+		i = biggest_attno;
+		old_value = toast_values[i];
+		new_value = toast_compress_datum(old_value);
+
+		if (DatumGetPointer(new_value) != NULL)
+		{
+			/* successful compression */
+			if (toast_free[i])
+				pfree(DatumGetPointer(old_value));
+			toast_values[i] = new_value;
+			toast_free[i] = true;
+			toast_sizes[i] = VARSIZE(DatumGetPointer(toast_values[i]));
+			need_change = true;
+			need_free = true;
+		}
+		else
+		{
+			/* incompressible, ignore on subsequent compression passes */
+			toast_action[i] = 'x';
+		}
+	}
+
+	/*
+	 * Finally we store attributes of type 'm' externally.  At this point we
+	 * increase the target tuple size, so that 'm' attributes aren't stored
+	 * externally unless really necessary.
+	 */
+	maxDataLen = TOAST_TUPLE_TARGET_MAIN - hoff;
+
+	while (heap_compute_data_size(tupleDesc,
+								  toast_values, toast_isnull) > maxDataLen &&
+		   rel->rd_rel->reltoastrelid != InvalidOid)
+	{
+		int			biggest_attno = -1;
+		int32		biggest_size = MAXALIGN(TOAST_POINTER_SIZE);
+		Datum		old_value;
+
+		/*--------
+		 * Search for the biggest yet inlined attribute with
+		 * attstorage = 'm'
+		 *--------
+		 */
+		for (i = 0; i < numAttrs; i++)
+		{
+			if (toast_action[i] == 'p')
+				continue;
+			if (VARATT_IS_EXTERNAL(DatumGetPointer(toast_values[i])))
+				continue;		/* can't happen, toast_action would be 'p' */
+			if (TupleDescAttr(tupleDesc, i)->attstorage != 'm')
+				continue;
+			if (toast_sizes[i] > biggest_size)
+			{
+				biggest_attno = i;
+				biggest_size = toast_sizes[i];
+			}
+		}
+
+		if (biggest_attno < 0)
+			break;
+
+		/*
+		 * Store this external
+		 */
+		i = biggest_attno;
+		old_value = toast_values[i];
+		toast_action[i] = 'p';
+		toast_values[i] = toast_save_datum(rel, toast_values[i],
+										   toast_oldexternal[i], options);
+		if (toast_free[i])
+			pfree(DatumGetPointer(old_value));
+		toast_free[i] = true;
+
+		need_change = true;
+		need_free = true;
+	}
+
+	/*
+	 * In the case we toasted any values, we need to build a new heap tuple
+	 * with the changed values.
+	 */
+	if (need_change)
+	{
+		HeapTupleHeader olddata = newtup->t_data;
+		HeapTupleHeader new_data;
+		int32		new_header_len;
+		int32		new_data_len;
+		int32		new_tuple_len;
+
+		/*
+		 * Calculate the new size of the tuple.
+		 *
+		 * Note: we used to assume here that the old tuple's t_hoff must equal
+		 * the new_header_len value, but that was incorrect.  The old tuple
+		 * might have a smaller-than-current natts, if there's been an ALTER
+		 * TABLE ADD COLUMN since it was stored; and that would lead to a
+		 * different conclusion about the size of the null bitmap, or even
+		 * whether there needs to be one at all.
+		 */
+		new_header_len = SizeofHeapTupleHeader;
+		if (has_nulls)
+			new_header_len += BITMAPLEN(numAttrs);
+		new_header_len = MAXALIGN(new_header_len);
+		new_data_len = heap_compute_data_size(tupleDesc,
+											  toast_values, toast_isnull);
+		new_tuple_len = new_header_len + new_data_len;
+
+		/*
+		 * Allocate and zero the space needed, and fill HeapTupleData fields.
+		 */
+		result_tuple = (HeapTuple) palloc0(HEAPTUPLESIZE + new_tuple_len);
+		result_tuple->t_len = new_tuple_len;
+		result_tuple->t_self = newtup->t_self;
+		result_tuple->t_tableOid = newtup->t_tableOid;
+		new_data = (HeapTupleHeader) ((char *) result_tuple + HEAPTUPLESIZE);
+		result_tuple->t_data = new_data;
+
+		/*
+		 * Copy the existing tuple header, but adjust natts and t_hoff.
+		 */
+		memcpy(new_data, olddata, SizeofHeapTupleHeader);
+		HeapTupleHeaderSetNatts(new_data, numAttrs);
+		new_data->t_hoff = new_header_len;
+
+		/* Copy over the data, and fill the null bitmap if needed */
+		heap_fill_tuple(tupleDesc,
+						toast_values,
+						toast_isnull,
+						(char *) new_data + new_header_len,
+						new_data_len,
+						&(new_data->t_infomask),
+						has_nulls ? new_data->t_bits : NULL);
+	}
+	else
+		result_tuple = newtup;
+
+	/*
+	 * Free allocated temp values
+	 */
+	if (need_free)
+		for (i = 0; i < numAttrs; i++)
+			if (toast_free[i])
+				pfree(DatumGetPointer(toast_values[i]));
+
+	/*
+	 * Delete external values from the old tuple
+	 */
+	if (need_delold)
+		for (i = 0; i < numAttrs; i++)
+			if (toast_delold[i])
+				toast_delete_datum(rel, toast_oldvalues[i], false);
+
+	return result_tuple;
+}
+
+
+/* ----------
+ * toast_flatten_tuple -
+ *
+ *	"Flatten" a tuple to contain no out-of-line toasted fields.
+ *	(This does not eliminate compressed or short-header datums.)
+ *
+ *	Note: we expect the caller already checked HeapTupleHasExternal(tup),
+ *	so there is no need for a short-circuit path.
+ * ----------
+ */
+HeapTuple
+toast_flatten_tuple(HeapTuple tup, TupleDesc tupleDesc)
+{
+	HeapTuple	new_tuple;
+	int			numAttrs = tupleDesc->natts;
+	int			i;
+	Datum		toast_values[MaxTupleAttributeNumber];
+	bool		toast_isnull[MaxTupleAttributeNumber];
+	bool		toast_free[MaxTupleAttributeNumber];
+
+	/*
+	 * Break down the tuple into fields.
+	 */
+	Assert(numAttrs <= MaxTupleAttributeNumber);
+	heap_deform_tuple(tup, tupleDesc, toast_values, toast_isnull);
+
+	memset(toast_free, 0, numAttrs * sizeof(bool));
+
+	for (i = 0; i < numAttrs; i++)
+	{
+		/*
+		 * Look at non-null varlena attributes
+		 */
+		if (!toast_isnull[i] && TupleDescAttr(tupleDesc, i)->attlen == -1)
+		{
+			struct varlena *new_value;
+
+			new_value = (struct varlena *) DatumGetPointer(toast_values[i]);
+			if (VARATT_IS_EXTERNAL(new_value))
+			{
+				new_value = heap_tuple_fetch_attr(new_value);
+				toast_values[i] = PointerGetDatum(new_value);
+				toast_free[i] = true;
+			}
+		}
+	}
+
+	/*
+	 * Form the reconfigured tuple.
+	 */
+	new_tuple = heap_form_tuple(tupleDesc, toast_values, toast_isnull);
+
+	/*
+	 * Be sure to copy the tuple's identity fields.  We also make a point of
+	 * copying visibility info, just in case anybody looks at those fields in
+	 * a syscache entry.
+	 */
+	new_tuple->t_self = tup->t_self;
+	new_tuple->t_tableOid = tup->t_tableOid;
+
+	new_tuple->t_data->t_choice = tup->t_data->t_choice;
+	new_tuple->t_data->t_ctid = tup->t_data->t_ctid;
+	new_tuple->t_data->t_infomask &= ~HEAP_XACT_MASK;
+	new_tuple->t_data->t_infomask |=
+		tup->t_data->t_infomask & HEAP_XACT_MASK;
+	new_tuple->t_data->t_infomask2 &= ~HEAP2_XACT_MASK;
+	new_tuple->t_data->t_infomask2 |=
+		tup->t_data->t_infomask2 & HEAP2_XACT_MASK;
+
+	/*
+	 * Free allocated temp values
+	 */
+	for (i = 0; i < numAttrs; i++)
+		if (toast_free[i])
+			pfree(DatumGetPointer(toast_values[i]));
+
+	return new_tuple;
+}
+
+
+/* ----------
+ * toast_flatten_tuple_to_datum -
+ *
+ *	"Flatten" a tuple containing out-of-line toasted fields into a Datum.
+ *	The result is always palloc'd in the current memory context.
+ *
+ *	We have a general rule that Datums of container types (rows, arrays,
+ *	ranges, etc) must not contain any external TOAST pointers.  Without
+ *	this rule, we'd have to look inside each Datum when preparing a tuple
+ *	for storage, which would be expensive and would fail to extend cleanly
+ *	to new sorts of container types.
+ *
+ *	However, we don't want to say that tuples represented as HeapTuples
+ *	can't contain toasted fields, so instead this routine should be called
+ *	when such a HeapTuple is being converted into a Datum.
+ *
+ *	While we're at it, we decompress any compressed fields too.  This is not
+ *	necessary for correctness, but reflects an expectation that compression
+ *	will be more effective if applied to the whole tuple not individual
+ *	fields.  We are not so concerned about that that we want to deconstruct
+ *	and reconstruct tuples just to get rid of compressed fields, however.
+ *	So callers typically won't call this unless they see that the tuple has
+ *	at least one external field.
+ *
+ *	On the other hand, in-line short-header varlena fields are left alone.
+ *	If we "untoasted" them here, they'd just get changed back to short-header
+ *	format anyway within heap_fill_tuple.
+ * ----------
+ */
+Datum
+toast_flatten_tuple_to_datum(HeapTupleHeader tup,
+							 uint32 tup_len,
+							 TupleDesc tupleDesc)
+{
+	HeapTupleHeader new_data;
+	int32		new_header_len;
+	int32		new_data_len;
+	int32		new_tuple_len;
+	HeapTupleData tmptup;
+	int			numAttrs = tupleDesc->natts;
+	int			i;
+	bool		has_nulls = false;
+	Datum		toast_values[MaxTupleAttributeNumber];
+	bool		toast_isnull[MaxTupleAttributeNumber];
+	bool		toast_free[MaxTupleAttributeNumber];
+
+	/* Build a temporary HeapTuple control structure */
+	tmptup.t_len = tup_len;
+	ItemPointerSetInvalid(&(tmptup.t_self));
+	tmptup.t_tableOid = InvalidOid;
+	tmptup.t_data = tup;
+
+	/*
+	 * Break down the tuple into fields.
+	 */
+	Assert(numAttrs <= MaxTupleAttributeNumber);
+	heap_deform_tuple(&tmptup, tupleDesc, toast_values, toast_isnull);
+
+	memset(toast_free, 0, numAttrs * sizeof(bool));
+
+	for (i = 0; i < numAttrs; i++)
+	{
+		/*
+		 * Look at non-null varlena attributes
+		 */
+		if (toast_isnull[i])
+			has_nulls = true;
+		else if (TupleDescAttr(tupleDesc, i)->attlen == -1)
+		{
+			struct varlena *new_value;
+
+			new_value = (struct varlena *) DatumGetPointer(toast_values[i]);
+			if (VARATT_IS_EXTERNAL(new_value) ||
+				VARATT_IS_COMPRESSED(new_value))
+			{
+				new_value = heap_tuple_untoast_attr(new_value);
+				toast_values[i] = PointerGetDatum(new_value);
+				toast_free[i] = true;
+			}
+		}
+	}
+
+	/*
+	 * Calculate the new size of the tuple.
+	 *
+	 * This should match the reconstruction code in toast_insert_or_update.
+	 */
+	new_header_len = SizeofHeapTupleHeader;
+	if (has_nulls)
+		new_header_len += BITMAPLEN(numAttrs);
+	new_header_len = MAXALIGN(new_header_len);
+	new_data_len = heap_compute_data_size(tupleDesc,
+										  toast_values, toast_isnull);
+	new_tuple_len = new_header_len + new_data_len;
+
+	new_data = (HeapTupleHeader) palloc0(new_tuple_len);
+
+	/*
+	 * Copy the existing tuple header, but adjust natts and t_hoff.
+	 */
+	memcpy(new_data, tup, SizeofHeapTupleHeader);
+	HeapTupleHeaderSetNatts(new_data, numAttrs);
+	new_data->t_hoff = new_header_len;
+
+	/* Set the composite-Datum header fields correctly */
+	HeapTupleHeaderSetDatumLength(new_data, new_tuple_len);
+	HeapTupleHeaderSetTypeId(new_data, tupleDesc->tdtypeid);
+	HeapTupleHeaderSetTypMod(new_data, tupleDesc->tdtypmod);
+
+	/* Copy over the data, and fill the null bitmap if needed */
+	heap_fill_tuple(tupleDesc,
+					toast_values,
+					toast_isnull,
+					(char *) new_data + new_header_len,
+					new_data_len,
+					&(new_data->t_infomask),
+					has_nulls ? new_data->t_bits : NULL);
+
+	/*
+	 * Free allocated temp values
+	 */
+	for (i = 0; i < numAttrs; i++)
+		if (toast_free[i])
+			pfree(DatumGetPointer(toast_values[i]));
+
+	return PointerGetDatum(new_data);
+}
+
+
+/* ----------
+ * toast_build_flattened_tuple -
+ *
+ *	Build a tuple containing no out-of-line toasted fields.
+ *	(This does not eliminate compressed or short-header datums.)
+ *
+ *	This is essentially just like heap_form_tuple, except that it will
+ *	expand any external-data pointers beforehand.
+ *
+ *	It's not very clear whether it would be preferable to decompress
+ *	in-line compressed datums while at it.  For now, we don't.
+ * ----------
+ */
+HeapTuple
+toast_build_flattened_tuple(TupleDesc tupleDesc,
+							Datum *values,
+							bool *isnull)
+{
+	HeapTuple	new_tuple;
+	int			numAttrs = tupleDesc->natts;
+	int			num_to_free;
+	int			i;
+	Datum		new_values[MaxTupleAttributeNumber];
+	Pointer		freeable_values[MaxTupleAttributeNumber];
+
+	/*
+	 * We can pass the caller's isnull array directly to heap_form_tuple, but
+	 * we potentially need to modify the values array.
+	 */
+	Assert(numAttrs <= MaxTupleAttributeNumber);
+	memcpy(new_values, values, numAttrs * sizeof(Datum));
+
+	num_to_free = 0;
+	for (i = 0; i < numAttrs; i++)
+	{
+		/*
+		 * Look at non-null varlena attributes
+		 */
+		if (!isnull[i] && TupleDescAttr(tupleDesc, i)->attlen == -1)
+		{
+			struct varlena *new_value;
+
+			new_value = (struct varlena *) DatumGetPointer(new_values[i]);
+			if (VARATT_IS_EXTERNAL(new_value))
+			{
+				new_value = heap_tuple_fetch_attr(new_value);
+				new_values[i] = PointerGetDatum(new_value);
+				freeable_values[num_to_free++] = (Pointer) new_value;
+			}
+		}
+	}
+
+	/*
+	 * Form the reconfigured tuple.
+	 */
+	new_tuple = heap_form_tuple(tupleDesc, new_values, isnull);
+
+	/*
+	 * Free allocated temp values
+	 */
+	for (i = 0; i < num_to_free; i++)
+		pfree(freeable_values[i]);
+
+	return new_tuple;
+}
diff --git a/src/backend/access/heap/rewriteheap.c b/src/backend/access/heap/rewriteheap.c
index 369694fa2e..c6f60227d0 100644
--- a/src/backend/access/heap/rewriteheap.c
+++ b/src/backend/access/heap/rewriteheap.c
@@ -109,9 +109,9 @@
 
 #include "access/heapam.h"
 #include "access/heapam_xlog.h"
+#include "access/heaptoast.h"
 #include "access/rewriteheap.h"
 #include "access/transam.h"
-#include "access/tuptoaster.h"
 #include "access/xact.h"
 #include "access/xloginsert.h"
 
diff --git a/src/backend/access/heap/tuptoaster.c b/src/backend/access/heap/tuptoaster.c
deleted file mode 100644
index 55d6e91d1c..0000000000
--- a/src/backend/access/heap/tuptoaster.c
+++ /dev/null
@@ -1,2411 +0,0 @@
-/*-------------------------------------------------------------------------
- *
- * tuptoaster.c
- *	  Support routines for external and compressed storage of
- *	  variable size attributes.
- *
- * Copyright (c) 2000-2019, PostgreSQL Global Development Group
- *
- *
- * IDENTIFICATION
- *	  src/backend/access/heap/tuptoaster.c
- *
- *
- * INTERFACE ROUTINES
- *		toast_insert_or_update -
- *			Try to make a given tuple fit into one page by compressing
- *			or moving off attributes
- *
- *		toast_delete -
- *			Reclaim toast storage when a tuple is deleted
- *
- *		heap_tuple_untoast_attr -
- *			Fetch back a given value from the "secondary" relation
- *
- *-------------------------------------------------------------------------
- */
-
-#include "postgres.h"
-
-#include <unistd.h>
-#include <fcntl.h>
-
-#include "access/genam.h"
-#include "access/heapam.h"
-#include "access/tuptoaster.h"
-#include "access/xact.h"
-#include "catalog/catalog.h"
-#include "common/pg_lzcompress.h"
-#include "miscadmin.h"
-#include "utils/expandeddatum.h"
-#include "utils/fmgroids.h"
-#include "utils/rel.h"
-#include "utils/snapmgr.h"
-#include "utils/typcache.h"
-
-
-#undef TOAST_DEBUG
-
-/*
- *	The information at the start of the compressed toast data.
- */
-typedef struct toast_compress_header
-{
-	int32		vl_len_;		/* varlena header (do not touch directly!) */
-	int32		rawsize;
-} toast_compress_header;
-
-/*
- * Utilities for manipulation of header information for compressed
- * toast entries.
- */
-#define TOAST_COMPRESS_HDRSZ		((int32) sizeof(toast_compress_header))
-#define TOAST_COMPRESS_RAWSIZE(ptr) (((toast_compress_header *) (ptr))->rawsize)
-#define TOAST_COMPRESS_RAWDATA(ptr) \
-	(((char *) (ptr)) + TOAST_COMPRESS_HDRSZ)
-#define TOAST_COMPRESS_SET_RAWSIZE(ptr, len) \
-	(((toast_compress_header *) (ptr))->rawsize = (len))
-
-static void toast_delete_datum(Relation rel, Datum value, bool is_speculative);
-static Datum toast_save_datum(Relation rel, Datum value,
-							  struct varlena *oldexternal, int options);
-static bool toastrel_valueid_exists(Relation toastrel, Oid valueid);
-static bool toastid_valueid_exists(Oid toastrelid, Oid valueid);
-static struct varlena *toast_fetch_datum(struct varlena *attr);
-static struct varlena *toast_fetch_datum_slice(struct varlena *attr,
-											   int32 sliceoffset, int32 length);
-static struct varlena *toast_decompress_datum(struct varlena *attr);
-static struct varlena *toast_decompress_datum_slice(struct varlena *attr, int32 slicelength);
-static int	toast_open_indexes(Relation toastrel,
-							   LOCKMODE lock,
-							   Relation **toastidxs,
-							   int *num_indexes);
-static void toast_close_indexes(Relation *toastidxs, int num_indexes,
-								LOCKMODE lock);
-static void init_toast_snapshot(Snapshot toast_snapshot);
-
-
-/* ----------
- * heap_tuple_fetch_attr -
- *
- *	Public entry point to get back a toasted value from
- *	external source (possibly still in compressed format).
- *
- * This will return a datum that contains all the data internally, ie, not
- * relying on external storage or memory, but it can still be compressed or
- * have a short header.  Note some callers assume that if the input is an
- * EXTERNAL datum, the result will be a pfree'able chunk.
- * ----------
- */
-struct varlena *
-heap_tuple_fetch_attr(struct varlena *attr)
-{
-	struct varlena *result;
-
-	if (VARATT_IS_EXTERNAL_ONDISK(attr))
-	{
-		/*
-		 * This is an external stored plain value
-		 */
-		result = toast_fetch_datum(attr);
-	}
-	else if (VARATT_IS_EXTERNAL_INDIRECT(attr))
-	{
-		/*
-		 * This is an indirect pointer --- dereference it
-		 */
-		struct varatt_indirect redirect;
-
-		VARATT_EXTERNAL_GET_POINTER(redirect, attr);
-		attr = (struct varlena *) redirect.pointer;
-
-		/* nested indirect Datums aren't allowed */
-		Assert(!VARATT_IS_EXTERNAL_INDIRECT(attr));
-
-		/* recurse if value is still external in some other way */
-		if (VARATT_IS_EXTERNAL(attr))
-			return heap_tuple_fetch_attr(attr);
-
-		/*
-		 * Copy into the caller's memory context, in case caller tries to
-		 * pfree the result.
-		 */
-		result = (struct varlena *) palloc(VARSIZE_ANY(attr));
-		memcpy(result, attr, VARSIZE_ANY(attr));
-	}
-	else if (VARATT_IS_EXTERNAL_EXPANDED(attr))
-	{
-		/*
-		 * This is an expanded-object pointer --- get flat format
-		 */
-		ExpandedObjectHeader *eoh;
-		Size		resultsize;
-
-		eoh = DatumGetEOHP(PointerGetDatum(attr));
-		resultsize = EOH_get_flat_size(eoh);
-		result = (struct varlena *) palloc(resultsize);
-		EOH_flatten_into(eoh, (void *) result, resultsize);
-	}
-	else
-	{
-		/*
-		 * This is a plain value inside of the main tuple - why am I called?
-		 */
-		result = attr;
-	}
-
-	return result;
-}
-
-
-/* ----------
- * heap_tuple_untoast_attr -
- *
- *	Public entry point to get back a toasted value from compression
- *	or external storage.  The result is always non-extended varlena form.
- *
- * Note some callers assume that if the input is an EXTERNAL or COMPRESSED
- * datum, the result will be a pfree'able chunk.
- * ----------
- */
-struct varlena *
-heap_tuple_untoast_attr(struct varlena *attr)
-{
-	if (VARATT_IS_EXTERNAL_ONDISK(attr))
-	{
-		/*
-		 * This is an externally stored datum --- fetch it back from there
-		 */
-		attr = toast_fetch_datum(attr);
-		/* If it's compressed, decompress it */
-		if (VARATT_IS_COMPRESSED(attr))
-		{
-			struct varlena *tmp = attr;
-
-			attr = toast_decompress_datum(tmp);
-			pfree(tmp);
-		}
-	}
-	else if (VARATT_IS_EXTERNAL_INDIRECT(attr))
-	{
-		/*
-		 * This is an indirect pointer --- dereference it
-		 */
-		struct varatt_indirect redirect;
-
-		VARATT_EXTERNAL_GET_POINTER(redirect, attr);
-		attr = (struct varlena *) redirect.pointer;
-
-		/* nested indirect Datums aren't allowed */
-		Assert(!VARATT_IS_EXTERNAL_INDIRECT(attr));
-
-		/* recurse in case value is still extended in some other way */
-		attr = heap_tuple_untoast_attr(attr);
-
-		/* if it isn't, we'd better copy it */
-		if (attr == (struct varlena *) redirect.pointer)
-		{
-			struct varlena *result;
-
-			result = (struct varlena *) palloc(VARSIZE_ANY(attr));
-			memcpy(result, attr, VARSIZE_ANY(attr));
-			attr = result;
-		}
-	}
-	else if (VARATT_IS_EXTERNAL_EXPANDED(attr))
-	{
-		/*
-		 * This is an expanded-object pointer --- get flat format
-		 */
-		attr = heap_tuple_fetch_attr(attr);
-		/* flatteners are not allowed to produce compressed/short output */
-		Assert(!VARATT_IS_EXTENDED(attr));
-	}
-	else if (VARATT_IS_COMPRESSED(attr))
-	{
-		/*
-		 * This is a compressed value inside of the main tuple
-		 */
-		attr = toast_decompress_datum(attr);
-	}
-	else if (VARATT_IS_SHORT(attr))
-	{
-		/*
-		 * This is a short-header varlena --- convert to 4-byte header format
-		 */
-		Size		data_size = VARSIZE_SHORT(attr) - VARHDRSZ_SHORT;
-		Size		new_size = data_size + VARHDRSZ;
-		struct varlena *new_attr;
-
-		new_attr = (struct varlena *) palloc(new_size);
-		SET_VARSIZE(new_attr, new_size);
-		memcpy(VARDATA(new_attr), VARDATA_SHORT(attr), data_size);
-		attr = new_attr;
-	}
-
-	return attr;
-}
-
-
-/* ----------
- * heap_tuple_untoast_attr_slice -
- *
- *		Public entry point to get back part of a toasted value
- *		from compression or external storage.
- * ----------
- */
-struct varlena *
-heap_tuple_untoast_attr_slice(struct varlena *attr,
-							  int32 sliceoffset, int32 slicelength)
-{
-	struct varlena *preslice;
-	struct varlena *result;
-	char	   *attrdata;
-	int32		attrsize;
-
-	if (VARATT_IS_EXTERNAL_ONDISK(attr))
-	{
-		struct varatt_external toast_pointer;
-
-		VARATT_EXTERNAL_GET_POINTER(toast_pointer, attr);
-
-		/* fast path for non-compressed external datums */
-		if (!VARATT_EXTERNAL_IS_COMPRESSED(toast_pointer))
-			return toast_fetch_datum_slice(attr, sliceoffset, slicelength);
-
-		/* fetch it back (compressed marker will get set automatically) */
-		preslice = toast_fetch_datum(attr);
-	}
-	else if (VARATT_IS_EXTERNAL_INDIRECT(attr))
-	{
-		struct varatt_indirect redirect;
-
-		VARATT_EXTERNAL_GET_POINTER(redirect, attr);
-
-		/* nested indirect Datums aren't allowed */
-		Assert(!VARATT_IS_EXTERNAL_INDIRECT(redirect.pointer));
-
-		return heap_tuple_untoast_attr_slice(redirect.pointer,
-											 sliceoffset, slicelength);
-	}
-	else if (VARATT_IS_EXTERNAL_EXPANDED(attr))
-	{
-		/* pass it off to heap_tuple_fetch_attr to flatten */
-		preslice = heap_tuple_fetch_attr(attr);
-	}
-	else
-		preslice = attr;
-
-	Assert(!VARATT_IS_EXTERNAL(preslice));
-
-	if (VARATT_IS_COMPRESSED(preslice))
-	{
-		struct varlena *tmp = preslice;
-
-		/* Decompress enough to encompass the slice and the offset */
-		if (slicelength > 0 && sliceoffset >= 0)
-			preslice = toast_decompress_datum_slice(tmp, slicelength + sliceoffset);
-		else
-			preslice = toast_decompress_datum(tmp);
-
-		if (tmp != attr)
-			pfree(tmp);
-	}
-
-	if (VARATT_IS_SHORT(preslice))
-	{
-		attrdata = VARDATA_SHORT(preslice);
-		attrsize = VARSIZE_SHORT(preslice) - VARHDRSZ_SHORT;
-	}
-	else
-	{
-		attrdata = VARDATA(preslice);
-		attrsize = VARSIZE(preslice) - VARHDRSZ;
-	}
-
-	/* slicing of datum for compressed cases and plain value */
-
-	if (sliceoffset >= attrsize)
-	{
-		sliceoffset = 0;
-		slicelength = 0;
-	}
-
-	if (((sliceoffset + slicelength) > attrsize) || slicelength < 0)
-		slicelength = attrsize - sliceoffset;
-
-	result = (struct varlena *) palloc(slicelength + VARHDRSZ);
-	SET_VARSIZE(result, slicelength + VARHDRSZ);
-
-	memcpy(VARDATA(result), attrdata + sliceoffset, slicelength);
-
-	if (preslice != attr)
-		pfree(preslice);
-
-	return result;
-}
-
-
-/* ----------
- * toast_raw_datum_size -
- *
- *	Return the raw (detoasted) size of a varlena datum
- *	(including the VARHDRSZ header)
- * ----------
- */
-Size
-toast_raw_datum_size(Datum value)
-{
-	struct varlena *attr = (struct varlena *) DatumGetPointer(value);
-	Size		result;
-
-	if (VARATT_IS_EXTERNAL_ONDISK(attr))
-	{
-		/* va_rawsize is the size of the original datum -- including header */
-		struct varatt_external toast_pointer;
-
-		VARATT_EXTERNAL_GET_POINTER(toast_pointer, attr);
-		result = toast_pointer.va_rawsize;
-	}
-	else if (VARATT_IS_EXTERNAL_INDIRECT(attr))
-	{
-		struct varatt_indirect toast_pointer;
-
-		VARATT_EXTERNAL_GET_POINTER(toast_pointer, attr);
-
-		/* nested indirect Datums aren't allowed */
-		Assert(!VARATT_IS_EXTERNAL_INDIRECT(toast_pointer.pointer));
-
-		return toast_raw_datum_size(PointerGetDatum(toast_pointer.pointer));
-	}
-	else if (VARATT_IS_EXTERNAL_EXPANDED(attr))
-	{
-		result = EOH_get_flat_size(DatumGetEOHP(value));
-	}
-	else if (VARATT_IS_COMPRESSED(attr))
-	{
-		/* here, va_rawsize is just the payload size */
-		result = VARRAWSIZE_4B_C(attr) + VARHDRSZ;
-	}
-	else if (VARATT_IS_SHORT(attr))
-	{
-		/*
-		 * we have to normalize the header length to VARHDRSZ or else the
-		 * callers of this function will be confused.
-		 */
-		result = VARSIZE_SHORT(attr) - VARHDRSZ_SHORT + VARHDRSZ;
-	}
-	else
-	{
-		/* plain untoasted datum */
-		result = VARSIZE(attr);
-	}
-	return result;
-}
-
-/* ----------
- * toast_datum_size
- *
- *	Return the physical storage size (possibly compressed) of a varlena datum
- * ----------
- */
-Size
-toast_datum_size(Datum value)
-{
-	struct varlena *attr = (struct varlena *) DatumGetPointer(value);
-	Size		result;
-
-	if (VARATT_IS_EXTERNAL_ONDISK(attr))
-	{
-		/*
-		 * Attribute is stored externally - return the extsize whether
-		 * compressed or not.  We do not count the size of the toast pointer
-		 * ... should we?
-		 */
-		struct varatt_external toast_pointer;
-
-		VARATT_EXTERNAL_GET_POINTER(toast_pointer, attr);
-		result = toast_pointer.va_extsize;
-	}
-	else if (VARATT_IS_EXTERNAL_INDIRECT(attr))
-	{
-		struct varatt_indirect toast_pointer;
-
-		VARATT_EXTERNAL_GET_POINTER(toast_pointer, attr);
-
-		/* nested indirect Datums aren't allowed */
-		Assert(!VARATT_IS_EXTERNAL_INDIRECT(attr));
-
-		return toast_datum_size(PointerGetDatum(toast_pointer.pointer));
-	}
-	else if (VARATT_IS_EXTERNAL_EXPANDED(attr))
-	{
-		result = EOH_get_flat_size(DatumGetEOHP(value));
-	}
-	else if (VARATT_IS_SHORT(attr))
-	{
-		result = VARSIZE_SHORT(attr);
-	}
-	else
-	{
-		/*
-		 * Attribute is stored inline either compressed or not, just calculate
-		 * the size of the datum in either case.
-		 */
-		result = VARSIZE(attr);
-	}
-	return result;
-}
-
-
-/* ----------
- * toast_delete -
- *
- *	Cascaded delete toast-entries on DELETE
- * ----------
- */
-void
-toast_delete(Relation rel, HeapTuple oldtup, bool is_speculative)
-{
-	TupleDesc	tupleDesc;
-	int			numAttrs;
-	int			i;
-	Datum		toast_values[MaxHeapAttributeNumber];
-	bool		toast_isnull[MaxHeapAttributeNumber];
-
-	/*
-	 * We should only ever be called for tuples of plain relations or
-	 * materialized views --- recursing on a toast rel is bad news.
-	 */
-	Assert(rel->rd_rel->relkind == RELKIND_RELATION ||
-		   rel->rd_rel->relkind == RELKIND_MATVIEW);
-
-	/*
-	 * Get the tuple descriptor and break down the tuple into fields.
-	 *
-	 * NOTE: it's debatable whether to use heap_deform_tuple() here or just
-	 * heap_getattr() only the varlena columns.  The latter could win if there
-	 * are few varlena columns and many non-varlena ones. However,
-	 * heap_deform_tuple costs only O(N) while the heap_getattr way would cost
-	 * O(N^2) if there are many varlena columns, so it seems better to err on
-	 * the side of linear cost.  (We won't even be here unless there's at
-	 * least one varlena column, by the way.)
-	 */
-	tupleDesc = rel->rd_att;
-	numAttrs = tupleDesc->natts;
-
-	Assert(numAttrs <= MaxHeapAttributeNumber);
-	heap_deform_tuple(oldtup, tupleDesc, toast_values, toast_isnull);
-
-	/*
-	 * Check for external stored attributes and delete them from the secondary
-	 * relation.
-	 */
-	for (i = 0; i < numAttrs; i++)
-	{
-		if (TupleDescAttr(tupleDesc, i)->attlen == -1)
-		{
-			Datum		value = toast_values[i];
-
-			if (toast_isnull[i])
-				continue;
-			else if (VARATT_IS_EXTERNAL_ONDISK(PointerGetDatum(value)))
-				toast_delete_datum(rel, value, is_speculative);
-		}
-	}
-}
-
-
-/* ----------
- * toast_insert_or_update -
- *
- *	Delete no-longer-used toast-entries and create new ones to
- *	make the new tuple fit on INSERT or UPDATE
- *
- * Inputs:
- *	newtup: the candidate new tuple to be inserted
- *	oldtup: the old row version for UPDATE, or NULL for INSERT
- *	options: options to be passed to heap_insert() for toast rows
- * Result:
- *	either newtup if no toasting is needed, or a palloc'd modified tuple
- *	that is what should actually get stored
- *
- * NOTE: neither newtup nor oldtup will be modified.  This is a change
- * from the pre-8.1 API of this routine.
- * ----------
- */
-HeapTuple
-toast_insert_or_update(Relation rel, HeapTuple newtup, HeapTuple oldtup,
-					   int options)
-{
-	HeapTuple	result_tuple;
-	TupleDesc	tupleDesc;
-	int			numAttrs;
-	int			i;
-
-	bool		need_change = false;
-	bool		need_free = false;
-	bool		need_delold = false;
-	bool		has_nulls = false;
-
-	Size		maxDataLen;
-	Size		hoff;
-
-	char		toast_action[MaxHeapAttributeNumber];
-	bool		toast_isnull[MaxHeapAttributeNumber];
-	bool		toast_oldisnull[MaxHeapAttributeNumber];
-	Datum		toast_values[MaxHeapAttributeNumber];
-	Datum		toast_oldvalues[MaxHeapAttributeNumber];
-	struct varlena *toast_oldexternal[MaxHeapAttributeNumber];
-	int32		toast_sizes[MaxHeapAttributeNumber];
-	bool		toast_free[MaxHeapAttributeNumber];
-	bool		toast_delold[MaxHeapAttributeNumber];
-
-	/*
-	 * Ignore the INSERT_SPECULATIVE option. Speculative insertions/super
-	 * deletions just normally insert/delete the toast values. It seems
-	 * easiest to deal with that here, instead on, potentially, multiple
-	 * callers.
-	 */
-	options &= ~HEAP_INSERT_SPECULATIVE;
-
-	/*
-	 * We should only ever be called for tuples of plain relations or
-	 * materialized views --- recursing on a toast rel is bad news.
-	 */
-	Assert(rel->rd_rel->relkind == RELKIND_RELATION ||
-		   rel->rd_rel->relkind == RELKIND_MATVIEW);
-
-	/*
-	 * Get the tuple descriptor and break down the tuple(s) into fields.
-	 */
-	tupleDesc = rel->rd_att;
-	numAttrs = tupleDesc->natts;
-
-	Assert(numAttrs <= MaxHeapAttributeNumber);
-	heap_deform_tuple(newtup, tupleDesc, toast_values, toast_isnull);
-	if (oldtup != NULL)
-		heap_deform_tuple(oldtup, tupleDesc, toast_oldvalues, toast_oldisnull);
-
-	/* ----------
-	 * Then collect information about the values given
-	 *
-	 * NOTE: toast_action[i] can have these values:
-	 *		' '		default handling
-	 *		'p'		already processed --- don't touch it
-	 *		'x'		incompressible, but OK to move off
-	 *
-	 * NOTE: toast_sizes[i] is only made valid for varlena attributes with
-	 *		toast_action[i] different from 'p'.
-	 * ----------
-	 */
-	memset(toast_action, ' ', numAttrs * sizeof(char));
-	memset(toast_oldexternal, 0, numAttrs * sizeof(struct varlena *));
-	memset(toast_free, 0, numAttrs * sizeof(bool));
-	memset(toast_delold, 0, numAttrs * sizeof(bool));
-
-	for (i = 0; i < numAttrs; i++)
-	{
-		Form_pg_attribute att = TupleDescAttr(tupleDesc, i);
-		struct varlena *old_value;
-		struct varlena *new_value;
-
-		if (oldtup != NULL)
-		{
-			/*
-			 * For UPDATE get the old and new values of this attribute
-			 */
-			old_value = (struct varlena *) DatumGetPointer(toast_oldvalues[i]);
-			new_value = (struct varlena *) DatumGetPointer(toast_values[i]);
-
-			/*
-			 * If the old value is stored on disk, check if it has changed so
-			 * we have to delete it later.
-			 */
-			if (att->attlen == -1 && !toast_oldisnull[i] &&
-				VARATT_IS_EXTERNAL_ONDISK(old_value))
-			{
-				if (toast_isnull[i] || !VARATT_IS_EXTERNAL_ONDISK(new_value) ||
-					memcmp((char *) old_value, (char *) new_value,
-						   VARSIZE_EXTERNAL(old_value)) != 0)
-				{
-					/*
-					 * The old external stored value isn't needed any more
-					 * after the update
-					 */
-					toast_delold[i] = true;
-					need_delold = true;
-				}
-				else
-				{
-					/*
-					 * This attribute isn't changed by this update so we reuse
-					 * the original reference to the old value in the new
-					 * tuple.
-					 */
-					toast_action[i] = 'p';
-					continue;
-				}
-			}
-		}
-		else
-		{
-			/*
-			 * For INSERT simply get the new value
-			 */
-			new_value = (struct varlena *) DatumGetPointer(toast_values[i]);
-		}
-
-		/*
-		 * Handle NULL attributes
-		 */
-		if (toast_isnull[i])
-		{
-			toast_action[i] = 'p';
-			has_nulls = true;
-			continue;
-		}
-
-		/*
-		 * Now look at varlena attributes
-		 */
-		if (att->attlen == -1)
-		{
-			/*
-			 * If the table's attribute says PLAIN always, force it so.
-			 */
-			if (att->attstorage == 'p')
-				toast_action[i] = 'p';
-
-			/*
-			 * We took care of UPDATE above, so any external value we find
-			 * still in the tuple must be someone else's that we cannot reuse
-			 * (this includes the case of an out-of-line in-memory datum).
-			 * Fetch it back (without decompression, unless we are forcing
-			 * PLAIN storage).  If necessary, we'll push it out as a new
-			 * external value below.
-			 */
-			if (VARATT_IS_EXTERNAL(new_value))
-			{
-				toast_oldexternal[i] = new_value;
-				if (att->attstorage == 'p')
-					new_value = heap_tuple_untoast_attr(new_value);
-				else
-					new_value = heap_tuple_fetch_attr(new_value);
-				toast_values[i] = PointerGetDatum(new_value);
-				toast_free[i] = true;
-				need_change = true;
-				need_free = true;
-			}
-
-			/*
-			 * Remember the size of this attribute
-			 */
-			toast_sizes[i] = VARSIZE_ANY(new_value);
-		}
-		else
-		{
-			/*
-			 * Not a varlena attribute, plain storage always
-			 */
-			toast_action[i] = 'p';
-		}
-	}
-
-	/* ----------
-	 * Compress and/or save external until data fits into target length
-	 *
-	 *	1: Inline compress attributes with attstorage 'x', and store very
-	 *	   large attributes with attstorage 'x' or 'e' external immediately
-	 *	2: Store attributes with attstorage 'x' or 'e' external
-	 *	3: Inline compress attributes with attstorage 'm'
-	 *	4: Store attributes with attstorage 'm' external
-	 * ----------
-	 */
-
-	/* compute header overhead --- this should match heap_form_tuple() */
-	hoff = SizeofHeapTupleHeader;
-	if (has_nulls)
-		hoff += BITMAPLEN(numAttrs);
-	hoff = MAXALIGN(hoff);
-	/* now convert to a limit on the tuple data size */
-	maxDataLen = RelationGetToastTupleTarget(rel, TOAST_TUPLE_TARGET) - hoff;
-
-	/*
-	 * Look for attributes with attstorage 'x' to compress.  Also find large
-	 * attributes with attstorage 'x' or 'e', and store them external.
-	 */
-	while (heap_compute_data_size(tupleDesc,
-								  toast_values, toast_isnull) > maxDataLen)
-	{
-		int			biggest_attno = -1;
-		int32		biggest_size = MAXALIGN(TOAST_POINTER_SIZE);
-		Datum		old_value;
-		Datum		new_value;
-
-		/*
-		 * Search for the biggest yet unprocessed internal attribute
-		 */
-		for (i = 0; i < numAttrs; i++)
-		{
-			Form_pg_attribute att = TupleDescAttr(tupleDesc, i);
-
-			if (toast_action[i] != ' ')
-				continue;
-			if (VARATT_IS_EXTERNAL(DatumGetPointer(toast_values[i])))
-				continue;		/* can't happen, toast_action would be 'p' */
-			if (VARATT_IS_COMPRESSED(DatumGetPointer(toast_values[i])))
-				continue;
-			if (att->attstorage != 'x' && att->attstorage != 'e')
-				continue;
-			if (toast_sizes[i] > biggest_size)
-			{
-				biggest_attno = i;
-				biggest_size = toast_sizes[i];
-			}
-		}
-
-		if (biggest_attno < 0)
-			break;
-
-		/*
-		 * Attempt to compress it inline, if it has attstorage 'x'
-		 */
-		i = biggest_attno;
-		if (TupleDescAttr(tupleDesc, i)->attstorage == 'x')
-		{
-			old_value = toast_values[i];
-			new_value = toast_compress_datum(old_value);
-
-			if (DatumGetPointer(new_value) != NULL)
-			{
-				/* successful compression */
-				if (toast_free[i])
-					pfree(DatumGetPointer(old_value));
-				toast_values[i] = new_value;
-				toast_free[i] = true;
-				toast_sizes[i] = VARSIZE(DatumGetPointer(toast_values[i]));
-				need_change = true;
-				need_free = true;
-			}
-			else
-			{
-				/* incompressible, ignore on subsequent compression passes */
-				toast_action[i] = 'x';
-			}
-		}
-		else
-		{
-			/* has attstorage 'e', ignore on subsequent compression passes */
-			toast_action[i] = 'x';
-		}
-
-		/*
-		 * If this value is by itself more than maxDataLen (after compression
-		 * if any), push it out to the toast table immediately, if possible.
-		 * This avoids uselessly compressing other fields in the common case
-		 * where we have one long field and several short ones.
-		 *
-		 * XXX maybe the threshold should be less than maxDataLen?
-		 */
-		if (toast_sizes[i] > maxDataLen &&
-			rel->rd_rel->reltoastrelid != InvalidOid)
-		{
-			old_value = toast_values[i];
-			toast_action[i] = 'p';
-			toast_values[i] = toast_save_datum(rel, toast_values[i],
-											   toast_oldexternal[i], options);
-			if (toast_free[i])
-				pfree(DatumGetPointer(old_value));
-			toast_free[i] = true;
-			need_change = true;
-			need_free = true;
-		}
-	}
-
-	/*
-	 * Second we look for attributes of attstorage 'x' or 'e' that are still
-	 * inline.  But skip this if there's no toast table to push them to.
-	 */
-	while (heap_compute_data_size(tupleDesc,
-								  toast_values, toast_isnull) > maxDataLen &&
-		   rel->rd_rel->reltoastrelid != InvalidOid)
-	{
-		int			biggest_attno = -1;
-		int32		biggest_size = MAXALIGN(TOAST_POINTER_SIZE);
-		Datum		old_value;
-
-		/*------
-		 * Search for the biggest yet inlined attribute with
-		 * attstorage equals 'x' or 'e'
-		 *------
-		 */
-		for (i = 0; i < numAttrs; i++)
-		{
-			Form_pg_attribute att = TupleDescAttr(tupleDesc, i);
-
-			if (toast_action[i] == 'p')
-				continue;
-			if (VARATT_IS_EXTERNAL(DatumGetPointer(toast_values[i])))
-				continue;		/* can't happen, toast_action would be 'p' */
-			if (att->attstorage != 'x' && att->attstorage != 'e')
-				continue;
-			if (toast_sizes[i] > biggest_size)
-			{
-				biggest_attno = i;
-				biggest_size = toast_sizes[i];
-			}
-		}
-
-		if (biggest_attno < 0)
-			break;
-
-		/*
-		 * Store this external
-		 */
-		i = biggest_attno;
-		old_value = toast_values[i];
-		toast_action[i] = 'p';
-		toast_values[i] = toast_save_datum(rel, toast_values[i],
-										   toast_oldexternal[i], options);
-		if (toast_free[i])
-			pfree(DatumGetPointer(old_value));
-		toast_free[i] = true;
-
-		need_change = true;
-		need_free = true;
-	}
-
-	/*
-	 * Round 3 - this time we take attributes with storage 'm' into
-	 * compression
-	 */
-	while (heap_compute_data_size(tupleDesc,
-								  toast_values, toast_isnull) > maxDataLen)
-	{
-		int			biggest_attno = -1;
-		int32		biggest_size = MAXALIGN(TOAST_POINTER_SIZE);
-		Datum		old_value;
-		Datum		new_value;
-
-		/*
-		 * Search for the biggest yet uncompressed internal attribute
-		 */
-		for (i = 0; i < numAttrs; i++)
-		{
-			if (toast_action[i] != ' ')
-				continue;
-			if (VARATT_IS_EXTERNAL(DatumGetPointer(toast_values[i])))
-				continue;		/* can't happen, toast_action would be 'p' */
-			if (VARATT_IS_COMPRESSED(DatumGetPointer(toast_values[i])))
-				continue;
-			if (TupleDescAttr(tupleDesc, i)->attstorage != 'm')
-				continue;
-			if (toast_sizes[i] > biggest_size)
-			{
-				biggest_attno = i;
-				biggest_size = toast_sizes[i];
-			}
-		}
-
-		if (biggest_attno < 0)
-			break;
-
-		/*
-		 * Attempt to compress it inline
-		 */
-		i = biggest_attno;
-		old_value = toast_values[i];
-		new_value = toast_compress_datum(old_value);
-
-		if (DatumGetPointer(new_value) != NULL)
-		{
-			/* successful compression */
-			if (toast_free[i])
-				pfree(DatumGetPointer(old_value));
-			toast_values[i] = new_value;
-			toast_free[i] = true;
-			toast_sizes[i] = VARSIZE(DatumGetPointer(toast_values[i]));
-			need_change = true;
-			need_free = true;
-		}
-		else
-		{
-			/* incompressible, ignore on subsequent compression passes */
-			toast_action[i] = 'x';
-		}
-	}
-
-	/*
-	 * Finally we store attributes of type 'm' externally.  At this point we
-	 * increase the target tuple size, so that 'm' attributes aren't stored
-	 * externally unless really necessary.
-	 */
-	maxDataLen = TOAST_TUPLE_TARGET_MAIN - hoff;
-
-	while (heap_compute_data_size(tupleDesc,
-								  toast_values, toast_isnull) > maxDataLen &&
-		   rel->rd_rel->reltoastrelid != InvalidOid)
-	{
-		int			biggest_attno = -1;
-		int32		biggest_size = MAXALIGN(TOAST_POINTER_SIZE);
-		Datum		old_value;
-
-		/*--------
-		 * Search for the biggest yet inlined attribute with
-		 * attstorage = 'm'
-		 *--------
-		 */
-		for (i = 0; i < numAttrs; i++)
-		{
-			if (toast_action[i] == 'p')
-				continue;
-			if (VARATT_IS_EXTERNAL(DatumGetPointer(toast_values[i])))
-				continue;		/* can't happen, toast_action would be 'p' */
-			if (TupleDescAttr(tupleDesc, i)->attstorage != 'm')
-				continue;
-			if (toast_sizes[i] > biggest_size)
-			{
-				biggest_attno = i;
-				biggest_size = toast_sizes[i];
-			}
-		}
-
-		if (biggest_attno < 0)
-			break;
-
-		/*
-		 * Store this external
-		 */
-		i = biggest_attno;
-		old_value = toast_values[i];
-		toast_action[i] = 'p';
-		toast_values[i] = toast_save_datum(rel, toast_values[i],
-										   toast_oldexternal[i], options);
-		if (toast_free[i])
-			pfree(DatumGetPointer(old_value));
-		toast_free[i] = true;
-
-		need_change = true;
-		need_free = true;
-	}
-
-	/*
-	 * In the case we toasted any values, we need to build a new heap tuple
-	 * with the changed values.
-	 */
-	if (need_change)
-	{
-		HeapTupleHeader olddata = newtup->t_data;
-		HeapTupleHeader new_data;
-		int32		new_header_len;
-		int32		new_data_len;
-		int32		new_tuple_len;
-
-		/*
-		 * Calculate the new size of the tuple.
-		 *
-		 * Note: we used to assume here that the old tuple's t_hoff must equal
-		 * the new_header_len value, but that was incorrect.  The old tuple
-		 * might have a smaller-than-current natts, if there's been an ALTER
-		 * TABLE ADD COLUMN since it was stored; and that would lead to a
-		 * different conclusion about the size of the null bitmap, or even
-		 * whether there needs to be one at all.
-		 */
-		new_header_len = SizeofHeapTupleHeader;
-		if (has_nulls)
-			new_header_len += BITMAPLEN(numAttrs);
-		new_header_len = MAXALIGN(new_header_len);
-		new_data_len = heap_compute_data_size(tupleDesc,
-											  toast_values, toast_isnull);
-		new_tuple_len = new_header_len + new_data_len;
-
-		/*
-		 * Allocate and zero the space needed, and fill HeapTupleData fields.
-		 */
-		result_tuple = (HeapTuple) palloc0(HEAPTUPLESIZE + new_tuple_len);
-		result_tuple->t_len = new_tuple_len;
-		result_tuple->t_self = newtup->t_self;
-		result_tuple->t_tableOid = newtup->t_tableOid;
-		new_data = (HeapTupleHeader) ((char *) result_tuple + HEAPTUPLESIZE);
-		result_tuple->t_data = new_data;
-
-		/*
-		 * Copy the existing tuple header, but adjust natts and t_hoff.
-		 */
-		memcpy(new_data, olddata, SizeofHeapTupleHeader);
-		HeapTupleHeaderSetNatts(new_data, numAttrs);
-		new_data->t_hoff = new_header_len;
-
-		/* Copy over the data, and fill the null bitmap if needed */
-		heap_fill_tuple(tupleDesc,
-						toast_values,
-						toast_isnull,
-						(char *) new_data + new_header_len,
-						new_data_len,
-						&(new_data->t_infomask),
-						has_nulls ? new_data->t_bits : NULL);
-	}
-	else
-		result_tuple = newtup;
-
-	/*
-	 * Free allocated temp values
-	 */
-	if (need_free)
-		for (i = 0; i < numAttrs; i++)
-			if (toast_free[i])
-				pfree(DatumGetPointer(toast_values[i]));
-
-	/*
-	 * Delete external values from the old tuple
-	 */
-	if (need_delold)
-		for (i = 0; i < numAttrs; i++)
-			if (toast_delold[i])
-				toast_delete_datum(rel, toast_oldvalues[i], false);
-
-	return result_tuple;
-}
-
-
-/* ----------
- * toast_flatten_tuple -
- *
- *	"Flatten" a tuple to contain no out-of-line toasted fields.
- *	(This does not eliminate compressed or short-header datums.)
- *
- *	Note: we expect the caller already checked HeapTupleHasExternal(tup),
- *	so there is no need for a short-circuit path.
- * ----------
- */
-HeapTuple
-toast_flatten_tuple(HeapTuple tup, TupleDesc tupleDesc)
-{
-	HeapTuple	new_tuple;
-	int			numAttrs = tupleDesc->natts;
-	int			i;
-	Datum		toast_values[MaxTupleAttributeNumber];
-	bool		toast_isnull[MaxTupleAttributeNumber];
-	bool		toast_free[MaxTupleAttributeNumber];
-
-	/*
-	 * Break down the tuple into fields.
-	 */
-	Assert(numAttrs <= MaxTupleAttributeNumber);
-	heap_deform_tuple(tup, tupleDesc, toast_values, toast_isnull);
-
-	memset(toast_free, 0, numAttrs * sizeof(bool));
-
-	for (i = 0; i < numAttrs; i++)
-	{
-		/*
-		 * Look at non-null varlena attributes
-		 */
-		if (!toast_isnull[i] && TupleDescAttr(tupleDesc, i)->attlen == -1)
-		{
-			struct varlena *new_value;
-
-			new_value = (struct varlena *) DatumGetPointer(toast_values[i]);
-			if (VARATT_IS_EXTERNAL(new_value))
-			{
-				new_value = heap_tuple_fetch_attr(new_value);
-				toast_values[i] = PointerGetDatum(new_value);
-				toast_free[i] = true;
-			}
-		}
-	}
-
-	/*
-	 * Form the reconfigured tuple.
-	 */
-	new_tuple = heap_form_tuple(tupleDesc, toast_values, toast_isnull);
-
-	/*
-	 * Be sure to copy the tuple's identity fields.  We also make a point of
-	 * copying visibility info, just in case anybody looks at those fields in
-	 * a syscache entry.
-	 */
-	new_tuple->t_self = tup->t_self;
-	new_tuple->t_tableOid = tup->t_tableOid;
-
-	new_tuple->t_data->t_choice = tup->t_data->t_choice;
-	new_tuple->t_data->t_ctid = tup->t_data->t_ctid;
-	new_tuple->t_data->t_infomask &= ~HEAP_XACT_MASK;
-	new_tuple->t_data->t_infomask |=
-		tup->t_data->t_infomask & HEAP_XACT_MASK;
-	new_tuple->t_data->t_infomask2 &= ~HEAP2_XACT_MASK;
-	new_tuple->t_data->t_infomask2 |=
-		tup->t_data->t_infomask2 & HEAP2_XACT_MASK;
-
-	/*
-	 * Free allocated temp values
-	 */
-	for (i = 0; i < numAttrs; i++)
-		if (toast_free[i])
-			pfree(DatumGetPointer(toast_values[i]));
-
-	return new_tuple;
-}
-
-
-/* ----------
- * toast_flatten_tuple_to_datum -
- *
- *	"Flatten" a tuple containing out-of-line toasted fields into a Datum.
- *	The result is always palloc'd in the current memory context.
- *
- *	We have a general rule that Datums of container types (rows, arrays,
- *	ranges, etc) must not contain any external TOAST pointers.  Without
- *	this rule, we'd have to look inside each Datum when preparing a tuple
- *	for storage, which would be expensive and would fail to extend cleanly
- *	to new sorts of container types.
- *
- *	However, we don't want to say that tuples represented as HeapTuples
- *	can't contain toasted fields, so instead this routine should be called
- *	when such a HeapTuple is being converted into a Datum.
- *
- *	While we're at it, we decompress any compressed fields too.  This is not
- *	necessary for correctness, but reflects an expectation that compression
- *	will be more effective if applied to the whole tuple not individual
- *	fields.  We are not so concerned about that that we want to deconstruct
- *	and reconstruct tuples just to get rid of compressed fields, however.
- *	So callers typically won't call this unless they see that the tuple has
- *	at least one external field.
- *
- *	On the other hand, in-line short-header varlena fields are left alone.
- *	If we "untoasted" them here, they'd just get changed back to short-header
- *	format anyway within heap_fill_tuple.
- * ----------
- */
-Datum
-toast_flatten_tuple_to_datum(HeapTupleHeader tup,
-							 uint32 tup_len,
-							 TupleDesc tupleDesc)
-{
-	HeapTupleHeader new_data;
-	int32		new_header_len;
-	int32		new_data_len;
-	int32		new_tuple_len;
-	HeapTupleData tmptup;
-	int			numAttrs = tupleDesc->natts;
-	int			i;
-	bool		has_nulls = false;
-	Datum		toast_values[MaxTupleAttributeNumber];
-	bool		toast_isnull[MaxTupleAttributeNumber];
-	bool		toast_free[MaxTupleAttributeNumber];
-
-	/* Build a temporary HeapTuple control structure */
-	tmptup.t_len = tup_len;
-	ItemPointerSetInvalid(&(tmptup.t_self));
-	tmptup.t_tableOid = InvalidOid;
-	tmptup.t_data = tup;
-
-	/*
-	 * Break down the tuple into fields.
-	 */
-	Assert(numAttrs <= MaxTupleAttributeNumber);
-	heap_deform_tuple(&tmptup, tupleDesc, toast_values, toast_isnull);
-
-	memset(toast_free, 0, numAttrs * sizeof(bool));
-
-	for (i = 0; i < numAttrs; i++)
-	{
-		/*
-		 * Look at non-null varlena attributes
-		 */
-		if (toast_isnull[i])
-			has_nulls = true;
-		else if (TupleDescAttr(tupleDesc, i)->attlen == -1)
-		{
-			struct varlena *new_value;
-
-			new_value = (struct varlena *) DatumGetPointer(toast_values[i]);
-			if (VARATT_IS_EXTERNAL(new_value) ||
-				VARATT_IS_COMPRESSED(new_value))
-			{
-				new_value = heap_tuple_untoast_attr(new_value);
-				toast_values[i] = PointerGetDatum(new_value);
-				toast_free[i] = true;
-			}
-		}
-	}
-
-	/*
-	 * Calculate the new size of the tuple.
-	 *
-	 * This should match the reconstruction code in toast_insert_or_update.
-	 */
-	new_header_len = SizeofHeapTupleHeader;
-	if (has_nulls)
-		new_header_len += BITMAPLEN(numAttrs);
-	new_header_len = MAXALIGN(new_header_len);
-	new_data_len = heap_compute_data_size(tupleDesc,
-										  toast_values, toast_isnull);
-	new_tuple_len = new_header_len + new_data_len;
-
-	new_data = (HeapTupleHeader) palloc0(new_tuple_len);
-
-	/*
-	 * Copy the existing tuple header, but adjust natts and t_hoff.
-	 */
-	memcpy(new_data, tup, SizeofHeapTupleHeader);
-	HeapTupleHeaderSetNatts(new_data, numAttrs);
-	new_data->t_hoff = new_header_len;
-
-	/* Set the composite-Datum header fields correctly */
-	HeapTupleHeaderSetDatumLength(new_data, new_tuple_len);
-	HeapTupleHeaderSetTypeId(new_data, tupleDesc->tdtypeid);
-	HeapTupleHeaderSetTypMod(new_data, tupleDesc->tdtypmod);
-
-	/* Copy over the data, and fill the null bitmap if needed */
-	heap_fill_tuple(tupleDesc,
-					toast_values,
-					toast_isnull,
-					(char *) new_data + new_header_len,
-					new_data_len,
-					&(new_data->t_infomask),
-					has_nulls ? new_data->t_bits : NULL);
-
-	/*
-	 * Free allocated temp values
-	 */
-	for (i = 0; i < numAttrs; i++)
-		if (toast_free[i])
-			pfree(DatumGetPointer(toast_values[i]));
-
-	return PointerGetDatum(new_data);
-}
-
-
-/* ----------
- * toast_build_flattened_tuple -
- *
- *	Build a tuple containing no out-of-line toasted fields.
- *	(This does not eliminate compressed or short-header datums.)
- *
- *	This is essentially just like heap_form_tuple, except that it will
- *	expand any external-data pointers beforehand.
- *
- *	It's not very clear whether it would be preferable to decompress
- *	in-line compressed datums while at it.  For now, we don't.
- * ----------
- */
-HeapTuple
-toast_build_flattened_tuple(TupleDesc tupleDesc,
-							Datum *values,
-							bool *isnull)
-{
-	HeapTuple	new_tuple;
-	int			numAttrs = tupleDesc->natts;
-	int			num_to_free;
-	int			i;
-	Datum		new_values[MaxTupleAttributeNumber];
-	Pointer		freeable_values[MaxTupleAttributeNumber];
-
-	/*
-	 * We can pass the caller's isnull array directly to heap_form_tuple, but
-	 * we potentially need to modify the values array.
-	 */
-	Assert(numAttrs <= MaxTupleAttributeNumber);
-	memcpy(new_values, values, numAttrs * sizeof(Datum));
-
-	num_to_free = 0;
-	for (i = 0; i < numAttrs; i++)
-	{
-		/*
-		 * Look at non-null varlena attributes
-		 */
-		if (!isnull[i] && TupleDescAttr(tupleDesc, i)->attlen == -1)
-		{
-			struct varlena *new_value;
-
-			new_value = (struct varlena *) DatumGetPointer(new_values[i]);
-			if (VARATT_IS_EXTERNAL(new_value))
-			{
-				new_value = heap_tuple_fetch_attr(new_value);
-				new_values[i] = PointerGetDatum(new_value);
-				freeable_values[num_to_free++] = (Pointer) new_value;
-			}
-		}
-	}
-
-	/*
-	 * Form the reconfigured tuple.
-	 */
-	new_tuple = heap_form_tuple(tupleDesc, new_values, isnull);
-
-	/*
-	 * Free allocated temp values
-	 */
-	for (i = 0; i < num_to_free; i++)
-		pfree(freeable_values[i]);
-
-	return new_tuple;
-}
-
-
-/* ----------
- * toast_compress_datum -
- *
- *	Create a compressed version of a varlena datum
- *
- *	If we fail (ie, compressed result is actually bigger than original)
- *	then return NULL.  We must not use compressed data if it'd expand
- *	the tuple!
- *
- *	We use VAR{SIZE,DATA}_ANY so we can handle short varlenas here without
- *	copying them.  But we can't handle external or compressed datums.
- * ----------
- */
-Datum
-toast_compress_datum(Datum value)
-{
-	struct varlena *tmp;
-	int32		valsize = VARSIZE_ANY_EXHDR(DatumGetPointer(value));
-	int32		len;
-
-	Assert(!VARATT_IS_EXTERNAL(DatumGetPointer(value)));
-	Assert(!VARATT_IS_COMPRESSED(DatumGetPointer(value)));
-
-	/*
-	 * No point in wasting a palloc cycle if value size is out of the allowed
-	 * range for compression
-	 */
-	if (valsize < PGLZ_strategy_default->min_input_size ||
-		valsize > PGLZ_strategy_default->max_input_size)
-		return PointerGetDatum(NULL);
-
-	tmp = (struct varlena *) palloc(PGLZ_MAX_OUTPUT(valsize) +
-									TOAST_COMPRESS_HDRSZ);
-
-	/*
-	 * We recheck the actual size even if pglz_compress() reports success,
-	 * because it might be satisfied with having saved as little as one byte
-	 * in the compressed data --- which could turn into a net loss once you
-	 * consider header and alignment padding.  Worst case, the compressed
-	 * format might require three padding bytes (plus header, which is
-	 * included in VARSIZE(tmp)), whereas the uncompressed format would take
-	 * only one header byte and no padding if the value is short enough.  So
-	 * we insist on a savings of more than 2 bytes to ensure we have a gain.
-	 */
-	len = pglz_compress(VARDATA_ANY(DatumGetPointer(value)),
-						valsize,
-						TOAST_COMPRESS_RAWDATA(tmp),
-						PGLZ_strategy_default);
-	if (len >= 0 &&
-		len + TOAST_COMPRESS_HDRSZ < valsize - 2)
-	{
-		TOAST_COMPRESS_SET_RAWSIZE(tmp, valsize);
-		SET_VARSIZE_COMPRESSED(tmp, len + TOAST_COMPRESS_HDRSZ);
-		/* successful compression */
-		return PointerGetDatum(tmp);
-	}
-	else
-	{
-		/* incompressible data */
-		pfree(tmp);
-		return PointerGetDatum(NULL);
-	}
-}
-
-
-/* ----------
- * toast_get_valid_index
- *
- *	Get OID of valid index associated to given toast relation. A toast
- *	relation can have only one valid index at the same time.
- */
-Oid
-toast_get_valid_index(Oid toastoid, LOCKMODE lock)
-{
-	int			num_indexes;
-	int			validIndex;
-	Oid			validIndexOid;
-	Relation   *toastidxs;
-	Relation	toastrel;
-
-	/* Open the toast relation */
-	toastrel = table_open(toastoid, lock);
-
-	/* Look for the valid index of the toast relation */
-	validIndex = toast_open_indexes(toastrel,
-									lock,
-									&toastidxs,
-									&num_indexes);
-	validIndexOid = RelationGetRelid(toastidxs[validIndex]);
-
-	/* Close the toast relation and all its indexes */
-	toast_close_indexes(toastidxs, num_indexes, lock);
-	table_close(toastrel, lock);
-
-	return validIndexOid;
-}
-
-
-/* ----------
- * toast_save_datum -
- *
- *	Save one single datum into the secondary relation and return
- *	a Datum reference for it.
- *
- * rel: the main relation we're working with (not the toast rel!)
- * value: datum to be pushed to toast storage
- * oldexternal: if not NULL, toast pointer previously representing the datum
- * options: options to be passed to heap_insert() for toast rows
- * ----------
- */
-static Datum
-toast_save_datum(Relation rel, Datum value,
-				 struct varlena *oldexternal, int options)
-{
-	Relation	toastrel;
-	Relation   *toastidxs;
-	HeapTuple	toasttup;
-	TupleDesc	toasttupDesc;
-	Datum		t_values[3];
-	bool		t_isnull[3];
-	CommandId	mycid = GetCurrentCommandId(true);
-	struct varlena *result;
-	struct varatt_external toast_pointer;
-	union
-	{
-		struct varlena hdr;
-		/* this is to make the union big enough for a chunk: */
-		char		data[TOAST_MAX_CHUNK_SIZE + VARHDRSZ];
-		/* ensure union is aligned well enough: */
-		int32		align_it;
-	}			chunk_data;
-	int32		chunk_size;
-	int32		chunk_seq = 0;
-	char	   *data_p;
-	int32		data_todo;
-	Pointer		dval = DatumGetPointer(value);
-	int			num_indexes;
-	int			validIndex;
-
-	Assert(!VARATT_IS_EXTERNAL(value));
-
-	/*
-	 * Open the toast relation and its indexes.  We can use the index to check
-	 * uniqueness of the OID we assign to the toasted item, even though it has
-	 * additional columns besides OID.
-	 */
-	toastrel = table_open(rel->rd_rel->reltoastrelid, RowExclusiveLock);
-	toasttupDesc = toastrel->rd_att;
-
-	/* Open all the toast indexes and look for the valid one */
-	validIndex = toast_open_indexes(toastrel,
-									RowExclusiveLock,
-									&toastidxs,
-									&num_indexes);
-
-	/*
-	 * Get the data pointer and length, and compute va_rawsize and va_extsize.
-	 *
-	 * va_rawsize is the size of the equivalent fully uncompressed datum, so
-	 * we have to adjust for short headers.
-	 *
-	 * va_extsize is the actual size of the data payload in the toast records.
-	 */
-	if (VARATT_IS_SHORT(dval))
-	{
-		data_p = VARDATA_SHORT(dval);
-		data_todo = VARSIZE_SHORT(dval) - VARHDRSZ_SHORT;
-		toast_pointer.va_rawsize = data_todo + VARHDRSZ;	/* as if not short */
-		toast_pointer.va_extsize = data_todo;
-	}
-	else if (VARATT_IS_COMPRESSED(dval))
-	{
-		data_p = VARDATA(dval);
-		data_todo = VARSIZE(dval) - VARHDRSZ;
-		/* rawsize in a compressed datum is just the size of the payload */
-		toast_pointer.va_rawsize = VARRAWSIZE_4B_C(dval) + VARHDRSZ;
-		toast_pointer.va_extsize = data_todo;
-		/* Assert that the numbers look like it's compressed */
-		Assert(VARATT_EXTERNAL_IS_COMPRESSED(toast_pointer));
-	}
-	else
-	{
-		data_p = VARDATA(dval);
-		data_todo = VARSIZE(dval) - VARHDRSZ;
-		toast_pointer.va_rawsize = VARSIZE(dval);
-		toast_pointer.va_extsize = data_todo;
-	}
-
-	/*
-	 * Insert the correct table OID into the result TOAST pointer.
-	 *
-	 * Normally this is the actual OID of the target toast table, but during
-	 * table-rewriting operations such as CLUSTER, we have to insert the OID
-	 * of the table's real permanent toast table instead.  rd_toastoid is set
-	 * if we have to substitute such an OID.
-	 */
-	if (OidIsValid(rel->rd_toastoid))
-		toast_pointer.va_toastrelid = rel->rd_toastoid;
-	else
-		toast_pointer.va_toastrelid = RelationGetRelid(toastrel);
-
-	/*
-	 * Choose an OID to use as the value ID for this toast value.
-	 *
-	 * Normally we just choose an unused OID within the toast table.  But
-	 * during table-rewriting operations where we are preserving an existing
-	 * toast table OID, we want to preserve toast value OIDs too.  So, if
-	 * rd_toastoid is set and we had a prior external value from that same
-	 * toast table, re-use its value ID.  If we didn't have a prior external
-	 * value (which is a corner case, but possible if the table's attstorage
-	 * options have been changed), we have to pick a value ID that doesn't
-	 * conflict with either new or existing toast value OIDs.
-	 */
-	if (!OidIsValid(rel->rd_toastoid))
-	{
-		/* normal case: just choose an unused OID */
-		toast_pointer.va_valueid =
-			GetNewOidWithIndex(toastrel,
-							   RelationGetRelid(toastidxs[validIndex]),
-							   (AttrNumber) 1);
-	}
-	else
-	{
-		/* rewrite case: check to see if value was in old toast table */
-		toast_pointer.va_valueid = InvalidOid;
-		if (oldexternal != NULL)
-		{
-			struct varatt_external old_toast_pointer;
-
-			Assert(VARATT_IS_EXTERNAL_ONDISK(oldexternal));
-			/* Must copy to access aligned fields */
-			VARATT_EXTERNAL_GET_POINTER(old_toast_pointer, oldexternal);
-			if (old_toast_pointer.va_toastrelid == rel->rd_toastoid)
-			{
-				/* This value came from the old toast table; reuse its OID */
-				toast_pointer.va_valueid = old_toast_pointer.va_valueid;
-
-				/*
-				 * There is a corner case here: the table rewrite might have
-				 * to copy both live and recently-dead versions of a row, and
-				 * those versions could easily reference the same toast value.
-				 * When we copy the second or later version of such a row,
-				 * reusing the OID will mean we select an OID that's already
-				 * in the new toast table.  Check for that, and if so, just
-				 * fall through without writing the data again.
-				 *
-				 * While annoying and ugly-looking, this is a good thing
-				 * because it ensures that we wind up with only one copy of
-				 * the toast value when there is only one copy in the old
-				 * toast table.  Before we detected this case, we'd have made
-				 * multiple copies, wasting space; and what's worse, the
-				 * copies belonging to already-deleted heap tuples would not
-				 * be reclaimed by VACUUM.
-				 */
-				if (toastrel_valueid_exists(toastrel,
-											toast_pointer.va_valueid))
-				{
-					/* Match, so short-circuit the data storage loop below */
-					data_todo = 0;
-				}
-			}
-		}
-		if (toast_pointer.va_valueid == InvalidOid)
-		{
-			/*
-			 * new value; must choose an OID that doesn't conflict in either
-			 * old or new toast table
-			 */
-			do
-			{
-				toast_pointer.va_valueid =
-					GetNewOidWithIndex(toastrel,
-									   RelationGetRelid(toastidxs[validIndex]),
-									   (AttrNumber) 1);
-			} while (toastid_valueid_exists(rel->rd_toastoid,
-											toast_pointer.va_valueid));
-		}
-	}
-
-	/*
-	 * Initialize constant parts of the tuple data
-	 */
-	t_values[0] = ObjectIdGetDatum(toast_pointer.va_valueid);
-	t_values[2] = PointerGetDatum(&chunk_data);
-	t_isnull[0] = false;
-	t_isnull[1] = false;
-	t_isnull[2] = false;
-
-	/*
-	 * Split up the item into chunks
-	 */
-	while (data_todo > 0)
-	{
-		int			i;
-
-		CHECK_FOR_INTERRUPTS();
-
-		/*
-		 * Calculate the size of this chunk
-		 */
-		chunk_size = Min(TOAST_MAX_CHUNK_SIZE, data_todo);
-
-		/*
-		 * Build a tuple and store it
-		 */
-		t_values[1] = Int32GetDatum(chunk_seq++);
-		SET_VARSIZE(&chunk_data, chunk_size + VARHDRSZ);
-		memcpy(VARDATA(&chunk_data), data_p, chunk_size);
-		toasttup = heap_form_tuple(toasttupDesc, t_values, t_isnull);
-
-		heap_insert(toastrel, toasttup, mycid, options, NULL);
-
-		/*
-		 * Create the index entry.  We cheat a little here by not using
-		 * FormIndexDatum: this relies on the knowledge that the index columns
-		 * are the same as the initial columns of the table for all the
-		 * indexes.  We also cheat by not providing an IndexInfo: this is okay
-		 * for now because btree doesn't need one, but we might have to be
-		 * more honest someday.
-		 *
-		 * Note also that there had better not be any user-created index on
-		 * the TOAST table, since we don't bother to update anything else.
-		 */
-		for (i = 0; i < num_indexes; i++)
-		{
-			/* Only index relations marked as ready can be updated */
-			if (toastidxs[i]->rd_index->indisready)
-				index_insert(toastidxs[i], t_values, t_isnull,
-							 &(toasttup->t_self),
-							 toastrel,
-							 toastidxs[i]->rd_index->indisunique ?
-							 UNIQUE_CHECK_YES : UNIQUE_CHECK_NO,
-							 NULL);
-		}
-
-		/*
-		 * Free memory
-		 */
-		heap_freetuple(toasttup);
-
-		/*
-		 * Move on to next chunk
-		 */
-		data_todo -= chunk_size;
-		data_p += chunk_size;
-	}
-
-	/*
-	 * Done - close toast relation and its indexes
-	 */
-	toast_close_indexes(toastidxs, num_indexes, RowExclusiveLock);
-	table_close(toastrel, RowExclusiveLock);
-
-	/*
-	 * Create the TOAST pointer value that we'll return
-	 */
-	result = (struct varlena *) palloc(TOAST_POINTER_SIZE);
-	SET_VARTAG_EXTERNAL(result, VARTAG_ONDISK);
-	memcpy(VARDATA_EXTERNAL(result), &toast_pointer, sizeof(toast_pointer));
-
-	return PointerGetDatum(result);
-}
-
-
-/* ----------
- * toast_delete_datum -
- *
- *	Delete a single external stored value.
- * ----------
- */
-static void
-toast_delete_datum(Relation rel, Datum value, bool is_speculative)
-{
-	struct varlena *attr = (struct varlena *) DatumGetPointer(value);
-	struct varatt_external toast_pointer;
-	Relation	toastrel;
-	Relation   *toastidxs;
-	ScanKeyData toastkey;
-	SysScanDesc toastscan;
-	HeapTuple	toasttup;
-	int			num_indexes;
-	int			validIndex;
-	SnapshotData SnapshotToast;
-
-	if (!VARATT_IS_EXTERNAL_ONDISK(attr))
-		return;
-
-	/* Must copy to access aligned fields */
-	VARATT_EXTERNAL_GET_POINTER(toast_pointer, attr);
-
-	/*
-	 * Open the toast relation and its indexes
-	 */
-	toastrel = table_open(toast_pointer.va_toastrelid, RowExclusiveLock);
-
-	/* Fetch valid relation used for process */
-	validIndex = toast_open_indexes(toastrel,
-									RowExclusiveLock,
-									&toastidxs,
-									&num_indexes);
-
-	/*
-	 * Setup a scan key to find chunks with matching va_valueid
-	 */
-	ScanKeyInit(&toastkey,
-				(AttrNumber) 1,
-				BTEqualStrategyNumber, F_OIDEQ,
-				ObjectIdGetDatum(toast_pointer.va_valueid));
-
-	/*
-	 * Find all the chunks.  (We don't actually care whether we see them in
-	 * sequence or not, but since we've already locked the index we might as
-	 * well use systable_beginscan_ordered.)
-	 */
-	init_toast_snapshot(&SnapshotToast);
-	toastscan = systable_beginscan_ordered(toastrel, toastidxs[validIndex],
-										   &SnapshotToast, 1, &toastkey);
-	while ((toasttup = systable_getnext_ordered(toastscan, ForwardScanDirection)) != NULL)
-	{
-		/*
-		 * Have a chunk, delete it
-		 */
-		if (is_speculative)
-			heap_abort_speculative(toastrel, &toasttup->t_self);
-		else
-			simple_heap_delete(toastrel, &toasttup->t_self);
-	}
-
-	/*
-	 * End scan and close relations
-	 */
-	systable_endscan_ordered(toastscan);
-	toast_close_indexes(toastidxs, num_indexes, RowExclusiveLock);
-	table_close(toastrel, RowExclusiveLock);
-}
-
-
-/* ----------
- * toastrel_valueid_exists -
- *
- *	Test whether a toast value with the given ID exists in the toast relation.
- *	For safety, we consider a value to exist if there are either live or dead
- *	toast rows with that ID; see notes for GetNewOidWithIndex().
- * ----------
- */
-static bool
-toastrel_valueid_exists(Relation toastrel, Oid valueid)
-{
-	bool		result = false;
-	ScanKeyData toastkey;
-	SysScanDesc toastscan;
-	int			num_indexes;
-	int			validIndex;
-	Relation   *toastidxs;
-
-	/* Fetch a valid index relation */
-	validIndex = toast_open_indexes(toastrel,
-									RowExclusiveLock,
-									&toastidxs,
-									&num_indexes);
-
-	/*
-	 * Setup a scan key to find chunks with matching va_valueid
-	 */
-	ScanKeyInit(&toastkey,
-				(AttrNumber) 1,
-				BTEqualStrategyNumber, F_OIDEQ,
-				ObjectIdGetDatum(valueid));
-
-	/*
-	 * Is there any such chunk?
-	 */
-	toastscan = systable_beginscan(toastrel,
-								   RelationGetRelid(toastidxs[validIndex]),
-								   true, SnapshotAny, 1, &toastkey);
-
-	if (systable_getnext(toastscan) != NULL)
-		result = true;
-
-	systable_endscan(toastscan);
-
-	/* Clean up */
-	toast_close_indexes(toastidxs, num_indexes, RowExclusiveLock);
-
-	return result;
-}
-
-/* ----------
- * toastid_valueid_exists -
- *
- *	As above, but work from toast rel's OID not an open relation
- * ----------
- */
-static bool
-toastid_valueid_exists(Oid toastrelid, Oid valueid)
-{
-	bool		result;
-	Relation	toastrel;
-
-	toastrel = table_open(toastrelid, AccessShareLock);
-
-	result = toastrel_valueid_exists(toastrel, valueid);
-
-	table_close(toastrel, AccessShareLock);
-
-	return result;
-}
-
-
-/* ----------
- * toast_fetch_datum -
- *
- *	Reconstruct an in memory Datum from the chunks saved
- *	in the toast relation
- * ----------
- */
-static struct varlena *
-toast_fetch_datum(struct varlena *attr)
-{
-	Relation	toastrel;
-	Relation   *toastidxs;
-	ScanKeyData toastkey;
-	SysScanDesc toastscan;
-	HeapTuple	ttup;
-	TupleDesc	toasttupDesc;
-	struct varlena *result;
-	struct varatt_external toast_pointer;
-	int32		ressize;
-	int32		residx,
-				nextidx;
-	int32		numchunks;
-	Pointer		chunk;
-	bool		isnull;
-	char	   *chunkdata;
-	int32		chunksize;
-	int			num_indexes;
-	int			validIndex;
-	SnapshotData SnapshotToast;
-
-	if (!VARATT_IS_EXTERNAL_ONDISK(attr))
-		elog(ERROR, "toast_fetch_datum shouldn't be called for non-ondisk datums");
-
-	/* Must copy to access aligned fields */
-	VARATT_EXTERNAL_GET_POINTER(toast_pointer, attr);
-
-	ressize = toast_pointer.va_extsize;
-	numchunks = ((ressize - 1) / TOAST_MAX_CHUNK_SIZE) + 1;
-
-	result = (struct varlena *) palloc(ressize + VARHDRSZ);
-
-	if (VARATT_EXTERNAL_IS_COMPRESSED(toast_pointer))
-		SET_VARSIZE_COMPRESSED(result, ressize + VARHDRSZ);
-	else
-		SET_VARSIZE(result, ressize + VARHDRSZ);
-
-	/*
-	 * Open the toast relation and its indexes
-	 */
-	toastrel = table_open(toast_pointer.va_toastrelid, AccessShareLock);
-	toasttupDesc = toastrel->rd_att;
-
-	/* Look for the valid index of the toast relation */
-	validIndex = toast_open_indexes(toastrel,
-									AccessShareLock,
-									&toastidxs,
-									&num_indexes);
-
-	/*
-	 * Setup a scan key to fetch from the index by va_valueid
-	 */
-	ScanKeyInit(&toastkey,
-				(AttrNumber) 1,
-				BTEqualStrategyNumber, F_OIDEQ,
-				ObjectIdGetDatum(toast_pointer.va_valueid));
-
-	/*
-	 * Read the chunks by index
-	 *
-	 * Note that because the index is actually on (valueid, chunkidx) we will
-	 * see the chunks in chunkidx order, even though we didn't explicitly ask
-	 * for it.
-	 */
-	nextidx = 0;
-
-	init_toast_snapshot(&SnapshotToast);
-	toastscan = systable_beginscan_ordered(toastrel, toastidxs[validIndex],
-										   &SnapshotToast, 1, &toastkey);
-	while ((ttup = systable_getnext_ordered(toastscan, ForwardScanDirection)) != NULL)
-	{
-		/*
-		 * Have a chunk, extract the sequence number and the data
-		 */
-		residx = DatumGetInt32(fastgetattr(ttup, 2, toasttupDesc, &isnull));
-		Assert(!isnull);
-		chunk = DatumGetPointer(fastgetattr(ttup, 3, toasttupDesc, &isnull));
-		Assert(!isnull);
-		if (!VARATT_IS_EXTENDED(chunk))
-		{
-			chunksize = VARSIZE(chunk) - VARHDRSZ;
-			chunkdata = VARDATA(chunk);
-		}
-		else if (VARATT_IS_SHORT(chunk))
-		{
-			/* could happen due to heap_form_tuple doing its thing */
-			chunksize = VARSIZE_SHORT(chunk) - VARHDRSZ_SHORT;
-			chunkdata = VARDATA_SHORT(chunk);
-		}
-		else
-		{
-			/* should never happen */
-			elog(ERROR, "found toasted toast chunk for toast value %u in %s",
-				 toast_pointer.va_valueid,
-				 RelationGetRelationName(toastrel));
-			chunksize = 0;		/* keep compiler quiet */
-			chunkdata = NULL;
-		}
-
-		/*
-		 * Some checks on the data we've found
-		 */
-		if (residx != nextidx)
-			elog(ERROR, "unexpected chunk number %d (expected %d) for toast value %u in %s",
-				 residx, nextidx,
-				 toast_pointer.va_valueid,
-				 RelationGetRelationName(toastrel));
-		if (residx < numchunks - 1)
-		{
-			if (chunksize != TOAST_MAX_CHUNK_SIZE)
-				elog(ERROR, "unexpected chunk size %d (expected %d) in chunk %d of %d for toast value %u in %s",
-					 chunksize, (int) TOAST_MAX_CHUNK_SIZE,
-					 residx, numchunks,
-					 toast_pointer.va_valueid,
-					 RelationGetRelationName(toastrel));
-		}
-		else if (residx == numchunks - 1)
-		{
-			if ((residx * TOAST_MAX_CHUNK_SIZE + chunksize) != ressize)
-				elog(ERROR, "unexpected chunk size %d (expected %d) in final chunk %d for toast value %u in %s",
-					 chunksize,
-					 (int) (ressize - residx * TOAST_MAX_CHUNK_SIZE),
-					 residx,
-					 toast_pointer.va_valueid,
-					 RelationGetRelationName(toastrel));
-		}
-		else
-			elog(ERROR, "unexpected chunk number %d (out of range %d..%d) for toast value %u in %s",
-				 residx,
-				 0, numchunks - 1,
-				 toast_pointer.va_valueid,
-				 RelationGetRelationName(toastrel));
-
-		/*
-		 * Copy the data into proper place in our result
-		 */
-		memcpy(VARDATA(result) + residx * TOAST_MAX_CHUNK_SIZE,
-			   chunkdata,
-			   chunksize);
-
-		nextidx++;
-	}
-
-	/*
-	 * Final checks that we successfully fetched the datum
-	 */
-	if (nextidx != numchunks)
-		elog(ERROR, "missing chunk number %d for toast value %u in %s",
-			 nextidx,
-			 toast_pointer.va_valueid,
-			 RelationGetRelationName(toastrel));
-
-	/*
-	 * End scan and close relations
-	 */
-	systable_endscan_ordered(toastscan);
-	toast_close_indexes(toastidxs, num_indexes, AccessShareLock);
-	table_close(toastrel, AccessShareLock);
-
-	return result;
-}
-
-/* ----------
- * toast_fetch_datum_slice -
- *
- *	Reconstruct a segment of a Datum from the chunks saved
- *	in the toast relation
- *
- *	Note that this function only supports non-compressed external datums.
- * ----------
- */
-static struct varlena *
-toast_fetch_datum_slice(struct varlena *attr, int32 sliceoffset, int32 length)
-{
-	Relation	toastrel;
-	Relation   *toastidxs;
-	ScanKeyData toastkey[3];
-	int			nscankeys;
-	SysScanDesc toastscan;
-	HeapTuple	ttup;
-	TupleDesc	toasttupDesc;
-	struct varlena *result;
-	struct varatt_external toast_pointer;
-	int32		attrsize;
-	int32		residx;
-	int32		nextidx;
-	int			numchunks;
-	int			startchunk;
-	int			endchunk;
-	int32		startoffset;
-	int32		endoffset;
-	int			totalchunks;
-	Pointer		chunk;
-	bool		isnull;
-	char	   *chunkdata;
-	int32		chunksize;
-	int32		chcpystrt;
-	int32		chcpyend;
-	int			num_indexes;
-	int			validIndex;
-	SnapshotData SnapshotToast;
-
-	if (!VARATT_IS_EXTERNAL_ONDISK(attr))
-		elog(ERROR, "toast_fetch_datum_slice shouldn't be called for non-ondisk datums");
-
-	/* Must copy to access aligned fields */
-	VARATT_EXTERNAL_GET_POINTER(toast_pointer, attr);
-
-	/*
-	 * It's nonsense to fetch slices of a compressed datum -- this isn't lo_*
-	 * we can't return a compressed datum which is meaningful to toast later
-	 */
-	Assert(!VARATT_EXTERNAL_IS_COMPRESSED(toast_pointer));
-
-	attrsize = toast_pointer.va_extsize;
-	totalchunks = ((attrsize - 1) / TOAST_MAX_CHUNK_SIZE) + 1;
-
-	if (sliceoffset >= attrsize)
-	{
-		sliceoffset = 0;
-		length = 0;
-	}
-
-	if (((sliceoffset + length) > attrsize) || length < 0)
-		length = attrsize - sliceoffset;
-
-	result = (struct varlena *) palloc(length + VARHDRSZ);
-
-	SET_VARSIZE(result, length + VARHDRSZ);
-
-	if (length == 0)
-		return result;			/* Can save a lot of work at this point! */
-
-	startchunk = sliceoffset / TOAST_MAX_CHUNK_SIZE;
-	endchunk = (sliceoffset + length - 1) / TOAST_MAX_CHUNK_SIZE;
-	numchunks = (endchunk - startchunk) + 1;
-
-	startoffset = sliceoffset % TOAST_MAX_CHUNK_SIZE;
-	endoffset = (sliceoffset + length - 1) % TOAST_MAX_CHUNK_SIZE;
-
-	/*
-	 * Open the toast relation and its indexes
-	 */
-	toastrel = table_open(toast_pointer.va_toastrelid, AccessShareLock);
-	toasttupDesc = toastrel->rd_att;
-
-	/* Look for the valid index of toast relation */
-	validIndex = toast_open_indexes(toastrel,
-									AccessShareLock,
-									&toastidxs,
-									&num_indexes);
-
-	/*
-	 * Setup a scan key to fetch from the index. This is either two keys or
-	 * three depending on the number of chunks.
-	 */
-	ScanKeyInit(&toastkey[0],
-				(AttrNumber) 1,
-				BTEqualStrategyNumber, F_OIDEQ,
-				ObjectIdGetDatum(toast_pointer.va_valueid));
-
-	/*
-	 * Use equality condition for one chunk, a range condition otherwise:
-	 */
-	if (numchunks == 1)
-	{
-		ScanKeyInit(&toastkey[1],
-					(AttrNumber) 2,
-					BTEqualStrategyNumber, F_INT4EQ,
-					Int32GetDatum(startchunk));
-		nscankeys = 2;
-	}
-	else
-	{
-		ScanKeyInit(&toastkey[1],
-					(AttrNumber) 2,
-					BTGreaterEqualStrategyNumber, F_INT4GE,
-					Int32GetDatum(startchunk));
-		ScanKeyInit(&toastkey[2],
-					(AttrNumber) 2,
-					BTLessEqualStrategyNumber, F_INT4LE,
-					Int32GetDatum(endchunk));
-		nscankeys = 3;
-	}
-
-	/*
-	 * Read the chunks by index
-	 *
-	 * The index is on (valueid, chunkidx) so they will come in order
-	 */
-	init_toast_snapshot(&SnapshotToast);
-	nextidx = startchunk;
-	toastscan = systable_beginscan_ordered(toastrel, toastidxs[validIndex],
-										   &SnapshotToast, nscankeys, toastkey);
-	while ((ttup = systable_getnext_ordered(toastscan, ForwardScanDirection)) != NULL)
-	{
-		/*
-		 * Have a chunk, extract the sequence number and the data
-		 */
-		residx = DatumGetInt32(fastgetattr(ttup, 2, toasttupDesc, &isnull));
-		Assert(!isnull);
-		chunk = DatumGetPointer(fastgetattr(ttup, 3, toasttupDesc, &isnull));
-		Assert(!isnull);
-		if (!VARATT_IS_EXTENDED(chunk))
-		{
-			chunksize = VARSIZE(chunk) - VARHDRSZ;
-			chunkdata = VARDATA(chunk);
-		}
-		else if (VARATT_IS_SHORT(chunk))
-		{
-			/* could happen due to heap_form_tuple doing its thing */
-			chunksize = VARSIZE_SHORT(chunk) - VARHDRSZ_SHORT;
-			chunkdata = VARDATA_SHORT(chunk);
-		}
-		else
-		{
-			/* should never happen */
-			elog(ERROR, "found toasted toast chunk for toast value %u in %s",
-				 toast_pointer.va_valueid,
-				 RelationGetRelationName(toastrel));
-			chunksize = 0;		/* keep compiler quiet */
-			chunkdata = NULL;
-		}
-
-		/*
-		 * Some checks on the data we've found
-		 */
-		if ((residx != nextidx) || (residx > endchunk) || (residx < startchunk))
-			elog(ERROR, "unexpected chunk number %d (expected %d) for toast value %u in %s",
-				 residx, nextidx,
-				 toast_pointer.va_valueid,
-				 RelationGetRelationName(toastrel));
-		if (residx < totalchunks - 1)
-		{
-			if (chunksize != TOAST_MAX_CHUNK_SIZE)
-				elog(ERROR, "unexpected chunk size %d (expected %d) in chunk %d of %d for toast value %u in %s when fetching slice",
-					 chunksize, (int) TOAST_MAX_CHUNK_SIZE,
-					 residx, totalchunks,
-					 toast_pointer.va_valueid,
-					 RelationGetRelationName(toastrel));
-		}
-		else if (residx == totalchunks - 1)
-		{
-			if ((residx * TOAST_MAX_CHUNK_SIZE + chunksize) != attrsize)
-				elog(ERROR, "unexpected chunk size %d (expected %d) in final chunk %d for toast value %u in %s when fetching slice",
-					 chunksize,
-					 (int) (attrsize - residx * TOAST_MAX_CHUNK_SIZE),
-					 residx,
-					 toast_pointer.va_valueid,
-					 RelationGetRelationName(toastrel));
-		}
-		else
-			elog(ERROR, "unexpected chunk number %d (out of range %d..%d) for toast value %u in %s",
-				 residx,
-				 0, totalchunks - 1,
-				 toast_pointer.va_valueid,
-				 RelationGetRelationName(toastrel));
-
-		/*
-		 * Copy the data into proper place in our result
-		 */
-		chcpystrt = 0;
-		chcpyend = chunksize - 1;
-		if (residx == startchunk)
-			chcpystrt = startoffset;
-		if (residx == endchunk)
-			chcpyend = endoffset;
-
-		memcpy(VARDATA(result) +
-			   (residx * TOAST_MAX_CHUNK_SIZE - sliceoffset) + chcpystrt,
-			   chunkdata + chcpystrt,
-			   (chcpyend - chcpystrt) + 1);
-
-		nextidx++;
-	}
-
-	/*
-	 * Final checks that we successfully fetched the datum
-	 */
-	if (nextidx != (endchunk + 1))
-		elog(ERROR, "missing chunk number %d for toast value %u in %s",
-			 nextidx,
-			 toast_pointer.va_valueid,
-			 RelationGetRelationName(toastrel));
-
-	/*
-	 * End scan and close relations
-	 */
-	systable_endscan_ordered(toastscan);
-	toast_close_indexes(toastidxs, num_indexes, AccessShareLock);
-	table_close(toastrel, AccessShareLock);
-
-	return result;
-}
-
-/* ----------
- * toast_decompress_datum -
- *
- * Decompress a compressed version of a varlena datum
- */
-static struct varlena *
-toast_decompress_datum(struct varlena *attr)
-{
-	struct varlena *result;
-
-	Assert(VARATT_IS_COMPRESSED(attr));
-
-	result = (struct varlena *)
-		palloc(TOAST_COMPRESS_RAWSIZE(attr) + VARHDRSZ);
-	SET_VARSIZE(result, TOAST_COMPRESS_RAWSIZE(attr) + VARHDRSZ);
-
-	if (pglz_decompress(TOAST_COMPRESS_RAWDATA(attr),
-						VARSIZE(attr) - TOAST_COMPRESS_HDRSZ,
-						VARDATA(result),
-						TOAST_COMPRESS_RAWSIZE(attr), true) < 0)
-		elog(ERROR, "compressed data is corrupted");
-
-	return result;
-}
-
-
-/* ----------
- * toast_decompress_datum_slice -
- *
- * Decompress the front of a compressed version of a varlena datum.
- * offset handling happens in heap_tuple_untoast_attr_slice.
- * Here we just decompress a slice from the front.
- */
-static struct varlena *
-toast_decompress_datum_slice(struct varlena *attr, int32 slicelength)
-{
-	struct varlena *result;
-	int32		rawsize;
-
-	Assert(VARATT_IS_COMPRESSED(attr));
-
-	result = (struct varlena *) palloc(slicelength + VARHDRSZ);
-
-	rawsize = pglz_decompress(TOAST_COMPRESS_RAWDATA(attr),
-							  VARSIZE(attr) - TOAST_COMPRESS_HDRSZ,
-							  VARDATA(result),
-							  slicelength, false);
-	if (rawsize < 0)
-		elog(ERROR, "compressed data is corrupted");
-
-	SET_VARSIZE(result, rawsize + VARHDRSZ);
-	return result;
-}
-
-
-/* ----------
- * toast_open_indexes
- *
- *	Get an array of the indexes associated to the given toast relation
- *	and return as well the position of the valid index used by the toast
- *	relation in this array. It is the responsibility of the caller of this
- *	function to close the indexes as well as free them.
- */
-static int
-toast_open_indexes(Relation toastrel,
-				   LOCKMODE lock,
-				   Relation **toastidxs,
-				   int *num_indexes)
-{
-	int			i = 0;
-	int			res = 0;
-	bool		found = false;
-	List	   *indexlist;
-	ListCell   *lc;
-
-	/* Get index list of the toast relation */
-	indexlist = RelationGetIndexList(toastrel);
-	Assert(indexlist != NIL);
-
-	*num_indexes = list_length(indexlist);
-
-	/* Open all the index relations */
-	*toastidxs = (Relation *) palloc(*num_indexes * sizeof(Relation));
-	foreach(lc, indexlist)
-		(*toastidxs)[i++] = index_open(lfirst_oid(lc), lock);
-
-	/* Fetch the first valid index in list */
-	for (i = 0; i < *num_indexes; i++)
-	{
-		Relation	toastidx = (*toastidxs)[i];
-
-		if (toastidx->rd_index->indisvalid)
-		{
-			res = i;
-			found = true;
-			break;
-		}
-	}
-
-	/*
-	 * Free index list, not necessary anymore as relations are opened and a
-	 * valid index has been found.
-	 */
-	list_free(indexlist);
-
-	/*
-	 * The toast relation should have one valid index, so something is going
-	 * wrong if there is nothing.
-	 */
-	if (!found)
-		elog(ERROR, "no valid index found for toast relation with Oid %u",
-			 RelationGetRelid(toastrel));
-
-	return res;
-}
-
-/* ----------
- * toast_close_indexes
- *
- *	Close an array of indexes for a toast relation and free it. This should
- *	be called for a set of indexes opened previously with toast_open_indexes.
- */
-static void
-toast_close_indexes(Relation *toastidxs, int num_indexes, LOCKMODE lock)
-{
-	int			i;
-
-	/* Close relations and clean up things */
-	for (i = 0; i < num_indexes; i++)
-		index_close(toastidxs[i], lock);
-	pfree(toastidxs);
-}
-
-/* ----------
- * init_toast_snapshot
- *
- *	Initialize an appropriate TOAST snapshot.  We must use an MVCC snapshot
- *	to initialize the TOAST snapshot; since we don't know which one to use,
- *	just use the oldest one.  This is safe: at worst, we will get a "snapshot
- *	too old" error that might have been avoided otherwise.
- */
-static void
-init_toast_snapshot(Snapshot toast_snapshot)
-{
-	Snapshot	snapshot = GetOldestSnapshot();
-
-	if (snapshot == NULL)
-		elog(ERROR, "no known snapshots");
-
-	InitToastSnapshot(*toast_snapshot, snapshot->lsn, snapshot->whenTaken);
-}
diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c
index e08320e829..07ade64c8b 100644
--- a/src/backend/access/transam/xlog.c
+++ b/src/backend/access/transam/xlog.c
@@ -24,12 +24,12 @@
 
 #include "access/clog.h"
 #include "access/commit_ts.h"
+#include "access/heaptoast.h"
 #include "access/multixact.h"
 #include "access/rewriteheap.h"
 #include "access/subtrans.h"
 #include "access/timeline.h"
 #include "access/transam.h"
-#include "access/tuptoaster.h"
 #include "access/twophase.h"
 #include "access/xact.h"
 #include "access/xlog_internal.h"
diff --git a/src/backend/commands/analyze.c b/src/backend/commands/analyze.c
index 6cb545c126..e3aa626738 100644
--- a/src/backend/commands/analyze.c
+++ b/src/backend/commands/analyze.c
@@ -16,6 +16,7 @@
 
 #include <math.h>
 
+#include "access/detoast.h"
 #include "access/genam.h"
 #include "access/multixact.h"
 #include "access/relation.h"
@@ -24,7 +25,6 @@
 #include "access/tableam.h"
 #include "access/transam.h"
 #include "access/tupconvert.h"
-#include "access/tuptoaster.h"
 #include "access/visibilitymap.h"
 #include "access/xact.h"
 #include "catalog/catalog.h"
diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c
index ebaec4f8dd..7b383499e9 100644
--- a/src/backend/commands/cluster.c
+++ b/src/backend/commands/cluster.c
@@ -23,7 +23,7 @@
 #include "access/relscan.h"
 #include "access/tableam.h"
 #include "access/transam.h"
-#include "access/tuptoaster.h"
+#include "access/toast_internals.h"
 #include "access/xact.h"
 #include "access/xlog.h"
 #include "catalog/pg_am.h"
diff --git a/src/backend/executor/execExprInterp.c b/src/backend/executor/execExprInterp.c
index 66a67c72b2..cfd3aa1fb8 100644
--- a/src/backend/executor/execExprInterp.c
+++ b/src/backend/executor/execExprInterp.c
@@ -56,7 +56,7 @@
  */
 #include "postgres.h"
 
-#include "access/tuptoaster.h"
+#include "access/heaptoast.h"
 #include "catalog/pg_type.h"
 #include "commands/sequence.h"
 #include "executor/execExpr.h"
diff --git a/src/backend/executor/execTuples.c b/src/backend/executor/execTuples.c
index a5cb7bba0f..7f2ba08b7e 100644
--- a/src/backend/executor/execTuples.c
+++ b/src/backend/executor/execTuples.c
@@ -57,9 +57,9 @@
  */
 #include "postgres.h"
 
+#include "access/heaptoast.h"
 #include "access/htup_details.h"
 #include "access/tupdesc_details.h"
-#include "access/tuptoaster.h"
 #include "funcapi.h"
 #include "catalog/pg_type.h"
 #include "nodes/nodeFuncs.h"
diff --git a/src/backend/executor/tstoreReceiver.c b/src/backend/executor/tstoreReceiver.c
index cf79feb6bd..c0c81c82da 100644
--- a/src/backend/executor/tstoreReceiver.c
+++ b/src/backend/executor/tstoreReceiver.c
@@ -20,7 +20,7 @@
 
 #include "postgres.h"
 
-#include "access/tuptoaster.h"
+#include "access/detoast.h"
 #include "executor/tstoreReceiver.h"
 
 
diff --git a/src/backend/replication/logical/reorderbuffer.c b/src/backend/replication/logical/reorderbuffer.c
index e7c32f2a13..717c2f4267 100644
--- a/src/backend/replication/logical/reorderbuffer.c
+++ b/src/backend/replication/logical/reorderbuffer.c
@@ -56,10 +56,10 @@
 #include <unistd.h>
 #include <sys/stat.h>
 
+#include "access/detoast.h"
 #include "access/heapam.h"
 #include "access/rewriteheap.h"
 #include "access/transam.h"
-#include "access/tuptoaster.h"
 #include "access/xact.h"
 #include "access/xlog_internal.h"
 #include "catalog/catalog.h"
diff --git a/src/backend/statistics/extended_stats.c b/src/backend/statistics/extended_stats.c
index ab187915c1..e43f913346 100644
--- a/src/backend/statistics/extended_stats.c
+++ b/src/backend/statistics/extended_stats.c
@@ -16,10 +16,10 @@
  */
 #include "postgres.h"
 
+#include "access/detoast.h"
 #include "access/genam.h"
 #include "access/htup_details.h"
 #include "access/table.h"
-#include "access/tuptoaster.h"
 #include "catalog/indexing.h"
 #include "catalog/pg_collation.h"
 #include "catalog/pg_statistic_ext.h"
diff --git a/src/backend/storage/large_object/inv_api.c b/src/backend/storage/large_object/inv_api.c
index a477cb9200..e591236343 100644
--- a/src/backend/storage/large_object/inv_api.c
+++ b/src/backend/storage/large_object/inv_api.c
@@ -32,10 +32,11 @@
 
 #include <limits.h>
 
+#include "access/detoast.h"
 #include "access/genam.h"
+#include "access/htup_details.h"
 #include "access/sysattr.h"
 #include "access/table.h"
-#include "access/tuptoaster.h"
 #include "access/xact.h"
 #include "catalog/dependency.h"
 #include "catalog/indexing.h"
diff --git a/src/backend/utils/adt/array_typanalyze.c b/src/backend/utils/adt/array_typanalyze.c
index eafb94b697..54f5849629 100644
--- a/src/backend/utils/adt/array_typanalyze.c
+++ b/src/backend/utils/adt/array_typanalyze.c
@@ -14,7 +14,7 @@
  */
 #include "postgres.h"
 
-#include "access/tuptoaster.h"
+#include "access/detoast.h"
 #include "commands/vacuum.h"
 #include "utils/array.h"
 #include "utils/builtins.h"
diff --git a/src/backend/utils/adt/datum.c b/src/backend/utils/adt/datum.c
index 81ea5a48e5..1568658bc9 100644
--- a/src/backend/utils/adt/datum.c
+++ b/src/backend/utils/adt/datum.c
@@ -42,7 +42,7 @@
 
 #include "postgres.h"
 
-#include "access/tuptoaster.h"
+#include "access/detoast.h"
 #include "fmgr.h"
 #include "utils/datum.h"
 #include "utils/expandeddatum.h"
diff --git a/src/backend/utils/adt/expandedrecord.c b/src/backend/utils/adt/expandedrecord.c
index 166c863026..369432d53c 100644
--- a/src/backend/utils/adt/expandedrecord.c
+++ b/src/backend/utils/adt/expandedrecord.c
@@ -18,8 +18,9 @@
  */
 #include "postgres.h"
 
+#include "access/detoast.h"
+#include "access/heaptoast.h"
 #include "access/htup_details.h"
-#include "access/tuptoaster.h"
 #include "catalog/heap.h"
 #include "catalog/pg_type.h"
 #include "utils/builtins.h"
diff --git a/src/backend/utils/adt/rowtypes.c b/src/backend/utils/adt/rowtypes.c
index aa7ec8735c..ea3e40a369 100644
--- a/src/backend/utils/adt/rowtypes.c
+++ b/src/backend/utils/adt/rowtypes.c
@@ -16,8 +16,8 @@
 
 #include <ctype.h>
 
+#include "access/detoast.h"
 #include "access/htup_details.h"
-#include "access/tuptoaster.h"
 #include "catalog/pg_type.h"
 #include "funcapi.h"
 #include "libpq/pqformat.h"
diff --git a/src/backend/utils/adt/tsgistidx.c b/src/backend/utils/adt/tsgistidx.c
index 4f256260fd..6ff71a49b8 100644
--- a/src/backend/utils/adt/tsgistidx.c
+++ b/src/backend/utils/adt/tsgistidx.c
@@ -15,7 +15,7 @@
 #include "postgres.h"
 
 #include "access/gist.h"
-#include "access/tuptoaster.h"
+#include "access/heaptoast.h"
 #include "port/pg_bitutils.h"
 #include "tsearch/ts_utils.h"
 #include "utils/builtins.h"
diff --git a/src/backend/utils/adt/varchar.c b/src/backend/utils/adt/varchar.c
index 332dc860c4..9d94399323 100644
--- a/src/backend/utils/adt/varchar.c
+++ b/src/backend/utils/adt/varchar.c
@@ -14,7 +14,7 @@
  */
 #include "postgres.h"
 
-#include "access/tuptoaster.h"
+#include "access/detoast.h"
 #include "catalog/pg_collation.h"
 #include "catalog/pg_type.h"
 #include "libpq/pqformat.h"
diff --git a/src/backend/utils/adt/varlena.c b/src/backend/utils/adt/varlena.c
index 0864838867..3685223922 100644
--- a/src/backend/utils/adt/varlena.c
+++ b/src/backend/utils/adt/varlena.c
@@ -17,7 +17,7 @@
 #include <ctype.h>
 #include <limits.h>
 
-#include "access/tuptoaster.h"
+#include "access/detoast.h"
 #include "catalog/pg_collation.h"
 #include "catalog/pg_type.h"
 #include "common/int.h"
diff --git a/src/backend/utils/cache/catcache.c b/src/backend/utils/cache/catcache.c
index 00def27881..c3e7d94aa5 100644
--- a/src/backend/utils/cache/catcache.c
+++ b/src/backend/utils/cache/catcache.c
@@ -15,10 +15,10 @@
 #include "postgres.h"
 
 #include "access/genam.h"
+#include "access/heaptoast.h"
 #include "access/relscan.h"
 #include "access/sysattr.h"
 #include "access/table.h"
-#include "access/tuptoaster.h"
 #include "access/valid.h"
 #include "access/xact.h"
 #include "catalog/pg_collation.h"
diff --git a/src/backend/utils/fmgr/fmgr.c b/src/backend/utils/fmgr/fmgr.c
index 9b640ccd40..74e36e62d3 100644
--- a/src/backend/utils/fmgr/fmgr.c
+++ b/src/backend/utils/fmgr/fmgr.c
@@ -15,7 +15,7 @@
 
 #include "postgres.h"
 
-#include "access/tuptoaster.h"
+#include "access/detoast.h"
 #include "catalog/pg_language.h"
 #include "catalog/pg_proc.h"
 #include "executor/functions.h"
diff --git a/src/bin/pg_resetwal/pg_resetwal.c b/src/bin/pg_resetwal/pg_resetwal.c
index 2734f87318..43b41a9b17 100644
--- a/src/bin/pg_resetwal/pg_resetwal.c
+++ b/src/bin/pg_resetwal/pg_resetwal.c
@@ -45,7 +45,7 @@
 #include <unistd.h>
 
 #include "access/transam.h"
-#include "access/tuptoaster.h"
+#include "access/heaptoast.h"
 #include "access/multixact.h"
 #include "access/xlog.h"
 #include "access/xlog_internal.h"
diff --git a/src/include/access/detoast.h b/src/include/access/detoast.h
new file mode 100644
index 0000000000..582af147ea
--- /dev/null
+++ b/src/include/access/detoast.h
@@ -0,0 +1,92 @@
+/*-------------------------------------------------------------------------
+ *
+ * detoast.h
+ *	  Access to compressed and external varlena values.
+ *
+ * Copyright (c) 2000-2019, PostgreSQL Global Development Group
+ *
+ * src/include/access/detoast.h
+ *
+ *-------------------------------------------------------------------------
+ */
+#ifndef DETOAST_H 
+#define DETOAST_H
+
+/*
+ * Testing whether an externally-stored value is compressed now requires
+ * comparing extsize (the actual length of the external data) to rawsize
+ * (the original uncompressed datum's size).  The latter includes VARHDRSZ
+ * overhead, the former doesn't.  We never use compression unless it actually
+ * saves space, so we expect either equality or less-than.
+ */
+#define VARATT_EXTERNAL_IS_COMPRESSED(toast_pointer) \
+	((toast_pointer).va_extsize < (toast_pointer).va_rawsize - VARHDRSZ)
+
+/*
+ * Macro to fetch the possibly-unaligned contents of an EXTERNAL datum
+ * into a local "struct varatt_external" toast pointer.  This should be
+ * just a memcpy, but some versions of gcc seem to produce broken code
+ * that assumes the datum contents are aligned.  Introducing an explicit
+ * intermediate "varattrib_1b_e *" variable seems to fix it.
+ */
+#define VARATT_EXTERNAL_GET_POINTER(toast_pointer, attr) \
+do { \
+	varattrib_1b_e *attre = (varattrib_1b_e *) (attr); \
+	Assert(VARATT_IS_EXTERNAL(attre)); \
+	Assert(VARSIZE_EXTERNAL(attre) == sizeof(toast_pointer) + VARHDRSZ_EXTERNAL); \
+	memcpy(&(toast_pointer), VARDATA_EXTERNAL(attre), sizeof(toast_pointer)); \
+} while (0)
+
+/* Size of an EXTERNAL datum that contains a standard TOAST pointer */
+#define TOAST_POINTER_SIZE (VARHDRSZ_EXTERNAL + sizeof(varatt_external))
+
+/* Size of an EXTERNAL datum that contains an indirection pointer */
+#define INDIRECT_POINTER_SIZE (VARHDRSZ_EXTERNAL + sizeof(varatt_indirect))
+
+/* ----------
+ * heap_tuple_fetch_attr() -
+ *
+ *		Fetches an external stored attribute from the toast
+ *		relation. Does NOT decompress it, if stored external
+ *		in compressed format.
+ * ----------
+ */
+extern struct varlena *heap_tuple_fetch_attr(struct varlena *attr);
+
+/* ----------
+ * heap_tuple_untoast_attr() -
+ *
+ *		Fully detoasts one attribute, fetching and/or decompressing
+ *		it as needed.
+ * ----------
+ */
+extern struct varlena *heap_tuple_untoast_attr(struct varlena *attr);
+
+/* ----------
+ * heap_tuple_untoast_attr_slice() -
+ *
+ *		Fetches only the specified portion of an attribute.
+ *		(Handles all cases for attribute storage)
+ * ----------
+ */
+extern struct varlena *heap_tuple_untoast_attr_slice(struct varlena *attr,
+							  int32 sliceoffset,
+							  int32 slicelength);
+
+/* ----------
+ * toast_raw_datum_size -
+ *
+ *	Return the raw (detoasted) size of a varlena datum
+ * ----------
+ */
+extern Size toast_raw_datum_size(Datum value);
+
+/* ----------
+ * toast_datum_size -
+ *
+ *	Return the storage size of a varlena datum
+ * ----------
+ */
+extern Size toast_datum_size(Datum value);
+
+#endif							/* DETOAST_H */
diff --git a/src/include/access/tuptoaster.h b/src/include/access/heaptoast.h
similarity index 57%
rename from src/include/access/tuptoaster.h
rename to src/include/access/heaptoast.h
index f0aea2496b..bf02d2c600 100644
--- a/src/include/access/tuptoaster.h
+++ b/src/include/access/heaptoast.h
@@ -1,29 +1,22 @@
 /*-------------------------------------------------------------------------
  *
- * tuptoaster.h
- *	  POSTGRES definitions for external and compressed storage
+ * heaptoast.h
+ *	  Heap-specific definitions for external and compressed storage
  *	  of variable size attributes.
  *
  * Copyright (c) 2000-2019, PostgreSQL Global Development Group
  *
- * src/include/access/tuptoaster.h
+ * src/include/access/heaptoast.h
  *
  *-------------------------------------------------------------------------
  */
-#ifndef TUPTOASTER_H
-#define TUPTOASTER_H
+#ifndef HEAPTOAST_H
+#define HEAPTOAST_H
 
 #include "access/htup_details.h"
 #include "storage/lockdefs.h"
 #include "utils/relcache.h"
 
-/*
- * This enables de-toasting of index entries.  Needed until VACUUM is
- * smart enough to rebuild indexes from scratch.
- */
-#define TOAST_INDEX_HACK
-
-
 /*
  * Find the maximum size of a tuple if there are to be N tuples per page.
  */
@@ -95,37 +88,6 @@
 	 sizeof(int32) -									\
 	 VARHDRSZ)
 
-/* Size of an EXTERNAL datum that contains a standard TOAST pointer */
-#define TOAST_POINTER_SIZE (VARHDRSZ_EXTERNAL + sizeof(varatt_external))
-
-/* Size of an EXTERNAL datum that contains an indirection pointer */
-#define INDIRECT_POINTER_SIZE (VARHDRSZ_EXTERNAL + sizeof(varatt_indirect))
-
-/*
- * Testing whether an externally-stored value is compressed now requires
- * comparing extsize (the actual length of the external data) to rawsize
- * (the original uncompressed datum's size).  The latter includes VARHDRSZ
- * overhead, the former doesn't.  We never use compression unless it actually
- * saves space, so we expect either equality or less-than.
- */
-#define VARATT_EXTERNAL_IS_COMPRESSED(toast_pointer) \
-	((toast_pointer).va_extsize < (toast_pointer).va_rawsize - VARHDRSZ)
-
-/*
- * Macro to fetch the possibly-unaligned contents of an EXTERNAL datum
- * into a local "struct varatt_external" toast pointer.  This should be
- * just a memcpy, but some versions of gcc seem to produce broken code
- * that assumes the datum contents are aligned.  Introducing an explicit
- * intermediate "varattrib_1b_e *" variable seems to fix it.
- */
-#define VARATT_EXTERNAL_GET_POINTER(toast_pointer, attr) \
-do { \
-	varattrib_1b_e *attre = (varattrib_1b_e *) (attr); \
-	Assert(VARATT_IS_EXTERNAL(attre)); \
-	Assert(VARSIZE_EXTERNAL(attre) == sizeof(toast_pointer) + VARHDRSZ_EXTERNAL); \
-	memcpy(&(toast_pointer), VARDATA_EXTERNAL(attre), sizeof(toast_pointer)); \
-} while (0)
-
 /* ----------
  * toast_insert_or_update -
  *
@@ -144,36 +106,6 @@ extern HeapTuple toast_insert_or_update(Relation rel,
  */
 extern void toast_delete(Relation rel, HeapTuple oldtup, bool is_speculative);
 
-/* ----------
- * heap_tuple_fetch_attr() -
- *
- *		Fetches an external stored attribute from the toast
- *		relation. Does NOT decompress it, if stored external
- *		in compressed format.
- * ----------
- */
-extern struct varlena *heap_tuple_fetch_attr(struct varlena *attr);
-
-/* ----------
- * heap_tuple_untoast_attr() -
- *
- *		Fully detoasts one attribute, fetching and/or decompressing
- *		it as needed.
- * ----------
- */
-extern struct varlena *heap_tuple_untoast_attr(struct varlena *attr);
-
-/* ----------
- * heap_tuple_untoast_attr_slice() -
- *
- *		Fetches only the specified portion of an attribute.
- *		(Handles all cases for attribute storage)
- * ----------
- */
-extern struct varlena *heap_tuple_untoast_attr_slice(struct varlena *attr,
-													 int32 sliceoffset,
-													 int32 slicelength);
-
 /* ----------
  * toast_flatten_tuple -
  *
@@ -204,36 +136,4 @@ extern HeapTuple toast_build_flattened_tuple(TupleDesc tupleDesc,
 											 Datum *values,
 											 bool *isnull);
 
-/* ----------
- * toast_compress_datum -
- *
- *	Create a compressed version of a varlena datum, if possible
- * ----------
- */
-extern Datum toast_compress_datum(Datum value);
-
-/* ----------
- * toast_raw_datum_size -
- *
- *	Return the raw (detoasted) size of a varlena datum
- * ----------
- */
-extern Size toast_raw_datum_size(Datum value);
-
-/* ----------
- * toast_datum_size -
- *
- *	Return the storage size of a varlena datum
- * ----------
- */
-extern Size toast_datum_size(Datum value);
-
-/* ----------
- * toast_get_valid_index -
- *
- *	Return OID of valid index associated to a toast relation
- * ----------
- */
-extern Oid	toast_get_valid_index(Oid toastoid, LOCKMODE lock);
-
-#endif							/* TUPTOASTER_H */
+#endif							/* HEAPTOAST_H */
diff --git a/src/include/access/toast_internals.h b/src/include/access/toast_internals.h
new file mode 100644
index 0000000000..8ac367fb9f
--- /dev/null
+++ b/src/include/access/toast_internals.h
@@ -0,0 +1,54 @@
+/*-------------------------------------------------------------------------
+ *
+ * toast_internals.h
+ *	  Internal definitions for the TOAST system.
+ *
+ * Copyright (c) 2000-2019, PostgreSQL Global Development Group
+ *
+ * src/include/access/toast_internals.h
+ *
+ *-------------------------------------------------------------------------
+ */
+#ifndef TOAST_INTERNALS_H
+#define TOAST_INTERNALS_H
+
+#include "storage/lockdefs.h"
+#include "utils/relcache.h"
+#include "utils/snapshot.h"
+
+/*
+ *	The information at the start of the compressed toast data.
+ */
+typedef struct toast_compress_header
+{
+	int32		vl_len_;		/* varlena header (do not touch directly!) */
+	int32		rawsize;
+} toast_compress_header;
+
+/*
+ * Utilities for manipulation of header information for compressed
+ * toast entries.
+ */
+#define TOAST_COMPRESS_HDRSZ		((int32) sizeof(toast_compress_header))
+#define TOAST_COMPRESS_RAWSIZE(ptr) (((toast_compress_header *) (ptr))->rawsize)
+#define TOAST_COMPRESS_RAWDATA(ptr) \
+	(((char *) (ptr)) + TOAST_COMPRESS_HDRSZ)
+#define TOAST_COMPRESS_SET_RAWSIZE(ptr, len) \
+	(((toast_compress_header *) (ptr))->rawsize = (len))
+
+extern Datum toast_compress_datum(Datum value);
+extern Oid	toast_get_valid_index(Oid toastoid, LOCKMODE lock);
+
+extern void toast_delete_datum(Relation rel, Datum value, bool is_speculative);
+extern Datum toast_save_datum(Relation rel, Datum value,
+				 struct varlena *oldexternal, int options);
+
+extern int toast_open_indexes(Relation toastrel,
+				   LOCKMODE lock,
+				   Relation **toastidxs,
+				   int *num_indexes);
+extern void toast_close_indexes(Relation *toastidxs, int num_indexes,
+					LOCKMODE lock);
+extern void init_toast_snapshot(Snapshot toast_snapshot);
+
+#endif							/* TOAST_INTERNALS_H */
diff --git a/src/pl/plpgsql/src/pl_exec.c b/src/pl/plpgsql/src/pl_exec.c
index 90a2257894..0f50e57dd6 100644
--- a/src/pl/plpgsql/src/pl_exec.c
+++ b/src/pl/plpgsql/src/pl_exec.c
@@ -17,10 +17,10 @@
 
 #include <ctype.h>
 
+#include "access/detoast.h"
 #include "access/htup_details.h"
 #include "access/transam.h"
 #include "access/tupconvert.h"
-#include "access/tuptoaster.h"
 #include "catalog/pg_proc.h"
 #include "catalog/pg_type.h"
 #include "commands/defrem.h"
diff --git a/src/test/regress/regress.c b/src/test/regress/regress.c
index 7f03b7e857..826556eb29 100644
--- a/src/test/regress/regress.c
+++ b/src/test/regress/regress.c
@@ -19,9 +19,9 @@
 #include <math.h>
 #include <signal.h>
 
+#include "access/detoast.h"
 #include "access/htup_details.h"
 #include "access/transam.h"
-#include "access/tuptoaster.h"
 #include "access/xact.h"
 #include "catalog/pg_operator.h"
 #include "catalog/pg_type.h"
-- 
2.17.2 (Apple Git-113)

From 7f3212a1c57942d8112481cd56c36e83e27e6059 Mon Sep 17 00:00:00 2001
From: Robert Haas <rhaas@postgresql.org>
Date: Tue, 14 May 2019 17:11:28 -0400
Subject: [PATCH v3 2/3] Create an API for inserting and deleting rows in TOAST
 tables.

This moves much of the non-heap-specific logic from toast_delete and
toast_insert_or_update into a helper functions accessible via a new
header, toast_helper.h.  Using the functions in this module, a table
AM can implement creation and deletion of TOAST table rows with
much less code duplication than was possible heretofore.  Some
table AMs won't want to use the TOAST logic at all, but for those
that do this will make that easier.
---
 src/backend/access/heap/heaptoast.c     | 400 +++---------------------
 src/backend/access/table/Makefile       |   2 +-
 src/backend/access/table/toast_helper.c | 331 ++++++++++++++++++++
 src/include/access/toast_helper.h       | 114 +++++++
 4 files changed, 490 insertions(+), 357 deletions(-)
 create mode 100644 src/backend/access/table/toast_helper.c
 create mode 100644 src/include/access/toast_helper.h

diff --git a/src/backend/access/heap/heaptoast.c b/src/backend/access/heap/heaptoast.c
index 5d105e3517..3a2118e1d8 100644
--- a/src/backend/access/heap/heaptoast.c
+++ b/src/backend/access/heap/heaptoast.c
@@ -27,6 +27,7 @@
 #include "access/detoast.h"
 #include "access/heapam.h"
 #include "access/heaptoast.h"
+#include "access/toast_helper.h"
 #include "access/toast_internals.h"
 
 
@@ -40,8 +41,6 @@ void
 toast_delete(Relation rel, HeapTuple oldtup, bool is_speculative)
 {
 	TupleDesc	tupleDesc;
-	int			numAttrs;
-	int			i;
 	Datum		toast_values[MaxHeapAttributeNumber];
 	bool		toast_isnull[MaxHeapAttributeNumber];
 
@@ -64,27 +63,12 @@ toast_delete(Relation rel, HeapTuple oldtup, bool is_speculative)
 	 * least one varlena column, by the way.)
 	 */
 	tupleDesc = rel->rd_att;
-	numAttrs = tupleDesc->natts;
 
-	Assert(numAttrs <= MaxHeapAttributeNumber);
+	Assert(tupleDesc->natts <= MaxHeapAttributeNumber);
 	heap_deform_tuple(oldtup, tupleDesc, toast_values, toast_isnull);
 
-	/*
-	 * Check for external stored attributes and delete them from the secondary
-	 * relation.
-	 */
-	for (i = 0; i < numAttrs; i++)
-	{
-		if (TupleDescAttr(tupleDesc, i)->attlen == -1)
-		{
-			Datum		value = toast_values[i];
-
-			if (toast_isnull[i])
-				continue;
-			else if (VARATT_IS_EXTERNAL_ONDISK(PointerGetDatum(value)))
-				toast_delete_datum(rel, value, is_speculative);
-		}
-	}
+	/* Do the real work. */
+	toast_delete_external(rel, toast_values, toast_isnull, is_speculative);
 }
 
 
@@ -113,25 +97,16 @@ toast_insert_or_update(Relation rel, HeapTuple newtup, HeapTuple oldtup,
 	HeapTuple	result_tuple;
 	TupleDesc	tupleDesc;
 	int			numAttrs;
-	int			i;
-
-	bool		need_change = false;
-	bool		need_free = false;
-	bool		need_delold = false;
-	bool		has_nulls = false;
 
 	Size		maxDataLen;
 	Size		hoff;
 
-	char		toast_action[MaxHeapAttributeNumber];
 	bool		toast_isnull[MaxHeapAttributeNumber];
 	bool		toast_oldisnull[MaxHeapAttributeNumber];
 	Datum		toast_values[MaxHeapAttributeNumber];
 	Datum		toast_oldvalues[MaxHeapAttributeNumber];
-	struct varlena *toast_oldexternal[MaxHeapAttributeNumber];
-	int32		toast_sizes[MaxHeapAttributeNumber];
-	bool		toast_free[MaxHeapAttributeNumber];
-	bool		toast_delold[MaxHeapAttributeNumber];
+	ToastAttrInfo	toast_attr[MaxHeapAttributeNumber];
+	ToastTupleContext	ttc;
 
 	/*
 	 * Ignore the INSERT_SPECULATIVE option. Speculative insertions/super
@@ -160,129 +135,24 @@ toast_insert_or_update(Relation rel, HeapTuple newtup, HeapTuple oldtup,
 		heap_deform_tuple(oldtup, tupleDesc, toast_oldvalues, toast_oldisnull);
 
 	/* ----------
-	 * Then collect information about the values given
-	 *
-	 * NOTE: toast_action[i] can have these values:
-	 *		' '		default handling
-	 *		'p'		already processed --- don't touch it
-	 *		'x'		incompressible, but OK to move off
-	 *
-	 * NOTE: toast_sizes[i] is only made valid for varlena attributes with
-	 *		toast_action[i] different from 'p'.
+	 * Prepare for toasting
 	 * ----------
 	 */
-	memset(toast_action, ' ', numAttrs * sizeof(char));
-	memset(toast_oldexternal, 0, numAttrs * sizeof(struct varlena *));
-	memset(toast_free, 0, numAttrs * sizeof(bool));
-	memset(toast_delold, 0, numAttrs * sizeof(bool));
-
-	for (i = 0; i < numAttrs; i++)
+	ttc.ttc_rel = rel;
+	ttc.ttc_values = toast_values;
+	ttc.ttc_isnull = toast_isnull;
+	if (oldtup == NULL)
 	{
-		Form_pg_attribute att = TupleDescAttr(tupleDesc, i);
-		struct varlena *old_value;
-		struct varlena *new_value;
-
-		if (oldtup != NULL)
-		{
-			/*
-			 * For UPDATE get the old and new values of this attribute
-			 */
-			old_value = (struct varlena *) DatumGetPointer(toast_oldvalues[i]);
-			new_value = (struct varlena *) DatumGetPointer(toast_values[i]);
-
-			/*
-			 * If the old value is stored on disk, check if it has changed so
-			 * we have to delete it later.
-			 */
-			if (att->attlen == -1 && !toast_oldisnull[i] &&
-				VARATT_IS_EXTERNAL_ONDISK(old_value))
-			{
-				if (toast_isnull[i] || !VARATT_IS_EXTERNAL_ONDISK(new_value) ||
-					memcmp((char *) old_value, (char *) new_value,
-						   VARSIZE_EXTERNAL(old_value)) != 0)
-				{
-					/*
-					 * The old external stored value isn't needed any more
-					 * after the update
-					 */
-					toast_delold[i] = true;
-					need_delold = true;
-				}
-				else
-				{
-					/*
-					 * This attribute isn't changed by this update so we reuse
-					 * the original reference to the old value in the new
-					 * tuple.
-					 */
-					toast_action[i] = 'p';
-					continue;
-				}
-			}
-		}
-		else
-		{
-			/*
-			 * For INSERT simply get the new value
-			 */
-			new_value = (struct varlena *) DatumGetPointer(toast_values[i]);
-		}
-
-		/*
-		 * Handle NULL attributes
-		 */
-		if (toast_isnull[i])
-		{
-			toast_action[i] = 'p';
-			has_nulls = true;
-			continue;
-		}
-
-		/*
-		 * Now look at varlena attributes
-		 */
-		if (att->attlen == -1)
-		{
-			/*
-			 * If the table's attribute says PLAIN always, force it so.
-			 */
-			if (att->attstorage == 'p')
-				toast_action[i] = 'p';
-
-			/*
-			 * We took care of UPDATE above, so any external value we find
-			 * still in the tuple must be someone else's that we cannot reuse
-			 * (this includes the case of an out-of-line in-memory datum).
-			 * Fetch it back (without decompression, unless we are forcing
-			 * PLAIN storage).  If necessary, we'll push it out as a new
-			 * external value below.
-			 */
-			if (VARATT_IS_EXTERNAL(new_value))
-			{
-				toast_oldexternal[i] = new_value;
-				if (att->attstorage == 'p')
-					new_value = heap_tuple_untoast_attr(new_value);
-				else
-					new_value = heap_tuple_fetch_attr(new_value);
-				toast_values[i] = PointerGetDatum(new_value);
-				toast_free[i] = true;
-				need_change = true;
-				need_free = true;
-			}
-
-			/*
-			 * Remember the size of this attribute
-			 */
-			toast_sizes[i] = VARSIZE_ANY(new_value);
-		}
-		else
-		{
-			/*
-			 * Not a varlena attribute, plain storage always
-			 */
-			toast_action[i] = 'p';
-		}
+		ttc.ttc_oldvalues = NULL;
+		ttc.ttc_oldisnull = NULL;
 	}
+	else
+	{
+		ttc.ttc_oldvalues = toast_oldvalues;
+		ttc.ttc_oldisnull = toast_oldisnull;
+	}
+	ttc.ttc_attr = toast_attr;
+	toast_tuple_init(&ttc);
 
 	/* ----------
 	 * Compress and/or save external until data fits into target length
@@ -297,7 +167,7 @@ toast_insert_or_update(Relation rel, HeapTuple newtup, HeapTuple oldtup,
 
 	/* compute header overhead --- this should match heap_form_tuple() */
 	hoff = SizeofHeapTupleHeader;
-	if (has_nulls)
+	if ((ttc.ttc_flags & TOAST_HAS_NULLS) != 0)
 		hoff += BITMAPLEN(numAttrs);
 	hoff = MAXALIGN(hoff);
 	/* now convert to a limit on the tuple data size */
@@ -310,66 +180,21 @@ toast_insert_or_update(Relation rel, HeapTuple newtup, HeapTuple oldtup,
 	while (heap_compute_data_size(tupleDesc,
 								  toast_values, toast_isnull) > maxDataLen)
 	{
-		int			biggest_attno = -1;
-		int32		biggest_size = MAXALIGN(TOAST_POINTER_SIZE);
-		Datum		old_value;
-		Datum		new_value;
-
-		/*
-		 * Search for the biggest yet unprocessed internal attribute
-		 */
-		for (i = 0; i < numAttrs; i++)
-		{
-			Form_pg_attribute att = TupleDescAttr(tupleDesc, i);
-
-			if (toast_action[i] != ' ')
-				continue;
-			if (VARATT_IS_EXTERNAL(DatumGetPointer(toast_values[i])))
-				continue;		/* can't happen, toast_action would be 'p' */
-			if (VARATT_IS_COMPRESSED(DatumGetPointer(toast_values[i])))
-				continue;
-			if (att->attstorage != 'x' && att->attstorage != 'e')
-				continue;
-			if (toast_sizes[i] > biggest_size)
-			{
-				biggest_attno = i;
-				biggest_size = toast_sizes[i];
-			}
-		}
+		int			biggest_attno;
 
+		biggest_attno = toast_tuple_find_biggest_attribute(&ttc, true, false);
 		if (biggest_attno < 0)
 			break;
 
 		/*
 		 * Attempt to compress it inline, if it has attstorage 'x'
 		 */
-		i = biggest_attno;
-		if (TupleDescAttr(tupleDesc, i)->attstorage == 'x')
-		{
-			old_value = toast_values[i];
-			new_value = toast_compress_datum(old_value);
-
-			if (DatumGetPointer(new_value) != NULL)
-			{
-				/* successful compression */
-				if (toast_free[i])
-					pfree(DatumGetPointer(old_value));
-				toast_values[i] = new_value;
-				toast_free[i] = true;
-				toast_sizes[i] = VARSIZE(DatumGetPointer(toast_values[i]));
-				need_change = true;
-				need_free = true;
-			}
-			else
-			{
-				/* incompressible, ignore on subsequent compression passes */
-				toast_action[i] = 'x';
-			}
-		}
+		if (TupleDescAttr(tupleDesc, biggest_attno)->attstorage == 'x')
+			toast_tuple_try_compression(&ttc, biggest_attno);
 		else
 		{
 			/* has attstorage 'e', ignore on subsequent compression passes */
-			toast_action[i] = 'x';
+			toast_attr[biggest_attno].tai_colflags |= TOASTCOL_INCOMPRESSIBLE;
 		}
 
 		/*
@@ -380,72 +205,26 @@ toast_insert_or_update(Relation rel, HeapTuple newtup, HeapTuple oldtup,
 		 *
 		 * XXX maybe the threshold should be less than maxDataLen?
 		 */
-		if (toast_sizes[i] > maxDataLen &&
+		if (toast_attr[biggest_attno].tai_size > maxDataLen &&
 			rel->rd_rel->reltoastrelid != InvalidOid)
-		{
-			old_value = toast_values[i];
-			toast_action[i] = 'p';
-			toast_values[i] = toast_save_datum(rel, toast_values[i],
-											   toast_oldexternal[i], options);
-			if (toast_free[i])
-				pfree(DatumGetPointer(old_value));
-			toast_free[i] = true;
-			need_change = true;
-			need_free = true;
-		}
+			toast_tuple_externalize(&ttc, biggest_attno, options);
 	}
 
 	/*
 	 * Second we look for attributes of attstorage 'x' or 'e' that are still
-	 * inline.  But skip this if there's no toast table to push them to.
+	 * inline, and make them external.  But skip this if there's no toast table
+	 * to push them to.
 	 */
 	while (heap_compute_data_size(tupleDesc,
 								  toast_values, toast_isnull) > maxDataLen &&
 		   rel->rd_rel->reltoastrelid != InvalidOid)
 	{
-		int			biggest_attno = -1;
-		int32		biggest_size = MAXALIGN(TOAST_POINTER_SIZE);
-		Datum		old_value;
-
-		/*------
-		 * Search for the biggest yet inlined attribute with
-		 * attstorage equals 'x' or 'e'
-		 *------
-		 */
-		for (i = 0; i < numAttrs; i++)
-		{
-			Form_pg_attribute att = TupleDescAttr(tupleDesc, i);
-
-			if (toast_action[i] == 'p')
-				continue;
-			if (VARATT_IS_EXTERNAL(DatumGetPointer(toast_values[i])))
-				continue;		/* can't happen, toast_action would be 'p' */
-			if (att->attstorage != 'x' && att->attstorage != 'e')
-				continue;
-			if (toast_sizes[i] > biggest_size)
-			{
-				biggest_attno = i;
-				biggest_size = toast_sizes[i];
-			}
-		}
+		int			biggest_attno;
 
+		biggest_attno = toast_tuple_find_biggest_attribute(&ttc, false, false);
 		if (biggest_attno < 0)
 			break;
-
-		/*
-		 * Store this external
-		 */
-		i = biggest_attno;
-		old_value = toast_values[i];
-		toast_action[i] = 'p';
-		toast_values[i] = toast_save_datum(rel, toast_values[i],
-										   toast_oldexternal[i], options);
-		if (toast_free[i])
-			pfree(DatumGetPointer(old_value));
-		toast_free[i] = true;
-
-		need_change = true;
-		need_free = true;
+		toast_tuple_externalize(&ttc, biggest_attno, options);
 	}
 
 	/*
@@ -455,57 +234,13 @@ toast_insert_or_update(Relation rel, HeapTuple newtup, HeapTuple oldtup,
 	while (heap_compute_data_size(tupleDesc,
 								  toast_values, toast_isnull) > maxDataLen)
 	{
-		int			biggest_attno = -1;
-		int32		biggest_size = MAXALIGN(TOAST_POINTER_SIZE);
-		Datum		old_value;
-		Datum		new_value;
-
-		/*
-		 * Search for the biggest yet uncompressed internal attribute
-		 */
-		for (i = 0; i < numAttrs; i++)
-		{
-			if (toast_action[i] != ' ')
-				continue;
-			if (VARATT_IS_EXTERNAL(DatumGetPointer(toast_values[i])))
-				continue;		/* can't happen, toast_action would be 'p' */
-			if (VARATT_IS_COMPRESSED(DatumGetPointer(toast_values[i])))
-				continue;
-			if (TupleDescAttr(tupleDesc, i)->attstorage != 'm')
-				continue;
-			if (toast_sizes[i] > biggest_size)
-			{
-				biggest_attno = i;
-				biggest_size = toast_sizes[i];
-			}
-		}
+		int			biggest_attno;
 
+		biggest_attno = toast_tuple_find_biggest_attribute(&ttc, true, true);
 		if (biggest_attno < 0)
 			break;
 
-		/*
-		 * Attempt to compress it inline
-		 */
-		i = biggest_attno;
-		old_value = toast_values[i];
-		new_value = toast_compress_datum(old_value);
-
-		if (DatumGetPointer(new_value) != NULL)
-		{
-			/* successful compression */
-			if (toast_free[i])
-				pfree(DatumGetPointer(old_value));
-			toast_values[i] = new_value;
-			toast_free[i] = true;
-			toast_sizes[i] = VARSIZE(DatumGetPointer(toast_values[i]));
-			need_change = true;
-			need_free = true;
-		}
-		else
-		{
-			/* incompressible, ignore on subsequent compression passes */
-			toast_action[i] = 'x';
-		}
+		toast_tuple_try_compression(&ttc, biggest_attno);
 	}
 
 	/*
@@ -519,54 +254,20 @@ toast_insert_or_update(Relation rel, HeapTuple newtup, HeapTuple oldtup,
 								  toast_values, toast_isnull) > maxDataLen &&
 		   rel->rd_rel->reltoastrelid != InvalidOid)
 	{
-		int			biggest_attno = -1;
-		int32		biggest_size = MAXALIGN(TOAST_POINTER_SIZE);
-		Datum		old_value;
-
-		/*--------
-		 * Search for the biggest yet inlined attribute with
-		 * attstorage = 'm'
-		 *--------
-		 */
-		for (i = 0; i < numAttrs; i++)
-		{
-			if (toast_action[i] == 'p')
-				continue;
-			if (VARATT_IS_EXTERNAL(DatumGetPointer(toast_values[i])))
-				continue;		/* can't happen, toast_action would be 'p' */
-			if (TupleDescAttr(tupleDesc, i)->attstorage != 'm')
-				continue;
-			if (toast_sizes[i] > biggest_size)
-			{
-				biggest_attno = i;
-				biggest_size = toast_sizes[i];
-			}
-		}
+		int			biggest_attno;
 
+		biggest_attno = toast_tuple_find_biggest_attribute(&ttc, false, true);
 		if (biggest_attno < 0)
 			break;
 
-		/*
-		 * Store this external
-		 */
-		i = biggest_attno;
-		old_value = toast_values[i];
-		toast_action[i] = 'p';
-		toast_values[i] = toast_save_datum(rel, toast_values[i],
-										   toast_oldexternal[i], options);
-		if (toast_free[i])
-			pfree(DatumGetPointer(old_value));
-		toast_free[i] = true;
-
-		need_change = true;
-		need_free = true;
+		toast_tuple_externalize(&ttc, biggest_attno, options);
 	}
 
 	/*
 	 * In the case we toasted any values, we need to build a new heap tuple
 	 * with the changed values.
 	 */
-	if (need_change)
+	if ((ttc.ttc_flags & TOAST_NEEDS_CHANGE) != 0)
 	{
 		HeapTupleHeader olddata = newtup->t_data;
 		HeapTupleHeader new_data;
@@ -585,7 +286,7 @@ toast_insert_or_update(Relation rel, HeapTuple newtup, HeapTuple oldtup,
 		 * whether there needs to be one at all.
 		 */
 		new_header_len = SizeofHeapTupleHeader;
-		if (has_nulls)
+		if ((ttc.ttc_flags & TOAST_HAS_NULLS) != 0)
 			new_header_len += BITMAPLEN(numAttrs);
 		new_header_len = MAXALIGN(new_header_len);
 		new_data_len = heap_compute_data_size(tupleDesc,
@@ -616,26 +317,13 @@ toast_insert_or_update(Relation rel, HeapTuple newtup, HeapTuple oldtup,
 						(char *) new_data + new_header_len,
 						new_data_len,
 						&(new_data->t_infomask),
-						has_nulls ? new_data->t_bits : NULL);
+						((ttc.ttc_flags & TOAST_HAS_NULLS) != 0) ?
+						new_data->t_bits : NULL);
 	}
 	else
 		result_tuple = newtup;
 
-	/*
-	 * Free allocated temp values
-	 */
-	if (need_free)
-		for (i = 0; i < numAttrs; i++)
-			if (toast_free[i])
-				pfree(DatumGetPointer(toast_values[i]));
-
-	/*
-	 * Delete external values from the old tuple
-	 */
-	if (need_delold)
-		for (i = 0; i < numAttrs; i++)
-			if (toast_delold[i])
-				toast_delete_datum(rel, toast_oldvalues[i], false);
+	toast_tuple_cleanup(&ttc);
 
 	return result_tuple;
 }
diff --git a/src/backend/access/table/Makefile b/src/backend/access/table/Makefile
index 55a0e5efad..b29df3f333 100644
--- a/src/backend/access/table/Makefile
+++ b/src/backend/access/table/Makefile
@@ -12,6 +12,6 @@ subdir = src/backend/access/table
 top_builddir = ../../../..
 include $(top_builddir)/src/Makefile.global
 
-OBJS = table.o tableam.o tableamapi.o
+OBJS = table.o tableam.o tableamapi.o toast_helper.o
 
 include $(top_srcdir)/src/backend/common.mk
diff --git a/src/backend/access/table/toast_helper.c b/src/backend/access/table/toast_helper.c
new file mode 100644
index 0000000000..ee119cea2d
--- /dev/null
+++ b/src/backend/access/table/toast_helper.c
@@ -0,0 +1,331 @@
+/*-------------------------------------------------------------------------
+ *
+ * toast_helper.c
+ *	  Helper functions for table AMs implementing compressed or
+ *    out-of-line storage of varlena attributes.
+ *
+ * Copyright (c) 2000-2019, PostgreSQL Global Development Group
+ *
+ * IDENTIFICATION
+ *	  src/backend/access/common/toast_helper.c
+ *
+ *-------------------------------------------------------------------------
+ */
+
+#include "postgres.h"
+
+#include "access/detoast.h"
+#include "access/table.h"
+#include "access/toast_helper.h"
+#include "access/toast_internals.h"
+
+/*
+ * Prepare to TOAST a tuple.
+ *
+ * tupleDesc, toast_values, and toast_isnull are required parameters; they
+ * provide the necessary details about the tuple to be toasted.
+ *
+ * toast_oldvalues and toast_oldisnull should be NULL for a newly-inserted
+ * tuple; for an update, they should describe the existing tuple.
+ *
+ * All of these arrays should have a length equal to tupleDesc->natts.
+ *
+ * On return, toast_flags and toast_attr will have been initialized.
+ * toast_flags is just a single uint8, but toast_attr is an caller-provided
+ * array with a length equal to tupleDesc->natts.  The caller need not
+ * perform any initialization of the array before calling this function.
+ */
+void
+toast_tuple_init(ToastTupleContext *ttc)
+{
+	TupleDesc	tupleDesc = ttc->ttc_rel->rd_att;
+	int			numAttrs = tupleDesc->natts;
+	int		i;
+
+	ttc->ttc_flags = 0;
+
+	for (i = 0; i < numAttrs; i++)
+	{
+		Form_pg_attribute att = TupleDescAttr(tupleDesc, i);
+		struct varlena *old_value;
+		struct varlena *new_value;
+
+		ttc->ttc_attr[i].tai_colflags = 0;
+		ttc->ttc_attr[i].tai_oldexternal = NULL;
+
+		if (ttc->ttc_oldvalues != NULL)
+		{
+			/*
+			 * For UPDATE get the old and new values of this attribute
+			 */
+			old_value =
+				(struct varlena *) DatumGetPointer(ttc->ttc_oldvalues[i]);
+			new_value =
+				(struct varlena *) DatumGetPointer(ttc->ttc_values[i]);
+
+			/*
+			 * If the old value is stored on disk, check if it has changed so
+			 * we have to delete it later.
+			 */
+			if (att->attlen == -1 && !ttc->ttc_oldisnull[i] &&
+				VARATT_IS_EXTERNAL_ONDISK(old_value))
+			{
+				if (ttc->ttc_isnull[i] ||
+					!VARATT_IS_EXTERNAL_ONDISK(new_value) ||
+					memcmp((char *) old_value, (char *) new_value,
+						   VARSIZE_EXTERNAL(old_value)) != 0)
+				{
+					/*
+					 * The old external stored value isn't needed any more
+					 * after the update
+					 */
+					ttc->ttc_attr[i].tai_colflags |= TOASTCOL_NEEDS_DELETE_OLD;
+					ttc->ttc_flags |= TOAST_NEEDS_DELETE_OLD;
+				}
+				else
+				{
+					/*
+					 * This attribute isn't changed by this update so we reuse
+					 * the original reference to the old value in the new
+					 * tuple.
+					 */
+					ttc->ttc_attr[i].tai_colflags |= TOASTCOL_IGNORE;
+					continue;
+				}
+			}
+		}
+		else
+		{
+			/*
+			 * For INSERT simply get the new value
+			 */
+			new_value = (struct varlena *) DatumGetPointer(ttc->ttc_values[i]);
+		}
+
+		/*
+		 * Handle NULL attributes
+		 */
+		if (ttc->ttc_isnull[i])
+		{
+			ttc->ttc_attr[i].tai_colflags |= TOASTCOL_IGNORE;
+			ttc->ttc_flags |= TOAST_HAS_NULLS;
+			continue;
+		}
+
+		/*
+		 * Now look at varlena attributes
+		 */
+		if (att->attlen == -1)
+		{
+			/*
+			 * If the table's attribute says PLAIN always, force it so.
+			 */
+			if (att->attstorage == 'p')
+				ttc->ttc_attr[i].tai_colflags |= TOASTCOL_IGNORE;
+
+			/*
+			 * We took care of UPDATE above, so any external value we find
+			 * still in the tuple must be someone else's that we cannot reuse
+			 * (this includes the case of an out-of-line in-memory datum).
+			 * Fetch it back (without decompression, unless we are forcing
+			 * PLAIN storage).  If necessary, we'll push it out as a new
+			 * external value below.
+			 */
+			if (VARATT_IS_EXTERNAL(new_value))
+			{
+				ttc->ttc_attr[i].tai_oldexternal = new_value;
+				if (att->attstorage == 'p')
+					new_value = heap_tuple_untoast_attr(new_value);
+				else
+					new_value = heap_tuple_fetch_attr(new_value);
+				ttc->ttc_values[i] = PointerGetDatum(new_value);
+				ttc->ttc_attr[i].tai_colflags |= TOASTCOL_NEEDS_FREE;
+				ttc->ttc_flags |= (TOAST_NEEDS_CHANGE | TOAST_NEEDS_FREE);
+			}
+
+			/*
+			 * Remember the size of this attribute
+			 */
+			ttc->ttc_attr[i].tai_size = VARSIZE_ANY(new_value);
+		}
+		else
+		{
+			/*
+			 * Not a varlena attribute, plain storage always
+			 */
+			ttc->ttc_attr[i].tai_colflags |= TOASTCOL_IGNORE;
+		}
+	}
+}
+
+/*
+ * Find the largest varlena attribute that satisfies certain criteria.
+ *
+ * The relevant column must not be marked TOASTCOL_IGNORE, and if the
+ * for_compression flag is passed as true, it must also not be marked
+ * TOASTCOL_INCOMPRESSIBLE.
+ *
+ * The column must have attstorage 'e' or 'x' if check_main is false, and
+ * must have attstorage 'm' if check_main is true.
+ *
+ * The column must have a minimum size of MAXALIGN(TOAST_POINTER_SIZE);
+ * if not, no benefit is to be expected by compressing it.
+ *
+ * The return value is the index of the biggest suitable column, or
+ * -1 if there is none.
+ */
+int
+toast_tuple_find_biggest_attribute(ToastTupleContext *ttc,
+								   bool for_compression, bool check_main)
+{
+	TupleDesc	tupleDesc = ttc->ttc_rel->rd_att;
+	int			numAttrs = tupleDesc->natts;
+	int			biggest_attno = -1;
+	int32		biggest_size = MAXALIGN(TOAST_POINTER_SIZE);
+	int32		skip_colflags = TOASTCOL_IGNORE;
+	int			i;
+
+	if (for_compression)
+		skip_colflags |= TOASTCOL_INCOMPRESSIBLE;
+
+	for (i = 0; i < numAttrs; i++)
+	{
+		Form_pg_attribute att = TupleDescAttr(tupleDesc, i);
+
+		if ((ttc->ttc_attr[i].tai_colflags & skip_colflags) != 0)
+			continue;
+		if (VARATT_IS_EXTERNAL(DatumGetPointer(ttc->ttc_values[i])))
+			continue;		/* can't happen, toast_action would be 'p' */
+		if (for_compression &&
+			VARATT_IS_COMPRESSED(DatumGetPointer(ttc->ttc_values[i])))
+			continue;
+		if (check_main && att->attstorage != 'm')
+			continue;
+		if (!check_main && att->attstorage != 'x' && att->attstorage != 'e')
+			continue;
+
+		if (ttc->ttc_attr[i].tai_size > biggest_size)
+		{
+			biggest_attno = i;
+			biggest_size = ttc->ttc_attr[i].tai_size;
+		}
+	}
+
+	return biggest_attno;
+}
+
+/*
+ * Try compression for an attribute.
+ *
+ * If we find that the attribute is not compressible, mark it so.
+ */
+void
+toast_tuple_try_compression(ToastTupleContext *ttc, int attribute)
+{
+	Datum  *value = &ttc->ttc_values[attribute];
+	Datum	new_value = toast_compress_datum(*value);
+	ToastAttrInfo  *attr = &ttc->ttc_attr[attribute];
+
+	if (DatumGetPointer(new_value) != NULL)
+	{
+		/* successful compression */
+		if ((attr->tai_colflags & TOASTCOL_NEEDS_FREE) != 0)
+			pfree(DatumGetPointer(*value));
+		*value = new_value;
+		attr->tai_colflags |= TOASTCOL_NEEDS_FREE;
+		attr->tai_size = VARSIZE(DatumGetPointer(*value));
+		ttc->ttc_flags |= (TOAST_NEEDS_CHANGE | TOAST_NEEDS_FREE);
+	}
+	else
+	{
+		/* incompressible, ignore on subsequent compression passes */
+		attr->tai_colflags |= TOASTCOL_INCOMPRESSIBLE;
+	}
+}
+
+/*
+ * Move an attribute to external storage.
+ */
+void
+toast_tuple_externalize(ToastTupleContext *ttc, int attribute, int options)
+{
+	Datum  *value = &ttc->ttc_values[attribute];
+	Datum	old_value = *value;
+	ToastAttrInfo  *attr = &ttc->ttc_attr[attribute];
+
+	attr->tai_colflags |= TOASTCOL_IGNORE;
+	*value = toast_save_datum(ttc->ttc_rel, old_value, attr->tai_oldexternal,
+							  options);
+	if ((attr->tai_colflags & TOASTCOL_NEEDS_FREE) != 0)
+		pfree(DatumGetPointer(old_value));
+	attr->tai_colflags |= TOASTCOL_NEEDS_FREE;
+	ttc->ttc_flags |= (TOAST_NEEDS_CHANGE | TOAST_NEEDS_FREE);
+}
+
+/*
+ * Perform appropriate cleanup after one tuple has been subjected to TOAST.
+ */
+void
+toast_tuple_cleanup(ToastTupleContext *ttc)
+{
+	TupleDesc	tupleDesc = ttc->ttc_rel->rd_att;
+	int			numAttrs = tupleDesc->natts;
+
+	/*
+	 * Free allocated temp values
+	 */
+	if ((ttc->ttc_flags & TOAST_NEEDS_FREE) != 0)
+	{
+		int		i;
+
+		for (i = 0; i < numAttrs; i++)
+		{
+			ToastAttrInfo  *attr = &ttc->ttc_attr[i];
+
+			if ((attr->tai_colflags & TOASTCOL_NEEDS_FREE) != 0)
+				pfree(DatumGetPointer(ttc->ttc_values[i]));
+		}
+	}
+
+	/*
+	 * Delete external values from the old tuple
+	 */
+	if ((ttc->ttc_flags & TOAST_NEEDS_DELETE_OLD) != 0)
+	{
+		int		i;
+
+		for (i = 0; i < numAttrs; i++)
+		{
+			ToastAttrInfo  *attr = &ttc->ttc_attr[i];
+
+			if ((attr->tai_colflags & TOASTCOL_NEEDS_DELETE_OLD) != 0)
+				toast_delete_datum(ttc->ttc_rel, ttc->ttc_oldvalues[i], false);
+		}
+	}
+}
+
+/*
+ * Check for external stored attributes and delete them from the secondary
+ * relation.
+ */
+void
+toast_delete_external(Relation rel, Datum *values, bool *isnull,
+					  bool is_speculative)
+{
+	TupleDesc	tupleDesc = rel->rd_att;
+	int			numAttrs = tupleDesc->natts;
+	int			i;
+
+	for (i = 0; i < numAttrs; i++)
+	{
+		if (TupleDescAttr(tupleDesc, i)->attlen == -1)
+		{
+			Datum		value = values[i];
+
+			if (isnull[i])
+				continue;
+			else if (VARATT_IS_EXTERNAL_ONDISK(PointerGetDatum(value)))
+				toast_delete_datum(rel, value, is_speculative);
+		}
+	}
+}
diff --git a/src/include/access/toast_helper.h b/src/include/access/toast_helper.h
new file mode 100644
index 0000000000..0fac6cc772
--- /dev/null
+++ b/src/include/access/toast_helper.h
@@ -0,0 +1,114 @@
+/*-------------------------------------------------------------------------
+ *
+ * toast_helper.h
+ *	  Helper functions for table AMs implementing compressed or
+ *    out-of-line storage of varlena attributes.
+ *
+ * Copyright (c) 2000-2019, PostgreSQL Global Development Group
+ *
+ * src/include/access/toast_helper.h
+ *
+ *-------------------------------------------------------------------------
+ */
+
+#ifndef TOAST_HELPER_H
+#define TOAST_HELPER_H
+
+#include "utils/rel.h"
+
+/*
+ * Information about one column of a tuple being toasted.
+ *
+ * NOTE: toast_action[i] can have these values:
+ *		' '		default handling
+ *		'p'		already processed --- don't touch it
+ *		'x'		incompressible, but OK to move off
+ *
+ * NOTE: toast_attr[i].tai_size is only made valid for varlena attributes with
+ * toast_action[i] different from 'p'.
+ */
+typedef struct
+{
+	struct varlena *tai_oldexternal;
+	int32		tai_size;
+	uint8		tai_colflags;
+} ToastAttrInfo;
+
+/*
+ * Information about one tuple being toasted.
+ */
+typedef struct
+{
+	/*
+	 * Before calling toast_tuple_init, the caller must initialize the
+	 * following fields.  Each array must have a length equal to
+	 * ttc_rel->rd_att->natts.  The tts_oldvalues and tts_oldisnull fields
+	 * should be NULL in the case of an insert.
+	 */
+	Relation	ttc_rel;			/* the relation that contains the tuple */
+	Datum	   *ttc_values;			/* values from the tuple columns */
+	bool	   *ttc_isnull;			/* null flags for the tuple columns */
+	Datum	   *ttc_oldvalues;		/* values from previous tuple */
+	bool	   *ttc_oldisnull;		/* null flags from previous tuple */
+
+	/*
+	 * Before calling toast_tuple_init, the caller should set tts_attr to
+	 * point to an array of ToastAttrInfo structures of a length equal to
+	 * tts_rel->rd_att->natts.  The contents of the array need not be
+	 * initialized.  ttc_flags also does not need to be initialized.
+	 */
+	uint8		ttc_flags;
+	ToastAttrInfo	*ttc_attr;
+} ToastTupleContext;
+
+/*
+ * Flags indicating the overall state of a TOAST operation.
+ *
+ * TOAST_NEEDS_DELETE_OLD indicates that one or more old TOAST datums need
+ * to be deleted.
+ *
+ * TOAST_NEEDS_FREE indicates that one or more TOAST values need to be freed.
+ *
+ * TOAST_HAS_NULLS indicates that nulls were found in the tuple being toasted.
+ *
+ * TOAST_NEEDS_CHANGE indicates that a new tuple needs to built; in other
+ * words, the toaster did something.
+ */
+#define TOAST_NEEDS_DELETE_OLD				0x0001
+#define TOAST_NEEDS_FREE					0x0002
+#define TOAST_HAS_NULLS						0x0004
+#define TOAST_NEEDS_CHANGE					0x0008
+
+/*
+ * Flags indicating the status of a TOAST operation with respect to a
+ * particular column.
+ *
+ * TOASTCOL_NEEDS_DELETE_OLD indicates that the old TOAST datums for this
+ * column need to be deleted.
+ *
+ * TOASTCOL_NEEDS_FREE indicates that the value for this column needs to
+ * be freed.
+ *
+ * TOASTCOL_IGNORE indicates that the toaster should not further process
+ * this column.
+ *
+ * TOASTCOL_INCOMPRESSIBLE indicates that this column has been found to
+ * be incompressible, but could be moved out-of-line.
+ */
+#define TOASTCOL_NEEDS_DELETE_OLD			TOAST_NEEDS_DELETE_OLD
+#define TOASTCOL_NEEDS_FREE					TOAST_NEEDS_FREE
+#define TOASTCOL_IGNORE						0x0010
+#define TOASTCOL_INCOMPRESSIBLE				0x0020
+
+extern void toast_tuple_init(ToastTupleContext *ttc);
+extern int toast_tuple_find_biggest_attribute(ToastTupleContext *ttc,
+								   bool for_compression, bool check_main);
+extern void toast_tuple_try_compression(ToastTupleContext *ttc, int attribute);
+extern void toast_tuple_externalize(ToastTupleContext *ttc, int attribute,
+						int options);
+extern void toast_tuple_cleanup(ToastTupleContext *ttc);
+
+extern void toast_delete_external(Relation rel, Datum *values, bool *isnull,
+					  bool is_speculative);
+
+#endif
-- 
2.17.2 (Apple Git-113)

From 480b42c5802164c40b44779c897ceaf0d4af8aaa Mon Sep 17 00:00:00 2001
From: Robert Haas <rhaas@postgresql.org>
Date: Mon, 8 Jul 2019 12:34:37 -0400
Subject: [PATCH 4/4] Rename attribute-detoasting functions.

The old names included the word "heap," which seems outdated now that
the heap is only one of potentially many table access methods.

Discussion: http://postgr.es/m/CA+TgmoZv-=2iWM4jcw5ZhJeL18HF96+W1yJeYrnGMYdkFFnEpQ@mail.gmail.com
---
 src/backend/access/common/detoast.c        | 26 +++++++++++-----------
 src/backend/access/common/indextuple.c     |  2 +-
 src/backend/access/heap/heaptoast.c        |  6 ++---
 src/backend/access/table/toast_helper.c    |  4 ++--
 src/backend/executor/tstoreReceiver.c      |  2 +-
 src/backend/storage/large_object/inv_api.c |  2 +-
 src/backend/utils/adt/expandedrecord.c     |  4 ++--
 src/backend/utils/fmgr/fmgr.c              |  8 +++----
 src/include/access/detoast.h               | 16 ++++++-------
 src/pl/plpgsql/src/pl_exec.c               |  2 +-
 src/test/regress/regress.c                 |  2 +-
 11 files changed, 37 insertions(+), 37 deletions(-)

diff --git a/src/backend/access/common/detoast.c b/src/backend/access/common/detoast.c
index 46feb91888..c66920d52b 100644
--- a/src/backend/access/common/detoast.c
+++ b/src/backend/access/common/detoast.c
@@ -31,7 +31,7 @@ static struct varlena *toast_decompress_datum(struct varlena *attr);
 static struct varlena *toast_decompress_datum_slice(struct varlena *attr, int32 slicelength);
 
 /* ----------
- * heap_tuple_fetch_attr -
+ * detoast_external_attr -
  *
  *	Public entry point to get back a toasted value from
  *	external source (possibly still in compressed format).
@@ -43,7 +43,7 @@ static struct varlena *toast_decompress_datum_slice(struct varlena *attr, int32
  * ----------
  */
 struct varlena *
-heap_tuple_fetch_attr(struct varlena *attr)
+detoast_external_attr(struct varlena *attr)
 {
 	struct varlena *result;
 
@@ -69,7 +69,7 @@ heap_tuple_fetch_attr(struct varlena *attr)
 
 		/* recurse if value is still external in some other way */
 		if (VARATT_IS_EXTERNAL(attr))
-			return heap_tuple_fetch_attr(attr);
+			return detoast_external_attr(attr);
 
 		/*
 		 * Copy into the caller's memory context, in case caller tries to
@@ -104,7 +104,7 @@ heap_tuple_fetch_attr(struct varlena *attr)
 
 
 /* ----------
- * heap_tuple_untoast_attr -
+ * detoast_attr -
  *
  *	Public entry point to get back a toasted value from compression
  *	or external storage.  The result is always non-extended varlena form.
@@ -114,7 +114,7 @@ heap_tuple_fetch_attr(struct varlena *attr)
  * ----------
  */
 struct varlena *
-heap_tuple_untoast_attr(struct varlena *attr)
+detoast_attr(struct varlena *attr)
 {
 	if (VARATT_IS_EXTERNAL_ONDISK(attr))
 	{
@@ -145,7 +145,7 @@ heap_tuple_untoast_attr(struct varlena *attr)
 		Assert(!VARATT_IS_EXTERNAL_INDIRECT(attr));
 
 		/* recurse in case value is still extended in some other way */
-		attr = heap_tuple_untoast_attr(attr);
+		attr = detoast_attr(attr);
 
 		/* if it isn't, we'd better copy it */
 		if (attr == (struct varlena *) redirect.pointer)
@@ -162,7 +162,7 @@ heap_tuple_untoast_attr(struct varlena *attr)
 		/*
 		 * This is an expanded-object pointer --- get flat format
 		 */
-		attr = heap_tuple_fetch_attr(attr);
+		attr = detoast_external_attr(attr);
 		/* flatteners are not allowed to produce compressed/short output */
 		Assert(!VARATT_IS_EXTENDED(attr));
 	}
@@ -193,14 +193,14 @@ heap_tuple_untoast_attr(struct varlena *attr)
 
 
 /* ----------
- * heap_tuple_untoast_attr_slice -
+ * detoast_attr_slice -
  *
  *		Public entry point to get back part of a toasted value
  *		from compression or external storage.
  * ----------
  */
 struct varlena *
-heap_tuple_untoast_attr_slice(struct varlena *attr,
+detoast_attr_slice(struct varlena *attr,
 							  int32 sliceoffset, int32 slicelength)
 {
 	struct varlena *preslice;
@@ -230,13 +230,13 @@ heap_tuple_untoast_attr_slice(struct varlena *attr,
 		/* nested indirect Datums aren't allowed */
 		Assert(!VARATT_IS_EXTERNAL_INDIRECT(redirect.pointer));
 
-		return heap_tuple_untoast_attr_slice(redirect.pointer,
+		return detoast_attr_slice(redirect.pointer,
 											 sliceoffset, slicelength);
 	}
 	else if (VARATT_IS_EXTERNAL_EXPANDED(attr))
 	{
-		/* pass it off to heap_tuple_fetch_attr to flatten */
-		preslice = heap_tuple_fetch_attr(attr);
+		/* pass it off to detoast_external_attr to flatten */
+		preslice = detoast_external_attr(attr);
 	}
 	else
 		preslice = attr;
@@ -727,7 +727,7 @@ toast_decompress_datum(struct varlena *attr)
  * toast_decompress_datum_slice -
  *
  * Decompress the front of a compressed version of a varlena datum.
- * offset handling happens in heap_tuple_untoast_attr_slice.
+ * offset handling happens in detoast_attr_slice.
  * Here we just decompress a slice from the front.
  */
 static struct varlena *
diff --git a/src/backend/access/common/indextuple.c b/src/backend/access/common/indextuple.c
index 07586201b9..8a5f5227a3 100644
--- a/src/backend/access/common/indextuple.c
+++ b/src/backend/access/common/indextuple.c
@@ -89,7 +89,7 @@ index_form_tuple(TupleDesc tupleDescriptor,
 		if (VARATT_IS_EXTERNAL(DatumGetPointer(values[i])))
 		{
 			untoasted_values[i] =
-				PointerGetDatum(heap_tuple_fetch_attr((struct varlena *)
+				PointerGetDatum(detoast_external_attr((struct varlena *)
 													  DatumGetPointer(values[i])));
 			untoasted_free[i] = true;
 		}
diff --git a/src/backend/access/heap/heaptoast.c b/src/backend/access/heap/heaptoast.c
index c0acefc97e..9221dc71d7 100644
--- a/src/backend/access/heap/heaptoast.c
+++ b/src/backend/access/heap/heaptoast.c
@@ -376,7 +376,7 @@ toast_flatten_tuple(HeapTuple tup, TupleDesc tupleDesc)
 			new_value = (struct varlena *) DatumGetPointer(toast_values[i]);
 			if (VARATT_IS_EXTERNAL(new_value))
 			{
-				new_value = heap_tuple_fetch_attr(new_value);
+				new_value = detoast_external_attr(new_value);
 				toast_values[i] = PointerGetDatum(new_value);
 				toast_free[i] = true;
 			}
@@ -491,7 +491,7 @@ toast_flatten_tuple_to_datum(HeapTupleHeader tup,
 			if (VARATT_IS_EXTERNAL(new_value) ||
 				VARATT_IS_COMPRESSED(new_value))
 			{
-				new_value = heap_tuple_untoast_attr(new_value);
+				new_value = detoast_attr(new_value);
 				toast_values[i] = PointerGetDatum(new_value);
 				toast_free[i] = true;
 			}
@@ -590,7 +590,7 @@ toast_build_flattened_tuple(TupleDesc tupleDesc,
 			new_value = (struct varlena *) DatumGetPointer(new_values[i]);
 			if (VARATT_IS_EXTERNAL(new_value))
 			{
-				new_value = heap_tuple_fetch_attr(new_value);
+				new_value = detoast_external_attr(new_value);
 				new_values[i] = PointerGetDatum(new_value);
 				freeable_values[num_to_free++] = (Pointer) new_value;
 			}
diff --git a/src/backend/access/table/toast_helper.c b/src/backend/access/table/toast_helper.c
index e33918a7f4..dedc123e31 100644
--- a/src/backend/access/table/toast_helper.c
+++ b/src/backend/access/table/toast_helper.c
@@ -136,9 +136,9 @@ toast_tuple_init(ToastTupleContext *ttc)
 			{
 				ttc->ttc_attr[i].tai_oldexternal = new_value;
 				if (att->attstorage == 'p')
-					new_value = heap_tuple_untoast_attr(new_value);
+					new_value = detoast_attr(new_value);
 				else
-					new_value = heap_tuple_fetch_attr(new_value);
+					new_value = detoast_external_attr(new_value);
 				ttc->ttc_values[i] = PointerGetDatum(new_value);
 				ttc->ttc_attr[i].tai_colflags |= TOASTCOL_NEEDS_FREE;
 				ttc->ttc_flags |= (TOAST_NEEDS_CHANGE | TOAST_NEEDS_FREE);
diff --git a/src/backend/executor/tstoreReceiver.c b/src/backend/executor/tstoreReceiver.c
index c0c81c82da..6306b7d0bd 100644
--- a/src/backend/executor/tstoreReceiver.c
+++ b/src/backend/executor/tstoreReceiver.c
@@ -133,7 +133,7 @@ tstoreReceiveSlot_detoast(TupleTableSlot *slot, DestReceiver *self)
 		{
 			if (VARATT_IS_EXTERNAL(DatumGetPointer(val)))
 			{
-				val = PointerGetDatum(heap_tuple_fetch_attr((struct varlena *)
+				val = PointerGetDatum(detoast_external_attr((struct varlena *)
 															DatumGetPointer(val)));
 				myState->tofree[nfree++] = val;
 			}
diff --git a/src/backend/storage/large_object/inv_api.c b/src/backend/storage/large_object/inv_api.c
index e591236343..263d5be12e 100644
--- a/src/backend/storage/large_object/inv_api.c
+++ b/src/backend/storage/large_object/inv_api.c
@@ -180,7 +180,7 @@ getdatafield(Form_pg_largeobject tuple,
 	if (VARATT_IS_EXTENDED(datafield))
 	{
 		datafield = (bytea *)
-			heap_tuple_untoast_attr((struct varlena *) datafield);
+			detoast_attr((struct varlena *) datafield);
 		freeit = true;
 	}
 	len = VARSIZE(datafield) - VARHDRSZ;
diff --git a/src/backend/utils/adt/expandedrecord.c b/src/backend/utils/adt/expandedrecord.c
index 369432d53c..d99d370b17 100644
--- a/src/backend/utils/adt/expandedrecord.c
+++ b/src/backend/utils/adt/expandedrecord.c
@@ -1159,7 +1159,7 @@ expanded_record_set_field_internal(ExpandedRecordHeader *erh, int fnumber,
 			{
 				/* Detoasting should be done in short-lived context. */
 				oldcxt = MemoryContextSwitchTo(get_short_term_cxt(erh));
-				newValue = PointerGetDatum(heap_tuple_fetch_attr((struct varlena *) DatumGetPointer(newValue)));
+				newValue = PointerGetDatum(detoast_external_attr((struct varlena *) DatumGetPointer(newValue)));
 				MemoryContextSwitchTo(oldcxt);
 			}
 			else
@@ -1305,7 +1305,7 @@ expanded_record_set_fields(ExpandedRecordHeader *erh,
 					if (expand_external)
 					{
 						/* Detoast as requested while copying the value */
-						newValue = PointerGetDatum(heap_tuple_fetch_attr((struct varlena *) DatumGetPointer(newValue)));
+						newValue = PointerGetDatum(detoast_external_attr((struct varlena *) DatumGetPointer(newValue)));
 					}
 					else
 					{
diff --git a/src/backend/utils/fmgr/fmgr.c b/src/backend/utils/fmgr/fmgr.c
index 74e36e62d3..aa94380a2c 100644
--- a/src/backend/utils/fmgr/fmgr.c
+++ b/src/backend/utils/fmgr/fmgr.c
@@ -1739,7 +1739,7 @@ struct varlena *
 pg_detoast_datum(struct varlena *datum)
 {
 	if (VARATT_IS_EXTENDED(datum))
-		return heap_tuple_untoast_attr(datum);
+		return detoast_attr(datum);
 	else
 		return datum;
 }
@@ -1748,7 +1748,7 @@ struct varlena *
 pg_detoast_datum_copy(struct varlena *datum)
 {
 	if (VARATT_IS_EXTENDED(datum))
-		return heap_tuple_untoast_attr(datum);
+		return detoast_attr(datum);
 	else
 	{
 		/* Make a modifiable copy of the varlena object */
@@ -1764,14 +1764,14 @@ struct varlena *
 pg_detoast_datum_slice(struct varlena *datum, int32 first, int32 count)
 {
 	/* Only get the specified portion from the toast rel */
-	return heap_tuple_untoast_attr_slice(datum, first, count);
+	return detoast_attr_slice(datum, first, count);
 }
 
 struct varlena *
 pg_detoast_datum_packed(struct varlena *datum)
 {
 	if (VARATT_IS_COMPRESSED(datum) || VARATT_IS_EXTERNAL(datum))
-		return heap_tuple_untoast_attr(datum);
+		return detoast_attr(datum);
 	else
 		return datum;
 }
diff --git a/src/include/access/detoast.h b/src/include/access/detoast.h
index 582af147ea..8c07124b76 100644
--- a/src/include/access/detoast.h
+++ b/src/include/access/detoast.h
@@ -44,34 +44,34 @@ do { \
 #define INDIRECT_POINTER_SIZE (VARHDRSZ_EXTERNAL + sizeof(varatt_indirect))
 
 /* ----------
- * heap_tuple_fetch_attr() -
+ * detoast_external_attr() -
  *
  *		Fetches an external stored attribute from the toast
  *		relation. Does NOT decompress it, if stored external
  *		in compressed format.
  * ----------
  */
-extern struct varlena *heap_tuple_fetch_attr(struct varlena *attr);
+extern struct varlena *detoast_external_attr(struct varlena *attr);
 
 /* ----------
- * heap_tuple_untoast_attr() -
+ * detoast_attr() -
  *
  *		Fully detoasts one attribute, fetching and/or decompressing
  *		it as needed.
  * ----------
  */
-extern struct varlena *heap_tuple_untoast_attr(struct varlena *attr);
+extern struct varlena *detoast_attr(struct varlena *attr);
 
 /* ----------
- * heap_tuple_untoast_attr_slice() -
+ * detoast_attr_slice() -
  *
  *		Fetches only the specified portion of an attribute.
  *		(Handles all cases for attribute storage)
  * ----------
  */
-extern struct varlena *heap_tuple_untoast_attr_slice(struct varlena *attr,
-							  int32 sliceoffset,
-							  int32 slicelength);
+extern struct varlena *detoast_attr_slice(struct varlena *attr,
+										  int32 sliceoffset,
+										  int32 slicelength);
 
 /* ----------
  * toast_raw_datum_size -
diff --git a/src/pl/plpgsql/src/pl_exec.c b/src/pl/plpgsql/src/pl_exec.c
index 3479fbd550..fe83fc7da9 100644
--- a/src/pl/plpgsql/src/pl_exec.c
+++ b/src/pl/plpgsql/src/pl_exec.c
@@ -8267,7 +8267,7 @@ assign_simple_var(PLpgSQL_execstate *estate, PLpgSQL_var *var,
 		 * pain, but there's little choice.
 		 */
 		oldcxt = MemoryContextSwitchTo(get_eval_mcontext(estate));
-		detoasted = PointerGetDatum(heap_tuple_fetch_attr((struct varlena *) DatumGetPointer(newvalue)));
+		detoasted = PointerGetDatum(detoast_external_attr((struct varlena *) DatumGetPointer(newvalue)));
 		MemoryContextSwitchTo(oldcxt);
 		/* Now's a good time to not leak the input value if it's freeable */
 		if (freeable)
diff --git a/src/test/regress/regress.c b/src/test/regress/regress.c
index 826556eb29..2bbeaa0460 100644
--- a/src/test/regress/regress.c
+++ b/src/test/regress/regress.c
@@ -558,7 +558,7 @@ make_tuple_indirect(PG_FUNCTION_ARGS)
 
 		/* copy datum, so it still lives later */
 		if (VARATT_IS_EXTERNAL_ONDISK(attr))
-			attr = heap_tuple_fetch_attr(attr);
+			attr = detoast_external_attr(attr);
 		else
 		{
 			struct varlena *oldattr = attr;
-- 
2.17.2 (Apple Git-113)

From d9cf0d906b8d4c171a3a90025480cb8dedd79497 Mon Sep 17 00:00:00 2001
From: Robert Haas <rhaas@postgresql.org>
Date: Tue, 11 Jun 2019 11:10:15 -0400
Subject: [PATCH 3/4] Allow TOAST tables to be implemented using table AMs
 other than heap.

toast_fetch_datum, toast_save_datum, and toast_delete_datum are
adjusted to use tableam rather than heap-specific functions.  This
might have some performance impact, but this patch attempts to
mitigate that by restructuring things so that we don't open and close
the toast table and indexes multiple times per tuple.

tableam now exposes an integer value (not a callback) for the
maximum TOAST chunk size, and has a new callback allowing table
AMs to specify the AM that should be used to implement the TOAST
table. Previously, the toast AM was always the same as the table AM.

Patch by me, tested by Prabhat Sabu.

Discussion: http://postgr.es/m/CA+TgmoZv-=2iWM4jcw5ZhJeL18HF96+W1yJeYrnGMYdkFFnEpQ@mail.gmail.com
---
 src/backend/access/common/detoast.c         |  62 +++++-----
 src/backend/access/common/toast_internals.c | 127 +++++++-------------
 src/backend/access/heap/heapam.c            |   6 +-
 src/backend/access/heap/heapam_handler.c    |  14 ++-
 src/backend/access/heap/heaptoast.c         |  19 ++-
 src/backend/access/index/genam.c            |  20 +++
 src/backend/access/table/toast_helper.c     | 107 ++++++++++++++---
 src/backend/catalog/toasting.c              |   2 +-
 src/include/access/genam.h                  |   5 +-
 src/include/access/heapam.h                 |   3 +-
 src/include/access/heaptoast.h              |   3 +-
 src/include/access/tableam.h                |  31 +++++
 src/include/access/toast_helper.h           |  18 ++-
 src/include/access/toast_internals.h        |  15 ++-
 14 files changed, 284 insertions(+), 148 deletions(-)

diff --git a/src/backend/access/common/detoast.c b/src/backend/access/common/detoast.c
index 49c94da557..46feb91888 100644
--- a/src/backend/access/common/detoast.c
+++ b/src/backend/access/common/detoast.c
@@ -15,10 +15,11 @@
 
 #include "access/detoast.h"
 #include "access/genam.h"
-#include "access/heaptoast.h"
 #include "access/table.h"
 #include "access/toast_internals.h"
+#include "access/tableam.h"
 #include "common/pg_lzcompress.h"
+#include "executor/tuptable.h"
 #include "utils/expandeddatum.h"
 #include "utils/fmgroids.h"
 #include "utils/rel.h"
@@ -303,8 +304,7 @@ toast_fetch_datum(struct varlena *attr)
 	Relation   *toastidxs;
 	ScanKeyData toastkey;
 	SysScanDesc toastscan;
-	HeapTuple	ttup;
-	TupleDesc	toasttupDesc;
+	TupleTableSlot *slot;
 	struct varlena *result;
 	struct varatt_external toast_pointer;
 	int32		ressize;
@@ -312,11 +312,11 @@ toast_fetch_datum(struct varlena *attr)
 				nextidx;
 	int32		numchunks;
 	Pointer		chunk;
-	bool		isnull;
 	char	   *chunkdata;
 	int32		chunksize;
 	int			num_indexes;
 	int			validIndex;
+	int			max_chunk_size;
 	SnapshotData SnapshotToast;
 
 	if (!VARATT_IS_EXTERNAL_ONDISK(attr))
@@ -326,7 +326,6 @@ toast_fetch_datum(struct varlena *attr)
 	VARATT_EXTERNAL_GET_POINTER(toast_pointer, attr);
 
 	ressize = toast_pointer.va_extsize;
-	numchunks = ((ressize - 1) / TOAST_MAX_CHUNK_SIZE) + 1;
 
 	result = (struct varlena *) palloc(ressize + VARHDRSZ);
 
@@ -339,7 +338,9 @@ toast_fetch_datum(struct varlena *attr)
 	 * Open the toast relation and its indexes
 	 */
 	toastrel = table_open(toast_pointer.va_toastrelid, AccessShareLock);
-	toasttupDesc = toastrel->rd_att;
+
+	max_chunk_size = toastrel->rd_tableam->toast_max_chunk_size;
+	numchunks = ((ressize - 1) / max_chunk_size) + 1;
 
 	/* Look for the valid index of the toast relation */
 	validIndex = toast_open_indexes(toastrel,
@@ -367,15 +368,15 @@ toast_fetch_datum(struct varlena *attr)
 	init_toast_snapshot(&SnapshotToast);
 	toastscan = systable_beginscan_ordered(toastrel, toastidxs[validIndex],
 										   &SnapshotToast, 1, &toastkey);
-	while ((ttup = systable_getnext_ordered(toastscan, ForwardScanDirection)) != NULL)
+	while ((slot = systable_getnextslot_ordered(toastscan, ForwardScanDirection)) != NULL)
 	{
 		/*
 		 * Have a chunk, extract the sequence number and the data
 		 */
-		residx = DatumGetInt32(fastgetattr(ttup, 2, toasttupDesc, &isnull));
-		Assert(!isnull);
-		chunk = DatumGetPointer(fastgetattr(ttup, 3, toasttupDesc, &isnull));
-		Assert(!isnull);
+		slot_getsomeattrs(slot, 3);
+		Assert(!slot->tts_isnull[1] && !slot->tts_isnull[2]);
+		residx = DatumGetInt32(slot->tts_values[1]);
+		chunk = DatumGetPointer(slot->tts_values[2]);
 		if (!VARATT_IS_EXTENDED(chunk))
 		{
 			chunksize = VARSIZE(chunk) - VARHDRSZ;
@@ -407,19 +408,19 @@ toast_fetch_datum(struct varlena *attr)
 				 RelationGetRelationName(toastrel));
 		if (residx < numchunks - 1)
 		{
-			if (chunksize != TOAST_MAX_CHUNK_SIZE)
+			if (chunksize != max_chunk_size)
 				elog(ERROR, "unexpected chunk size %d (expected %d) in chunk %d of %d for toast value %u in %s",
-					 chunksize, (int) TOAST_MAX_CHUNK_SIZE,
+					 chunksize, max_chunk_size,
 					 residx, numchunks,
 					 toast_pointer.va_valueid,
 					 RelationGetRelationName(toastrel));
 		}
 		else if (residx == numchunks - 1)
 		{
-			if ((residx * TOAST_MAX_CHUNK_SIZE + chunksize) != ressize)
+			if ((residx * max_chunk_size + chunksize) != ressize)
 				elog(ERROR, "unexpected chunk size %d (expected %d) in final chunk %d for toast value %u in %s",
 					 chunksize,
-					 (int) (ressize - residx * TOAST_MAX_CHUNK_SIZE),
+					 (int) (ressize - residx * max_chunk_size),
 					 residx,
 					 toast_pointer.va_valueid,
 					 RelationGetRelationName(toastrel));
@@ -434,7 +435,7 @@ toast_fetch_datum(struct varlena *attr)
 		/*
 		 * Copy the data into proper place in our result
 		 */
-		memcpy(VARDATA(result) + residx * TOAST_MAX_CHUNK_SIZE,
+		memcpy(VARDATA(result) + residx * max_chunk_size,
 			   chunkdata,
 			   chunksize);
 
@@ -498,6 +499,7 @@ toast_fetch_datum_slice(struct varlena *attr, int32 sliceoffset, int32 length)
 	int32		chcpyend;
 	int			num_indexes;
 	int			validIndex;
+	int			max_chunk_size;
 	SnapshotData SnapshotToast;
 
 	if (!VARATT_IS_EXTERNAL_ONDISK(attr))
@@ -513,7 +515,6 @@ toast_fetch_datum_slice(struct varlena *attr, int32 sliceoffset, int32 length)
 	Assert(!VARATT_EXTERNAL_IS_COMPRESSED(toast_pointer));
 
 	attrsize = toast_pointer.va_extsize;
-	totalchunks = ((attrsize - 1) / TOAST_MAX_CHUNK_SIZE) + 1;
 
 	if (sliceoffset >= attrsize)
 	{
@@ -531,19 +532,22 @@ toast_fetch_datum_slice(struct varlena *attr, int32 sliceoffset, int32 length)
 	if (length == 0)
 		return result;			/* Can save a lot of work at this point! */
 
-	startchunk = sliceoffset / TOAST_MAX_CHUNK_SIZE;
-	endchunk = (sliceoffset + length - 1) / TOAST_MAX_CHUNK_SIZE;
-	numchunks = (endchunk - startchunk) + 1;
-
-	startoffset = sliceoffset % TOAST_MAX_CHUNK_SIZE;
-	endoffset = (sliceoffset + length - 1) % TOAST_MAX_CHUNK_SIZE;
-
 	/*
 	 * Open the toast relation and its indexes
 	 */
 	toastrel = table_open(toast_pointer.va_toastrelid, AccessShareLock);
 	toasttupDesc = toastrel->rd_att;
 
+	max_chunk_size = toastrel->rd_tableam->toast_max_chunk_size;
+	totalchunks = ((attrsize - 1) / max_chunk_size) + 1;
+
+	startchunk = sliceoffset / max_chunk_size;
+	endchunk = (sliceoffset + length - 1) / max_chunk_size;
+	numchunks = (endchunk - startchunk) + 1;
+
+	startoffset = sliceoffset % max_chunk_size;
+	endoffset = (sliceoffset + length - 1) % max_chunk_size;
+
 	/* Look for the valid index of toast relation */
 	validIndex = toast_open_indexes(toastrel,
 									AccessShareLock,
@@ -632,19 +636,19 @@ toast_fetch_datum_slice(struct varlena *attr, int32 sliceoffset, int32 length)
 				 RelationGetRelationName(toastrel));
 		if (residx < totalchunks - 1)
 		{
-			if (chunksize != TOAST_MAX_CHUNK_SIZE)
+			if (chunksize != max_chunk_size)
 				elog(ERROR, "unexpected chunk size %d (expected %d) in chunk %d of %d for toast value %u in %s when fetching slice",
-					 chunksize, (int) TOAST_MAX_CHUNK_SIZE,
+					 chunksize, max_chunk_size,
 					 residx, totalchunks,
 					 toast_pointer.va_valueid,
 					 RelationGetRelationName(toastrel));
 		}
 		else if (residx == totalchunks - 1)
 		{
-			if ((residx * TOAST_MAX_CHUNK_SIZE + chunksize) != attrsize)
+			if ((residx * max_chunk_size + chunksize) != attrsize)
 				elog(ERROR, "unexpected chunk size %d (expected %d) in final chunk %d for toast value %u in %s when fetching slice",
 					 chunksize,
-					 (int) (attrsize - residx * TOAST_MAX_CHUNK_SIZE),
+					 (int) (attrsize - residx * max_chunk_size),
 					 residx,
 					 toast_pointer.va_valueid,
 					 RelationGetRelationName(toastrel));
@@ -667,7 +671,7 @@ toast_fetch_datum_slice(struct varlena *attr, int32 sliceoffset, int32 length)
 			chcpyend = endoffset;
 
 		memcpy(VARDATA(result) +
-			   (residx * TOAST_MAX_CHUNK_SIZE - sliceoffset) + chcpystrt,
+			   (residx * max_chunk_size - sliceoffset) + chcpystrt,
 			   chunkdata + chcpystrt,
 			   (chcpyend - chcpystrt) + 1);
 
diff --git a/src/backend/access/common/toast_internals.c b/src/backend/access/common/toast_internals.c
index a971242490..beb303034d 100644
--- a/src/backend/access/common/toast_internals.c
+++ b/src/backend/access/common/toast_internals.c
@@ -15,9 +15,8 @@
 
 #include "access/detoast.h"
 #include "access/genam.h"
-#include "access/heapam.h"
-#include "access/heaptoast.h"
 #include "access/table.h"
+#include "access/tableam.h"
 #include "access/toast_internals.h"
 #include "access/xact.h"
 #include "catalog/catalog.h"
@@ -100,22 +99,21 @@ toast_compress_datum(Datum value)
  *	Save one single datum into the secondary relation and return
  *	a Datum reference for it.
  *
- * rel: the main relation we're working with (not the toast rel!)
+ * toastrel: the TOAST relation we're working with (not the main rel!)
+ * toastslot: a slot corresponding to 'toastrel'
+ * num_indexes, toastidxs, validIndex: as returned by toast_open_indexes
+ * toastoid: the toast OID that should be inserted into the new TOAST pointer
  * value: datum to be pushed to toast storage
  * oldexternal: if not NULL, toast pointer previously representing the datum
- * options: options to be passed to heap_insert() for toast rows
+ * options: options to be passed to table_tuple_insert() for toast rows
  * ----------
  */
 Datum
-toast_save_datum(Relation rel, Datum value,
-				 struct varlena *oldexternal, int options)
+toast_save_datum(Relation toastrel, TupleTableSlot *toastslot,
+				 int num_indexes, Relation *toastidxs, int validIndex,
+				 Oid toastoid, Datum value, struct varlena *oldexternal,
+				 int options, int max_chunk_size)
 {
-	Relation	toastrel;
-	Relation   *toastidxs;
-	HeapTuple	toasttup;
-	TupleDesc	toasttupDesc;
-	Datum		t_values[3];
-	bool		t_isnull[3];
 	CommandId	mycid = GetCurrentCommandId(true);
 	struct varlena *result;
 	struct varatt_external toast_pointer;
@@ -123,7 +121,7 @@ toast_save_datum(Relation rel, Datum value,
 	{
 		struct varlena hdr;
 		/* this is to make the union big enough for a chunk: */
-		char		data[TOAST_MAX_CHUNK_SIZE + VARHDRSZ];
+		char		data[BLCKSZ + VARHDRSZ];
 		/* ensure union is aligned well enough: */
 		int32		align_it;
 	}			chunk_data;
@@ -132,24 +130,9 @@ toast_save_datum(Relation rel, Datum value,
 	char	   *data_p;
 	int32		data_todo;
 	Pointer		dval = DatumGetPointer(value);
-	int			num_indexes;
-	int			validIndex;
 
 	Assert(!VARATT_IS_EXTERNAL(value));
-
-	/*
-	 * Open the toast relation and its indexes.  We can use the index to check
-	 * uniqueness of the OID we assign to the toasted item, even though it has
-	 * additional columns besides OID.
-	 */
-	toastrel = table_open(rel->rd_rel->reltoastrelid, RowExclusiveLock);
-	toasttupDesc = toastrel->rd_att;
-
-	/* Open all the toast indexes and look for the valid one */
-	validIndex = toast_open_indexes(toastrel,
-									RowExclusiveLock,
-									&toastidxs,
-									&num_indexes);
+	Assert(max_chunk_size <= BLCKSZ);
 
 	/*
 	 * Get the data pointer and length, and compute va_rawsize and va_extsize.
@@ -189,11 +172,11 @@ toast_save_datum(Relation rel, Datum value,
 	 *
 	 * Normally this is the actual OID of the target toast table, but during
 	 * table-rewriting operations such as CLUSTER, we have to insert the OID
-	 * of the table's real permanent toast table instead.  rd_toastoid is set
+	 * of the table's real permanent toast table instead.  toastoid is set
 	 * if we have to substitute such an OID.
 	 */
-	if (OidIsValid(rel->rd_toastoid))
-		toast_pointer.va_toastrelid = rel->rd_toastoid;
+	if (OidIsValid(toastoid))
+		toast_pointer.va_toastrelid = toastoid;
 	else
 		toast_pointer.va_toastrelid = RelationGetRelid(toastrel);
 
@@ -209,7 +192,7 @@ toast_save_datum(Relation rel, Datum value,
 	 * options have been changed), we have to pick a value ID that doesn't
 	 * conflict with either new or existing toast value OIDs.
 	 */
-	if (!OidIsValid(rel->rd_toastoid))
+	if (!OidIsValid(toastoid))
 	{
 		/* normal case: just choose an unused OID */
 		toast_pointer.va_valueid =
@@ -228,7 +211,7 @@ toast_save_datum(Relation rel, Datum value,
 			Assert(VARATT_IS_EXTERNAL_ONDISK(oldexternal));
 			/* Must copy to access aligned fields */
 			VARATT_EXTERNAL_GET_POINTER(old_toast_pointer, oldexternal);
-			if (old_toast_pointer.va_toastrelid == rel->rd_toastoid)
+			if (old_toast_pointer.va_toastrelid == toastoid)
 			{
 				/* This value came from the old toast table; reuse its OID */
 				toast_pointer.va_valueid = old_toast_pointer.va_valueid;
@@ -270,20 +253,11 @@ toast_save_datum(Relation rel, Datum value,
 					GetNewOidWithIndex(toastrel,
 									   RelationGetRelid(toastidxs[validIndex]),
 									   (AttrNumber) 1);
-			} while (toastid_valueid_exists(rel->rd_toastoid,
+			} while (toastid_valueid_exists(toastoid,
 											toast_pointer.va_valueid));
 		}
 	}
 
-	/*
-	 * Initialize constant parts of the tuple data
-	 */
-	t_values[0] = ObjectIdGetDatum(toast_pointer.va_valueid);
-	t_values[2] = PointerGetDatum(&chunk_data);
-	t_isnull[0] = false;
-	t_isnull[1] = false;
-	t_isnull[2] = false;
-
 	/*
 	 * Split up the item into chunks
 	 */
@@ -296,17 +270,22 @@ toast_save_datum(Relation rel, Datum value,
 		/*
 		 * Calculate the size of this chunk
 		 */
-		chunk_size = Min(TOAST_MAX_CHUNK_SIZE, data_todo);
+		chunk_size = Min(max_chunk_size, data_todo);
 
 		/*
 		 * Build a tuple and store it
 		 */
-		t_values[1] = Int32GetDatum(chunk_seq++);
+		toastslot->tts_values[0] = ObjectIdGetDatum(toast_pointer.va_valueid);
+		toastslot->tts_values[1] = Int32GetDatum(chunk_seq++);
 		SET_VARSIZE(&chunk_data, chunk_size + VARHDRSZ);
 		memcpy(VARDATA(&chunk_data), data_p, chunk_size);
-		toasttup = heap_form_tuple(toasttupDesc, t_values, t_isnull);
+		toastslot->tts_values[2] = PointerGetDatum(&chunk_data);
+		toastslot->tts_isnull[0] = false;
+		toastslot->tts_isnull[1] = false;
+		toastslot->tts_isnull[2] = false;
+		ExecStoreVirtualTuple(toastslot);
 
-		heap_insert(toastrel, toasttup, mycid, options, NULL);
+		table_tuple_insert(toastrel, toastslot, mycid, options, NULL);
 
 		/*
 		 * Create the index entry.  We cheat a little here by not using
@@ -323,8 +302,9 @@ toast_save_datum(Relation rel, Datum value,
 		{
 			/* Only index relations marked as ready can be updated */
 			if (toastidxs[i]->rd_index->indisready)
-				index_insert(toastidxs[i], t_values, t_isnull,
-							 &(toasttup->t_self),
+				index_insert(toastidxs[i], toastslot->tts_values,
+							 toastslot->tts_isnull,
+							 &(toastslot->tts_tid),
 							 toastrel,
 							 toastidxs[i]->rd_index->indisunique ?
 							 UNIQUE_CHECK_YES : UNIQUE_CHECK_NO,
@@ -332,9 +312,9 @@ toast_save_datum(Relation rel, Datum value,
 		}
 
 		/*
-		 * Free memory
+		 * Clear slot
 		 */
-		heap_freetuple(toasttup);
+		ExecClearTuple(toastslot);
 
 		/*
 		 * Move on to next chunk
@@ -343,12 +323,6 @@ toast_save_datum(Relation rel, Datum value,
 		data_p += chunk_size;
 	}
 
-	/*
-	 * Done - close toast relation and its indexes
-	 */
-	toast_close_indexes(toastidxs, num_indexes, RowExclusiveLock);
-	table_close(toastrel, RowExclusiveLock);
-
 	/*
 	 * Create the TOAST pointer value that we'll return
 	 */
@@ -366,35 +340,24 @@ toast_save_datum(Relation rel, Datum value,
  * ----------
  */
 void
-toast_delete_datum(Relation rel, Datum value, bool is_speculative)
+toast_delete_datum(Relation toastrel, int num_indexes, Relation *toastidxs,
+				   int validIndex, Datum value, bool is_speculative,
+				   uint32 specToken)
 {
 	struct varlena *attr = (struct varlena *) DatumGetPointer(value);
 	struct varatt_external toast_pointer;
-	Relation	toastrel;
-	Relation   *toastidxs;
 	ScanKeyData toastkey;
 	SysScanDesc toastscan;
-	HeapTuple	toasttup;
-	int			num_indexes;
-	int			validIndex;
+	TupleTableSlot *slot;
 	SnapshotData SnapshotToast;
 
-	if (!VARATT_IS_EXTERNAL_ONDISK(attr))
-		return;
+	Assert(VARATT_IS_EXTERNAL_ONDISK(attr));
 
 	/* Must copy to access aligned fields */
 	VARATT_EXTERNAL_GET_POINTER(toast_pointer, attr);
 
-	/*
-	 * Open the toast relation and its indexes
-	 */
-	toastrel = table_open(toast_pointer.va_toastrelid, RowExclusiveLock);
-
-	/* Fetch valid relation used for process */
-	validIndex = toast_open_indexes(toastrel,
-									RowExclusiveLock,
-									&toastidxs,
-									&num_indexes);
+	/* Check that caller gave us the correct TOAST relation. */
+	Assert(toast_pointer.va_toastrelid == RelationGetRelid(toastrel));
 
 	/*
 	 * Setup a scan key to find chunks with matching va_valueid
@@ -412,23 +375,19 @@ toast_delete_datum(Relation rel, Datum value, bool is_speculative)
 	init_toast_snapshot(&SnapshotToast);
 	toastscan = systable_beginscan_ordered(toastrel, toastidxs[validIndex],
 										   &SnapshotToast, 1, &toastkey);
-	while ((toasttup = systable_getnext_ordered(toastscan, ForwardScanDirection)) != NULL)
+	while ((slot = systable_getnextslot_ordered(toastscan, ForwardScanDirection)) != NULL)
 	{
 		/*
 		 * Have a chunk, delete it
 		 */
 		if (is_speculative)
-			heap_abort_speculative(toastrel, &toasttup->t_self);
+			table_tuple_complete_speculative(toastrel, slot, specToken, false);
 		else
-			simple_heap_delete(toastrel, &toasttup->t_self);
+			simple_table_tuple_delete(toastrel, &slot->tts_tid, &SnapshotToast);
 	}
 
-	/*
-	 * End scan and close relations
-	 */
+	/* End scan */
 	systable_endscan_ordered(toastscan);
-	toast_close_indexes(toastidxs, num_indexes, RowExclusiveLock);
-	table_close(toastrel, RowExclusiveLock);
 }
 
 /* ----------
diff --git a/src/backend/access/heap/heapam.c b/src/backend/access/heap/heapam.c
index ce141b734b..d0f05aada3 100644
--- a/src/backend/access/heap/heapam.c
+++ b/src/backend/access/heap/heapam.c
@@ -2814,7 +2814,7 @@ l1:
 		Assert(!HeapTupleHasExternal(&tp));
 	}
 	else if (HeapTupleHasExternal(&tp))
-		toast_delete(relation, &tp, false);
+		toast_delete(relation, &tp, false, 0);
 
 	/*
 	 * Mark tuple for invalidation from system caches at next command
@@ -5568,7 +5568,7 @@ heap_finish_speculative(Relation relation, ItemPointer tid)
  * confirmation records.
  */
 void
-heap_abort_speculative(Relation relation, ItemPointer tid)
+heap_abort_speculative(Relation relation, ItemPointer tid, uint32 specToken)
 {
 	TransactionId xid = GetCurrentTransactionId();
 	ItemId		lp;
@@ -5677,7 +5677,7 @@ heap_abort_speculative(Relation relation, ItemPointer tid)
 	if (HeapTupleHasExternal(&tp))
 	{
 		Assert(!IsToastRelation(relation));
-		toast_delete(relation, &tp, true);
+		toast_delete(relation, &tp, true, specToken);
 	}
 
 	/*
diff --git a/src/backend/access/heap/heapam_handler.c b/src/backend/access/heap/heapam_handler.c
index 72c8bfcaf1..df710e8212 100644
--- a/src/backend/access/heap/heapam_handler.c
+++ b/src/backend/access/heap/heapam_handler.c
@@ -30,6 +30,7 @@
 #include "access/rewriteheap.h"
 #include "access/tableam.h"
 #include "access/tsmapi.h"
+#include "access/heaptoast.h"
 #include "access/xact.h"
 #include "catalog/catalog.h"
 #include "catalog/index.h"
@@ -295,7 +296,7 @@ heapam_tuple_complete_speculative(Relation relation, TupleTableSlot *slot,
 	if (succeeded)
 		heap_finish_speculative(relation, &slot->tts_tid);
 	else
-		heap_abort_speculative(relation, &slot->tts_tid);
+		heap_abort_speculative(relation, &slot->tts_tid, specToken);
 
 	if (shouldFree)
 		pfree(tuple);
@@ -2062,6 +2063,15 @@ heapam_relation_needs_toast_table(Relation rel)
 	return (tuple_length > TOAST_TUPLE_THRESHOLD);
 }
 
+/*
+ * TOAST tables for heap relations are just heap relations.
+ */
+static Oid
+heapam_relation_toast_am(Relation rel)
+{
+	return rel->rd_rel->relam;
+}
+
 
 /* ------------------------------------------------------------------------
  * Planner related callbacks for the heap AM
@@ -2646,6 +2656,8 @@ static const TableAmRoutine heapam_methods = {
 
 	.relation_size = heapam_relation_size,
 	.relation_needs_toast_table = heapam_relation_needs_toast_table,
+	.relation_toast_am = heapam_relation_toast_am,
+	.toast_max_chunk_size = TOAST_MAX_CHUNK_SIZE,
 
 	.relation_estimate_size = heapam_estimate_rel_size,
 
diff --git a/src/backend/access/heap/heaptoast.c b/src/backend/access/heap/heaptoast.c
index fbf9294598..c0acefc97e 100644
--- a/src/backend/access/heap/heaptoast.c
+++ b/src/backend/access/heap/heaptoast.c
@@ -38,7 +38,8 @@
  * ----------
  */
 void
-toast_delete(Relation rel, HeapTuple oldtup, bool is_speculative)
+toast_delete(Relation rel, HeapTuple oldtup, bool is_speculative,
+			 uint32 specToken)
 {
 	TupleDesc	tupleDesc;
 	Datum		toast_values[MaxHeapAttributeNumber];
@@ -68,7 +69,8 @@ toast_delete(Relation rel, HeapTuple oldtup, bool is_speculative)
 	heap_deform_tuple(oldtup, tupleDesc, toast_values, toast_isnull);
 
 	/* Do the real work. */
-	toast_delete_external(rel, toast_values, toast_isnull, is_speculative);
+	toast_delete_external(rel, toast_values, toast_isnull, is_speculative,
+						  specToken);
 }
 
 
@@ -151,6 +153,8 @@ toast_insert_or_update(Relation rel, HeapTuple newtup, HeapTuple oldtup,
 		ttc.ttc_oldvalues = toast_oldvalues;
 		ttc.ttc_oldisnull = toast_oldisnull;
 	}
+	ttc.ttc_toastrel = NULL;
+	ttc.ttc_toastslot = NULL;
 	ttc.ttc_attr = toast_attr;
 	toast_tuple_init(&ttc);
 
@@ -207,7 +211,8 @@ toast_insert_or_update(Relation rel, HeapTuple newtup, HeapTuple oldtup,
 		 */
 		if (toast_attr[biggest_attno].tai_size > maxDataLen &&
 			rel->rd_rel->reltoastrelid != InvalidOid)
-			toast_tuple_externalize(&ttc, biggest_attno, options);
+			toast_tuple_externalize(&ttc, biggest_attno, options,
+									TOAST_MAX_CHUNK_SIZE);
 	}
 
 	/*
@@ -224,7 +229,8 @@ toast_insert_or_update(Relation rel, HeapTuple newtup, HeapTuple oldtup,
 		biggest_attno = toast_tuple_find_biggest_attribute(&ttc, false, false);
 		if (biggest_attno < 0)
 			break;
-		toast_tuple_externalize(&ttc, biggest_attno, options);
+		toast_tuple_externalize(&ttc, biggest_attno, options,
+								TOAST_MAX_CHUNK_SIZE);
 	}
 
 	/*
@@ -260,7 +266,8 @@ toast_insert_or_update(Relation rel, HeapTuple newtup, HeapTuple oldtup,
 		if (biggest_attno < 0)
 			break;
 
-		toast_tuple_externalize(&ttc, biggest_attno, options);
+		toast_tuple_externalize(&ttc, biggest_attno, options,
+								TOAST_MAX_CHUNK_SIZE);
 	}
 
 	/*
@@ -323,7 +330,7 @@ toast_insert_or_update(Relation rel, HeapTuple newtup, HeapTuple oldtup,
 	else
 		result_tuple = newtup;
 
-	toast_tuple_cleanup(&ttc);
+	toast_tuple_cleanup(&ttc, true);
 
 	return result_tuple;
 }
diff --git a/src/backend/access/index/genam.c b/src/backend/access/index/genam.c
index 42aaa5bad6..4264bad4e7 100644
--- a/src/backend/access/index/genam.c
+++ b/src/backend/access/index/genam.c
@@ -642,6 +642,26 @@ systable_getnext_ordered(SysScanDesc sysscan, ScanDirection direction)
 	return htup;
 }
 
+/*
+ * systable_getnextslot_ordered
+ *
+ * Return a slot containing the next tuple from an ordered catalog scan,
+ * or NULL if there are no more tuples.
+ */
+TupleTableSlot *
+systable_getnextslot_ordered(SysScanDesc sysscan, ScanDirection direction)
+{
+	Assert(sysscan->irel);
+	if (!index_getnext_slot(sysscan->iscan, direction, sysscan->slot))
+		return NULL;
+
+	/* See notes in systable_getnext */
+	if (sysscan->iscan->xs_recheck)
+		elog(ERROR, "system catalog scans with lossy index conditions are not implemented");
+
+	return sysscan->slot;
+}
+
 /*
  * systable_endscan_ordered --- close scan, release resources
  */
diff --git a/src/backend/access/table/toast_helper.c b/src/backend/access/table/toast_helper.c
index 7532b4f865..e33918a7f4 100644
--- a/src/backend/access/table/toast_helper.c
+++ b/src/backend/access/table/toast_helper.c
@@ -17,6 +17,7 @@
 #include "access/detoast.h"
 #include "access/table.h"
 #include "access/toast_helper.h"
+#include "access/tableam.h"
 #include "access/toast_internals.h"
 
 /*
@@ -247,26 +248,49 @@ toast_tuple_try_compression(ToastTupleContext *ttc, int attribute)
  * Move an attribute to external storage.
  */
 void
-toast_tuple_externalize(ToastTupleContext *ttc, int attribute, int options)
+toast_tuple_externalize(ToastTupleContext *ttc, int attribute, int options,
+						int max_chunk_size)
 {
 	Datum	   *value = &ttc->ttc_values[attribute];
 	Datum		old_value = *value;
 	ToastAttrInfo *attr = &ttc->ttc_attr[attribute];
 
-	attr->tai_colflags |= TOASTCOL_IGNORE;
-	*value = toast_save_datum(ttc->ttc_rel, old_value, attr->tai_oldexternal,
-							  options);
+	/* Initialize for TOAST table access, if not yet done. */
+	if (ttc->ttc_toastrel == NULL)
+	{
+		ttc->ttc_toastrel =
+			table_open(ttc->ttc_rel->rd_rel->reltoastrelid, RowExclusiveLock);
+		ttc->ttc_validtoastidx = toast_open_indexes(ttc->ttc_toastrel,
+													RowExclusiveLock,
+													&ttc->ttc_toastidxs,
+													&ttc->ttc_ntoastidxs);
+	}
+	if (ttc->ttc_toastslot == NULL)
+		ttc->ttc_toastslot = table_slot_create(ttc->ttc_toastrel, NULL);
+
+	/* Do the real work. */
+	*value = toast_save_datum(ttc->ttc_toastrel, ttc->ttc_toastslot,
+							  ttc->ttc_ntoastidxs, ttc->ttc_toastidxs,
+							  ttc->ttc_validtoastidx,
+							  ttc->ttc_rel->rd_toastoid,
+							  old_value, attr->tai_oldexternal,
+							  options, max_chunk_size);
+
+	/* Update bookkeeping information. */
 	if ((attr->tai_colflags & TOASTCOL_NEEDS_FREE) != 0)
 		pfree(DatumGetPointer(old_value));
-	attr->tai_colflags |= TOASTCOL_NEEDS_FREE;
+	attr->tai_colflags |= (TOASTCOL_NEEDS_FREE | TOASTCOL_IGNORE);
 	ttc->ttc_flags |= (TOAST_NEEDS_CHANGE | TOAST_NEEDS_FREE);
 }
 
 /*
  * Perform appropriate cleanup after one tuple has been subjected to TOAST.
+ *
+ * Pass cleanup_toastrel as true to destroy and clear ttc_toastrel and
+ * ttc_toastslot, or false if caller will do it.
  */
 void
-toast_tuple_cleanup(ToastTupleContext *ttc)
+toast_tuple_cleanup(ToastTupleContext *ttc, bool cleanup_toastrel)
 {
 	TupleDesc	tupleDesc = ttc->ttc_rel->rd_att;
 	int			numAttrs = tupleDesc->natts;
@@ -294,14 +318,46 @@ toast_tuple_cleanup(ToastTupleContext *ttc)
 	{
 		int			i;
 
+		/* Initialize for TOAST table access, if not yet done. */
+		if (ttc->ttc_toastrel == NULL)
+		{
+			ttc->ttc_toastrel =
+				table_open(ttc->ttc_rel->rd_rel->reltoastrelid,
+						   RowExclusiveLock);
+			ttc->ttc_validtoastidx = toast_open_indexes(ttc->ttc_toastrel,
+														RowExclusiveLock,
+														&ttc->ttc_toastidxs,
+														&ttc->ttc_ntoastidxs);
+		}
+
+		/* Delete those attributes which require it. */
 		for (i = 0; i < numAttrs; i++)
 		{
 			ToastAttrInfo *attr = &ttc->ttc_attr[i];
 
 			if ((attr->tai_colflags & TOASTCOL_NEEDS_DELETE_OLD) != 0)
-				toast_delete_datum(ttc->ttc_rel, ttc->ttc_oldvalues[i], false);
+				toast_delete_datum(ttc->ttc_toastrel, ttc->ttc_ntoastidxs,
+								   ttc->ttc_toastidxs, ttc->ttc_validtoastidx,
+								   ttc->ttc_oldvalues[i], false, 0);
 		}
 	}
+
+	/*
+	 * Close toast table and indexes and drop slot, if previously done and
+	 * if caller requests it.
+	 */
+	if (cleanup_toastrel && ttc->ttc_toastrel != NULL)
+	{
+		if (ttc->ttc_toastslot != NULL)
+		{
+			ExecDropSingleTupleTableSlot(ttc->ttc_toastslot);
+			ttc->ttc_toastslot = NULL;
+		}
+		toast_close_indexes(ttc->ttc_toastidxs, ttc->ttc_ntoastidxs,
+							RowExclusiveLock);
+		table_close(ttc->ttc_toastrel, RowExclusiveLock);
+		ttc->ttc_toastrel = NULL;
+	}
 }
 
 /*
@@ -310,22 +366,43 @@ toast_tuple_cleanup(ToastTupleContext *ttc)
  */
 void
 toast_delete_external(Relation rel, Datum *values, bool *isnull,
-					  bool is_speculative)
+					  bool is_speculative, uint32 specToken)
 {
 	TupleDesc	tupleDesc = rel->rd_att;
 	int			numAttrs = tupleDesc->natts;
 	int			i;
+	Relation    toastrel = NULL;
+	Relation   *toastidxs;
+	int         num_indexes;
+	int         validIndex;
 
 	for (i = 0; i < numAttrs; i++)
 	{
-		if (TupleDescAttr(tupleDesc, i)->attlen == -1)
-		{
-			Datum		value = values[i];
+		Datum	value;
+
+		if (isnull[i] || TupleDescAttr(tupleDesc, i)->attlen != -1)
+			continue;
+
+		value = values[i];
+		if (!VARATT_IS_EXTERNAL_ONDISK(PointerGetDatum(value)))
+			continue;
 
-			if (isnull[i])
-				continue;
-			else if (VARATT_IS_EXTERNAL_ONDISK(PointerGetDatum(value)))
-				toast_delete_datum(rel, value, is_speculative);
+		/* Initialize for TOAST table access, if not yet done. */
+		if (toastrel == NULL)
+		{
+			toastrel = table_open(rel->rd_rel->reltoastrelid,
+								  RowExclusiveLock);
+			validIndex = toast_open_indexes(toastrel, RowExclusiveLock,
+											&toastidxs, &num_indexes);
 		}
+
+		toast_delete_datum(toastrel, num_indexes, toastidxs, validIndex,
+						   value, is_speculative, specToken);
+	}
+
+	if (toastrel != NULL)
+	{
+		toast_close_indexes(toastidxs, num_indexes, RowExclusiveLock);
+		table_close(toastrel, RowExclusiveLock);
 	}
 }
diff --git a/src/backend/catalog/toasting.c b/src/backend/catalog/toasting.c
index de6282a667..f082463bf6 100644
--- a/src/backend/catalog/toasting.c
+++ b/src/backend/catalog/toasting.c
@@ -258,7 +258,7 @@ create_toast_table(Relation rel, Oid toastOid, Oid toastIndexOid,
 										   toast_typid,
 										   InvalidOid,
 										   rel->rd_rel->relowner,
-										   rel->rd_rel->relam,
+										   table_relation_toast_am(rel),
 										   tupdesc,
 										   NIL,
 										   RELKIND_TOASTVALUE,
diff --git a/src/include/access/genam.h b/src/include/access/genam.h
index 8c053be2ca..a8f5076420 100644
--- a/src/include/access/genam.h
+++ b/src/include/access/genam.h
@@ -21,8 +21,9 @@
 #include "utils/relcache.h"
 #include "utils/snapshot.h"
 
-/* We don't want this file to depend on execnodes.h. */
+/* We don't want this file to depend on execnodes.h or tuptable.h. */
 struct IndexInfo;
+struct TupleTableSlot;
 
 /*
  * Struct for statistics returned by ambuild
@@ -212,6 +213,8 @@ extern SysScanDesc systable_beginscan_ordered(Relation heapRelation,
 											  int nkeys, ScanKey key);
 extern HeapTuple systable_getnext_ordered(SysScanDesc sysscan,
 										  ScanDirection direction);
+extern struct TupleTableSlot *systable_getnextslot_ordered(SysScanDesc sysscan,
+														   ScanDirection direction);
 extern void systable_endscan_ordered(SysScanDesc sysscan);
 
 #endif							/* GENAM_H */
diff --git a/src/include/access/heapam.h b/src/include/access/heapam.h
index 858bcb6bc9..6ee0c6efa7 100644
--- a/src/include/access/heapam.h
+++ b/src/include/access/heapam.h
@@ -143,7 +143,8 @@ extern TM_Result heap_delete(Relation relation, ItemPointer tid,
 							 CommandId cid, Snapshot crosscheck, bool wait,
 							 struct TM_FailureData *tmfd, bool changingPart);
 extern void heap_finish_speculative(Relation relation, ItemPointer tid);
-extern void heap_abort_speculative(Relation relation, ItemPointer tid);
+extern void heap_abort_speculative(Relation relation, ItemPointer tid,
+					   uint32 specToken);
 extern TM_Result heap_update(Relation relation, ItemPointer otid,
 							 HeapTuple newtup,
 							 CommandId cid, Snapshot crosscheck, bool wait,
diff --git a/src/include/access/heaptoast.h b/src/include/access/heaptoast.h
index bf02d2c600..07d36ac968 100644
--- a/src/include/access/heaptoast.h
+++ b/src/include/access/heaptoast.h
@@ -104,7 +104,8 @@ extern HeapTuple toast_insert_or_update(Relation rel,
  *	Called by heap_delete().
  * ----------
  */
-extern void toast_delete(Relation rel, HeapTuple oldtup, bool is_speculative);
+extern void toast_delete(Relation rel, HeapTuple oldtup,
+			 bool is_speculative, uint32 specToken);
 
 /* ----------
  * toast_flatten_tuple -
diff --git a/src/include/access/tableam.h b/src/include/access/tableam.h
index fd07773b74..bf0192f976 100644
--- a/src/include/access/tableam.h
+++ b/src/include/access/tableam.h
@@ -581,6 +581,27 @@ typedef struct TableAmRoutine
 	 */
 	bool		(*relation_needs_toast_table) (Relation rel);
 
+	/*
+	 * This callback should return the OID of the table AM that implements
+	 * TOAST tables for this AM.  If the relation_needs_toast_table callback
+	 * always returns false, this callback is not required.
+	 */
+	Oid		    (*relation_toast_am) (Relation rel);
+
+	/*
+	 * If this table AM can be used to implement a TOAST table, the following
+	 * field should be set to the maximum number of bytes that can be stored
+	 * in a single TOAST chunk.  It must not be set to a value greater than
+	 * BLCKSZ.  If this table AM is not used to implement a TOAST table, this
+	 * value is ignored.
+	 *
+	 * (Note that there is no requirement that the TOAST table be implemented
+	 * using the same AM as the table to which it is attached.  If this AM
+	 * has TOAST tables but uses some other AM to implement them, this value
+	 * is ignored; it is a property of the TOAST table, not the parent table.)
+	 */
+	int			toast_max_chunk_size;
+
 
 	/* ------------------------------------------------------------------------
 	 * Planner related functions.
@@ -1604,6 +1625,16 @@ table_relation_needs_toast_table(Relation rel)
 	return rel->rd_tableam->relation_needs_toast_table(rel);
 }
 
+/*
+ * Return the OID of the AM that should be used to implement the TOAST table
+ * for this relation.
+ */
+static inline Oid
+table_relation_toast_am(Relation rel)
+{
+	return rel->rd_tableam->relation_toast_am(rel);
+}
+
 
 /* ----------------------------------------------------------------------------
  * Planner related functionality
diff --git a/src/include/access/toast_helper.h b/src/include/access/toast_helper.h
index 7cefacb0ea..cfb4ae0385 100644
--- a/src/include/access/toast_helper.h
+++ b/src/include/access/toast_helper.h
@@ -14,6 +14,7 @@
 #ifndef TOAST_HELPER_H
 #define TOAST_HELPER_H
 
+#include "executor/tuptable.h"
 #include "utils/rel.h"
 
 /*
@@ -51,6 +52,17 @@ typedef struct
 	Datum	   *ttc_oldvalues;	/* values from previous tuple */
 	bool	   *ttc_oldisnull;	/* null flags from previous tuple */
 
+	/*
+	 * Before calling toast_tuple_init, the caller should either initialize
+	 * all of these fields or else set ttc_toastrel and ttc_toastslot to NULL.
+	 * In the latter case, all of the fields will be initialized as required.
+	 */
+	Relation	ttc_toastrel;	/* the toast table for the relation */
+	TupleTableSlot *ttc_toastslot;	/* a slot for the toast table */
+	int			ttc_ntoastidxs; /* # of toast indexes for toast table */
+	Relation   *ttc_toastidxs;	/* array of those toast indexes */
+	int			ttc_validtoastidx;	/* the valid toast index */
+
 	/*
 	 * Before calling toast_tuple_init, the caller should set tts_attr to
 	 * point to an array of ToastAttrInfo structures of a length equal to
@@ -106,10 +118,10 @@ extern int	toast_tuple_find_biggest_attribute(ToastTupleContext *ttc,
 											   bool check_main);
 extern void toast_tuple_try_compression(ToastTupleContext *ttc, int attribute);
 extern void toast_tuple_externalize(ToastTupleContext *ttc, int attribute,
-									int options);
-extern void toast_tuple_cleanup(ToastTupleContext *ttc);
+									int options, int max_chunk_size);
+extern void toast_tuple_cleanup(ToastTupleContext *ttc, bool cleanup_toastrel);
 
 extern void toast_delete_external(Relation rel, Datum *values, bool *isnull,
-								  bool is_speculative);
+								  bool is_speculative, uint32 specToken);
 
 #endif
diff --git a/src/include/access/toast_internals.h b/src/include/access/toast_internals.h
index 494b07a4b1..96f61baf80 100644
--- a/src/include/access/toast_internals.h
+++ b/src/include/access/toast_internals.h
@@ -16,6 +16,8 @@
 #include "utils/relcache.h"
 #include "utils/snapshot.h"
 
+struct TupleTableSlot;
+
 /*
  *	The information at the start of the compressed toast data.
  */
@@ -39,9 +41,16 @@ typedef struct toast_compress_header
 extern Datum toast_compress_datum(Datum value);
 extern Oid	toast_get_valid_index(Oid toastoid, LOCKMODE lock);
 
-extern void toast_delete_datum(Relation rel, Datum value, bool is_speculative);
-extern Datum toast_save_datum(Relation rel, Datum value,
-							  struct varlena *oldexternal, int options);
+extern void toast_delete_datum(Relation toastrel, int num_indexes,
+							   Relation *toastidxs, int validIndex,
+							   Datum value, bool is_speculative,
+							   uint32 specToken);
+extern Datum toast_save_datum(Relation toastrel,
+							  struct TupleTableSlot *toastslot,
+							  int num_indexes, Relation *toastidxs,
+							  int validIndex, Oid toastoid,
+							  Datum value, struct varlena *oldexternal,
+							  int options, int max_chunk_size);
 
 extern int	toast_open_indexes(Relation toastrel,
 							   LOCKMODE lock,
-- 
2.17.2 (Apple Git-113)

From 94bad91ad572e803f2504d287fcbf7e191f6c083 Mon Sep 17 00:00:00 2001
From: Robert Haas <rhaas@postgresql.org>
Date: Mon, 8 Jul 2019 12:02:16 -0400
Subject: [PATCH 2/4] Create an API for inserting and deleting rows in TOAST
 tables.

This moves much of the non-heap-specific logic from toast_delete and
toast_insert_or_update into a helper functions accessible via a new
header, toast_helper.h.  Using the functions in this module, a table
AM can implement creation and deletion of TOAST table rows with
much less code duplication than was possible heretofore.  Some
table AMs won't want to use the TOAST logic at all, but for those
that do this will make that easier.

Discussion: http://postgr.es/m/CA+TgmoZv-=2iWM4jcw5ZhJeL18HF96+W1yJeYrnGMYdkFFnEpQ@mail.gmail.com
---
 src/backend/access/heap/heaptoast.c     | 400 +++---------------------
 src/backend/access/table/Makefile       |   2 +-
 src/backend/access/table/toast_helper.c | 331 ++++++++++++++++++++
 src/include/access/toast_helper.h       | 115 +++++++
 src/tools/pgindent/typedefs.list        |   2 +
 5 files changed, 493 insertions(+), 357 deletions(-)
 create mode 100644 src/backend/access/table/toast_helper.c
 create mode 100644 src/include/access/toast_helper.h

diff --git a/src/backend/access/heap/heaptoast.c b/src/backend/access/heap/heaptoast.c
index 5d105e3517..fbf9294598 100644
--- a/src/backend/access/heap/heaptoast.c
+++ b/src/backend/access/heap/heaptoast.c
@@ -27,6 +27,7 @@
 #include "access/detoast.h"
 #include "access/heapam.h"
 #include "access/heaptoast.h"
+#include "access/toast_helper.h"
 #include "access/toast_internals.h"
 
 
@@ -40,8 +41,6 @@ void
 toast_delete(Relation rel, HeapTuple oldtup, bool is_speculative)
 {
 	TupleDesc	tupleDesc;
-	int			numAttrs;
-	int			i;
 	Datum		toast_values[MaxHeapAttributeNumber];
 	bool		toast_isnull[MaxHeapAttributeNumber];
 
@@ -64,27 +63,12 @@ toast_delete(Relation rel, HeapTuple oldtup, bool is_speculative)
 	 * least one varlena column, by the way.)
 	 */
 	tupleDesc = rel->rd_att;
-	numAttrs = tupleDesc->natts;
 
-	Assert(numAttrs <= MaxHeapAttributeNumber);
+	Assert(tupleDesc->natts <= MaxHeapAttributeNumber);
 	heap_deform_tuple(oldtup, tupleDesc, toast_values, toast_isnull);
 
-	/*
-	 * Check for external stored attributes and delete them from the secondary
-	 * relation.
-	 */
-	for (i = 0; i < numAttrs; i++)
-	{
-		if (TupleDescAttr(tupleDesc, i)->attlen == -1)
-		{
-			Datum		value = toast_values[i];
-
-			if (toast_isnull[i])
-				continue;
-			else if (VARATT_IS_EXTERNAL_ONDISK(PointerGetDatum(value)))
-				toast_delete_datum(rel, value, is_speculative);
-		}
-	}
+	/* Do the real work. */
+	toast_delete_external(rel, toast_values, toast_isnull, is_speculative);
 }
 
 
@@ -113,25 +97,16 @@ toast_insert_or_update(Relation rel, HeapTuple newtup, HeapTuple oldtup,
 	HeapTuple	result_tuple;
 	TupleDesc	tupleDesc;
 	int			numAttrs;
-	int			i;
-
-	bool		need_change = false;
-	bool		need_free = false;
-	bool		need_delold = false;
-	bool		has_nulls = false;
 
 	Size		maxDataLen;
 	Size		hoff;
 
-	char		toast_action[MaxHeapAttributeNumber];
 	bool		toast_isnull[MaxHeapAttributeNumber];
 	bool		toast_oldisnull[MaxHeapAttributeNumber];
 	Datum		toast_values[MaxHeapAttributeNumber];
 	Datum		toast_oldvalues[MaxHeapAttributeNumber];
-	struct varlena *toast_oldexternal[MaxHeapAttributeNumber];
-	int32		toast_sizes[MaxHeapAttributeNumber];
-	bool		toast_free[MaxHeapAttributeNumber];
-	bool		toast_delold[MaxHeapAttributeNumber];
+	ToastAttrInfo toast_attr[MaxHeapAttributeNumber];
+	ToastTupleContext ttc;
 
 	/*
 	 * Ignore the INSERT_SPECULATIVE option. Speculative insertions/super
@@ -160,129 +135,24 @@ toast_insert_or_update(Relation rel, HeapTuple newtup, HeapTuple oldtup,
 		heap_deform_tuple(oldtup, tupleDesc, toast_oldvalues, toast_oldisnull);
 
 	/* ----------
-	 * Then collect information about the values given
-	 *
-	 * NOTE: toast_action[i] can have these values:
-	 *		' '		default handling
-	 *		'p'		already processed --- don't touch it
-	 *		'x'		incompressible, but OK to move off
-	 *
-	 * NOTE: toast_sizes[i] is only made valid for varlena attributes with
-	 *		toast_action[i] different from 'p'.
+	 * Prepare for toasting
 	 * ----------
 	 */
-	memset(toast_action, ' ', numAttrs * sizeof(char));
-	memset(toast_oldexternal, 0, numAttrs * sizeof(struct varlena *));
-	memset(toast_free, 0, numAttrs * sizeof(bool));
-	memset(toast_delold, 0, numAttrs * sizeof(bool));
-
-	for (i = 0; i < numAttrs; i++)
+	ttc.ttc_rel = rel;
+	ttc.ttc_values = toast_values;
+	ttc.ttc_isnull = toast_isnull;
+	if (oldtup == NULL)
 	{
-		Form_pg_attribute att = TupleDescAttr(tupleDesc, i);
-		struct varlena *old_value;
-		struct varlena *new_value;
-
-		if (oldtup != NULL)
-		{
-			/*
-			 * For UPDATE get the old and new values of this attribute
-			 */
-			old_value = (struct varlena *) DatumGetPointer(toast_oldvalues[i]);
-			new_value = (struct varlena *) DatumGetPointer(toast_values[i]);
-
-			/*
-			 * If the old value is stored on disk, check if it has changed so
-			 * we have to delete it later.
-			 */
-			if (att->attlen == -1 && !toast_oldisnull[i] &&
-				VARATT_IS_EXTERNAL_ONDISK(old_value))
-			{
-				if (toast_isnull[i] || !VARATT_IS_EXTERNAL_ONDISK(new_value) ||
-					memcmp((char *) old_value, (char *) new_value,
-						   VARSIZE_EXTERNAL(old_value)) != 0)
-				{
-					/*
-					 * The old external stored value isn't needed any more
-					 * after the update
-					 */
-					toast_delold[i] = true;
-					need_delold = true;
-				}
-				else
-				{
-					/*
-					 * This attribute isn't changed by this update so we reuse
-					 * the original reference to the old value in the new
-					 * tuple.
-					 */
-					toast_action[i] = 'p';
-					continue;
-				}
-			}
-		}
-		else
-		{
-			/*
-			 * For INSERT simply get the new value
-			 */
-			new_value = (struct varlena *) DatumGetPointer(toast_values[i]);
-		}
-
-		/*
-		 * Handle NULL attributes
-		 */
-		if (toast_isnull[i])
-		{
-			toast_action[i] = 'p';
-			has_nulls = true;
-			continue;
-		}
-
-		/*
-		 * Now look at varlena attributes
-		 */
-		if (att->attlen == -1)
-		{
-			/*
-			 * If the table's attribute says PLAIN always, force it so.
-			 */
-			if (att->attstorage == 'p')
-				toast_action[i] = 'p';
-
-			/*
-			 * We took care of UPDATE above, so any external value we find
-			 * still in the tuple must be someone else's that we cannot reuse
-			 * (this includes the case of an out-of-line in-memory datum).
-			 * Fetch it back (without decompression, unless we are forcing
-			 * PLAIN storage).  If necessary, we'll push it out as a new
-			 * external value below.
-			 */
-			if (VARATT_IS_EXTERNAL(new_value))
-			{
-				toast_oldexternal[i] = new_value;
-				if (att->attstorage == 'p')
-					new_value = heap_tuple_untoast_attr(new_value);
-				else
-					new_value = heap_tuple_fetch_attr(new_value);
-				toast_values[i] = PointerGetDatum(new_value);
-				toast_free[i] = true;
-				need_change = true;
-				need_free = true;
-			}
-
-			/*
-			 * Remember the size of this attribute
-			 */
-			toast_sizes[i] = VARSIZE_ANY(new_value);
-		}
-		else
-		{
-			/*
-			 * Not a varlena attribute, plain storage always
-			 */
-			toast_action[i] = 'p';
-		}
+		ttc.ttc_oldvalues = NULL;
+		ttc.ttc_oldisnull = NULL;
 	}
+	else
+	{
+		ttc.ttc_oldvalues = toast_oldvalues;
+		ttc.ttc_oldisnull = toast_oldisnull;
+	}
+	ttc.ttc_attr = toast_attr;
+	toast_tuple_init(&ttc);
 
 	/* ----------
 	 * Compress and/or save external until data fits into target length
@@ -297,7 +167,7 @@ toast_insert_or_update(Relation rel, HeapTuple newtup, HeapTuple oldtup,
 
 	/* compute header overhead --- this should match heap_form_tuple() */
 	hoff = SizeofHeapTupleHeader;
-	if (has_nulls)
+	if ((ttc.ttc_flags & TOAST_HAS_NULLS) != 0)
 		hoff += BITMAPLEN(numAttrs);
 	hoff = MAXALIGN(hoff);
 	/* now convert to a limit on the tuple data size */
@@ -310,66 +180,21 @@ toast_insert_or_update(Relation rel, HeapTuple newtup, HeapTuple oldtup,
 	while (heap_compute_data_size(tupleDesc,
 								  toast_values, toast_isnull) > maxDataLen)
 	{
-		int			biggest_attno = -1;
-		int32		biggest_size = MAXALIGN(TOAST_POINTER_SIZE);
-		Datum		old_value;
-		Datum		new_value;
-
-		/*
-		 * Search for the biggest yet unprocessed internal attribute
-		 */
-		for (i = 0; i < numAttrs; i++)
-		{
-			Form_pg_attribute att = TupleDescAttr(tupleDesc, i);
-
-			if (toast_action[i] != ' ')
-				continue;
-			if (VARATT_IS_EXTERNAL(DatumGetPointer(toast_values[i])))
-				continue;		/* can't happen, toast_action would be 'p' */
-			if (VARATT_IS_COMPRESSED(DatumGetPointer(toast_values[i])))
-				continue;
-			if (att->attstorage != 'x' && att->attstorage != 'e')
-				continue;
-			if (toast_sizes[i] > biggest_size)
-			{
-				biggest_attno = i;
-				biggest_size = toast_sizes[i];
-			}
-		}
+		int			biggest_attno;
 
+		biggest_attno = toast_tuple_find_biggest_attribute(&ttc, true, false);
 		if (biggest_attno < 0)
 			break;
 
 		/*
 		 * Attempt to compress it inline, if it has attstorage 'x'
 		 */
-		i = biggest_attno;
-		if (TupleDescAttr(tupleDesc, i)->attstorage == 'x')
-		{
-			old_value = toast_values[i];
-			new_value = toast_compress_datum(old_value);
-
-			if (DatumGetPointer(new_value) != NULL)
-			{
-				/* successful compression */
-				if (toast_free[i])
-					pfree(DatumGetPointer(old_value));
-				toast_values[i] = new_value;
-				toast_free[i] = true;
-				toast_sizes[i] = VARSIZE(DatumGetPointer(toast_values[i]));
-				need_change = true;
-				need_free = true;
-			}
-			else
-			{
-				/* incompressible, ignore on subsequent compression passes */
-				toast_action[i] = 'x';
-			}
-		}
+		if (TupleDescAttr(tupleDesc, biggest_attno)->attstorage == 'x')
+			toast_tuple_try_compression(&ttc, biggest_attno);
 		else
 		{
 			/* has attstorage 'e', ignore on subsequent compression passes */
-			toast_action[i] = 'x';
+			toast_attr[biggest_attno].tai_colflags |= TOASTCOL_INCOMPRESSIBLE;
 		}
 
 		/*
@@ -380,72 +205,26 @@ toast_insert_or_update(Relation rel, HeapTuple newtup, HeapTuple oldtup,
 		 *
 		 * XXX maybe the threshold should be less than maxDataLen?
 		 */
-		if (toast_sizes[i] > maxDataLen &&
+		if (toast_attr[biggest_attno].tai_size > maxDataLen &&
 			rel->rd_rel->reltoastrelid != InvalidOid)
-		{
-			old_value = toast_values[i];
-			toast_action[i] = 'p';
-			toast_values[i] = toast_save_datum(rel, toast_values[i],
-											   toast_oldexternal[i], options);
-			if (toast_free[i])
-				pfree(DatumGetPointer(old_value));
-			toast_free[i] = true;
-			need_change = true;
-			need_free = true;
-		}
+			toast_tuple_externalize(&ttc, biggest_attno, options);
 	}
 
 	/*
 	 * Second we look for attributes of attstorage 'x' or 'e' that are still
-	 * inline.  But skip this if there's no toast table to push them to.
+	 * inline, and make them external.  But skip this if there's no toast
+	 * table to push them to.
 	 */
 	while (heap_compute_data_size(tupleDesc,
 								  toast_values, toast_isnull) > maxDataLen &&
 		   rel->rd_rel->reltoastrelid != InvalidOid)
 	{
-		int			biggest_attno = -1;
-		int32		biggest_size = MAXALIGN(TOAST_POINTER_SIZE);
-		Datum		old_value;
-
-		/*------
-		 * Search for the biggest yet inlined attribute with
-		 * attstorage equals 'x' or 'e'
-		 *------
-		 */
-		for (i = 0; i < numAttrs; i++)
-		{
-			Form_pg_attribute att = TupleDescAttr(tupleDesc, i);
-
-			if (toast_action[i] == 'p')
-				continue;
-			if (VARATT_IS_EXTERNAL(DatumGetPointer(toast_values[i])))
-				continue;		/* can't happen, toast_action would be 'p' */
-			if (att->attstorage != 'x' && att->attstorage != 'e')
-				continue;
-			if (toast_sizes[i] > biggest_size)
-			{
-				biggest_attno = i;
-				biggest_size = toast_sizes[i];
-			}
-		}
+		int			biggest_attno;
 
+		biggest_attno = toast_tuple_find_biggest_attribute(&ttc, false, false);
 		if (biggest_attno < 0)
 			break;
-
-		/*
-		 * Store this external
-		 */
-		i = biggest_attno;
-		old_value = toast_values[i];
-		toast_action[i] = 'p';
-		toast_values[i] = toast_save_datum(rel, toast_values[i],
-										   toast_oldexternal[i], options);
-		if (toast_free[i])
-			pfree(DatumGetPointer(old_value));
-		toast_free[i] = true;
-
-		need_change = true;
-		need_free = true;
+		toast_tuple_externalize(&ttc, biggest_attno, options);
 	}
 
 	/*
@@ -455,57 +234,13 @@ toast_insert_or_update(Relation rel, HeapTuple newtup, HeapTuple oldtup,
 	while (heap_compute_data_size(tupleDesc,
 								  toast_values, toast_isnull) > maxDataLen)
 	{
-		int			biggest_attno = -1;
-		int32		biggest_size = MAXALIGN(TOAST_POINTER_SIZE);
-		Datum		old_value;
-		Datum		new_value;
-
-		/*
-		 * Search for the biggest yet uncompressed internal attribute
-		 */
-		for (i = 0; i < numAttrs; i++)
-		{
-			if (toast_action[i] != ' ')
-				continue;
-			if (VARATT_IS_EXTERNAL(DatumGetPointer(toast_values[i])))
-				continue;		/* can't happen, toast_action would be 'p' */
-			if (VARATT_IS_COMPRESSED(DatumGetPointer(toast_values[i])))
-				continue;
-			if (TupleDescAttr(tupleDesc, i)->attstorage != 'm')
-				continue;
-			if (toast_sizes[i] > biggest_size)
-			{
-				biggest_attno = i;
-				biggest_size = toast_sizes[i];
-			}
-		}
+		int			biggest_attno;
 
+		biggest_attno = toast_tuple_find_biggest_attribute(&ttc, true, true);
 		if (biggest_attno < 0)
 			break;
 
-		/*
-		 * Attempt to compress it inline
-		 */
-		i = biggest_attno;
-		old_value = toast_values[i];
-		new_value = toast_compress_datum(old_value);
-
-		if (DatumGetPointer(new_value) != NULL)
-		{
-			/* successful compression */
-			if (toast_free[i])
-				pfree(DatumGetPointer(old_value));
-			toast_values[i] = new_value;
-			toast_free[i] = true;
-			toast_sizes[i] = VARSIZE(DatumGetPointer(toast_values[i]));
-			need_change = true;
-			need_free = true;
-		}
-		else
-		{
-			/* incompressible, ignore on subsequent compression passes */
-			toast_action[i] = 'x';
-		}
+		toast_tuple_try_compression(&ttc, biggest_attno);
 	}
 
 	/*
@@ -519,54 +254,20 @@ toast_insert_or_update(Relation rel, HeapTuple newtup, HeapTuple oldtup,
 								  toast_values, toast_isnull) > maxDataLen &&
 		   rel->rd_rel->reltoastrelid != InvalidOid)
 	{
-		int			biggest_attno = -1;
-		int32		biggest_size = MAXALIGN(TOAST_POINTER_SIZE);
-		Datum		old_value;
-
-		/*--------
-		 * Search for the biggest yet inlined attribute with
-		 * attstorage = 'm'
-		 *--------
-		 */
-		for (i = 0; i < numAttrs; i++)
-		{
-			if (toast_action[i] == 'p')
-				continue;
-			if (VARATT_IS_EXTERNAL(DatumGetPointer(toast_values[i])))
-				continue;		/* can't happen, toast_action would be 'p' */
-			if (TupleDescAttr(tupleDesc, i)->attstorage != 'm')
-				continue;
-			if (toast_sizes[i] > biggest_size)
-			{
-				biggest_attno = i;
-				biggest_size = toast_sizes[i];
-			}
-		}
+		int			biggest_attno;
 
+		biggest_attno = toast_tuple_find_biggest_attribute(&ttc, false, true);
 		if (biggest_attno < 0)
 			break;
 
-		/*
-		 * Store this external
-		 */
-		i = biggest_attno;
-		old_value = toast_values[i];
-		toast_action[i] = 'p';
-		toast_values[i] = toast_save_datum(rel, toast_values[i],
-										   toast_oldexternal[i], options);
-		if (toast_free[i])
-			pfree(DatumGetPointer(old_value));
-		toast_free[i] = true;
-
-		need_change = true;
-		need_free = true;
+		toast_tuple_externalize(&ttc, biggest_attno, options);
 	}
 
 	/*
 	 * In the case we toasted any values, we need to build a new heap tuple
 	 * with the changed values.
 	 */
-	if (need_change)
+	if ((ttc.ttc_flags & TOAST_NEEDS_CHANGE) != 0)
 	{
 		HeapTupleHeader olddata = newtup->t_data;
 		HeapTupleHeader new_data;
@@ -585,7 +286,7 @@ toast_insert_or_update(Relation rel, HeapTuple newtup, HeapTuple oldtup,
 		 * whether there needs to be one at all.
 		 */
 		new_header_len = SizeofHeapTupleHeader;
-		if (has_nulls)
+		if ((ttc.ttc_flags & TOAST_HAS_NULLS) != 0)
 			new_header_len += BITMAPLEN(numAttrs);
 		new_header_len = MAXALIGN(new_header_len);
 		new_data_len = heap_compute_data_size(tupleDesc,
@@ -616,26 +317,13 @@ toast_insert_or_update(Relation rel, HeapTuple newtup, HeapTuple oldtup,
 						(char *) new_data + new_header_len,
 						new_data_len,
 						&(new_data->t_infomask),
-						has_nulls ? new_data->t_bits : NULL);
+						((ttc.ttc_flags & TOAST_HAS_NULLS) != 0) ?
+						new_data->t_bits : NULL);
 	}
 	else
 		result_tuple = newtup;
 
-	/*
-	 * Free allocated temp values
-	 */
-	if (need_free)
-		for (i = 0; i < numAttrs; i++)
-			if (toast_free[i])
-				pfree(DatumGetPointer(toast_values[i]));
-
-	/*
-	 * Delete external values from the old tuple
-	 */
-	if (need_delold)
-		for (i = 0; i < numAttrs; i++)
-			if (toast_delold[i])
-				toast_delete_datum(rel, toast_oldvalues[i], false);
+	toast_tuple_cleanup(&ttc);
 
 	return result_tuple;
 }
diff --git a/src/backend/access/table/Makefile b/src/backend/access/table/Makefile
index 55a0e5efad..b29df3f333 100644
--- a/src/backend/access/table/Makefile
+++ b/src/backend/access/table/Makefile
@@ -12,6 +12,6 @@ subdir = src/backend/access/table
 top_builddir = ../../../..
 include $(top_builddir)/src/Makefile.global
 
-OBJS = table.o tableam.o tableamapi.o
+OBJS = table.o tableam.o tableamapi.o toast_helper.o
 
 include $(top_srcdir)/src/backend/common.mk
diff --git a/src/backend/access/table/toast_helper.c b/src/backend/access/table/toast_helper.c
new file mode 100644
index 0000000000..7532b4f865
--- /dev/null
+++ b/src/backend/access/table/toast_helper.c
@@ -0,0 +1,331 @@
+/*-------------------------------------------------------------------------
+ *
+ * toast_helper.c
+ *	  Helper functions for table AMs implementing compressed or
+ *    out-of-line storage of varlena attributes.
+ *
+ * Copyright (c) 2000-2019, PostgreSQL Global Development Group
+ *
+ * IDENTIFICATION
+ *	  src/backend/access/common/toast_helper.c
+ *
+ *-------------------------------------------------------------------------
+ */
+
+#include "postgres.h"
+
+#include "access/detoast.h"
+#include "access/table.h"
+#include "access/toast_helper.h"
+#include "access/toast_internals.h"
+
+/*
+ * Prepare to TOAST a tuple.
+ *
+ * tupleDesc, toast_values, and toast_isnull are required parameters; they
+ * provide the necessary details about the tuple to be toasted.
+ *
+ * toast_oldvalues and toast_oldisnull should be NULL for a newly-inserted
+ * tuple; for an update, they should describe the existing tuple.
+ *
+ * All of these arrays should have a length equal to tupleDesc->natts.
+ *
+ * On return, toast_flags and toast_attr will have been initialized.
+ * toast_flags is just a single uint8, but toast_attr is an caller-provided
+ * array with a length equal to tupleDesc->natts.  The caller need not
+ * perform any initialization of the array before calling this function.
+ */
+void
+toast_tuple_init(ToastTupleContext *ttc)
+{
+	TupleDesc	tupleDesc = ttc->ttc_rel->rd_att;
+	int			numAttrs = tupleDesc->natts;
+	int			i;
+
+	ttc->ttc_flags = 0;
+
+	for (i = 0; i < numAttrs; i++)
+	{
+		Form_pg_attribute att = TupleDescAttr(tupleDesc, i);
+		struct varlena *old_value;
+		struct varlena *new_value;
+
+		ttc->ttc_attr[i].tai_colflags = 0;
+		ttc->ttc_attr[i].tai_oldexternal = NULL;
+
+		if (ttc->ttc_oldvalues != NULL)
+		{
+			/*
+			 * For UPDATE get the old and new values of this attribute
+			 */
+			old_value =
+				(struct varlena *) DatumGetPointer(ttc->ttc_oldvalues[i]);
+			new_value =
+				(struct varlena *) DatumGetPointer(ttc->ttc_values[i]);
+
+			/*
+			 * If the old value is stored on disk, check if it has changed so
+			 * we have to delete it later.
+			 */
+			if (att->attlen == -1 && !ttc->ttc_oldisnull[i] &&
+				VARATT_IS_EXTERNAL_ONDISK(old_value))
+			{
+				if (ttc->ttc_isnull[i] ||
+					!VARATT_IS_EXTERNAL_ONDISK(new_value) ||
+					memcmp((char *) old_value, (char *) new_value,
+						   VARSIZE_EXTERNAL(old_value)) != 0)
+				{
+					/*
+					 * The old external stored value isn't needed any more
+					 * after the update
+					 */
+					ttc->ttc_attr[i].tai_colflags |= TOASTCOL_NEEDS_DELETE_OLD;
+					ttc->ttc_flags |= TOAST_NEEDS_DELETE_OLD;
+				}
+				else
+				{
+					/*
+					 * This attribute isn't changed by this update so we reuse
+					 * the original reference to the old value in the new
+					 * tuple.
+					 */
+					ttc->ttc_attr[i].tai_colflags |= TOASTCOL_IGNORE;
+					continue;
+				}
+			}
+		}
+		else
+		{
+			/*
+			 * For INSERT simply get the new value
+			 */
+			new_value = (struct varlena *) DatumGetPointer(ttc->ttc_values[i]);
+		}
+
+		/*
+		 * Handle NULL attributes
+		 */
+		if (ttc->ttc_isnull[i])
+		{
+			ttc->ttc_attr[i].tai_colflags |= TOASTCOL_IGNORE;
+			ttc->ttc_flags |= TOAST_HAS_NULLS;
+			continue;
+		}
+
+		/*
+		 * Now look at varlena attributes
+		 */
+		if (att->attlen == -1)
+		{
+			/*
+			 * If the table's attribute says PLAIN always, force it so.
+			 */
+			if (att->attstorage == 'p')
+				ttc->ttc_attr[i].tai_colflags |= TOASTCOL_IGNORE;
+
+			/*
+			 * We took care of UPDATE above, so any external value we find
+			 * still in the tuple must be someone else's that we cannot reuse
+			 * (this includes the case of an out-of-line in-memory datum).
+			 * Fetch it back (without decompression, unless we are forcing
+			 * PLAIN storage).  If necessary, we'll push it out as a new
+			 * external value below.
+			 */
+			if (VARATT_IS_EXTERNAL(new_value))
+			{
+				ttc->ttc_attr[i].tai_oldexternal = new_value;
+				if (att->attstorage == 'p')
+					new_value = heap_tuple_untoast_attr(new_value);
+				else
+					new_value = heap_tuple_fetch_attr(new_value);
+				ttc->ttc_values[i] = PointerGetDatum(new_value);
+				ttc->ttc_attr[i].tai_colflags |= TOASTCOL_NEEDS_FREE;
+				ttc->ttc_flags |= (TOAST_NEEDS_CHANGE | TOAST_NEEDS_FREE);
+			}
+
+			/*
+			 * Remember the size of this attribute
+			 */
+			ttc->ttc_attr[i].tai_size = VARSIZE_ANY(new_value);
+		}
+		else
+		{
+			/*
+			 * Not a varlena attribute, plain storage always
+			 */
+			ttc->ttc_attr[i].tai_colflags |= TOASTCOL_IGNORE;
+		}
+	}
+}
+
+/*
+ * Find the largest varlena attribute that satisfies certain criteria.
+ *
+ * The relevant column must not be marked TOASTCOL_IGNORE, and if the
+ * for_compression flag is passed as true, it must also not be marked
+ * TOASTCOL_INCOMPRESSIBLE.
+ *
+ * The column must have attstorage 'e' or 'x' if check_main is false, and
+ * must have attstorage 'm' if check_main is true.
+ *
+ * The column must have a minimum size of MAXALIGN(TOAST_POINTER_SIZE);
+ * if not, no benefit is to be expected by compressing it.
+ *
+ * The return value is the index of the biggest suitable column, or
+ * -1 if there is none.
+ */
+int
+toast_tuple_find_biggest_attribute(ToastTupleContext *ttc,
+								   bool for_compression, bool check_main)
+{
+	TupleDesc	tupleDesc = ttc->ttc_rel->rd_att;
+	int			numAttrs = tupleDesc->natts;
+	int			biggest_attno = -1;
+	int32		biggest_size = MAXALIGN(TOAST_POINTER_SIZE);
+	int32		skip_colflags = TOASTCOL_IGNORE;
+	int			i;
+
+	if (for_compression)
+		skip_colflags |= TOASTCOL_INCOMPRESSIBLE;
+
+	for (i = 0; i < numAttrs; i++)
+	{
+		Form_pg_attribute att = TupleDescAttr(tupleDesc, i);
+
+		if ((ttc->ttc_attr[i].tai_colflags & skip_colflags) != 0)
+			continue;
+		if (VARATT_IS_EXTERNAL(DatumGetPointer(ttc->ttc_values[i])))
+			continue;			/* can't happen, toast_action would be 'p' */
+		if (for_compression &&
+			VARATT_IS_COMPRESSED(DatumGetPointer(ttc->ttc_values[i])))
+			continue;
+		if (check_main && att->attstorage != 'm')
+			continue;
+		if (!check_main && att->attstorage != 'x' && att->attstorage != 'e')
+			continue;
+
+		if (ttc->ttc_attr[i].tai_size > biggest_size)
+		{
+			biggest_attno = i;
+			biggest_size = ttc->ttc_attr[i].tai_size;
+		}
+	}
+
+	return biggest_attno;
+}
+
+/*
+ * Try compression for an attribute.
+ *
+ * If we find that the attribute is not compressible, mark it so.
+ */
+void
+toast_tuple_try_compression(ToastTupleContext *ttc, int attribute)
+{
+	Datum	   *value = &ttc->ttc_values[attribute];
+	Datum		new_value = toast_compress_datum(*value);
+	ToastAttrInfo *attr = &ttc->ttc_attr[attribute];
+
+	if (DatumGetPointer(new_value) != NULL)
+	{
+		/* successful compression */
+		if ((attr->tai_colflags & TOASTCOL_NEEDS_FREE) != 0)
+			pfree(DatumGetPointer(*value));
+		*value = new_value;
+		attr->tai_colflags |= TOASTCOL_NEEDS_FREE;
+		attr->tai_size = VARSIZE(DatumGetPointer(*value));
+		ttc->ttc_flags |= (TOAST_NEEDS_CHANGE | TOAST_NEEDS_FREE);
+	}
+	else
+	{
+		/* incompressible, ignore on subsequent compression passes */
+		attr->tai_colflags |= TOASTCOL_INCOMPRESSIBLE;
+	}
+}
+
+/*
+ * Move an attribute to external storage.
+ */
+void
+toast_tuple_externalize(ToastTupleContext *ttc, int attribute, int options)
+{
+	Datum	   *value = &ttc->ttc_values[attribute];
+	Datum		old_value = *value;
+	ToastAttrInfo *attr = &ttc->ttc_attr[attribute];
+
+	attr->tai_colflags |= TOASTCOL_IGNORE;
+	*value = toast_save_datum(ttc->ttc_rel, old_value, attr->tai_oldexternal,
+							  options);
+	if ((attr->tai_colflags & TOASTCOL_NEEDS_FREE) != 0)
+		pfree(DatumGetPointer(old_value));
+	attr->tai_colflags |= TOASTCOL_NEEDS_FREE;
+	ttc->ttc_flags |= (TOAST_NEEDS_CHANGE | TOAST_NEEDS_FREE);
+}
+
+/*
+ * Perform appropriate cleanup after one tuple has been subjected to TOAST.
+ */
+void
+toast_tuple_cleanup(ToastTupleContext *ttc)
+{
+	TupleDesc	tupleDesc = ttc->ttc_rel->rd_att;
+	int			numAttrs = tupleDesc->natts;
+
+	/*
+	 * Free allocated temp values
+	 */
+	if ((ttc->ttc_flags & TOAST_NEEDS_FREE) != 0)
+	{
+		int			i;
+
+		for (i = 0; i < numAttrs; i++)
+		{
+			ToastAttrInfo *attr = &ttc->ttc_attr[i];
+
+			if ((attr->tai_colflags & TOASTCOL_NEEDS_FREE) != 0)
+				pfree(DatumGetPointer(ttc->ttc_values[i]));
+		}
+	}
+
+	/*
+	 * Delete external values from the old tuple
+	 */
+	if ((ttc->ttc_flags & TOAST_NEEDS_DELETE_OLD) != 0)
+	{
+		int			i;
+
+		for (i = 0; i < numAttrs; i++)
+		{
+			ToastAttrInfo *attr = &ttc->ttc_attr[i];
+
+			if ((attr->tai_colflags & TOASTCOL_NEEDS_DELETE_OLD) != 0)
+				toast_delete_datum(ttc->ttc_rel, ttc->ttc_oldvalues[i], false);
+		}
+	}
+}
+
+/*
+ * Check for external stored attributes and delete them from the secondary
+ * relation.
+ */
+void
+toast_delete_external(Relation rel, Datum *values, bool *isnull,
+					  bool is_speculative)
+{
+	TupleDesc	tupleDesc = rel->rd_att;
+	int			numAttrs = tupleDesc->natts;
+	int			i;
+
+	for (i = 0; i < numAttrs; i++)
+	{
+		if (TupleDescAttr(tupleDesc, i)->attlen == -1)
+		{
+			Datum		value = values[i];
+
+			if (isnull[i])
+				continue;
+			else if (VARATT_IS_EXTERNAL_ONDISK(PointerGetDatum(value)))
+				toast_delete_datum(rel, value, is_speculative);
+		}
+	}
+}
diff --git a/src/include/access/toast_helper.h b/src/include/access/toast_helper.h
new file mode 100644
index 0000000000..7cefacb0ea
--- /dev/null
+++ b/src/include/access/toast_helper.h
@@ -0,0 +1,115 @@
+/*-------------------------------------------------------------------------
+ *
+ * toast_helper.h
+ *	  Helper functions for table AMs implementing compressed or
+ *    out-of-line storage of varlena attributes.
+ *
+ * Copyright (c) 2000-2019, PostgreSQL Global Development Group
+ *
+ * src/include/access/toast_helper.h
+ *
+ *-------------------------------------------------------------------------
+ */
+
+#ifndef TOAST_HELPER_H
+#define TOAST_HELPER_H
+
+#include "utils/rel.h"
+
+/*
+ * Information about one column of a tuple being toasted.
+ *
+ * NOTE: toast_action[i] can have these values:
+ *		' '		default handling
+ *		'p'		already processed --- don't touch it
+ *		'x'		incompressible, but OK to move off
+ *
+ * NOTE: toast_attr[i].tai_size is only made valid for varlena attributes with
+ * toast_action[i] different from 'p'.
+ */
+typedef struct
+{
+	struct varlena *tai_oldexternal;
+	int32		tai_size;
+	uint8		tai_colflags;
+} ToastAttrInfo;
+
+/*
+ * Information about one tuple being toasted.
+ */
+typedef struct
+{
+	/*
+	 * Before calling toast_tuple_init, the caller must initialize the
+	 * following fields.  Each array must have a length equal to
+	 * ttc_rel->rd_att->natts.  The tts_oldvalues and tts_oldisnull fields
+	 * should be NULL in the case of an insert.
+	 */
+	Relation	ttc_rel;		/* the relation that contains the tuple */
+	Datum	   *ttc_values;		/* values from the tuple columns */
+	bool	   *ttc_isnull;		/* null flags for the tuple columns */
+	Datum	   *ttc_oldvalues;	/* values from previous tuple */
+	bool	   *ttc_oldisnull;	/* null flags from previous tuple */
+
+	/*
+	 * Before calling toast_tuple_init, the caller should set tts_attr to
+	 * point to an array of ToastAttrInfo structures of a length equal to
+	 * tts_rel->rd_att->natts.  The contents of the array need not be
+	 * initialized.  ttc_flags also does not need to be initialized.
+	 */
+	uint8		ttc_flags;
+	ToastAttrInfo *ttc_attr;
+} ToastTupleContext;
+
+/*
+ * Flags indicating the overall state of a TOAST operation.
+ *
+ * TOAST_NEEDS_DELETE_OLD indicates that one or more old TOAST datums need
+ * to be deleted.
+ *
+ * TOAST_NEEDS_FREE indicates that one or more TOAST values need to be freed.
+ *
+ * TOAST_HAS_NULLS indicates that nulls were found in the tuple being toasted.
+ *
+ * TOAST_NEEDS_CHANGE indicates that a new tuple needs to built; in other
+ * words, the toaster did something.
+ */
+#define TOAST_NEEDS_DELETE_OLD				0x0001
+#define TOAST_NEEDS_FREE					0x0002
+#define TOAST_HAS_NULLS						0x0004
+#define TOAST_NEEDS_CHANGE					0x0008
+
+/*
+ * Flags indicating the status of a TOAST operation with respect to a
+ * particular column.
+ *
+ * TOASTCOL_NEEDS_DELETE_OLD indicates that the old TOAST datums for this
+ * column need to be deleted.
+ *
+ * TOASTCOL_NEEDS_FREE indicates that the value for this column needs to
+ * be freed.
+ *
+ * TOASTCOL_IGNORE indicates that the toaster should not further process
+ * this column.
+ *
+ * TOASTCOL_INCOMPRESSIBLE indicates that this column has been found to
+ * be incompressible, but could be moved out-of-line.
+ */
+#define TOASTCOL_NEEDS_DELETE_OLD			TOAST_NEEDS_DELETE_OLD
+#define TOASTCOL_NEEDS_FREE					TOAST_NEEDS_FREE
+#define TOASTCOL_IGNORE						0x0010
+#define TOASTCOL_INCOMPRESSIBLE				0x0020
+
+extern void toast_tuple_init(ToastTupleContext *ttc);
+extern int	toast_tuple_find_biggest_attribute(ToastTupleContext *ttc,
+											   bool for_compression,
+											   bool check_main);
+extern void toast_tuple_try_compression(ToastTupleContext *ttc, int attribute);
+extern void toast_tuple_externalize(ToastTupleContext *ttc, int attribute,
+									int options);
+extern void toast_tuple_cleanup(ToastTupleContext *ttc);
+
+extern void toast_delete_external(Relation rel, Datum *values, bool *isnull,
+								  bool is_speculative);
+
+#endif
diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list
index 432d2d812e..f3cdfa8a22 100644
--- a/src/tools/pgindent/typedefs.list
+++ b/src/tools/pgindent/typedefs.list
@@ -2349,6 +2349,8 @@ TBlockState
 TIDBitmap
 TM_FailureData
 TM_Result
+ToastAttrInfo
+ToastTupleContext
 TOKEN_DEFAULT_DACL
 TOKEN_INFORMATION_CLASS
 TOKEN_PRIVILEGES
-- 
2.17.2 (Apple Git-113)

From 1fb29977574a43c18e4d3f73f5c4563989cedd51 Mon Sep 17 00:00:00 2001
From: Robert Haas <rhaas@postgresql.org>
Date: Mon, 8 Jul 2019 11:58:05 -0400
Subject: [PATCH 1/4] Split tuptoaster.c into three separate files.

detoast.c/h contain functions required to detoast a datum, partially
or completely, plus a few other utility functions for examining the
size of toasted datums.

toast_internals.c/h contain functions that are used internally to the
TOAST subsystem but which (mostly) do not need to be accessed from
outside.

heaptoast.c/h contains code that is intrinsically specific to the
heap AM, either because it operates on HeapTuples or is based on the
layout of a heap page.

detoast.c and toast_internals.c are placed in
src/backend/access/common rather than src/backend/access/heap.  At
present, both files still have dependencies on the heap, but that will
be improved in a future commit.

Discussion: http://postgr.es/m/CA+TgmoZv-=2iWM4jcw5ZhJeL18HF96+W1yJeYrnGMYdkFFnEpQ@mail.gmail.com
---
 doc/src/sgml/storage.sgml                     |    2 +-
 src/backend/access/common/Makefile            |    5 +-
 src/backend/access/common/detoast.c           |  859 ++++++
 src/backend/access/common/heaptuple.c         |    4 +-
 src/backend/access/common/indextuple.c        |    9 +-
 src/backend/access/common/reloptions.c        |    2 +-
 src/backend/access/common/toast_internals.c   |  632 +++++
 src/backend/access/heap/Makefile              |    2 +-
 src/backend/access/heap/heapam.c              |    2 +-
 src/backend/access/heap/heapam_handler.c      |    2 +-
 src/backend/access/heap/heaptoast.c           |  917 +++++++
 src/backend/access/heap/rewriteheap.c         |    2 +-
 src/backend/access/heap/tuptoaster.c          | 2411 -----------------
 src/backend/access/transam/xlog.c             |    2 +-
 src/backend/commands/analyze.c                |    2 +-
 src/backend/commands/cluster.c                |    2 +-
 src/backend/executor/execExprInterp.c         |    2 +-
 src/backend/executor/execTuples.c             |    2 +-
 src/backend/executor/tstoreReceiver.c         |    2 +-
 .../replication/logical/reorderbuffer.c       |    2 +-
 src/backend/statistics/extended_stats.c       |    2 +-
 src/backend/storage/large_object/inv_api.c    |    3 +-
 src/backend/utils/adt/array_typanalyze.c      |    2 +-
 src/backend/utils/adt/datum.c                 |    2 +-
 src/backend/utils/adt/expandedrecord.c        |    3 +-
 src/backend/utils/adt/rowtypes.c              |    2 +-
 src/backend/utils/adt/tsgistidx.c             |    2 +-
 src/backend/utils/adt/varchar.c               |    2 +-
 src/backend/utils/adt/varlena.c               |    2 +-
 src/backend/utils/cache/catcache.c            |    2 +-
 src/backend/utils/fmgr/fmgr.c                 |    2 +-
 src/bin/pg_resetwal/pg_resetwal.c             |    2 +-
 src/include/access/detoast.h                  |   92 +
 .../access/{tuptoaster.h => heaptoast.h}      |  112 +-
 src/include/access/toast_internals.h          |   54 +
 src/pl/plpgsql/src/pl_exec.c                  |    2 +-
 src/test/regress/regress.c                    |    2 +-
 37 files changed, 2602 insertions(+), 2549 deletions(-)
 create mode 100644 src/backend/access/common/detoast.c
 create mode 100644 src/backend/access/common/toast_internals.c
 create mode 100644 src/backend/access/heap/heaptoast.c
 delete mode 100644 src/backend/access/heap/tuptoaster.c
 create mode 100644 src/include/access/detoast.h
 rename src/include/access/{tuptoaster.h => heaptoast.h} (57%)
 create mode 100644 src/include/access/toast_internals.h

diff --git a/doc/src/sgml/storage.sgml b/doc/src/sgml/storage.sgml
index 1047c77a63..78bd030346 100644
--- a/doc/src/sgml/storage.sgml
+++ b/doc/src/sgml/storage.sgml
@@ -382,7 +382,7 @@ The oldest and most common type is a pointer to out-of-line data stored in
 a <firstterm><acronym>TOAST</acronym> table</firstterm> that is separate from, but
 associated with, the table containing the <acronym>TOAST</acronym> pointer datum
 itself.  These <firstterm>on-disk</firstterm> pointer datums are created by the
-<acronym>TOAST</acronym> management code (in <filename>access/heap/tuptoaster.c</filename>)
+<acronym>TOAST</acronym> management code (in <filename>access/common/toast_internals.c</filename>)
 when a tuple to be stored on disk is too large to be stored as-is.
 Further details appear in <xref linkend="storage-toast-ondisk"/>.
 Alternatively, a <acronym>TOAST</acronym> pointer datum can contain a pointer to
diff --git a/src/backend/access/common/Makefile b/src/backend/access/common/Makefile
index d469504337..9ac19d9f9e 100644
--- a/src/backend/access/common/Makefile
+++ b/src/backend/access/common/Makefile
@@ -12,7 +12,8 @@ subdir = src/backend/access/common
 top_builddir = ../../../..
 include $(top_builddir)/src/Makefile.global
 
-OBJS = bufmask.o heaptuple.o indextuple.o printsimple.o printtup.o \
-	relation.o reloptions.o scankey.o session.o tupconvert.o tupdesc.o
+OBJS = bufmask.o detoast.o heaptuple.o indextuple.o printsimple.o \
+	printtup.o relation.o reloptions.o scankey.o session.o toast_internals.o \
+	tupconvert.o tupdesc.o
 
 include $(top_srcdir)/src/backend/common.mk
diff --git a/src/backend/access/common/detoast.c b/src/backend/access/common/detoast.c
new file mode 100644
index 0000000000..49c94da557
--- /dev/null
+++ b/src/backend/access/common/detoast.c
@@ -0,0 +1,859 @@
+/*-------------------------------------------------------------------------
+ *
+ * detoast.c
+ *	  Retrieve compressed or external variable size attributes.
+ *
+ * Copyright (c) 2000-2019, PostgreSQL Global Development Group
+ *
+ * IDENTIFICATION
+ *	  src/backend/access/common/detoast.c
+ *
+ *-------------------------------------------------------------------------
+ */
+
+#include "postgres.h"
+
+#include "access/detoast.h"
+#include "access/genam.h"
+#include "access/heaptoast.h"
+#include "access/table.h"
+#include "access/toast_internals.h"
+#include "common/pg_lzcompress.h"
+#include "utils/expandeddatum.h"
+#include "utils/fmgroids.h"
+#include "utils/rel.h"
+
+static struct varlena *toast_fetch_datum(struct varlena *attr);
+static struct varlena *toast_fetch_datum_slice(struct varlena *attr,
+											   int32 sliceoffset, int32 length);
+static struct varlena *toast_decompress_datum(struct varlena *attr);
+static struct varlena *toast_decompress_datum_slice(struct varlena *attr, int32 slicelength);
+
+/* ----------
+ * heap_tuple_fetch_attr -
+ *
+ *	Public entry point to get back a toasted value from
+ *	external source (possibly still in compressed format).
+ *
+ * This will return a datum that contains all the data internally, ie, not
+ * relying on external storage or memory, but it can still be compressed or
+ * have a short header.  Note some callers assume that if the input is an
+ * EXTERNAL datum, the result will be a pfree'able chunk.
+ * ----------
+ */
+struct varlena *
+heap_tuple_fetch_attr(struct varlena *attr)
+{
+	struct varlena *result;
+
+	if (VARATT_IS_EXTERNAL_ONDISK(attr))
+	{
+		/*
+		 * This is an external stored plain value
+		 */
+		result = toast_fetch_datum(attr);
+	}
+	else if (VARATT_IS_EXTERNAL_INDIRECT(attr))
+	{
+		/*
+		 * This is an indirect pointer --- dereference it
+		 */
+		struct varatt_indirect redirect;
+
+		VARATT_EXTERNAL_GET_POINTER(redirect, attr);
+		attr = (struct varlena *) redirect.pointer;
+
+		/* nested indirect Datums aren't allowed */
+		Assert(!VARATT_IS_EXTERNAL_INDIRECT(attr));
+
+		/* recurse if value is still external in some other way */
+		if (VARATT_IS_EXTERNAL(attr))
+			return heap_tuple_fetch_attr(attr);
+
+		/*
+		 * Copy into the caller's memory context, in case caller tries to
+		 * pfree the result.
+		 */
+		result = (struct varlena *) palloc(VARSIZE_ANY(attr));
+		memcpy(result, attr, VARSIZE_ANY(attr));
+	}
+	else if (VARATT_IS_EXTERNAL_EXPANDED(attr))
+	{
+		/*
+		 * This is an expanded-object pointer --- get flat format
+		 */
+		ExpandedObjectHeader *eoh;
+		Size		resultsize;
+
+		eoh = DatumGetEOHP(PointerGetDatum(attr));
+		resultsize = EOH_get_flat_size(eoh);
+		result = (struct varlena *) palloc(resultsize);
+		EOH_flatten_into(eoh, (void *) result, resultsize);
+	}
+	else
+	{
+		/*
+		 * This is a plain value inside of the main tuple - why am I called?
+		 */
+		result = attr;
+	}
+
+	return result;
+}
+
+
+/* ----------
+ * heap_tuple_untoast_attr -
+ *
+ *	Public entry point to get back a toasted value from compression
+ *	or external storage.  The result is always non-extended varlena form.
+ *
+ * Note some callers assume that if the input is an EXTERNAL or COMPRESSED
+ * datum, the result will be a pfree'able chunk.
+ * ----------
+ */
+struct varlena *
+heap_tuple_untoast_attr(struct varlena *attr)
+{
+	if (VARATT_IS_EXTERNAL_ONDISK(attr))
+	{
+		/*
+		 * This is an externally stored datum --- fetch it back from there
+		 */
+		attr = toast_fetch_datum(attr);
+		/* If it's compressed, decompress it */
+		if (VARATT_IS_COMPRESSED(attr))
+		{
+			struct varlena *tmp = attr;
+
+			attr = toast_decompress_datum(tmp);
+			pfree(tmp);
+		}
+	}
+	else if (VARATT_IS_EXTERNAL_INDIRECT(attr))
+	{
+		/*
+		 * This is an indirect pointer --- dereference it
+		 */
+		struct varatt_indirect redirect;
+
+		VARATT_EXTERNAL_GET_POINTER(redirect, attr);
+		attr = (struct varlena *) redirect.pointer;
+
+		/* nested indirect Datums aren't allowed */
+		Assert(!VARATT_IS_EXTERNAL_INDIRECT(attr));
+
+		/* recurse in case value is still extended in some other way */
+		attr = heap_tuple_untoast_attr(attr);
+
+		/* if it isn't, we'd better copy it */
+		if (attr == (struct varlena *) redirect.pointer)
+		{
+			struct varlena *result;
+
+			result = (struct varlena *) palloc(VARSIZE_ANY(attr));
+			memcpy(result, attr, VARSIZE_ANY(attr));
+			attr = result;
+		}
+	}
+	else if (VARATT_IS_EXTERNAL_EXPANDED(attr))
+	{
+		/*
+		 * This is an expanded-object pointer --- get flat format
+		 */
+		attr = heap_tuple_fetch_attr(attr);
+		/* flatteners are not allowed to produce compressed/short output */
+		Assert(!VARATT_IS_EXTENDED(attr));
+	}
+	else if (VARATT_IS_COMPRESSED(attr))
+	{
+		/*
+		 * This is a compressed value inside of the main tuple
+		 */
+		attr = toast_decompress_datum(attr);
+	}
+	else if (VARATT_IS_SHORT(attr))
+	{
+		/*
+		 * This is a short-header varlena --- convert to 4-byte header format
+		 */
+		Size		data_size = VARSIZE_SHORT(attr) - VARHDRSZ_SHORT;
+		Size		new_size = data_size + VARHDRSZ;
+		struct varlena *new_attr;
+
+		new_attr = (struct varlena *) palloc(new_size);
+		SET_VARSIZE(new_attr, new_size);
+		memcpy(VARDATA(new_attr), VARDATA_SHORT(attr), data_size);
+		attr = new_attr;
+	}
+
+	return attr;
+}
+
+
+/* ----------
+ * heap_tuple_untoast_attr_slice -
+ *
+ *		Public entry point to get back part of a toasted value
+ *		from compression or external storage.
+ * ----------
+ */
+struct varlena *
+heap_tuple_untoast_attr_slice(struct varlena *attr,
+							  int32 sliceoffset, int32 slicelength)
+{
+	struct varlena *preslice;
+	struct varlena *result;
+	char	   *attrdata;
+	int32		attrsize;
+
+	if (VARATT_IS_EXTERNAL_ONDISK(attr))
+	{
+		struct varatt_external toast_pointer;
+
+		VARATT_EXTERNAL_GET_POINTER(toast_pointer, attr);
+
+		/* fast path for non-compressed external datums */
+		if (!VARATT_EXTERNAL_IS_COMPRESSED(toast_pointer))
+			return toast_fetch_datum_slice(attr, sliceoffset, slicelength);
+
+		/* fetch it back (compressed marker will get set automatically) */
+		preslice = toast_fetch_datum(attr);
+	}
+	else if (VARATT_IS_EXTERNAL_INDIRECT(attr))
+	{
+		struct varatt_indirect redirect;
+
+		VARATT_EXTERNAL_GET_POINTER(redirect, attr);
+
+		/* nested indirect Datums aren't allowed */
+		Assert(!VARATT_IS_EXTERNAL_INDIRECT(redirect.pointer));
+
+		return heap_tuple_untoast_attr_slice(redirect.pointer,
+											 sliceoffset, slicelength);
+	}
+	else if (VARATT_IS_EXTERNAL_EXPANDED(attr))
+	{
+		/* pass it off to heap_tuple_fetch_attr to flatten */
+		preslice = heap_tuple_fetch_attr(attr);
+	}
+	else
+		preslice = attr;
+
+	Assert(!VARATT_IS_EXTERNAL(preslice));
+
+	if (VARATT_IS_COMPRESSED(preslice))
+	{
+		struct varlena *tmp = preslice;
+
+		/* Decompress enough to encompass the slice and the offset */
+		if (slicelength > 0 && sliceoffset >= 0)
+			preslice = toast_decompress_datum_slice(tmp, slicelength + sliceoffset);
+		else
+			preslice = toast_decompress_datum(tmp);
+
+		if (tmp != attr)
+			pfree(tmp);
+	}
+
+	if (VARATT_IS_SHORT(preslice))
+	{
+		attrdata = VARDATA_SHORT(preslice);
+		attrsize = VARSIZE_SHORT(preslice) - VARHDRSZ_SHORT;
+	}
+	else
+	{
+		attrdata = VARDATA(preslice);
+		attrsize = VARSIZE(preslice) - VARHDRSZ;
+	}
+
+	/* slicing of datum for compressed cases and plain value */
+
+	if (sliceoffset >= attrsize)
+	{
+		sliceoffset = 0;
+		slicelength = 0;
+	}
+
+	if (((sliceoffset + slicelength) > attrsize) || slicelength < 0)
+		slicelength = attrsize - sliceoffset;
+
+	result = (struct varlena *) palloc(slicelength + VARHDRSZ);
+	SET_VARSIZE(result, slicelength + VARHDRSZ);
+
+	memcpy(VARDATA(result), attrdata + sliceoffset, slicelength);
+
+	if (preslice != attr)
+		pfree(preslice);
+
+	return result;
+}
+
+/* ----------
+ * toast_fetch_datum -
+ *
+ *	Reconstruct an in memory Datum from the chunks saved
+ *	in the toast relation
+ * ----------
+ */
+static struct varlena *
+toast_fetch_datum(struct varlena *attr)
+{
+	Relation	toastrel;
+	Relation   *toastidxs;
+	ScanKeyData toastkey;
+	SysScanDesc toastscan;
+	HeapTuple	ttup;
+	TupleDesc	toasttupDesc;
+	struct varlena *result;
+	struct varatt_external toast_pointer;
+	int32		ressize;
+	int32		residx,
+				nextidx;
+	int32		numchunks;
+	Pointer		chunk;
+	bool		isnull;
+	char	   *chunkdata;
+	int32		chunksize;
+	int			num_indexes;
+	int			validIndex;
+	SnapshotData SnapshotToast;
+
+	if (!VARATT_IS_EXTERNAL_ONDISK(attr))
+		elog(ERROR, "toast_fetch_datum shouldn't be called for non-ondisk datums");
+
+	/* Must copy to access aligned fields */
+	VARATT_EXTERNAL_GET_POINTER(toast_pointer, attr);
+
+	ressize = toast_pointer.va_extsize;
+	numchunks = ((ressize - 1) / TOAST_MAX_CHUNK_SIZE) + 1;
+
+	result = (struct varlena *) palloc(ressize + VARHDRSZ);
+
+	if (VARATT_EXTERNAL_IS_COMPRESSED(toast_pointer))
+		SET_VARSIZE_COMPRESSED(result, ressize + VARHDRSZ);
+	else
+		SET_VARSIZE(result, ressize + VARHDRSZ);
+
+	/*
+	 * Open the toast relation and its indexes
+	 */
+	toastrel = table_open(toast_pointer.va_toastrelid, AccessShareLock);
+	toasttupDesc = toastrel->rd_att;
+
+	/* Look for the valid index of the toast relation */
+	validIndex = toast_open_indexes(toastrel,
+									AccessShareLock,
+									&toastidxs,
+									&num_indexes);
+
+	/*
+	 * Setup a scan key to fetch from the index by va_valueid
+	 */
+	ScanKeyInit(&toastkey,
+				(AttrNumber) 1,
+				BTEqualStrategyNumber, F_OIDEQ,
+				ObjectIdGetDatum(toast_pointer.va_valueid));
+
+	/*
+	 * Read the chunks by index
+	 *
+	 * Note that because the index is actually on (valueid, chunkidx) we will
+	 * see the chunks in chunkidx order, even though we didn't explicitly ask
+	 * for it.
+	 */
+	nextidx = 0;
+
+	init_toast_snapshot(&SnapshotToast);
+	toastscan = systable_beginscan_ordered(toastrel, toastidxs[validIndex],
+										   &SnapshotToast, 1, &toastkey);
+	while ((ttup = systable_getnext_ordered(toastscan, ForwardScanDirection)) != NULL)
+	{
+		/*
+		 * Have a chunk, extract the sequence number and the data
+		 */
+		residx = DatumGetInt32(fastgetattr(ttup, 2, toasttupDesc, &isnull));
+		Assert(!isnull);
+		chunk = DatumGetPointer(fastgetattr(ttup, 3, toasttupDesc, &isnull));
+		Assert(!isnull);
+		if (!VARATT_IS_EXTENDED(chunk))
+		{
+			chunksize = VARSIZE(chunk) - VARHDRSZ;
+			chunkdata = VARDATA(chunk);
+		}
+		else if (VARATT_IS_SHORT(chunk))
+		{
+			/* could happen due to heap_form_tuple doing its thing */
+			chunksize = VARSIZE_SHORT(chunk) - VARHDRSZ_SHORT;
+			chunkdata = VARDATA_SHORT(chunk);
+		}
+		else
+		{
+			/* should never happen */
+			elog(ERROR, "found toasted toast chunk for toast value %u in %s",
+				 toast_pointer.va_valueid,
+				 RelationGetRelationName(toastrel));
+			chunksize = 0;		/* keep compiler quiet */
+			chunkdata = NULL;
+		}
+
+		/*
+		 * Some checks on the data we've found
+		 */
+		if (residx != nextidx)
+			elog(ERROR, "unexpected chunk number %d (expected %d) for toast value %u in %s",
+				 residx, nextidx,
+				 toast_pointer.va_valueid,
+				 RelationGetRelationName(toastrel));
+		if (residx < numchunks - 1)
+		{
+			if (chunksize != TOAST_MAX_CHUNK_SIZE)
+				elog(ERROR, "unexpected chunk size %d (expected %d) in chunk %d of %d for toast value %u in %s",
+					 chunksize, (int) TOAST_MAX_CHUNK_SIZE,
+					 residx, numchunks,
+					 toast_pointer.va_valueid,
+					 RelationGetRelationName(toastrel));
+		}
+		else if (residx == numchunks - 1)
+		{
+			if ((residx * TOAST_MAX_CHUNK_SIZE + chunksize) != ressize)
+				elog(ERROR, "unexpected chunk size %d (expected %d) in final chunk %d for toast value %u in %s",
+					 chunksize,
+					 (int) (ressize - residx * TOAST_MAX_CHUNK_SIZE),
+					 residx,
+					 toast_pointer.va_valueid,
+					 RelationGetRelationName(toastrel));
+		}
+		else
+			elog(ERROR, "unexpected chunk number %d (out of range %d..%d) for toast value %u in %s",
+				 residx,
+				 0, numchunks - 1,
+				 toast_pointer.va_valueid,
+				 RelationGetRelationName(toastrel));
+
+		/*
+		 * Copy the data into proper place in our result
+		 */
+		memcpy(VARDATA(result) + residx * TOAST_MAX_CHUNK_SIZE,
+			   chunkdata,
+			   chunksize);
+
+		nextidx++;
+	}
+
+	/*
+	 * Final checks that we successfully fetched the datum
+	 */
+	if (nextidx != numchunks)
+		elog(ERROR, "missing chunk number %d for toast value %u in %s",
+			 nextidx,
+			 toast_pointer.va_valueid,
+			 RelationGetRelationName(toastrel));
+
+	/*
+	 * End scan and close relations
+	 */
+	systable_endscan_ordered(toastscan);
+	toast_close_indexes(toastidxs, num_indexes, AccessShareLock);
+	table_close(toastrel, AccessShareLock);
+
+	return result;
+}
+
+/* ----------
+ * toast_fetch_datum_slice -
+ *
+ *	Reconstruct a segment of a Datum from the chunks saved
+ *	in the toast relation
+ *
+ *	Note that this function only supports non-compressed external datums.
+ * ----------
+ */
+static struct varlena *
+toast_fetch_datum_slice(struct varlena *attr, int32 sliceoffset, int32 length)
+{
+	Relation	toastrel;
+	Relation   *toastidxs;
+	ScanKeyData toastkey[3];
+	int			nscankeys;
+	SysScanDesc toastscan;
+	HeapTuple	ttup;
+	TupleDesc	toasttupDesc;
+	struct varlena *result;
+	struct varatt_external toast_pointer;
+	int32		attrsize;
+	int32		residx;
+	int32		nextidx;
+	int			numchunks;
+	int			startchunk;
+	int			endchunk;
+	int32		startoffset;
+	int32		endoffset;
+	int			totalchunks;
+	Pointer		chunk;
+	bool		isnull;
+	char	   *chunkdata;
+	int32		chunksize;
+	int32		chcpystrt;
+	int32		chcpyend;
+	int			num_indexes;
+	int			validIndex;
+	SnapshotData SnapshotToast;
+
+	if (!VARATT_IS_EXTERNAL_ONDISK(attr))
+		elog(ERROR, "toast_fetch_datum_slice shouldn't be called for non-ondisk datums");
+
+	/* Must copy to access aligned fields */
+	VARATT_EXTERNAL_GET_POINTER(toast_pointer, attr);
+
+	/*
+	 * It's nonsense to fetch slices of a compressed datum -- this isn't lo_*
+	 * we can't return a compressed datum which is meaningful to toast later
+	 */
+	Assert(!VARATT_EXTERNAL_IS_COMPRESSED(toast_pointer));
+
+	attrsize = toast_pointer.va_extsize;
+	totalchunks = ((attrsize - 1) / TOAST_MAX_CHUNK_SIZE) + 1;
+
+	if (sliceoffset >= attrsize)
+	{
+		sliceoffset = 0;
+		length = 0;
+	}
+
+	if (((sliceoffset + length) > attrsize) || length < 0)
+		length = attrsize - sliceoffset;
+
+	result = (struct varlena *) palloc(length + VARHDRSZ);
+
+	SET_VARSIZE(result, length + VARHDRSZ);
+
+	if (length == 0)
+		return result;			/* Can save a lot of work at this point! */
+
+	startchunk = sliceoffset / TOAST_MAX_CHUNK_SIZE;
+	endchunk = (sliceoffset + length - 1) / TOAST_MAX_CHUNK_SIZE;
+	numchunks = (endchunk - startchunk) + 1;
+
+	startoffset = sliceoffset % TOAST_MAX_CHUNK_SIZE;
+	endoffset = (sliceoffset + length - 1) % TOAST_MAX_CHUNK_SIZE;
+
+	/*
+	 * Open the toast relation and its indexes
+	 */
+	toastrel = table_open(toast_pointer.va_toastrelid, AccessShareLock);
+	toasttupDesc = toastrel->rd_att;
+
+	/* Look for the valid index of toast relation */
+	validIndex = toast_open_indexes(toastrel,
+									AccessShareLock,
+									&toastidxs,
+									&num_indexes);
+
+	/*
+	 * Setup a scan key to fetch from the index. This is either two keys or
+	 * three depending on the number of chunks.
+	 */
+	ScanKeyInit(&toastkey[0],
+				(AttrNumber) 1,
+				BTEqualStrategyNumber, F_OIDEQ,
+				ObjectIdGetDatum(toast_pointer.va_valueid));
+
+	/*
+	 * Use equality condition for one chunk, a range condition otherwise:
+	 */
+	if (numchunks == 1)
+	{
+		ScanKeyInit(&toastkey[1],
+					(AttrNumber) 2,
+					BTEqualStrategyNumber, F_INT4EQ,
+					Int32GetDatum(startchunk));
+		nscankeys = 2;
+	}
+	else
+	{
+		ScanKeyInit(&toastkey[1],
+					(AttrNumber) 2,
+					BTGreaterEqualStrategyNumber, F_INT4GE,
+					Int32GetDatum(startchunk));
+		ScanKeyInit(&toastkey[2],
+					(AttrNumber) 2,
+					BTLessEqualStrategyNumber, F_INT4LE,
+					Int32GetDatum(endchunk));
+		nscankeys = 3;
+	}
+
+	/*
+	 * Read the chunks by index
+	 *
+	 * The index is on (valueid, chunkidx) so they will come in order
+	 */
+	init_toast_snapshot(&SnapshotToast);
+	nextidx = startchunk;
+	toastscan = systable_beginscan_ordered(toastrel, toastidxs[validIndex],
+										   &SnapshotToast, nscankeys, toastkey);
+	while ((ttup = systable_getnext_ordered(toastscan, ForwardScanDirection)) != NULL)
+	{
+		/*
+		 * Have a chunk, extract the sequence number and the data
+		 */
+		residx = DatumGetInt32(fastgetattr(ttup, 2, toasttupDesc, &isnull));
+		Assert(!isnull);
+		chunk = DatumGetPointer(fastgetattr(ttup, 3, toasttupDesc, &isnull));
+		Assert(!isnull);
+		if (!VARATT_IS_EXTENDED(chunk))
+		{
+			chunksize = VARSIZE(chunk) - VARHDRSZ;
+			chunkdata = VARDATA(chunk);
+		}
+		else if (VARATT_IS_SHORT(chunk))
+		{
+			/* could happen due to heap_form_tuple doing its thing */
+			chunksize = VARSIZE_SHORT(chunk) - VARHDRSZ_SHORT;
+			chunkdata = VARDATA_SHORT(chunk);
+		}
+		else
+		{
+			/* should never happen */
+			elog(ERROR, "found toasted toast chunk for toast value %u in %s",
+				 toast_pointer.va_valueid,
+				 RelationGetRelationName(toastrel));
+			chunksize = 0;		/* keep compiler quiet */
+			chunkdata = NULL;
+		}
+
+		/*
+		 * Some checks on the data we've found
+		 */
+		if ((residx != nextidx) || (residx > endchunk) || (residx < startchunk))
+			elog(ERROR, "unexpected chunk number %d (expected %d) for toast value %u in %s",
+				 residx, nextidx,
+				 toast_pointer.va_valueid,
+				 RelationGetRelationName(toastrel));
+		if (residx < totalchunks - 1)
+		{
+			if (chunksize != TOAST_MAX_CHUNK_SIZE)
+				elog(ERROR, "unexpected chunk size %d (expected %d) in chunk %d of %d for toast value %u in %s when fetching slice",
+					 chunksize, (int) TOAST_MAX_CHUNK_SIZE,
+					 residx, totalchunks,
+					 toast_pointer.va_valueid,
+					 RelationGetRelationName(toastrel));
+		}
+		else if (residx == totalchunks - 1)
+		{
+			if ((residx * TOAST_MAX_CHUNK_SIZE + chunksize) != attrsize)
+				elog(ERROR, "unexpected chunk size %d (expected %d) in final chunk %d for toast value %u in %s when fetching slice",
+					 chunksize,
+					 (int) (attrsize - residx * TOAST_MAX_CHUNK_SIZE),
+					 residx,
+					 toast_pointer.va_valueid,
+					 RelationGetRelationName(toastrel));
+		}
+		else
+			elog(ERROR, "unexpected chunk number %d (out of range %d..%d) for toast value %u in %s",
+				 residx,
+				 0, totalchunks - 1,
+				 toast_pointer.va_valueid,
+				 RelationGetRelationName(toastrel));
+
+		/*
+		 * Copy the data into proper place in our result
+		 */
+		chcpystrt = 0;
+		chcpyend = chunksize - 1;
+		if (residx == startchunk)
+			chcpystrt = startoffset;
+		if (residx == endchunk)
+			chcpyend = endoffset;
+
+		memcpy(VARDATA(result) +
+			   (residx * TOAST_MAX_CHUNK_SIZE - sliceoffset) + chcpystrt,
+			   chunkdata + chcpystrt,
+			   (chcpyend - chcpystrt) + 1);
+
+		nextidx++;
+	}
+
+	/*
+	 * Final checks that we successfully fetched the datum
+	 */
+	if (nextidx != (endchunk + 1))
+		elog(ERROR, "missing chunk number %d for toast value %u in %s",
+			 nextidx,
+			 toast_pointer.va_valueid,
+			 RelationGetRelationName(toastrel));
+
+	/*
+	 * End scan and close relations
+	 */
+	systable_endscan_ordered(toastscan);
+	toast_close_indexes(toastidxs, num_indexes, AccessShareLock);
+	table_close(toastrel, AccessShareLock);
+
+	return result;
+}
+
+/* ----------
+ * toast_decompress_datum -
+ *
+ * Decompress a compressed version of a varlena datum
+ */
+static struct varlena *
+toast_decompress_datum(struct varlena *attr)
+{
+	struct varlena *result;
+
+	Assert(VARATT_IS_COMPRESSED(attr));
+
+	result = (struct varlena *)
+		palloc(TOAST_COMPRESS_RAWSIZE(attr) + VARHDRSZ);
+	SET_VARSIZE(result, TOAST_COMPRESS_RAWSIZE(attr) + VARHDRSZ);
+
+	if (pglz_decompress(TOAST_COMPRESS_RAWDATA(attr),
+						VARSIZE(attr) - TOAST_COMPRESS_HDRSZ,
+						VARDATA(result),
+						TOAST_COMPRESS_RAWSIZE(attr), true) < 0)
+		elog(ERROR, "compressed data is corrupted");
+
+	return result;
+}
+
+
+/* ----------
+ * toast_decompress_datum_slice -
+ *
+ * Decompress the front of a compressed version of a varlena datum.
+ * offset handling happens in heap_tuple_untoast_attr_slice.
+ * Here we just decompress a slice from the front.
+ */
+static struct varlena *
+toast_decompress_datum_slice(struct varlena *attr, int32 slicelength)
+{
+	struct varlena *result;
+	int32		rawsize;
+
+	Assert(VARATT_IS_COMPRESSED(attr));
+
+	result = (struct varlena *) palloc(slicelength + VARHDRSZ);
+
+	rawsize = pglz_decompress(TOAST_COMPRESS_RAWDATA(attr),
+							  VARSIZE(attr) - TOAST_COMPRESS_HDRSZ,
+							  VARDATA(result),
+							  slicelength, false);
+	if (rawsize < 0)
+		elog(ERROR, "compressed data is corrupted");
+
+	SET_VARSIZE(result, rawsize + VARHDRSZ);
+	return result;
+}
+
+/* ----------
+ * toast_raw_datum_size -
+ *
+ *	Return the raw (detoasted) size of a varlena datum
+ *	(including the VARHDRSZ header)
+ * ----------
+ */
+Size
+toast_raw_datum_size(Datum value)
+{
+	struct varlena *attr = (struct varlena *) DatumGetPointer(value);
+	Size		result;
+
+	if (VARATT_IS_EXTERNAL_ONDISK(attr))
+	{
+		/* va_rawsize is the size of the original datum -- including header */
+		struct varatt_external toast_pointer;
+
+		VARATT_EXTERNAL_GET_POINTER(toast_pointer, attr);
+		result = toast_pointer.va_rawsize;
+	}
+	else if (VARATT_IS_EXTERNAL_INDIRECT(attr))
+	{
+		struct varatt_indirect toast_pointer;
+
+		VARATT_EXTERNAL_GET_POINTER(toast_pointer, attr);
+
+		/* nested indirect Datums aren't allowed */
+		Assert(!VARATT_IS_EXTERNAL_INDIRECT(toast_pointer.pointer));
+
+		return toast_raw_datum_size(PointerGetDatum(toast_pointer.pointer));
+	}
+	else if (VARATT_IS_EXTERNAL_EXPANDED(attr))
+	{
+		result = EOH_get_flat_size(DatumGetEOHP(value));
+	}
+	else if (VARATT_IS_COMPRESSED(attr))
+	{
+		/* here, va_rawsize is just the payload size */
+		result = VARRAWSIZE_4B_C(attr) + VARHDRSZ;
+	}
+	else if (VARATT_IS_SHORT(attr))
+	{
+		/*
+		 * we have to normalize the header length to VARHDRSZ or else the
+		 * callers of this function will be confused.
+		 */
+		result = VARSIZE_SHORT(attr) - VARHDRSZ_SHORT + VARHDRSZ;
+	}
+	else
+	{
+		/* plain untoasted datum */
+		result = VARSIZE(attr);
+	}
+	return result;
+}
+
+/* ----------
+ * toast_datum_size
+ *
+ *	Return the physical storage size (possibly compressed) of a varlena datum
+ * ----------
+ */
+Size
+toast_datum_size(Datum value)
+{
+	struct varlena *attr = (struct varlena *) DatumGetPointer(value);
+	Size		result;
+
+	if (VARATT_IS_EXTERNAL_ONDISK(attr))
+	{
+		/*
+		 * Attribute is stored externally - return the extsize whether
+		 * compressed or not.  We do not count the size of the toast pointer
+		 * ... should we?
+		 */
+		struct varatt_external toast_pointer;
+
+		VARATT_EXTERNAL_GET_POINTER(toast_pointer, attr);
+		result = toast_pointer.va_extsize;
+	}
+	else if (VARATT_IS_EXTERNAL_INDIRECT(attr))
+	{
+		struct varatt_indirect toast_pointer;
+
+		VARATT_EXTERNAL_GET_POINTER(toast_pointer, attr);
+
+		/* nested indirect Datums aren't allowed */
+		Assert(!VARATT_IS_EXTERNAL_INDIRECT(attr));
+
+		return toast_datum_size(PointerGetDatum(toast_pointer.pointer));
+	}
+	else if (VARATT_IS_EXTERNAL_EXPANDED(attr))
+	{
+		result = EOH_get_flat_size(DatumGetEOHP(value));
+	}
+	else if (VARATT_IS_SHORT(attr))
+	{
+		result = VARSIZE_SHORT(attr);
+	}
+	else
+	{
+		/*
+		 * Attribute is stored inline either compressed or not, just calculate
+		 * the size of the datum in either case.
+		 */
+		result = VARSIZE(attr);
+	}
+	return result;
+}
diff --git a/src/backend/access/common/heaptuple.c b/src/backend/access/common/heaptuple.c
index a48a6cd757..cc948958d7 100644
--- a/src/backend/access/common/heaptuple.c
+++ b/src/backend/access/common/heaptuple.c
@@ -18,7 +18,7 @@
  * (In performance-critical code paths we can use pg_detoast_datum_packed
  * and the appropriate access macros to avoid that overhead.)  Note that this
  * conversion is performed directly in heap_form_tuple, without invoking
- * tuptoaster.c.
+ * heaptoast.c.
  *
  * This change will break any code that assumes it needn't detoast values
  * that have been put into a tuple but never sent to disk.  Hopefully there
@@ -57,9 +57,9 @@
 
 #include "postgres.h"
 
+#include "access/heaptoast.h"
 #include "access/sysattr.h"
 #include "access/tupdesc_details.h"
-#include "access/tuptoaster.h"
 #include "executor/tuptable.h"
 #include "utils/expandeddatum.h"
 
diff --git a/src/backend/access/common/indextuple.c b/src/backend/access/common/indextuple.c
index cb23be859d..07586201b9 100644
--- a/src/backend/access/common/indextuple.c
+++ b/src/backend/access/common/indextuple.c
@@ -16,10 +16,17 @@
 
 #include "postgres.h"
 
+#include "access/detoast.h"
+#include "access/heaptoast.h"
 #include "access/htup_details.h"
 #include "access/itup.h"
-#include "access/tuptoaster.h"
+#include "access/toast_internals.h"
 
+/*
+ * This enables de-toasting of index entries.  Needed until VACUUM is
+ * smart enough to rebuild indexes from scratch.
+ */
+#define TOAST_INDEX_HACK
 
 /* ----------------------------------------------------------------
  *				  index_ tuple interface routines
diff --git a/src/backend/access/common/reloptions.c b/src/backend/access/common/reloptions.c
index 5773021499..e1ec873600 100644
--- a/src/backend/access/common/reloptions.c
+++ b/src/backend/access/common/reloptions.c
@@ -19,11 +19,11 @@
 
 #include "access/gist_private.h"
 #include "access/hash.h"
+#include "access/heaptoast.h"
 #include "access/htup_details.h"
 #include "access/nbtree.h"
 #include "access/reloptions.h"
 #include "access/spgist.h"
-#include "access/tuptoaster.h"
 #include "catalog/pg_type.h"
 #include "commands/defrem.h"
 #include "commands/tablespace.h"
diff --git a/src/backend/access/common/toast_internals.c b/src/backend/access/common/toast_internals.c
new file mode 100644
index 0000000000..a971242490
--- /dev/null
+++ b/src/backend/access/common/toast_internals.c
@@ -0,0 +1,632 @@
+/*-------------------------------------------------------------------------
+ *
+ * toast_internals.c
+ *	  Functions for internal use by the TOAST system.
+ *
+ * Copyright (c) 2000-2019, PostgreSQL Global Development Group
+ *
+ * IDENTIFICATION
+ *	  src/backend/access/common/toast_internals.c
+ *
+ *-------------------------------------------------------------------------
+ */
+
+#include "postgres.h"
+
+#include "access/detoast.h"
+#include "access/genam.h"
+#include "access/heapam.h"
+#include "access/heaptoast.h"
+#include "access/table.h"
+#include "access/toast_internals.h"
+#include "access/xact.h"
+#include "catalog/catalog.h"
+#include "common/pg_lzcompress.h"
+#include "miscadmin.h"
+#include "utils/fmgroids.h"
+#include "utils/rel.h"
+#include "utils/snapmgr.h"
+
+static bool toastrel_valueid_exists(Relation toastrel, Oid valueid);
+static bool toastid_valueid_exists(Oid toastrelid, Oid valueid);
+
+/* ----------
+ * toast_compress_datum -
+ *
+ *	Create a compressed version of a varlena datum
+ *
+ *	If we fail (ie, compressed result is actually bigger than original)
+ *	then return NULL.  We must not use compressed data if it'd expand
+ *	the tuple!
+ *
+ *	We use VAR{SIZE,DATA}_ANY so we can handle short varlenas here without
+ *	copying them.  But we can't handle external or compressed datums.
+ * ----------
+ */
+Datum
+toast_compress_datum(Datum value)
+{
+	struct varlena *tmp;
+	int32		valsize = VARSIZE_ANY_EXHDR(DatumGetPointer(value));
+	int32		len;
+
+	Assert(!VARATT_IS_EXTERNAL(DatumGetPointer(value)));
+	Assert(!VARATT_IS_COMPRESSED(DatumGetPointer(value)));
+
+	/*
+	 * No point in wasting a palloc cycle if value size is out of the allowed
+	 * range for compression
+	 */
+	if (valsize < PGLZ_strategy_default->min_input_size ||
+		valsize > PGLZ_strategy_default->max_input_size)
+		return PointerGetDatum(NULL);
+
+	tmp = (struct varlena *) palloc(PGLZ_MAX_OUTPUT(valsize) +
+									TOAST_COMPRESS_HDRSZ);
+
+	/*
+	 * We recheck the actual size even if pglz_compress() reports success,
+	 * because it might be satisfied with having saved as little as one byte
+	 * in the compressed data --- which could turn into a net loss once you
+	 * consider header and alignment padding.  Worst case, the compressed
+	 * format might require three padding bytes (plus header, which is
+	 * included in VARSIZE(tmp)), whereas the uncompressed format would take
+	 * only one header byte and no padding if the value is short enough.  So
+	 * we insist on a savings of more than 2 bytes to ensure we have a gain.
+	 */
+	len = pglz_compress(VARDATA_ANY(DatumGetPointer(value)),
+						valsize,
+						TOAST_COMPRESS_RAWDATA(tmp),
+						PGLZ_strategy_default);
+	if (len >= 0 &&
+		len + TOAST_COMPRESS_HDRSZ < valsize - 2)
+	{
+		TOAST_COMPRESS_SET_RAWSIZE(tmp, valsize);
+		SET_VARSIZE_COMPRESSED(tmp, len + TOAST_COMPRESS_HDRSZ);
+		/* successful compression */
+		return PointerGetDatum(tmp);
+	}
+	else
+	{
+		/* incompressible data */
+		pfree(tmp);
+		return PointerGetDatum(NULL);
+	}
+}
+
+/* ----------
+ * toast_save_datum -
+ *
+ *	Save one single datum into the secondary relation and return
+ *	a Datum reference for it.
+ *
+ * rel: the main relation we're working with (not the toast rel!)
+ * value: datum to be pushed to toast storage
+ * oldexternal: if not NULL, toast pointer previously representing the datum
+ * options: options to be passed to heap_insert() for toast rows
+ * ----------
+ */
+Datum
+toast_save_datum(Relation rel, Datum value,
+				 struct varlena *oldexternal, int options)
+{
+	Relation	toastrel;
+	Relation   *toastidxs;
+	HeapTuple	toasttup;
+	TupleDesc	toasttupDesc;
+	Datum		t_values[3];
+	bool		t_isnull[3];
+	CommandId	mycid = GetCurrentCommandId(true);
+	struct varlena *result;
+	struct varatt_external toast_pointer;
+	union
+	{
+		struct varlena hdr;
+		/* this is to make the union big enough for a chunk: */
+		char		data[TOAST_MAX_CHUNK_SIZE + VARHDRSZ];
+		/* ensure union is aligned well enough: */
+		int32		align_it;
+	}			chunk_data;
+	int32		chunk_size;
+	int32		chunk_seq = 0;
+	char	   *data_p;
+	int32		data_todo;
+	Pointer		dval = DatumGetPointer(value);
+	int			num_indexes;
+	int			validIndex;
+
+	Assert(!VARATT_IS_EXTERNAL(value));
+
+	/*
+	 * Open the toast relation and its indexes.  We can use the index to check
+	 * uniqueness of the OID we assign to the toasted item, even though it has
+	 * additional columns besides OID.
+	 */
+	toastrel = table_open(rel->rd_rel->reltoastrelid, RowExclusiveLock);
+	toasttupDesc = toastrel->rd_att;
+
+	/* Open all the toast indexes and look for the valid one */
+	validIndex = toast_open_indexes(toastrel,
+									RowExclusiveLock,
+									&toastidxs,
+									&num_indexes);
+
+	/*
+	 * Get the data pointer and length, and compute va_rawsize and va_extsize.
+	 *
+	 * va_rawsize is the size of the equivalent fully uncompressed datum, so
+	 * we have to adjust for short headers.
+	 *
+	 * va_extsize is the actual size of the data payload in the toast records.
+	 */
+	if (VARATT_IS_SHORT(dval))
+	{
+		data_p = VARDATA_SHORT(dval);
+		data_todo = VARSIZE_SHORT(dval) - VARHDRSZ_SHORT;
+		toast_pointer.va_rawsize = data_todo + VARHDRSZ;	/* as if not short */
+		toast_pointer.va_extsize = data_todo;
+	}
+	else if (VARATT_IS_COMPRESSED(dval))
+	{
+		data_p = VARDATA(dval);
+		data_todo = VARSIZE(dval) - VARHDRSZ;
+		/* rawsize in a compressed datum is just the size of the payload */
+		toast_pointer.va_rawsize = VARRAWSIZE_4B_C(dval) + VARHDRSZ;
+		toast_pointer.va_extsize = data_todo;
+		/* Assert that the numbers look like it's compressed */
+		Assert(VARATT_EXTERNAL_IS_COMPRESSED(toast_pointer));
+	}
+	else
+	{
+		data_p = VARDATA(dval);
+		data_todo = VARSIZE(dval) - VARHDRSZ;
+		toast_pointer.va_rawsize = VARSIZE(dval);
+		toast_pointer.va_extsize = data_todo;
+	}
+
+	/*
+	 * Insert the correct table OID into the result TOAST pointer.
+	 *
+	 * Normally this is the actual OID of the target toast table, but during
+	 * table-rewriting operations such as CLUSTER, we have to insert the OID
+	 * of the table's real permanent toast table instead.  rd_toastoid is set
+	 * if we have to substitute such an OID.
+	 */
+	if (OidIsValid(rel->rd_toastoid))
+		toast_pointer.va_toastrelid = rel->rd_toastoid;
+	else
+		toast_pointer.va_toastrelid = RelationGetRelid(toastrel);
+
+	/*
+	 * Choose an OID to use as the value ID for this toast value.
+	 *
+	 * Normally we just choose an unused OID within the toast table.  But
+	 * during table-rewriting operations where we are preserving an existing
+	 * toast table OID, we want to preserve toast value OIDs too.  So, if
+	 * rd_toastoid is set and we had a prior external value from that same
+	 * toast table, re-use its value ID.  If we didn't have a prior external
+	 * value (which is a corner case, but possible if the table's attstorage
+	 * options have been changed), we have to pick a value ID that doesn't
+	 * conflict with either new or existing toast value OIDs.
+	 */
+	if (!OidIsValid(rel->rd_toastoid))
+	{
+		/* normal case: just choose an unused OID */
+		toast_pointer.va_valueid =
+			GetNewOidWithIndex(toastrel,
+							   RelationGetRelid(toastidxs[validIndex]),
+							   (AttrNumber) 1);
+	}
+	else
+	{
+		/* rewrite case: check to see if value was in old toast table */
+		toast_pointer.va_valueid = InvalidOid;
+		if (oldexternal != NULL)
+		{
+			struct varatt_external old_toast_pointer;
+
+			Assert(VARATT_IS_EXTERNAL_ONDISK(oldexternal));
+			/* Must copy to access aligned fields */
+			VARATT_EXTERNAL_GET_POINTER(old_toast_pointer, oldexternal);
+			if (old_toast_pointer.va_toastrelid == rel->rd_toastoid)
+			{
+				/* This value came from the old toast table; reuse its OID */
+				toast_pointer.va_valueid = old_toast_pointer.va_valueid;
+
+				/*
+				 * There is a corner case here: the table rewrite might have
+				 * to copy both live and recently-dead versions of a row, and
+				 * those versions could easily reference the same toast value.
+				 * When we copy the second or later version of such a row,
+				 * reusing the OID will mean we select an OID that's already
+				 * in the new toast table.  Check for that, and if so, just
+				 * fall through without writing the data again.
+				 *
+				 * While annoying and ugly-looking, this is a good thing
+				 * because it ensures that we wind up with only one copy of
+				 * the toast value when there is only one copy in the old
+				 * toast table.  Before we detected this case, we'd have made
+				 * multiple copies, wasting space; and what's worse, the
+				 * copies belonging to already-deleted heap tuples would not
+				 * be reclaimed by VACUUM.
+				 */
+				if (toastrel_valueid_exists(toastrel,
+											toast_pointer.va_valueid))
+				{
+					/* Match, so short-circuit the data storage loop below */
+					data_todo = 0;
+				}
+			}
+		}
+		if (toast_pointer.va_valueid == InvalidOid)
+		{
+			/*
+			 * new value; must choose an OID that doesn't conflict in either
+			 * old or new toast table
+			 */
+			do
+			{
+				toast_pointer.va_valueid =
+					GetNewOidWithIndex(toastrel,
+									   RelationGetRelid(toastidxs[validIndex]),
+									   (AttrNumber) 1);
+			} while (toastid_valueid_exists(rel->rd_toastoid,
+											toast_pointer.va_valueid));
+		}
+	}
+
+	/*
+	 * Initialize constant parts of the tuple data
+	 */
+	t_values[0] = ObjectIdGetDatum(toast_pointer.va_valueid);
+	t_values[2] = PointerGetDatum(&chunk_data);
+	t_isnull[0] = false;
+	t_isnull[1] = false;
+	t_isnull[2] = false;
+
+	/*
+	 * Split up the item into chunks
+	 */
+	while (data_todo > 0)
+	{
+		int			i;
+
+		CHECK_FOR_INTERRUPTS();
+
+		/*
+		 * Calculate the size of this chunk
+		 */
+		chunk_size = Min(TOAST_MAX_CHUNK_SIZE, data_todo);
+
+		/*
+		 * Build a tuple and store it
+		 */
+		t_values[1] = Int32GetDatum(chunk_seq++);
+		SET_VARSIZE(&chunk_data, chunk_size + VARHDRSZ);
+		memcpy(VARDATA(&chunk_data), data_p, chunk_size);
+		toasttup = heap_form_tuple(toasttupDesc, t_values, t_isnull);
+
+		heap_insert(toastrel, toasttup, mycid, options, NULL);
+
+		/*
+		 * Create the index entry.  We cheat a little here by not using
+		 * FormIndexDatum: this relies on the knowledge that the index columns
+		 * are the same as the initial columns of the table for all the
+		 * indexes.  We also cheat by not providing an IndexInfo: this is okay
+		 * for now because btree doesn't need one, but we might have to be
+		 * more honest someday.
+		 *
+		 * Note also that there had better not be any user-created index on
+		 * the TOAST table, since we don't bother to update anything else.
+		 */
+		for (i = 0; i < num_indexes; i++)
+		{
+			/* Only index relations marked as ready can be updated */
+			if (toastidxs[i]->rd_index->indisready)
+				index_insert(toastidxs[i], t_values, t_isnull,
+							 &(toasttup->t_self),
+							 toastrel,
+							 toastidxs[i]->rd_index->indisunique ?
+							 UNIQUE_CHECK_YES : UNIQUE_CHECK_NO,
+							 NULL);
+		}
+
+		/*
+		 * Free memory
+		 */
+		heap_freetuple(toasttup);
+
+		/*
+		 * Move on to next chunk
+		 */
+		data_todo -= chunk_size;
+		data_p += chunk_size;
+	}
+
+	/*
+	 * Done - close toast relation and its indexes
+	 */
+	toast_close_indexes(toastidxs, num_indexes, RowExclusiveLock);
+	table_close(toastrel, RowExclusiveLock);
+
+	/*
+	 * Create the TOAST pointer value that we'll return
+	 */
+	result = (struct varlena *) palloc(TOAST_POINTER_SIZE);
+	SET_VARTAG_EXTERNAL(result, VARTAG_ONDISK);
+	memcpy(VARDATA_EXTERNAL(result), &toast_pointer, sizeof(toast_pointer));
+
+	return PointerGetDatum(result);
+}
+
+/* ----------
+ * toast_delete_datum -
+ *
+ *	Delete a single external stored value.
+ * ----------
+ */
+void
+toast_delete_datum(Relation rel, Datum value, bool is_speculative)
+{
+	struct varlena *attr = (struct varlena *) DatumGetPointer(value);
+	struct varatt_external toast_pointer;
+	Relation	toastrel;
+	Relation   *toastidxs;
+	ScanKeyData toastkey;
+	SysScanDesc toastscan;
+	HeapTuple	toasttup;
+	int			num_indexes;
+	int			validIndex;
+	SnapshotData SnapshotToast;
+
+	if (!VARATT_IS_EXTERNAL_ONDISK(attr))
+		return;
+
+	/* Must copy to access aligned fields */
+	VARATT_EXTERNAL_GET_POINTER(toast_pointer, attr);
+
+	/*
+	 * Open the toast relation and its indexes
+	 */
+	toastrel = table_open(toast_pointer.va_toastrelid, RowExclusiveLock);
+
+	/* Fetch valid relation used for process */
+	validIndex = toast_open_indexes(toastrel,
+									RowExclusiveLock,
+									&toastidxs,
+									&num_indexes);
+
+	/*
+	 * Setup a scan key to find chunks with matching va_valueid
+	 */
+	ScanKeyInit(&toastkey,
+				(AttrNumber) 1,
+				BTEqualStrategyNumber, F_OIDEQ,
+				ObjectIdGetDatum(toast_pointer.va_valueid));
+
+	/*
+	 * Find all the chunks.  (We don't actually care whether we see them in
+	 * sequence or not, but since we've already locked the index we might as
+	 * well use systable_beginscan_ordered.)
+	 */
+	init_toast_snapshot(&SnapshotToast);
+	toastscan = systable_beginscan_ordered(toastrel, toastidxs[validIndex],
+										   &SnapshotToast, 1, &toastkey);
+	while ((toasttup = systable_getnext_ordered(toastscan, ForwardScanDirection)) != NULL)
+	{
+		/*
+		 * Have a chunk, delete it
+		 */
+		if (is_speculative)
+			heap_abort_speculative(toastrel, &toasttup->t_self);
+		else
+			simple_heap_delete(toastrel, &toasttup->t_self);
+	}
+
+	/*
+	 * End scan and close relations
+	 */
+	systable_endscan_ordered(toastscan);
+	toast_close_indexes(toastidxs, num_indexes, RowExclusiveLock);
+	table_close(toastrel, RowExclusiveLock);
+}
+
+/* ----------
+ * toastrel_valueid_exists -
+ *
+ *	Test whether a toast value with the given ID exists in the toast relation.
+ *	For safety, we consider a value to exist if there are either live or dead
+ *	toast rows with that ID; see notes for GetNewOidWithIndex().
+ * ----------
+ */
+static bool
+toastrel_valueid_exists(Relation toastrel, Oid valueid)
+{
+	bool		result = false;
+	ScanKeyData toastkey;
+	SysScanDesc toastscan;
+	int			num_indexes;
+	int			validIndex;
+	Relation   *toastidxs;
+
+	/* Fetch a valid index relation */
+	validIndex = toast_open_indexes(toastrel,
+									RowExclusiveLock,
+									&toastidxs,
+									&num_indexes);
+
+	/*
+	 * Setup a scan key to find chunks with matching va_valueid
+	 */
+	ScanKeyInit(&toastkey,
+				(AttrNumber) 1,
+				BTEqualStrategyNumber, F_OIDEQ,
+				ObjectIdGetDatum(valueid));
+
+	/*
+	 * Is there any such chunk?
+	 */
+	toastscan = systable_beginscan(toastrel,
+								   RelationGetRelid(toastidxs[validIndex]),
+								   true, SnapshotAny, 1, &toastkey);
+
+	if (systable_getnext(toastscan) != NULL)
+		result = true;
+
+	systable_endscan(toastscan);
+
+	/* Clean up */
+	toast_close_indexes(toastidxs, num_indexes, RowExclusiveLock);
+
+	return result;
+}
+
+/* ----------
+ * toastid_valueid_exists -
+ *
+ *	As above, but work from toast rel's OID not an open relation
+ * ----------
+ */
+static bool
+toastid_valueid_exists(Oid toastrelid, Oid valueid)
+{
+	bool		result;
+	Relation	toastrel;
+
+	toastrel = table_open(toastrelid, AccessShareLock);
+
+	result = toastrel_valueid_exists(toastrel, valueid);
+
+	table_close(toastrel, AccessShareLock);
+
+	return result;
+}
+
+/* ----------
+ * toast_get_valid_index
+ *
+ *	Get OID of valid index associated to given toast relation. A toast
+ *	relation can have only one valid index at the same time.
+ */
+Oid
+toast_get_valid_index(Oid toastoid, LOCKMODE lock)
+{
+	int			num_indexes;
+	int			validIndex;
+	Oid			validIndexOid;
+	Relation   *toastidxs;
+	Relation	toastrel;
+
+	/* Open the toast relation */
+	toastrel = table_open(toastoid, lock);
+
+	/* Look for the valid index of the toast relation */
+	validIndex = toast_open_indexes(toastrel,
+									lock,
+									&toastidxs,
+									&num_indexes);
+	validIndexOid = RelationGetRelid(toastidxs[validIndex]);
+
+	/* Close the toast relation and all its indexes */
+	toast_close_indexes(toastidxs, num_indexes, lock);
+	table_close(toastrel, lock);
+
+	return validIndexOid;
+}
+
+/* ----------
+ * toast_open_indexes
+ *
+ *	Get an array of the indexes associated to the given toast relation
+ *	and return as well the position of the valid index used by the toast
+ *	relation in this array. It is the responsibility of the caller of this
+ *	function to close the indexes as well as free them.
+ */
+int
+toast_open_indexes(Relation toastrel,
+				   LOCKMODE lock,
+				   Relation **toastidxs,
+				   int *num_indexes)
+{
+	int			i = 0;
+	int			res = 0;
+	bool		found = false;
+	List	   *indexlist;
+	ListCell   *lc;
+
+	/* Get index list of the toast relation */
+	indexlist = RelationGetIndexList(toastrel);
+	Assert(indexlist != NIL);
+
+	*num_indexes = list_length(indexlist);
+
+	/* Open all the index relations */
+	*toastidxs = (Relation *) palloc(*num_indexes * sizeof(Relation));
+	foreach(lc, indexlist)
+		(*toastidxs)[i++] = index_open(lfirst_oid(lc), lock);
+
+	/* Fetch the first valid index in list */
+	for (i = 0; i < *num_indexes; i++)
+	{
+		Relation	toastidx = (*toastidxs)[i];
+
+		if (toastidx->rd_index->indisvalid)
+		{
+			res = i;
+			found = true;
+			break;
+		}
+	}
+
+	/*
+	 * Free index list, not necessary anymore as relations are opened and a
+	 * valid index has been found.
+	 */
+	list_free(indexlist);
+
+	/*
+	 * The toast relation should have one valid index, so something is going
+	 * wrong if there is nothing.
+	 */
+	if (!found)
+		elog(ERROR, "no valid index found for toast relation with Oid %u",
+			 RelationGetRelid(toastrel));
+
+	return res;
+}
+
+/* ----------
+ * toast_close_indexes
+ *
+ *	Close an array of indexes for a toast relation and free it. This should
+ *	be called for a set of indexes opened previously with toast_open_indexes.
+ */
+void
+toast_close_indexes(Relation *toastidxs, int num_indexes, LOCKMODE lock)
+{
+	int			i;
+
+	/* Close relations and clean up things */
+	for (i = 0; i < num_indexes; i++)
+		index_close(toastidxs[i], lock);
+	pfree(toastidxs);
+}
+
+/* ----------
+ * init_toast_snapshot
+ *
+ *	Initialize an appropriate TOAST snapshot.  We must use an MVCC snapshot
+ *	to initialize the TOAST snapshot; since we don't know which one to use,
+ *	just use the oldest one.  This is safe: at worst, we will get a "snapshot
+ *	too old" error that might have been avoided otherwise.
+ */
+void
+init_toast_snapshot(Snapshot toast_snapshot)
+{
+	Snapshot	snapshot = GetOldestSnapshot();
+
+	if (snapshot == NULL)
+		elog(ERROR, "no known snapshots");
+
+	InitToastSnapshot(*toast_snapshot, snapshot->lsn, snapshot->whenTaken);
+}
diff --git a/src/backend/access/heap/Makefile b/src/backend/access/heap/Makefile
index b2a017249b..38497b09c0 100644
--- a/src/backend/access/heap/Makefile
+++ b/src/backend/access/heap/Makefile
@@ -13,6 +13,6 @@ top_builddir = ../../../..
 include $(top_builddir)/src/Makefile.global
 
 OBJS = heapam.o heapam_handler.o heapam_visibility.o hio.o pruneheap.o rewriteheap.o \
-	syncscan.o tuptoaster.o vacuumlazy.o visibilitymap.o
+	syncscan.o heaptoast.o vacuumlazy.o visibilitymap.o
 
 include $(top_srcdir)/src/backend/common.mk
diff --git a/src/backend/access/heap/heapam.c b/src/backend/access/heap/heapam.c
index d768b9b061..ce141b734b 100644
--- a/src/backend/access/heap/heapam.c
+++ b/src/backend/access/heap/heapam.c
@@ -36,6 +36,7 @@
 #include "access/genam.h"
 #include "access/heapam.h"
 #include "access/heapam_xlog.h"
+#include "access/heaptoast.h"
 #include "access/hio.h"
 #include "access/multixact.h"
 #include "access/parallel.h"
@@ -43,7 +44,6 @@
 #include "access/sysattr.h"
 #include "access/tableam.h"
 #include "access/transam.h"
-#include "access/tuptoaster.h"
 #include "access/valid.h"
 #include "access/visibilitymap.h"
 #include "access/xact.h"
diff --git a/src/backend/access/heap/heapam_handler.c b/src/backend/access/heap/heapam_handler.c
index fc19f40a2e..72c8bfcaf1 100644
--- a/src/backend/access/heap/heapam_handler.c
+++ b/src/backend/access/heap/heapam_handler.c
@@ -25,11 +25,11 @@
 
 #include "access/genam.h"
 #include "access/heapam.h"
+#include "access/heaptoast.h"
 #include "access/multixact.h"
 #include "access/rewriteheap.h"
 #include "access/tableam.h"
 #include "access/tsmapi.h"
-#include "access/tuptoaster.h"
 #include "access/xact.h"
 #include "catalog/catalog.h"
 #include "catalog/index.h"
diff --git a/src/backend/access/heap/heaptoast.c b/src/backend/access/heap/heaptoast.c
new file mode 100644
index 0000000000..5d105e3517
--- /dev/null
+++ b/src/backend/access/heap/heaptoast.c
@@ -0,0 +1,917 @@
+/*-------------------------------------------------------------------------
+ *
+ * heaptoast.c
+ *	  Heap-specific definitions for external and compressed storage
+ *	  of variable size attributes.
+ *
+ * Copyright (c) 2000-2019, PostgreSQL Global Development Group
+ *
+ *
+ * IDENTIFICATION
+ *	  src/backend/access/heap/heaptoast.c
+ *
+ *
+ * INTERFACE ROUTINES
+ *		toast_insert_or_update -
+ *			Try to make a given tuple fit into one page by compressing
+ *			or moving off attributes
+ *
+ *		toast_delete -
+ *			Reclaim toast storage when a tuple is deleted
+ *
+ *-------------------------------------------------------------------------
+ */
+
+#include "postgres.h"
+
+#include "access/detoast.h"
+#include "access/heapam.h"
+#include "access/heaptoast.h"
+#include "access/toast_internals.h"
+
+
+/* ----------
+ * toast_delete -
+ *
+ *	Cascaded delete toast-entries on DELETE
+ * ----------
+ */
+void
+toast_delete(Relation rel, HeapTuple oldtup, bool is_speculative)
+{
+	TupleDesc	tupleDesc;
+	int			numAttrs;
+	int			i;
+	Datum		toast_values[MaxHeapAttributeNumber];
+	bool		toast_isnull[MaxHeapAttributeNumber];
+
+	/*
+	 * We should only ever be called for tuples of plain relations or
+	 * materialized views --- recursing on a toast rel is bad news.
+	 */
+	Assert(rel->rd_rel->relkind == RELKIND_RELATION ||
+		   rel->rd_rel->relkind == RELKIND_MATVIEW);
+
+	/*
+	 * Get the tuple descriptor and break down the tuple into fields.
+	 *
+	 * NOTE: it's debatable whether to use heap_deform_tuple() here or just
+	 * heap_getattr() only the varlena columns.  The latter could win if there
+	 * are few varlena columns and many non-varlena ones. However,
+	 * heap_deform_tuple costs only O(N) while the heap_getattr way would cost
+	 * O(N^2) if there are many varlena columns, so it seems better to err on
+	 * the side of linear cost.  (We won't even be here unless there's at
+	 * least one varlena column, by the way.)
+	 */
+	tupleDesc = rel->rd_att;
+	numAttrs = tupleDesc->natts;
+
+	Assert(numAttrs <= MaxHeapAttributeNumber);
+	heap_deform_tuple(oldtup, tupleDesc, toast_values, toast_isnull);
+
+	/*
+	 * Check for external stored attributes and delete them from the secondary
+	 * relation.
+	 */
+	for (i = 0; i < numAttrs; i++)
+	{
+		if (TupleDescAttr(tupleDesc, i)->attlen == -1)
+		{
+			Datum		value = toast_values[i];
+
+			if (toast_isnull[i])
+				continue;
+			else if (VARATT_IS_EXTERNAL_ONDISK(PointerGetDatum(value)))
+				toast_delete_datum(rel, value, is_speculative);
+		}
+	}
+}
+
+
+/* ----------
+ * toast_insert_or_update -
+ *
+ *	Delete no-longer-used toast-entries and create new ones to
+ *	make the new tuple fit on INSERT or UPDATE
+ *
+ * Inputs:
+ *	newtup: the candidate new tuple to be inserted
+ *	oldtup: the old row version for UPDATE, or NULL for INSERT
+ *	options: options to be passed to heap_insert() for toast rows
+ * Result:
+ *	either newtup if no toasting is needed, or a palloc'd modified tuple
+ *	that is what should actually get stored
+ *
+ * NOTE: neither newtup nor oldtup will be modified.  This is a change
+ * from the pre-8.1 API of this routine.
+ * ----------
+ */
+HeapTuple
+toast_insert_or_update(Relation rel, HeapTuple newtup, HeapTuple oldtup,
+					   int options)
+{
+	HeapTuple	result_tuple;
+	TupleDesc	tupleDesc;
+	int			numAttrs;
+	int			i;
+
+	bool		need_change = false;
+	bool		need_free = false;
+	bool		need_delold = false;
+	bool		has_nulls = false;
+
+	Size		maxDataLen;
+	Size		hoff;
+
+	char		toast_action[MaxHeapAttributeNumber];
+	bool		toast_isnull[MaxHeapAttributeNumber];
+	bool		toast_oldisnull[MaxHeapAttributeNumber];
+	Datum		toast_values[MaxHeapAttributeNumber];
+	Datum		toast_oldvalues[MaxHeapAttributeNumber];
+	struct varlena *toast_oldexternal[MaxHeapAttributeNumber];
+	int32		toast_sizes[MaxHeapAttributeNumber];
+	bool		toast_free[MaxHeapAttributeNumber];
+	bool		toast_delold[MaxHeapAttributeNumber];
+
+	/*
+	 * Ignore the INSERT_SPECULATIVE option. Speculative insertions/super
+	 * deletions just normally insert/delete the toast values. It seems
+	 * easiest to deal with that here, instead on, potentially, multiple
+	 * callers.
+	 */
+	options &= ~HEAP_INSERT_SPECULATIVE;
+
+	/*
+	 * We should only ever be called for tuples of plain relations or
+	 * materialized views --- recursing on a toast rel is bad news.
+	 */
+	Assert(rel->rd_rel->relkind == RELKIND_RELATION ||
+		   rel->rd_rel->relkind == RELKIND_MATVIEW);
+
+	/*
+	 * Get the tuple descriptor and break down the tuple(s) into fields.
+	 */
+	tupleDesc = rel->rd_att;
+	numAttrs = tupleDesc->natts;
+
+	Assert(numAttrs <= MaxHeapAttributeNumber);
+	heap_deform_tuple(newtup, tupleDesc, toast_values, toast_isnull);
+	if (oldtup != NULL)
+		heap_deform_tuple(oldtup, tupleDesc, toast_oldvalues, toast_oldisnull);
+
+	/* ----------
+	 * Then collect information about the values given
+	 *
+	 * NOTE: toast_action[i] can have these values:
+	 *		' '		default handling
+	 *		'p'		already processed --- don't touch it
+	 *		'x'		incompressible, but OK to move off
+	 *
+	 * NOTE: toast_sizes[i] is only made valid for varlena attributes with
+	 *		toast_action[i] different from 'p'.
+	 * ----------
+	 */
+	memset(toast_action, ' ', numAttrs * sizeof(char));
+	memset(toast_oldexternal, 0, numAttrs * sizeof(struct varlena *));
+	memset(toast_free, 0, numAttrs * sizeof(bool));
+	memset(toast_delold, 0, numAttrs * sizeof(bool));
+
+	for (i = 0; i < numAttrs; i++)
+	{
+		Form_pg_attribute att = TupleDescAttr(tupleDesc, i);
+		struct varlena *old_value;
+		struct varlena *new_value;
+
+		if (oldtup != NULL)
+		{
+			/*
+			 * For UPDATE get the old and new values of this attribute
+			 */
+			old_value = (struct varlena *) DatumGetPointer(toast_oldvalues[i]);
+			new_value = (struct varlena *) DatumGetPointer(toast_values[i]);
+
+			/*
+			 * If the old value is stored on disk, check if it has changed so
+			 * we have to delete it later.
+			 */
+			if (att->attlen == -1 && !toast_oldisnull[i] &&
+				VARATT_IS_EXTERNAL_ONDISK(old_value))
+			{
+				if (toast_isnull[i] || !VARATT_IS_EXTERNAL_ONDISK(new_value) ||
+					memcmp((char *) old_value, (char *) new_value,
+						   VARSIZE_EXTERNAL(old_value)) != 0)
+				{
+					/*
+					 * The old external stored value isn't needed any more
+					 * after the update
+					 */
+					toast_delold[i] = true;
+					need_delold = true;
+				}
+				else
+				{
+					/*
+					 * This attribute isn't changed by this update so we reuse
+					 * the original reference to the old value in the new
+					 * tuple.
+					 */
+					toast_action[i] = 'p';
+					continue;
+				}
+			}
+		}
+		else
+		{
+			/*
+			 * For INSERT simply get the new value
+			 */
+			new_value = (struct varlena *) DatumGetPointer(toast_values[i]);
+		}
+
+		/*
+		 * Handle NULL attributes
+		 */
+		if (toast_isnull[i])
+		{
+			toast_action[i] = 'p';
+			has_nulls = true;
+			continue;
+		}
+
+		/*
+		 * Now look at varlena attributes
+		 */
+		if (att->attlen == -1)
+		{
+			/*
+			 * If the table's attribute says PLAIN always, force it so.
+			 */
+			if (att->attstorage == 'p')
+				toast_action[i] = 'p';
+
+			/*
+			 * We took care of UPDATE above, so any external value we find
+			 * still in the tuple must be someone else's that we cannot reuse
+			 * (this includes the case of an out-of-line in-memory datum).
+			 * Fetch it back (without decompression, unless we are forcing
+			 * PLAIN storage).  If necessary, we'll push it out as a new
+			 * external value below.
+			 */
+			if (VARATT_IS_EXTERNAL(new_value))
+			{
+				toast_oldexternal[i] = new_value;
+				if (att->attstorage == 'p')
+					new_value = heap_tuple_untoast_attr(new_value);
+				else
+					new_value = heap_tuple_fetch_attr(new_value);
+				toast_values[i] = PointerGetDatum(new_value);
+				toast_free[i] = true;
+				need_change = true;
+				need_free = true;
+			}
+
+			/*
+			 * Remember the size of this attribute
+			 */
+			toast_sizes[i] = VARSIZE_ANY(new_value);
+		}
+		else
+		{
+			/*
+			 * Not a varlena attribute, plain storage always
+			 */
+			toast_action[i] = 'p';
+		}
+	}
+
+	/* ----------
+	 * Compress and/or save external until data fits into target length
+	 *
+	 *	1: Inline compress attributes with attstorage 'x', and store very
+	 *	   large attributes with attstorage 'x' or 'e' external immediately
+	 *	2: Store attributes with attstorage 'x' or 'e' external
+	 *	3: Inline compress attributes with attstorage 'm'
+	 *	4: Store attributes with attstorage 'm' external
+	 * ----------
+	 */
+
+	/* compute header overhead --- this should match heap_form_tuple() */
+	hoff = SizeofHeapTupleHeader;
+	if (has_nulls)
+		hoff += BITMAPLEN(numAttrs);
+	hoff = MAXALIGN(hoff);
+	/* now convert to a limit on the tuple data size */
+	maxDataLen = RelationGetToastTupleTarget(rel, TOAST_TUPLE_TARGET) - hoff;
+
+	/*
+	 * Look for attributes with attstorage 'x' to compress.  Also find large
+	 * attributes with attstorage 'x' or 'e', and store them external.
+	 */
+	while (heap_compute_data_size(tupleDesc,
+								  toast_values, toast_isnull) > maxDataLen)
+	{
+		int			biggest_attno = -1;
+		int32		biggest_size = MAXALIGN(TOAST_POINTER_SIZE);
+		Datum		old_value;
+		Datum		new_value;
+
+		/*
+		 * Search for the biggest yet unprocessed internal attribute
+		 */
+		for (i = 0; i < numAttrs; i++)
+		{
+			Form_pg_attribute att = TupleDescAttr(tupleDesc, i);
+
+			if (toast_action[i] != ' ')
+				continue;
+			if (VARATT_IS_EXTERNAL(DatumGetPointer(toast_values[i])))
+				continue;		/* can't happen, toast_action would be 'p' */
+			if (VARATT_IS_COMPRESSED(DatumGetPointer(toast_values[i])))
+				continue;
+			if (att->attstorage != 'x' && att->attstorage != 'e')
+				continue;
+			if (toast_sizes[i] > biggest_size)
+			{
+				biggest_attno = i;
+				biggest_size = toast_sizes[i];
+			}
+		}
+
+		if (biggest_attno < 0)
+			break;
+
+		/*
+		 * Attempt to compress it inline, if it has attstorage 'x'
+		 */
+		i = biggest_attno;
+		if (TupleDescAttr(tupleDesc, i)->attstorage == 'x')
+		{
+			old_value = toast_values[i];
+			new_value = toast_compress_datum(old_value);
+
+			if (DatumGetPointer(new_value) != NULL)
+			{
+				/* successful compression */
+				if (toast_free[i])
+					pfree(DatumGetPointer(old_value));
+				toast_values[i] = new_value;
+				toast_free[i] = true;
+				toast_sizes[i] = VARSIZE(DatumGetPointer(toast_values[i]));
+				need_change = true;
+				need_free = true;
+			}
+			else
+			{
+				/* incompressible, ignore on subsequent compression passes */
+				toast_action[i] = 'x';
+			}
+		}
+		else
+		{
+			/* has attstorage 'e', ignore on subsequent compression passes */
+			toast_action[i] = 'x';
+		}
+
+		/*
+		 * If this value is by itself more than maxDataLen (after compression
+		 * if any), push it out to the toast table immediately, if possible.
+		 * This avoids uselessly compressing other fields in the common case
+		 * where we have one long field and several short ones.
+		 *
+		 * XXX maybe the threshold should be less than maxDataLen?
+		 */
+		if (toast_sizes[i] > maxDataLen &&
+			rel->rd_rel->reltoastrelid != InvalidOid)
+		{
+			old_value = toast_values[i];
+			toast_action[i] = 'p';
+			toast_values[i] = toast_save_datum(rel, toast_values[i],
+											   toast_oldexternal[i], options);
+			if (toast_free[i])
+				pfree(DatumGetPointer(old_value));
+			toast_free[i] = true;
+			need_change = true;
+			need_free = true;
+		}
+	}
+
+	/*
+	 * Second we look for attributes of attstorage 'x' or 'e' that are still
+	 * inline.  But skip this if there's no toast table to push them to.
+	 */
+	while (heap_compute_data_size(tupleDesc,
+								  toast_values, toast_isnull) > maxDataLen &&
+		   rel->rd_rel->reltoastrelid != InvalidOid)
+	{
+		int			biggest_attno = -1;
+		int32		biggest_size = MAXALIGN(TOAST_POINTER_SIZE);
+		Datum		old_value;
+
+		/*------
+		 * Search for the biggest yet inlined attribute with
+		 * attstorage equals 'x' or 'e'
+		 *------
+		 */
+		for (i = 0; i < numAttrs; i++)
+		{
+			Form_pg_attribute att = TupleDescAttr(tupleDesc, i);
+
+			if (toast_action[i] == 'p')
+				continue;
+			if (VARATT_IS_EXTERNAL(DatumGetPointer(toast_values[i])))
+				continue;		/* can't happen, toast_action would be 'p' */
+			if (att->attstorage != 'x' && att->attstorage != 'e')
+				continue;
+			if (toast_sizes[i] > biggest_size)
+			{
+				biggest_attno = i;
+				biggest_size = toast_sizes[i];
+			}
+		}
+
+		if (biggest_attno < 0)
+			break;
+
+		/*
+		 * Store this external
+		 */
+		i = biggest_attno;
+		old_value = toast_values[i];
+		toast_action[i] = 'p';
+		toast_values[i] = toast_save_datum(rel, toast_values[i],
+										   toast_oldexternal[i], options);
+		if (toast_free[i])
+			pfree(DatumGetPointer(old_value));
+		toast_free[i] = true;
+
+		need_change = true;
+		need_free = true;
+	}
+
+	/*
+	 * Round 3 - this time we take attributes with storage 'm' into
+	 * compression
+	 */
+	while (heap_compute_data_size(tupleDesc,
+								  toast_values, toast_isnull) > maxDataLen)
+	{
+		int			biggest_attno = -1;
+		int32		biggest_size = MAXALIGN(TOAST_POINTER_SIZE);
+		Datum		old_value;
+		Datum		new_value;
+
+		/*
+		 * Search for the biggest yet uncompressed internal attribute
+		 */
+		for (i = 0; i < numAttrs; i++)
+		{
+			if (toast_action[i] != ' ')
+				continue;
+			if (VARATT_IS_EXTERNAL(DatumGetPointer(toast_values[i])))
+				continue;		/* can't happen, toast_action would be 'p' */
+			if (VARATT_IS_COMPRESSED(DatumGetPointer(toast_values[i])))
+				continue;
+			if (TupleDescAttr(tupleDesc, i)->attstorage != 'm')
+				continue;
+			if (toast_sizes[i] > biggest_size)
+			{
+				biggest_attno = i;
+				biggest_size = toast_sizes[i];
+			}
+		}
+
+		if (biggest_attno < 0)
+			break;
+
+		/*
+		 * Attempt to compress it inline
+		 */
+		i = biggest_attno;
+		old_value = toast_values[i];
+		new_value = toast_compress_datum(old_value);
+
+		if (DatumGetPointer(new_value) != NULL)
+		{
+			/* successful compression */
+			if (toast_free[i])
+				pfree(DatumGetPointer(old_value));
+			toast_values[i] = new_value;
+			toast_free[i] = true;
+			toast_sizes[i] = VARSIZE(DatumGetPointer(toast_values[i]));
+			need_change = true;
+			need_free = true;
+		}
+		else
+		{
+			/* incompressible, ignore on subsequent compression passes */
+			toast_action[i] = 'x';
+		}
+	}
+
+	/*
+	 * Finally we store attributes of type 'm' externally.  At this point we
+	 * increase the target tuple size, so that 'm' attributes aren't stored
+	 * externally unless really necessary.
+	 */
+	maxDataLen = TOAST_TUPLE_TARGET_MAIN - hoff;
+
+	while (heap_compute_data_size(tupleDesc,
+								  toast_values, toast_isnull) > maxDataLen &&
+		   rel->rd_rel->reltoastrelid != InvalidOid)
+	{
+		int			biggest_attno = -1;
+		int32		biggest_size = MAXALIGN(TOAST_POINTER_SIZE);
+		Datum		old_value;
+
+		/*--------
+		 * Search for the biggest yet inlined attribute with
+		 * attstorage = 'm'
+		 *--------
+		 */
+		for (i = 0; i < numAttrs; i++)
+		{
+			if (toast_action[i] == 'p')
+				continue;
+			if (VARATT_IS_EXTERNAL(DatumGetPointer(toast_values[i])))
+				continue;		/* can't happen, toast_action would be 'p' */
+			if (TupleDescAttr(tupleDesc, i)->attstorage != 'm')
+				continue;
+			if (toast_sizes[i] > biggest_size)
+			{
+				biggest_attno = i;
+				biggest_size = toast_sizes[i];
+			}
+		}
+
+		if (biggest_attno < 0)
+			break;
+
+		/*
+		 * Store this external
+		 */
+		i = biggest_attno;
+		old_value = toast_values[i];
+		toast_action[i] = 'p';
+		toast_values[i] = toast_save_datum(rel, toast_values[i],
+										   toast_oldexternal[i], options);
+		if (toast_free[i])
+			pfree(DatumGetPointer(old_value));
+		toast_free[i] = true;
+
+		need_change = true;
+		need_free = true;
+	}
+
+	/*
+	 * In the case we toasted any values, we need to build a new heap tuple
+	 * with the changed values.
+	 */
+	if (need_change)
+	{
+		HeapTupleHeader olddata = newtup->t_data;
+		HeapTupleHeader new_data;
+		int32		new_header_len;
+		int32		new_data_len;
+		int32		new_tuple_len;
+
+		/*
+		 * Calculate the new size of the tuple.
+		 *
+		 * Note: we used to assume here that the old tuple's t_hoff must equal
+		 * the new_header_len value, but that was incorrect.  The old tuple
+		 * might have a smaller-than-current natts, if there's been an ALTER
+		 * TABLE ADD COLUMN since it was stored; and that would lead to a
+		 * different conclusion about the size of the null bitmap, or even
+		 * whether there needs to be one at all.
+		 */
+		new_header_len = SizeofHeapTupleHeader;
+		if (has_nulls)
+			new_header_len += BITMAPLEN(numAttrs);
+		new_header_len = MAXALIGN(new_header_len);
+		new_data_len = heap_compute_data_size(tupleDesc,
+											  toast_values, toast_isnull);
+		new_tuple_len = new_header_len + new_data_len;
+
+		/*
+		 * Allocate and zero the space needed, and fill HeapTupleData fields.
+		 */
+		result_tuple = (HeapTuple) palloc0(HEAPTUPLESIZE + new_tuple_len);
+		result_tuple->t_len = new_tuple_len;
+		result_tuple->t_self = newtup->t_self;
+		result_tuple->t_tableOid = newtup->t_tableOid;
+		new_data = (HeapTupleHeader) ((char *) result_tuple + HEAPTUPLESIZE);
+		result_tuple->t_data = new_data;
+
+		/*
+		 * Copy the existing tuple header, but adjust natts and t_hoff.
+		 */
+		memcpy(new_data, olddata, SizeofHeapTupleHeader);
+		HeapTupleHeaderSetNatts(new_data, numAttrs);
+		new_data->t_hoff = new_header_len;
+
+		/* Copy over the data, and fill the null bitmap if needed */
+		heap_fill_tuple(tupleDesc,
+						toast_values,
+						toast_isnull,
+						(char *) new_data + new_header_len,
+						new_data_len,
+						&(new_data->t_infomask),
+						has_nulls ? new_data->t_bits : NULL);
+	}
+	else
+		result_tuple = newtup;
+
+	/*
+	 * Free allocated temp values
+	 */
+	if (need_free)
+		for (i = 0; i < numAttrs; i++)
+			if (toast_free[i])
+				pfree(DatumGetPointer(toast_values[i]));
+
+	/*
+	 * Delete external values from the old tuple
+	 */
+	if (need_delold)
+		for (i = 0; i < numAttrs; i++)
+			if (toast_delold[i])
+				toast_delete_datum(rel, toast_oldvalues[i], false);
+
+	return result_tuple;
+}
+
+
+/* ----------
+ * toast_flatten_tuple -
+ *
+ *	"Flatten" a tuple to contain no out-of-line toasted fields.
+ *	(This does not eliminate compressed or short-header datums.)
+ *
+ *	Note: we expect the caller already checked HeapTupleHasExternal(tup),
+ *	so there is no need for a short-circuit path.
+ * ----------
+ */
+HeapTuple
+toast_flatten_tuple(HeapTuple tup, TupleDesc tupleDesc)
+{
+	HeapTuple	new_tuple;
+	int			numAttrs = tupleDesc->natts;
+	int			i;
+	Datum		toast_values[MaxTupleAttributeNumber];
+	bool		toast_isnull[MaxTupleAttributeNumber];
+	bool		toast_free[MaxTupleAttributeNumber];
+
+	/*
+	 * Break down the tuple into fields.
+	 */
+	Assert(numAttrs <= MaxTupleAttributeNumber);
+	heap_deform_tuple(tup, tupleDesc, toast_values, toast_isnull);
+
+	memset(toast_free, 0, numAttrs * sizeof(bool));
+
+	for (i = 0; i < numAttrs; i++)
+	{
+		/*
+		 * Look at non-null varlena attributes
+		 */
+		if (!toast_isnull[i] && TupleDescAttr(tupleDesc, i)->attlen == -1)
+		{
+			struct varlena *new_value;
+
+			new_value = (struct varlena *) DatumGetPointer(toast_values[i]);
+			if (VARATT_IS_EXTERNAL(new_value))
+			{
+				new_value = heap_tuple_fetch_attr(new_value);
+				toast_values[i] = PointerGetDatum(new_value);
+				toast_free[i] = true;
+			}
+		}
+	}
+
+	/*
+	 * Form the reconfigured tuple.
+	 */
+	new_tuple = heap_form_tuple(tupleDesc, toast_values, toast_isnull);
+
+	/*
+	 * Be sure to copy the tuple's identity fields.  We also make a point of
+	 * copying visibility info, just in case anybody looks at those fields in
+	 * a syscache entry.
+	 */
+	new_tuple->t_self = tup->t_self;
+	new_tuple->t_tableOid = tup->t_tableOid;
+
+	new_tuple->t_data->t_choice = tup->t_data->t_choice;
+	new_tuple->t_data->t_ctid = tup->t_data->t_ctid;
+	new_tuple->t_data->t_infomask &= ~HEAP_XACT_MASK;
+	new_tuple->t_data->t_infomask |=
+		tup->t_data->t_infomask & HEAP_XACT_MASK;
+	new_tuple->t_data->t_infomask2 &= ~HEAP2_XACT_MASK;
+	new_tuple->t_data->t_infomask2 |=
+		tup->t_data->t_infomask2 & HEAP2_XACT_MASK;
+
+	/*
+	 * Free allocated temp values
+	 */
+	for (i = 0; i < numAttrs; i++)
+		if (toast_free[i])
+			pfree(DatumGetPointer(toast_values[i]));
+
+	return new_tuple;
+}
+
+
+/* ----------
+ * toast_flatten_tuple_to_datum -
+ *
+ *	"Flatten" a tuple containing out-of-line toasted fields into a Datum.
+ *	The result is always palloc'd in the current memory context.
+ *
+ *	We have a general rule that Datums of container types (rows, arrays,
+ *	ranges, etc) must not contain any external TOAST pointers.  Without
+ *	this rule, we'd have to look inside each Datum when preparing a tuple
+ *	for storage, which would be expensive and would fail to extend cleanly
+ *	to new sorts of container types.
+ *
+ *	However, we don't want to say that tuples represented as HeapTuples
+ *	can't contain toasted fields, so instead this routine should be called
+ *	when such a HeapTuple is being converted into a Datum.
+ *
+ *	While we're at it, we decompress any compressed fields too.  This is not
+ *	necessary for correctness, but reflects an expectation that compression
+ *	will be more effective if applied to the whole tuple not individual
+ *	fields.  We are not so concerned about that that we want to deconstruct
+ *	and reconstruct tuples just to get rid of compressed fields, however.
+ *	So callers typically won't call this unless they see that the tuple has
+ *	at least one external field.
+ *
+ *	On the other hand, in-line short-header varlena fields are left alone.
+ *	If we "untoasted" them here, they'd just get changed back to short-header
+ *	format anyway within heap_fill_tuple.
+ * ----------
+ */
+Datum
+toast_flatten_tuple_to_datum(HeapTupleHeader tup,
+							 uint32 tup_len,
+							 TupleDesc tupleDesc)
+{
+	HeapTupleHeader new_data;
+	int32		new_header_len;
+	int32		new_data_len;
+	int32		new_tuple_len;
+	HeapTupleData tmptup;
+	int			numAttrs = tupleDesc->natts;
+	int			i;
+	bool		has_nulls = false;
+	Datum		toast_values[MaxTupleAttributeNumber];
+	bool		toast_isnull[MaxTupleAttributeNumber];
+	bool		toast_free[MaxTupleAttributeNumber];
+
+	/* Build a temporary HeapTuple control structure */
+	tmptup.t_len = tup_len;
+	ItemPointerSetInvalid(&(tmptup.t_self));
+	tmptup.t_tableOid = InvalidOid;
+	tmptup.t_data = tup;
+
+	/*
+	 * Break down the tuple into fields.
+	 */
+	Assert(numAttrs <= MaxTupleAttributeNumber);
+	heap_deform_tuple(&tmptup, tupleDesc, toast_values, toast_isnull);
+
+	memset(toast_free, 0, numAttrs * sizeof(bool));
+
+	for (i = 0; i < numAttrs; i++)
+	{
+		/*
+		 * Look at non-null varlena attributes
+		 */
+		if (toast_isnull[i])
+			has_nulls = true;
+		else if (TupleDescAttr(tupleDesc, i)->attlen == -1)
+		{
+			struct varlena *new_value;
+
+			new_value = (struct varlena *) DatumGetPointer(toast_values[i]);
+			if (VARATT_IS_EXTERNAL(new_value) ||
+				VARATT_IS_COMPRESSED(new_value))
+			{
+				new_value = heap_tuple_untoast_attr(new_value);
+				toast_values[i] = PointerGetDatum(new_value);
+				toast_free[i] = true;
+			}
+		}
+	}
+
+	/*
+	 * Calculate the new size of the tuple.
+	 *
+	 * This should match the reconstruction code in toast_insert_or_update.
+	 */
+	new_header_len = SizeofHeapTupleHeader;
+	if (has_nulls)
+		new_header_len += BITMAPLEN(numAttrs);
+	new_header_len = MAXALIGN(new_header_len);
+	new_data_len = heap_compute_data_size(tupleDesc,
+										  toast_values, toast_isnull);
+	new_tuple_len = new_header_len + new_data_len;
+
+	new_data = (HeapTupleHeader) palloc0(new_tuple_len);
+
+	/*
+	 * Copy the existing tuple header, but adjust natts and t_hoff.
+	 */
+	memcpy(new_data, tup, SizeofHeapTupleHeader);
+	HeapTupleHeaderSetNatts(new_data, numAttrs);
+	new_data->t_hoff = new_header_len;
+
+	/* Set the composite-Datum header fields correctly */
+	HeapTupleHeaderSetDatumLength(new_data, new_tuple_len);
+	HeapTupleHeaderSetTypeId(new_data, tupleDesc->tdtypeid);
+	HeapTupleHeaderSetTypMod(new_data, tupleDesc->tdtypmod);
+
+	/* Copy over the data, and fill the null bitmap if needed */
+	heap_fill_tuple(tupleDesc,
+					toast_values,
+					toast_isnull,
+					(char *) new_data + new_header_len,
+					new_data_len,
+					&(new_data->t_infomask),
+					has_nulls ? new_data->t_bits : NULL);
+
+	/*
+	 * Free allocated temp values
+	 */
+	for (i = 0; i < numAttrs; i++)
+		if (toast_free[i])
+			pfree(DatumGetPointer(toast_values[i]));
+
+	return PointerGetDatum(new_data);
+}
+
+
+/* ----------
+ * toast_build_flattened_tuple -
+ *
+ *	Build a tuple containing no out-of-line toasted fields.
+ *	(This does not eliminate compressed or short-header datums.)
+ *
+ *	This is essentially just like heap_form_tuple, except that it will
+ *	expand any external-data pointers beforehand.
+ *
+ *	It's not very clear whether it would be preferable to decompress
+ *	in-line compressed datums while at it.  For now, we don't.
+ * ----------
+ */
+HeapTuple
+toast_build_flattened_tuple(TupleDesc tupleDesc,
+							Datum *values,
+							bool *isnull)
+{
+	HeapTuple	new_tuple;
+	int			numAttrs = tupleDesc->natts;
+	int			num_to_free;
+	int			i;
+	Datum		new_values[MaxTupleAttributeNumber];
+	Pointer		freeable_values[MaxTupleAttributeNumber];
+
+	/*
+	 * We can pass the caller's isnull array directly to heap_form_tuple, but
+	 * we potentially need to modify the values array.
+	 */
+	Assert(numAttrs <= MaxTupleAttributeNumber);
+	memcpy(new_values, values, numAttrs * sizeof(Datum));
+
+	num_to_free = 0;
+	for (i = 0; i < numAttrs; i++)
+	{
+		/*
+		 * Look at non-null varlena attributes
+		 */
+		if (!isnull[i] && TupleDescAttr(tupleDesc, i)->attlen == -1)
+		{
+			struct varlena *new_value;
+
+			new_value = (struct varlena *) DatumGetPointer(new_values[i]);
+			if (VARATT_IS_EXTERNAL(new_value))
+			{
+				new_value = heap_tuple_fetch_attr(new_value);
+				new_values[i] = PointerGetDatum(new_value);
+				freeable_values[num_to_free++] = (Pointer) new_value;
+			}
+		}
+	}
+
+	/*
+	 * Form the reconfigured tuple.
+	 */
+	new_tuple = heap_form_tuple(tupleDesc, new_values, isnull);
+
+	/*
+	 * Free allocated temp values
+	 */
+	for (i = 0; i < num_to_free; i++)
+		pfree(freeable_values[i]);
+
+	return new_tuple;
+}
diff --git a/src/backend/access/heap/rewriteheap.c b/src/backend/access/heap/rewriteheap.c
index 72a448ad31..9f4f60a7c3 100644
--- a/src/backend/access/heap/rewriteheap.c
+++ b/src/backend/access/heap/rewriteheap.c
@@ -109,9 +109,9 @@
 
 #include "access/heapam.h"
 #include "access/heapam_xlog.h"
+#include "access/heaptoast.h"
 #include "access/rewriteheap.h"
 #include "access/transam.h"
-#include "access/tuptoaster.h"
 #include "access/xact.h"
 #include "access/xloginsert.h"
 
diff --git a/src/backend/access/heap/tuptoaster.c b/src/backend/access/heap/tuptoaster.c
deleted file mode 100644
index 55d6e91d1c..0000000000
--- a/src/backend/access/heap/tuptoaster.c
+++ /dev/null
@@ -1,2411 +0,0 @@
-/*-------------------------------------------------------------------------
- *
- * tuptoaster.c
- *	  Support routines for external and compressed storage of
- *	  variable size attributes.
- *
- * Copyright (c) 2000-2019, PostgreSQL Global Development Group
- *
- *
- * IDENTIFICATION
- *	  src/backend/access/heap/tuptoaster.c
- *
- *
- * INTERFACE ROUTINES
- *		toast_insert_or_update -
- *			Try to make a given tuple fit into one page by compressing
- *			or moving off attributes
- *
- *		toast_delete -
- *			Reclaim toast storage when a tuple is deleted
- *
- *		heap_tuple_untoast_attr -
- *			Fetch back a given value from the "secondary" relation
- *
- *-------------------------------------------------------------------------
- */
-
-#include "postgres.h"
-
-#include <unistd.h>
-#include <fcntl.h>
-
-#include "access/genam.h"
-#include "access/heapam.h"
-#include "access/tuptoaster.h"
-#include "access/xact.h"
-#include "catalog/catalog.h"
-#include "common/pg_lzcompress.h"
-#include "miscadmin.h"
-#include "utils/expandeddatum.h"
-#include "utils/fmgroids.h"
-#include "utils/rel.h"
-#include "utils/snapmgr.h"
-#include "utils/typcache.h"
-
-
-#undef TOAST_DEBUG
-
-/*
- *	The information at the start of the compressed toast data.
- */
-typedef struct toast_compress_header
-{
-	int32		vl_len_;		/* varlena header (do not touch directly!) */
-	int32		rawsize;
-} toast_compress_header;
-
-/*
- * Utilities for manipulation of header information for compressed
- * toast entries.
- */
-#define TOAST_COMPRESS_HDRSZ		((int32) sizeof(toast_compress_header))
-#define TOAST_COMPRESS_RAWSIZE(ptr) (((toast_compress_header *) (ptr))->rawsize)
-#define TOAST_COMPRESS_RAWDATA(ptr) \
-	(((char *) (ptr)) + TOAST_COMPRESS_HDRSZ)
-#define TOAST_COMPRESS_SET_RAWSIZE(ptr, len) \
-	(((toast_compress_header *) (ptr))->rawsize = (len))
-
-static void toast_delete_datum(Relation rel, Datum value, bool is_speculative);
-static Datum toast_save_datum(Relation rel, Datum value,
-							  struct varlena *oldexternal, int options);
-static bool toastrel_valueid_exists(Relation toastrel, Oid valueid);
-static bool toastid_valueid_exists(Oid toastrelid, Oid valueid);
-static struct varlena *toast_fetch_datum(struct varlena *attr);
-static struct varlena *toast_fetch_datum_slice(struct varlena *attr,
-											   int32 sliceoffset, int32 length);
-static struct varlena *toast_decompress_datum(struct varlena *attr);
-static struct varlena *toast_decompress_datum_slice(struct varlena *attr, int32 slicelength);
-static int	toast_open_indexes(Relation toastrel,
-							   LOCKMODE lock,
-							   Relation **toastidxs,
-							   int *num_indexes);
-static void toast_close_indexes(Relation *toastidxs, int num_indexes,
-								LOCKMODE lock);
-static void init_toast_snapshot(Snapshot toast_snapshot);
-
-
-/* ----------
- * heap_tuple_fetch_attr -
- *
- *	Public entry point to get back a toasted value from
- *	external source (possibly still in compressed format).
- *
- * This will return a datum that contains all the data internally, ie, not
- * relying on external storage or memory, but it can still be compressed or
- * have a short header.  Note some callers assume that if the input is an
- * EXTERNAL datum, the result will be a pfree'able chunk.
- * ----------
- */
-struct varlena *
-heap_tuple_fetch_attr(struct varlena *attr)
-{
-	struct varlena *result;
-
-	if (VARATT_IS_EXTERNAL_ONDISK(attr))
-	{
-		/*
-		 * This is an external stored plain value
-		 */
-		result = toast_fetch_datum(attr);
-	}
-	else if (VARATT_IS_EXTERNAL_INDIRECT(attr))
-	{
-		/*
-		 * This is an indirect pointer --- dereference it
-		 */
-		struct varatt_indirect redirect;
-
-		VARATT_EXTERNAL_GET_POINTER(redirect, attr);
-		attr = (struct varlena *) redirect.pointer;
-
-		/* nested indirect Datums aren't allowed */
-		Assert(!VARATT_IS_EXTERNAL_INDIRECT(attr));
-
-		/* recurse if value is still external in some other way */
-		if (VARATT_IS_EXTERNAL(attr))
-			return heap_tuple_fetch_attr(attr);
-
-		/*
-		 * Copy into the caller's memory context, in case caller tries to
-		 * pfree the result.
-		 */
-		result = (struct varlena *) palloc(VARSIZE_ANY(attr));
-		memcpy(result, attr, VARSIZE_ANY(attr));
-	}
-	else if (VARATT_IS_EXTERNAL_EXPANDED(attr))
-	{
-		/*
-		 * This is an expanded-object pointer --- get flat format
-		 */
-		ExpandedObjectHeader *eoh;
-		Size		resultsize;
-
-		eoh = DatumGetEOHP(PointerGetDatum(attr));
-		resultsize = EOH_get_flat_size(eoh);
-		result = (struct varlena *) palloc(resultsize);
-		EOH_flatten_into(eoh, (void *) result, resultsize);
-	}
-	else
-	{
-		/*
-		 * This is a plain value inside of the main tuple - why am I called?
-		 */
-		result = attr;
-	}
-
-	return result;
-}
-
-
-/* ----------
- * heap_tuple_untoast_attr -
- *
- *	Public entry point to get back a toasted value from compression
- *	or external storage.  The result is always non-extended varlena form.
- *
- * Note some callers assume that if the input is an EXTERNAL or COMPRESSED
- * datum, the result will be a pfree'able chunk.
- * ----------
- */
-struct varlena *
-heap_tuple_untoast_attr(struct varlena *attr)
-{
-	if (VARATT_IS_EXTERNAL_ONDISK(attr))
-	{
-		/*
-		 * This is an externally stored datum --- fetch it back from there
-		 */
-		attr = toast_fetch_datum(attr);
-		/* If it's compressed, decompress it */
-		if (VARATT_IS_COMPRESSED(attr))
-		{
-			struct varlena *tmp = attr;
-
-			attr = toast_decompress_datum(tmp);
-			pfree(tmp);
-		}
-	}
-	else if (VARATT_IS_EXTERNAL_INDIRECT(attr))
-	{
-		/*
-		 * This is an indirect pointer --- dereference it
-		 */
-		struct varatt_indirect redirect;
-
-		VARATT_EXTERNAL_GET_POINTER(redirect, attr);
-		attr = (struct varlena *) redirect.pointer;
-
-		/* nested indirect Datums aren't allowed */
-		Assert(!VARATT_IS_EXTERNAL_INDIRECT(attr));
-
-		/* recurse in case value is still extended in some other way */
-		attr = heap_tuple_untoast_attr(attr);
-
-		/* if it isn't, we'd better copy it */
-		if (attr == (struct varlena *) redirect.pointer)
-		{
-			struct varlena *result;
-
-			result = (struct varlena *) palloc(VARSIZE_ANY(attr));
-			memcpy(result, attr, VARSIZE_ANY(attr));
-			attr = result;
-		}
-	}
-	else if (VARATT_IS_EXTERNAL_EXPANDED(attr))
-	{
-		/*
-		 * This is an expanded-object pointer --- get flat format
-		 */
-		attr = heap_tuple_fetch_attr(attr);
-		/* flatteners are not allowed to produce compressed/short output */
-		Assert(!VARATT_IS_EXTENDED(attr));
-	}
-	else if (VARATT_IS_COMPRESSED(attr))
-	{
-		/*
-		 * This is a compressed value inside of the main tuple
-		 */
-		attr = toast_decompress_datum(attr);
-	}
-	else if (VARATT_IS_SHORT(attr))
-	{
-		/*
-		 * This is a short-header varlena --- convert to 4-byte header format
-		 */
-		Size		data_size = VARSIZE_SHORT(attr) - VARHDRSZ_SHORT;
-		Size		new_size = data_size + VARHDRSZ;
-		struct varlena *new_attr;
-
-		new_attr = (struct varlena *) palloc(new_size);
-		SET_VARSIZE(new_attr, new_size);
-		memcpy(VARDATA(new_attr), VARDATA_SHORT(attr), data_size);
-		attr = new_attr;
-	}
-
-	return attr;
-}
-
-
-/* ----------
- * heap_tuple_untoast_attr_slice -
- *
- *		Public entry point to get back part of a toasted value
- *		from compression or external storage.
- * ----------
- */
-struct varlena *
-heap_tuple_untoast_attr_slice(struct varlena *attr,
-							  int32 sliceoffset, int32 slicelength)
-{
-	struct varlena *preslice;
-	struct varlena *result;
-	char	   *attrdata;
-	int32		attrsize;
-
-	if (VARATT_IS_EXTERNAL_ONDISK(attr))
-	{
-		struct varatt_external toast_pointer;
-
-		VARATT_EXTERNAL_GET_POINTER(toast_pointer, attr);
-
-		/* fast path for non-compressed external datums */
-		if (!VARATT_EXTERNAL_IS_COMPRESSED(toast_pointer))
-			return toast_fetch_datum_slice(attr, sliceoffset, slicelength);
-
-		/* fetch it back (compressed marker will get set automatically) */
-		preslice = toast_fetch_datum(attr);
-	}
-	else if (VARATT_IS_EXTERNAL_INDIRECT(attr))
-	{
-		struct varatt_indirect redirect;
-
-		VARATT_EXTERNAL_GET_POINTER(redirect, attr);
-
-		/* nested indirect Datums aren't allowed */
-		Assert(!VARATT_IS_EXTERNAL_INDIRECT(redirect.pointer));
-
-		return heap_tuple_untoast_attr_slice(redirect.pointer,
-											 sliceoffset, slicelength);
-	}
-	else if (VARATT_IS_EXTERNAL_EXPANDED(attr))
-	{
-		/* pass it off to heap_tuple_fetch_attr to flatten */
-		preslice = heap_tuple_fetch_attr(attr);
-	}
-	else
-		preslice = attr;
-
-	Assert(!VARATT_IS_EXTERNAL(preslice));
-
-	if (VARATT_IS_COMPRESSED(preslice))
-	{
-		struct varlena *tmp = preslice;
-
-		/* Decompress enough to encompass the slice and the offset */
-		if (slicelength > 0 && sliceoffset >= 0)
-			preslice = toast_decompress_datum_slice(tmp, slicelength + sliceoffset);
-		else
-			preslice = toast_decompress_datum(tmp);
-
-		if (tmp != attr)
-			pfree(tmp);
-	}
-
-	if (VARATT_IS_SHORT(preslice))
-	{
-		attrdata = VARDATA_SHORT(preslice);
-		attrsize = VARSIZE_SHORT(preslice) - VARHDRSZ_SHORT;
-	}
-	else
-	{
-		attrdata = VARDATA(preslice);
-		attrsize = VARSIZE(preslice) - VARHDRSZ;
-	}
-
-	/* slicing of datum for compressed cases and plain value */
-
-	if (sliceoffset >= attrsize)
-	{
-		sliceoffset = 0;
-		slicelength = 0;
-	}
-
-	if (((sliceoffset + slicelength) > attrsize) || slicelength < 0)
-		slicelength = attrsize - sliceoffset;
-
-	result = (struct varlena *) palloc(slicelength + VARHDRSZ);
-	SET_VARSIZE(result, slicelength + VARHDRSZ);
-
-	memcpy(VARDATA(result), attrdata + sliceoffset, slicelength);
-
-	if (preslice != attr)
-		pfree(preslice);
-
-	return result;
-}
-
-
-/* ----------
- * toast_raw_datum_size -
- *
- *	Return the raw (detoasted) size of a varlena datum
- *	(including the VARHDRSZ header)
- * ----------
- */
-Size
-toast_raw_datum_size(Datum value)
-{
-	struct varlena *attr = (struct varlena *) DatumGetPointer(value);
-	Size		result;
-
-	if (VARATT_IS_EXTERNAL_ONDISK(attr))
-	{
-		/* va_rawsize is the size of the original datum -- including header */
-		struct varatt_external toast_pointer;
-
-		VARATT_EXTERNAL_GET_POINTER(toast_pointer, attr);
-		result = toast_pointer.va_rawsize;
-	}
-	else if (VARATT_IS_EXTERNAL_INDIRECT(attr))
-	{
-		struct varatt_indirect toast_pointer;
-
-		VARATT_EXTERNAL_GET_POINTER(toast_pointer, attr);
-
-		/* nested indirect Datums aren't allowed */
-		Assert(!VARATT_IS_EXTERNAL_INDIRECT(toast_pointer.pointer));
-
-		return toast_raw_datum_size(PointerGetDatum(toast_pointer.pointer));
-	}
-	else if (VARATT_IS_EXTERNAL_EXPANDED(attr))
-	{
-		result = EOH_get_flat_size(DatumGetEOHP(value));
-	}
-	else if (VARATT_IS_COMPRESSED(attr))
-	{
-		/* here, va_rawsize is just the payload size */
-		result = VARRAWSIZE_4B_C(attr) + VARHDRSZ;
-	}
-	else if (VARATT_IS_SHORT(attr))
-	{
-		/*
-		 * we have to normalize the header length to VARHDRSZ or else the
-		 * callers of this function will be confused.
-		 */
-		result = VARSIZE_SHORT(attr) - VARHDRSZ_SHORT + VARHDRSZ;
-	}
-	else
-	{
-		/* plain untoasted datum */
-		result = VARSIZE(attr);
-	}
-	return result;
-}
-
-/* ----------
- * toast_datum_size
- *
- *	Return the physical storage size (possibly compressed) of a varlena datum
- * ----------
- */
-Size
-toast_datum_size(Datum value)
-{
-	struct varlena *attr = (struct varlena *) DatumGetPointer(value);
-	Size		result;
-
-	if (VARATT_IS_EXTERNAL_ONDISK(attr))
-	{
-		/*
-		 * Attribute is stored externally - return the extsize whether
-		 * compressed or not.  We do not count the size of the toast pointer
-		 * ... should we?
-		 */
-		struct varatt_external toast_pointer;
-
-		VARATT_EXTERNAL_GET_POINTER(toast_pointer, attr);
-		result = toast_pointer.va_extsize;
-	}
-	else if (VARATT_IS_EXTERNAL_INDIRECT(attr))
-	{
-		struct varatt_indirect toast_pointer;
-
-		VARATT_EXTERNAL_GET_POINTER(toast_pointer, attr);
-
-		/* nested indirect Datums aren't allowed */
-		Assert(!VARATT_IS_EXTERNAL_INDIRECT(attr));
-
-		return toast_datum_size(PointerGetDatum(toast_pointer.pointer));
-	}
-	else if (VARATT_IS_EXTERNAL_EXPANDED(attr))
-	{
-		result = EOH_get_flat_size(DatumGetEOHP(value));
-	}
-	else if (VARATT_IS_SHORT(attr))
-	{
-		result = VARSIZE_SHORT(attr);
-	}
-	else
-	{
-		/*
-		 * Attribute is stored inline either compressed or not, just calculate
-		 * the size of the datum in either case.
-		 */
-		result = VARSIZE(attr);
-	}
-	return result;
-}
-
-
-/* ----------
- * toast_delete -
- *
- *	Cascaded delete toast-entries on DELETE
- * ----------
- */
-void
-toast_delete(Relation rel, HeapTuple oldtup, bool is_speculative)
-{
-	TupleDesc	tupleDesc;
-	int			numAttrs;
-	int			i;
-	Datum		toast_values[MaxHeapAttributeNumber];
-	bool		toast_isnull[MaxHeapAttributeNumber];
-
-	/*
-	 * We should only ever be called for tuples of plain relations or
-	 * materialized views --- recursing on a toast rel is bad news.
-	 */
-	Assert(rel->rd_rel->relkind == RELKIND_RELATION ||
-		   rel->rd_rel->relkind == RELKIND_MATVIEW);
-
-	/*
-	 * Get the tuple descriptor and break down the tuple into fields.
-	 *
-	 * NOTE: it's debatable whether to use heap_deform_tuple() here or just
-	 * heap_getattr() only the varlena columns.  The latter could win if there
-	 * are few varlena columns and many non-varlena ones. However,
-	 * heap_deform_tuple costs only O(N) while the heap_getattr way would cost
-	 * O(N^2) if there are many varlena columns, so it seems better to err on
-	 * the side of linear cost.  (We won't even be here unless there's at
-	 * least one varlena column, by the way.)
-	 */
-	tupleDesc = rel->rd_att;
-	numAttrs = tupleDesc->natts;
-
-	Assert(numAttrs <= MaxHeapAttributeNumber);
-	heap_deform_tuple(oldtup, tupleDesc, toast_values, toast_isnull);
-
-	/*
-	 * Check for external stored attributes and delete them from the secondary
-	 * relation.
-	 */
-	for (i = 0; i < numAttrs; i++)
-	{
-		if (TupleDescAttr(tupleDesc, i)->attlen == -1)
-		{
-			Datum		value = toast_values[i];
-
-			if (toast_isnull[i])
-				continue;
-			else if (VARATT_IS_EXTERNAL_ONDISK(PointerGetDatum(value)))
-				toast_delete_datum(rel, value, is_speculative);
-		}
-	}
-}
-
-
-/* ----------
- * toast_insert_or_update -
- *
- *	Delete no-longer-used toast-entries and create new ones to
- *	make the new tuple fit on INSERT or UPDATE
- *
- * Inputs:
- *	newtup: the candidate new tuple to be inserted
- *	oldtup: the old row version for UPDATE, or NULL for INSERT
- *	options: options to be passed to heap_insert() for toast rows
- * Result:
- *	either newtup if no toasting is needed, or a palloc'd modified tuple
- *	that is what should actually get stored
- *
- * NOTE: neither newtup nor oldtup will be modified.  This is a change
- * from the pre-8.1 API of this routine.
- * ----------
- */
-HeapTuple
-toast_insert_or_update(Relation rel, HeapTuple newtup, HeapTuple oldtup,
-					   int options)
-{
-	HeapTuple	result_tuple;
-	TupleDesc	tupleDesc;
-	int			numAttrs;
-	int			i;
-
-	bool		need_change = false;
-	bool		need_free = false;
-	bool		need_delold = false;
-	bool		has_nulls = false;
-
-	Size		maxDataLen;
-	Size		hoff;
-
-	char		toast_action[MaxHeapAttributeNumber];
-	bool		toast_isnull[MaxHeapAttributeNumber];
-	bool		toast_oldisnull[MaxHeapAttributeNumber];
-	Datum		toast_values[MaxHeapAttributeNumber];
-	Datum		toast_oldvalues[MaxHeapAttributeNumber];
-	struct varlena *toast_oldexternal[MaxHeapAttributeNumber];
-	int32		toast_sizes[MaxHeapAttributeNumber];
-	bool		toast_free[MaxHeapAttributeNumber];
-	bool		toast_delold[MaxHeapAttributeNumber];
-
-	/*
-	 * Ignore the INSERT_SPECULATIVE option. Speculative insertions/super
-	 * deletions just normally insert/delete the toast values. It seems
-	 * easiest to deal with that here, instead on, potentially, multiple
-	 * callers.
-	 */
-	options &= ~HEAP_INSERT_SPECULATIVE;
-
-	/*
-	 * We should only ever be called for tuples of plain relations or
-	 * materialized views --- recursing on a toast rel is bad news.
-	 */
-	Assert(rel->rd_rel->relkind == RELKIND_RELATION ||
-		   rel->rd_rel->relkind == RELKIND_MATVIEW);
-
-	/*
-	 * Get the tuple descriptor and break down the tuple(s) into fields.
-	 */
-	tupleDesc = rel->rd_att;
-	numAttrs = tupleDesc->natts;
-
-	Assert(numAttrs <= MaxHeapAttributeNumber);
-	heap_deform_tuple(newtup, tupleDesc, toast_values, toast_isnull);
-	if (oldtup != NULL)
-		heap_deform_tuple(oldtup, tupleDesc, toast_oldvalues, toast_oldisnull);
-
-	/* ----------
-	 * Then collect information about the values given
-	 *
-	 * NOTE: toast_action[i] can have these values:
-	 *		' '		default handling
-	 *		'p'		already processed --- don't touch it
-	 *		'x'		incompressible, but OK to move off
-	 *
-	 * NOTE: toast_sizes[i] is only made valid for varlena attributes with
-	 *		toast_action[i] different from 'p'.
-	 * ----------
-	 */
-	memset(toast_action, ' ', numAttrs * sizeof(char));
-	memset(toast_oldexternal, 0, numAttrs * sizeof(struct varlena *));
-	memset(toast_free, 0, numAttrs * sizeof(bool));
-	memset(toast_delold, 0, numAttrs * sizeof(bool));
-
-	for (i = 0; i < numAttrs; i++)
-	{
-		Form_pg_attribute att = TupleDescAttr(tupleDesc, i);
-		struct varlena *old_value;
-		struct varlena *new_value;
-
-		if (oldtup != NULL)
-		{
-			/*
-			 * For UPDATE get the old and new values of this attribute
-			 */
-			old_value = (struct varlena *) DatumGetPointer(toast_oldvalues[i]);
-			new_value = (struct varlena *) DatumGetPointer(toast_values[i]);
-
-			/*
-			 * If the old value is stored on disk, check if it has changed so
-			 * we have to delete it later.
-			 */
-			if (att->attlen == -1 && !toast_oldisnull[i] &&
-				VARATT_IS_EXTERNAL_ONDISK(old_value))
-			{
-				if (toast_isnull[i] || !VARATT_IS_EXTERNAL_ONDISK(new_value) ||
-					memcmp((char *) old_value, (char *) new_value,
-						   VARSIZE_EXTERNAL(old_value)) != 0)
-				{
-					/*
-					 * The old external stored value isn't needed any more
-					 * after the update
-					 */
-					toast_delold[i] = true;
-					need_delold = true;
-				}
-				else
-				{
-					/*
-					 * This attribute isn't changed by this update so we reuse
-					 * the original reference to the old value in the new
-					 * tuple.
-					 */
-					toast_action[i] = 'p';
-					continue;
-				}
-			}
-		}
-		else
-		{
-			/*
-			 * For INSERT simply get the new value
-			 */
-			new_value = (struct varlena *) DatumGetPointer(toast_values[i]);
-		}
-
-		/*
-		 * Handle NULL attributes
-		 */
-		if (toast_isnull[i])
-		{
-			toast_action[i] = 'p';
-			has_nulls = true;
-			continue;
-		}
-
-		/*
-		 * Now look at varlena attributes
-		 */
-		if (att->attlen == -1)
-		{
-			/*
-			 * If the table's attribute says PLAIN always, force it so.
-			 */
-			if (att->attstorage == 'p')
-				toast_action[i] = 'p';
-
-			/*
-			 * We took care of UPDATE above, so any external value we find
-			 * still in the tuple must be someone else's that we cannot reuse
-			 * (this includes the case of an out-of-line in-memory datum).
-			 * Fetch it back (without decompression, unless we are forcing
-			 * PLAIN storage).  If necessary, we'll push it out as a new
-			 * external value below.
-			 */
-			if (VARATT_IS_EXTERNAL(new_value))
-			{
-				toast_oldexternal[i] = new_value;
-				if (att->attstorage == 'p')
-					new_value = heap_tuple_untoast_attr(new_value);
-				else
-					new_value = heap_tuple_fetch_attr(new_value);
-				toast_values[i] = PointerGetDatum(new_value);
-				toast_free[i] = true;
-				need_change = true;
-				need_free = true;
-			}
-
-			/*
-			 * Remember the size of this attribute
-			 */
-			toast_sizes[i] = VARSIZE_ANY(new_value);
-		}
-		else
-		{
-			/*
-			 * Not a varlena attribute, plain storage always
-			 */
-			toast_action[i] = 'p';
-		}
-	}
-
-	/* ----------
-	 * Compress and/or save external until data fits into target length
-	 *
-	 *	1: Inline compress attributes with attstorage 'x', and store very
-	 *	   large attributes with attstorage 'x' or 'e' external immediately
-	 *	2: Store attributes with attstorage 'x' or 'e' external
-	 *	3: Inline compress attributes with attstorage 'm'
-	 *	4: Store attributes with attstorage 'm' external
-	 * ----------
-	 */
-
-	/* compute header overhead --- this should match heap_form_tuple() */
-	hoff = SizeofHeapTupleHeader;
-	if (has_nulls)
-		hoff += BITMAPLEN(numAttrs);
-	hoff = MAXALIGN(hoff);
-	/* now convert to a limit on the tuple data size */
-	maxDataLen = RelationGetToastTupleTarget(rel, TOAST_TUPLE_TARGET) - hoff;
-
-	/*
-	 * Look for attributes with attstorage 'x' to compress.  Also find large
-	 * attributes with attstorage 'x' or 'e', and store them external.
-	 */
-	while (heap_compute_data_size(tupleDesc,
-								  toast_values, toast_isnull) > maxDataLen)
-	{
-		int			biggest_attno = -1;
-		int32		biggest_size = MAXALIGN(TOAST_POINTER_SIZE);
-		Datum		old_value;
-		Datum		new_value;
-
-		/*
-		 * Search for the biggest yet unprocessed internal attribute
-		 */
-		for (i = 0; i < numAttrs; i++)
-		{
-			Form_pg_attribute att = TupleDescAttr(tupleDesc, i);
-
-			if (toast_action[i] != ' ')
-				continue;
-			if (VARATT_IS_EXTERNAL(DatumGetPointer(toast_values[i])))
-				continue;		/* can't happen, toast_action would be 'p' */
-			if (VARATT_IS_COMPRESSED(DatumGetPointer(toast_values[i])))
-				continue;
-			if (att->attstorage != 'x' && att->attstorage != 'e')
-				continue;
-			if (toast_sizes[i] > biggest_size)
-			{
-				biggest_attno = i;
-				biggest_size = toast_sizes[i];
-			}
-		}
-
-		if (biggest_attno < 0)
-			break;
-
-		/*
-		 * Attempt to compress it inline, if it has attstorage 'x'
-		 */
-		i = biggest_attno;
-		if (TupleDescAttr(tupleDesc, i)->attstorage == 'x')
-		{
-			old_value = toast_values[i];
-			new_value = toast_compress_datum(old_value);
-
-			if (DatumGetPointer(new_value) != NULL)
-			{
-				/* successful compression */
-				if (toast_free[i])
-					pfree(DatumGetPointer(old_value));
-				toast_values[i] = new_value;
-				toast_free[i] = true;
-				toast_sizes[i] = VARSIZE(DatumGetPointer(toast_values[i]));
-				need_change = true;
-				need_free = true;
-			}
-			else
-			{
-				/* incompressible, ignore on subsequent compression passes */
-				toast_action[i] = 'x';
-			}
-		}
-		else
-		{
-			/* has attstorage 'e', ignore on subsequent compression passes */
-			toast_action[i] = 'x';
-		}
-
-		/*
-		 * If this value is by itself more than maxDataLen (after compression
-		 * if any), push it out to the toast table immediately, if possible.
-		 * This avoids uselessly compressing other fields in the common case
-		 * where we have one long field and several short ones.
-		 *
-		 * XXX maybe the threshold should be less than maxDataLen?
-		 */
-		if (toast_sizes[i] > maxDataLen &&
-			rel->rd_rel->reltoastrelid != InvalidOid)
-		{
-			old_value = toast_values[i];
-			toast_action[i] = 'p';
-			toast_values[i] = toast_save_datum(rel, toast_values[i],
-											   toast_oldexternal[i], options);
-			if (toast_free[i])
-				pfree(DatumGetPointer(old_value));
-			toast_free[i] = true;
-			need_change = true;
-			need_free = true;
-		}
-	}
-
-	/*
-	 * Second we look for attributes of attstorage 'x' or 'e' that are still
-	 * inline.  But skip this if there's no toast table to push them to.
-	 */
-	while (heap_compute_data_size(tupleDesc,
-								  toast_values, toast_isnull) > maxDataLen &&
-		   rel->rd_rel->reltoastrelid != InvalidOid)
-	{
-		int			biggest_attno = -1;
-		int32		biggest_size = MAXALIGN(TOAST_POINTER_SIZE);
-		Datum		old_value;
-
-		/*------
-		 * Search for the biggest yet inlined attribute with
-		 * attstorage equals 'x' or 'e'
-		 *------
-		 */
-		for (i = 0; i < numAttrs; i++)
-		{
-			Form_pg_attribute att = TupleDescAttr(tupleDesc, i);
-
-			if (toast_action[i] == 'p')
-				continue;
-			if (VARATT_IS_EXTERNAL(DatumGetPointer(toast_values[i])))
-				continue;		/* can't happen, toast_action would be 'p' */
-			if (att->attstorage != 'x' && att->attstorage != 'e')
-				continue;
-			if (toast_sizes[i] > biggest_size)
-			{
-				biggest_attno = i;
-				biggest_size = toast_sizes[i];
-			}
-		}
-
-		if (biggest_attno < 0)
-			break;
-
-		/*
-		 * Store this external
-		 */
-		i = biggest_attno;
-		old_value = toast_values[i];
-		toast_action[i] = 'p';
-		toast_values[i] = toast_save_datum(rel, toast_values[i],
-										   toast_oldexternal[i], options);
-		if (toast_free[i])
-			pfree(DatumGetPointer(old_value));
-		toast_free[i] = true;
-
-		need_change = true;
-		need_free = true;
-	}
-
-	/*
-	 * Round 3 - this time we take attributes with storage 'm' into
-	 * compression
-	 */
-	while (heap_compute_data_size(tupleDesc,
-								  toast_values, toast_isnull) > maxDataLen)
-	{
-		int			biggest_attno = -1;
-		int32		biggest_size = MAXALIGN(TOAST_POINTER_SIZE);
-		Datum		old_value;
-		Datum		new_value;
-
-		/*
-		 * Search for the biggest yet uncompressed internal attribute
-		 */
-		for (i = 0; i < numAttrs; i++)
-		{
-			if (toast_action[i] != ' ')
-				continue;
-			if (VARATT_IS_EXTERNAL(DatumGetPointer(toast_values[i])))
-				continue;		/* can't happen, toast_action would be 'p' */
-			if (VARATT_IS_COMPRESSED(DatumGetPointer(toast_values[i])))
-				continue;
-			if (TupleDescAttr(tupleDesc, i)->attstorage != 'm')
-				continue;
-			if (toast_sizes[i] > biggest_size)
-			{
-				biggest_attno = i;
-				biggest_size = toast_sizes[i];
-			}
-		}
-
-		if (biggest_attno < 0)
-			break;
-
-		/*
-		 * Attempt to compress it inline
-		 */
-		i = biggest_attno;
-		old_value = toast_values[i];
-		new_value = toast_compress_datum(old_value);
-
-		if (DatumGetPointer(new_value) != NULL)
-		{
-			/* successful compression */
-			if (toast_free[i])
-				pfree(DatumGetPointer(old_value));
-			toast_values[i] = new_value;
-			toast_free[i] = true;
-			toast_sizes[i] = VARSIZE(DatumGetPointer(toast_values[i]));
-			need_change = true;
-			need_free = true;
-		}
-		else
-		{
-			/* incompressible, ignore on subsequent compression passes */
-			toast_action[i] = 'x';
-		}
-	}
-
-	/*
-	 * Finally we store attributes of type 'm' externally.  At this point we
-	 * increase the target tuple size, so that 'm' attributes aren't stored
-	 * externally unless really necessary.
-	 */
-	maxDataLen = TOAST_TUPLE_TARGET_MAIN - hoff;
-
-	while (heap_compute_data_size(tupleDesc,
-								  toast_values, toast_isnull) > maxDataLen &&
-		   rel->rd_rel->reltoastrelid != InvalidOid)
-	{
-		int			biggest_attno = -1;
-		int32		biggest_size = MAXALIGN(TOAST_POINTER_SIZE);
-		Datum		old_value;
-
-		/*--------
-		 * Search for the biggest yet inlined attribute with
-		 * attstorage = 'm'
-		 *--------
-		 */
-		for (i = 0; i < numAttrs; i++)
-		{
-			if (toast_action[i] == 'p')
-				continue;
-			if (VARATT_IS_EXTERNAL(DatumGetPointer(toast_values[i])))
-				continue;		/* can't happen, toast_action would be 'p' */
-			if (TupleDescAttr(tupleDesc, i)->attstorage != 'm')
-				continue;
-			if (toast_sizes[i] > biggest_size)
-			{
-				biggest_attno = i;
-				biggest_size = toast_sizes[i];
-			}
-		}
-
-		if (biggest_attno < 0)
-			break;
-
-		/*
-		 * Store this external
-		 */
-		i = biggest_attno;
-		old_value = toast_values[i];
-		toast_action[i] = 'p';
-		toast_values[i] = toast_save_datum(rel, toast_values[i],
-										   toast_oldexternal[i], options);
-		if (toast_free[i])
-			pfree(DatumGetPointer(old_value));
-		toast_free[i] = true;
-
-		need_change = true;
-		need_free = true;
-	}
-
-	/*
-	 * In the case we toasted any values, we need to build a new heap tuple
-	 * with the changed values.
-	 */
-	if (need_change)
-	{
-		HeapTupleHeader olddata = newtup->t_data;
-		HeapTupleHeader new_data;
-		int32		new_header_len;
-		int32		new_data_len;
-		int32		new_tuple_len;
-
-		/*
-		 * Calculate the new size of the tuple.
-		 *
-		 * Note: we used to assume here that the old tuple's t_hoff must equal
-		 * the new_header_len value, but that was incorrect.  The old tuple
-		 * might have a smaller-than-current natts, if there's been an ALTER
-		 * TABLE ADD COLUMN since it was stored; and that would lead to a
-		 * different conclusion about the size of the null bitmap, or even
-		 * whether there needs to be one at all.
-		 */
-		new_header_len = SizeofHeapTupleHeader;
-		if (has_nulls)
-			new_header_len += BITMAPLEN(numAttrs);
-		new_header_len = MAXALIGN(new_header_len);
-		new_data_len = heap_compute_data_size(tupleDesc,
-											  toast_values, toast_isnull);
-		new_tuple_len = new_header_len + new_data_len;
-
-		/*
-		 * Allocate and zero the space needed, and fill HeapTupleData fields.
-		 */
-		result_tuple = (HeapTuple) palloc0(HEAPTUPLESIZE + new_tuple_len);
-		result_tuple->t_len = new_tuple_len;
-		result_tuple->t_self = newtup->t_self;
-		result_tuple->t_tableOid = newtup->t_tableOid;
-		new_data = (HeapTupleHeader) ((char *) result_tuple + HEAPTUPLESIZE);
-		result_tuple->t_data = new_data;
-
-		/*
-		 * Copy the existing tuple header, but adjust natts and t_hoff.
-		 */
-		memcpy(new_data, olddata, SizeofHeapTupleHeader);
-		HeapTupleHeaderSetNatts(new_data, numAttrs);
-		new_data->t_hoff = new_header_len;
-
-		/* Copy over the data, and fill the null bitmap if needed */
-		heap_fill_tuple(tupleDesc,
-						toast_values,
-						toast_isnull,
-						(char *) new_data + new_header_len,
-						new_data_len,
-						&(new_data->t_infomask),
-						has_nulls ? new_data->t_bits : NULL);
-	}
-	else
-		result_tuple = newtup;
-
-	/*
-	 * Free allocated temp values
-	 */
-	if (need_free)
-		for (i = 0; i < numAttrs; i++)
-			if (toast_free[i])
-				pfree(DatumGetPointer(toast_values[i]));
-
-	/*
-	 * Delete external values from the old tuple
-	 */
-	if (need_delold)
-		for (i = 0; i < numAttrs; i++)
-			if (toast_delold[i])
-				toast_delete_datum(rel, toast_oldvalues[i], false);
-
-	return result_tuple;
-}
-
-
-/* ----------
- * toast_flatten_tuple -
- *
- *	"Flatten" a tuple to contain no out-of-line toasted fields.
- *	(This does not eliminate compressed or short-header datums.)
- *
- *	Note: we expect the caller already checked HeapTupleHasExternal(tup),
- *	so there is no need for a short-circuit path.
- * ----------
- */
-HeapTuple
-toast_flatten_tuple(HeapTuple tup, TupleDesc tupleDesc)
-{
-	HeapTuple	new_tuple;
-	int			numAttrs = tupleDesc->natts;
-	int			i;
-	Datum		toast_values[MaxTupleAttributeNumber];
-	bool		toast_isnull[MaxTupleAttributeNumber];
-	bool		toast_free[MaxTupleAttributeNumber];
-
-	/*
-	 * Break down the tuple into fields.
-	 */
-	Assert(numAttrs <= MaxTupleAttributeNumber);
-	heap_deform_tuple(tup, tupleDesc, toast_values, toast_isnull);
-
-	memset(toast_free, 0, numAttrs * sizeof(bool));
-
-	for (i = 0; i < numAttrs; i++)
-	{
-		/*
-		 * Look at non-null varlena attributes
-		 */
-		if (!toast_isnull[i] && TupleDescAttr(tupleDesc, i)->attlen == -1)
-		{
-			struct varlena *new_value;
-
-			new_value = (struct varlena *) DatumGetPointer(toast_values[i]);
-			if (VARATT_IS_EXTERNAL(new_value))
-			{
-				new_value = heap_tuple_fetch_attr(new_value);
-				toast_values[i] = PointerGetDatum(new_value);
-				toast_free[i] = true;
-			}
-		}
-	}
-
-	/*
-	 * Form the reconfigured tuple.
-	 */
-	new_tuple = heap_form_tuple(tupleDesc, toast_values, toast_isnull);
-
-	/*
-	 * Be sure to copy the tuple's identity fields.  We also make a point of
-	 * copying visibility info, just in case anybody looks at those fields in
-	 * a syscache entry.
-	 */
-	new_tuple->t_self = tup->t_self;
-	new_tuple->t_tableOid = tup->t_tableOid;
-
-	new_tuple->t_data->t_choice = tup->t_data->t_choice;
-	new_tuple->t_data->t_ctid = tup->t_data->t_ctid;
-	new_tuple->t_data->t_infomask &= ~HEAP_XACT_MASK;
-	new_tuple->t_data->t_infomask |=
-		tup->t_data->t_infomask & HEAP_XACT_MASK;
-	new_tuple->t_data->t_infomask2 &= ~HEAP2_XACT_MASK;
-	new_tuple->t_data->t_infomask2 |=
-		tup->t_data->t_infomask2 & HEAP2_XACT_MASK;
-
-	/*
-	 * Free allocated temp values
-	 */
-	for (i = 0; i < numAttrs; i++)
-		if (toast_free[i])
-			pfree(DatumGetPointer(toast_values[i]));
-
-	return new_tuple;
-}
-
-
-/* ----------
- * toast_flatten_tuple_to_datum -
- *
- *	"Flatten" a tuple containing out-of-line toasted fields into a Datum.
- *	The result is always palloc'd in the current memory context.
- *
- *	We have a general rule that Datums of container types (rows, arrays,
- *	ranges, etc) must not contain any external TOAST pointers.  Without
- *	this rule, we'd have to look inside each Datum when preparing a tuple
- *	for storage, which would be expensive and would fail to extend cleanly
- *	to new sorts of container types.
- *
- *	However, we don't want to say that tuples represented as HeapTuples
- *	can't contain toasted fields, so instead this routine should be called
- *	when such a HeapTuple is being converted into a Datum.
- *
- *	While we're at it, we decompress any compressed fields too.  This is not
- *	necessary for correctness, but reflects an expectation that compression
- *	will be more effective if applied to the whole tuple not individual
- *	fields.  We are not so concerned about that that we want to deconstruct
- *	and reconstruct tuples just to get rid of compressed fields, however.
- *	So callers typically won't call this unless they see that the tuple has
- *	at least one external field.
- *
- *	On the other hand, in-line short-header varlena fields are left alone.
- *	If we "untoasted" them here, they'd just get changed back to short-header
- *	format anyway within heap_fill_tuple.
- * ----------
- */
-Datum
-toast_flatten_tuple_to_datum(HeapTupleHeader tup,
-							 uint32 tup_len,
-							 TupleDesc tupleDesc)
-{
-	HeapTupleHeader new_data;
-	int32		new_header_len;
-	int32		new_data_len;
-	int32		new_tuple_len;
-	HeapTupleData tmptup;
-	int			numAttrs = tupleDesc->natts;
-	int			i;
-	bool		has_nulls = false;
-	Datum		toast_values[MaxTupleAttributeNumber];
-	bool		toast_isnull[MaxTupleAttributeNumber];
-	bool		toast_free[MaxTupleAttributeNumber];
-
-	/* Build a temporary HeapTuple control structure */
-	tmptup.t_len = tup_len;
-	ItemPointerSetInvalid(&(tmptup.t_self));
-	tmptup.t_tableOid = InvalidOid;
-	tmptup.t_data = tup;
-
-	/*
-	 * Break down the tuple into fields.
-	 */
-	Assert(numAttrs <= MaxTupleAttributeNumber);
-	heap_deform_tuple(&tmptup, tupleDesc, toast_values, toast_isnull);
-
-	memset(toast_free, 0, numAttrs * sizeof(bool));
-
-	for (i = 0; i < numAttrs; i++)
-	{
-		/*
-		 * Look at non-null varlena attributes
-		 */
-		if (toast_isnull[i])
-			has_nulls = true;
-		else if (TupleDescAttr(tupleDesc, i)->attlen == -1)
-		{
-			struct varlena *new_value;
-
-			new_value = (struct varlena *) DatumGetPointer(toast_values[i]);
-			if (VARATT_IS_EXTERNAL(new_value) ||
-				VARATT_IS_COMPRESSED(new_value))
-			{
-				new_value = heap_tuple_untoast_attr(new_value);
-				toast_values[i] = PointerGetDatum(new_value);
-				toast_free[i] = true;
-			}
-		}
-	}
-
-	/*
-	 * Calculate the new size of the tuple.
-	 *
-	 * This should match the reconstruction code in toast_insert_or_update.
-	 */
-	new_header_len = SizeofHeapTupleHeader;
-	if (has_nulls)
-		new_header_len += BITMAPLEN(numAttrs);
-	new_header_len = MAXALIGN(new_header_len);
-	new_data_len = heap_compute_data_size(tupleDesc,
-										  toast_values, toast_isnull);
-	new_tuple_len = new_header_len + new_data_len;
-
-	new_data = (HeapTupleHeader) palloc0(new_tuple_len);
-
-	/*
-	 * Copy the existing tuple header, but adjust natts and t_hoff.
-	 */
-	memcpy(new_data, tup, SizeofHeapTupleHeader);
-	HeapTupleHeaderSetNatts(new_data, numAttrs);
-	new_data->t_hoff = new_header_len;
-
-	/* Set the composite-Datum header fields correctly */
-	HeapTupleHeaderSetDatumLength(new_data, new_tuple_len);
-	HeapTupleHeaderSetTypeId(new_data, tupleDesc->tdtypeid);
-	HeapTupleHeaderSetTypMod(new_data, tupleDesc->tdtypmod);
-
-	/* Copy over the data, and fill the null bitmap if needed */
-	heap_fill_tuple(tupleDesc,
-					toast_values,
-					toast_isnull,
-					(char *) new_data + new_header_len,
-					new_data_len,
-					&(new_data->t_infomask),
-					has_nulls ? new_data->t_bits : NULL);
-
-	/*
-	 * Free allocated temp values
-	 */
-	for (i = 0; i < numAttrs; i++)
-		if (toast_free[i])
-			pfree(DatumGetPointer(toast_values[i]));
-
-	return PointerGetDatum(new_data);
-}
-
-
-/* ----------
- * toast_build_flattened_tuple -
- *
- *	Build a tuple containing no out-of-line toasted fields.
- *	(This does not eliminate compressed or short-header datums.)
- *
- *	This is essentially just like heap_form_tuple, except that it will
- *	expand any external-data pointers beforehand.
- *
- *	It's not very clear whether it would be preferable to decompress
- *	in-line compressed datums while at it.  For now, we don't.
- * ----------
- */
-HeapTuple
-toast_build_flattened_tuple(TupleDesc tupleDesc,
-							Datum *values,
-							bool *isnull)
-{
-	HeapTuple	new_tuple;
-	int			numAttrs = tupleDesc->natts;
-	int			num_to_free;
-	int			i;
-	Datum		new_values[MaxTupleAttributeNumber];
-	Pointer		freeable_values[MaxTupleAttributeNumber];
-
-	/*
-	 * We can pass the caller's isnull array directly to heap_form_tuple, but
-	 * we potentially need to modify the values array.
-	 */
-	Assert(numAttrs <= MaxTupleAttributeNumber);
-	memcpy(new_values, values, numAttrs * sizeof(Datum));
-
-	num_to_free = 0;
-	for (i = 0; i < numAttrs; i++)
-	{
-		/*
-		 * Look at non-null varlena attributes
-		 */
-		if (!isnull[i] && TupleDescAttr(tupleDesc, i)->attlen == -1)
-		{
-			struct varlena *new_value;
-
-			new_value = (struct varlena *) DatumGetPointer(new_values[i]);
-			if (VARATT_IS_EXTERNAL(new_value))
-			{
-				new_value = heap_tuple_fetch_attr(new_value);
-				new_values[i] = PointerGetDatum(new_value);
-				freeable_values[num_to_free++] = (Pointer) new_value;
-			}
-		}
-	}
-
-	/*
-	 * Form the reconfigured tuple.
-	 */
-	new_tuple = heap_form_tuple(tupleDesc, new_values, isnull);
-
-	/*
-	 * Free allocated temp values
-	 */
-	for (i = 0; i < num_to_free; i++)
-		pfree(freeable_values[i]);
-
-	return new_tuple;
-}
-
-
-/* ----------
- * toast_compress_datum -
- *
- *	Create a compressed version of a varlena datum
- *
- *	If we fail (ie, compressed result is actually bigger than original)
- *	then return NULL.  We must not use compressed data if it'd expand
- *	the tuple!
- *
- *	We use VAR{SIZE,DATA}_ANY so we can handle short varlenas here without
- *	copying them.  But we can't handle external or compressed datums.
- * ----------
- */
-Datum
-toast_compress_datum(Datum value)
-{
-	struct varlena *tmp;
-	int32		valsize = VARSIZE_ANY_EXHDR(DatumGetPointer(value));
-	int32		len;
-
-	Assert(!VARATT_IS_EXTERNAL(DatumGetPointer(value)));
-	Assert(!VARATT_IS_COMPRESSED(DatumGetPointer(value)));
-
-	/*
-	 * No point in wasting a palloc cycle if value size is out of the allowed
-	 * range for compression
-	 */
-	if (valsize < PGLZ_strategy_default->min_input_size ||
-		valsize > PGLZ_strategy_default->max_input_size)
-		return PointerGetDatum(NULL);
-
-	tmp = (struct varlena *) palloc(PGLZ_MAX_OUTPUT(valsize) +
-									TOAST_COMPRESS_HDRSZ);
-
-	/*
-	 * We recheck the actual size even if pglz_compress() reports success,
-	 * because it might be satisfied with having saved as little as one byte
-	 * in the compressed data --- which could turn into a net loss once you
-	 * consider header and alignment padding.  Worst case, the compressed
-	 * format might require three padding bytes (plus header, which is
-	 * included in VARSIZE(tmp)), whereas the uncompressed format would take
-	 * only one header byte and no padding if the value is short enough.  So
-	 * we insist on a savings of more than 2 bytes to ensure we have a gain.
-	 */
-	len = pglz_compress(VARDATA_ANY(DatumGetPointer(value)),
-						valsize,
-						TOAST_COMPRESS_RAWDATA(tmp),
-						PGLZ_strategy_default);
-	if (len >= 0 &&
-		len + TOAST_COMPRESS_HDRSZ < valsize - 2)
-	{
-		TOAST_COMPRESS_SET_RAWSIZE(tmp, valsize);
-		SET_VARSIZE_COMPRESSED(tmp, len + TOAST_COMPRESS_HDRSZ);
-		/* successful compression */
-		return PointerGetDatum(tmp);
-	}
-	else
-	{
-		/* incompressible data */
-		pfree(tmp);
-		return PointerGetDatum(NULL);
-	}
-}
-
-
-/* ----------
- * toast_get_valid_index
- *
- *	Get OID of valid index associated to given toast relation. A toast
- *	relation can have only one valid index at the same time.
- */
-Oid
-toast_get_valid_index(Oid toastoid, LOCKMODE lock)
-{
-	int			num_indexes;
-	int			validIndex;
-	Oid			validIndexOid;
-	Relation   *toastidxs;
-	Relation	toastrel;
-
-	/* Open the toast relation */
-	toastrel = table_open(toastoid, lock);
-
-	/* Look for the valid index of the toast relation */
-	validIndex = toast_open_indexes(toastrel,
-									lock,
-									&toastidxs,
-									&num_indexes);
-	validIndexOid = RelationGetRelid(toastidxs[validIndex]);
-
-	/* Close the toast relation and all its indexes */
-	toast_close_indexes(toastidxs, num_indexes, lock);
-	table_close(toastrel, lock);
-
-	return validIndexOid;
-}
-
-
-/* ----------
- * toast_save_datum -
- *
- *	Save one single datum into the secondary relation and return
- *	a Datum reference for it.
- *
- * rel: the main relation we're working with (not the toast rel!)
- * value: datum to be pushed to toast storage
- * oldexternal: if not NULL, toast pointer previously representing the datum
- * options: options to be passed to heap_insert() for toast rows
- * ----------
- */
-static Datum
-toast_save_datum(Relation rel, Datum value,
-				 struct varlena *oldexternal, int options)
-{
-	Relation	toastrel;
-	Relation   *toastidxs;
-	HeapTuple	toasttup;
-	TupleDesc	toasttupDesc;
-	Datum		t_values[3];
-	bool		t_isnull[3];
-	CommandId	mycid = GetCurrentCommandId(true);
-	struct varlena *result;
-	struct varatt_external toast_pointer;
-	union
-	{
-		struct varlena hdr;
-		/* this is to make the union big enough for a chunk: */
-		char		data[TOAST_MAX_CHUNK_SIZE + VARHDRSZ];
-		/* ensure union is aligned well enough: */
-		int32		align_it;
-	}			chunk_data;
-	int32		chunk_size;
-	int32		chunk_seq = 0;
-	char	   *data_p;
-	int32		data_todo;
-	Pointer		dval = DatumGetPointer(value);
-	int			num_indexes;
-	int			validIndex;
-
-	Assert(!VARATT_IS_EXTERNAL(value));
-
-	/*
-	 * Open the toast relation and its indexes.  We can use the index to check
-	 * uniqueness of the OID we assign to the toasted item, even though it has
-	 * additional columns besides OID.
-	 */
-	toastrel = table_open(rel->rd_rel->reltoastrelid, RowExclusiveLock);
-	toasttupDesc = toastrel->rd_att;
-
-	/* Open all the toast indexes and look for the valid one */
-	validIndex = toast_open_indexes(toastrel,
-									RowExclusiveLock,
-									&toastidxs,
-									&num_indexes);
-
-	/*
-	 * Get the data pointer and length, and compute va_rawsize and va_extsize.
-	 *
-	 * va_rawsize is the size of the equivalent fully uncompressed datum, so
-	 * we have to adjust for short headers.
-	 *
-	 * va_extsize is the actual size of the data payload in the toast records.
-	 */
-	if (VARATT_IS_SHORT(dval))
-	{
-		data_p = VARDATA_SHORT(dval);
-		data_todo = VARSIZE_SHORT(dval) - VARHDRSZ_SHORT;
-		toast_pointer.va_rawsize = data_todo + VARHDRSZ;	/* as if not short */
-		toast_pointer.va_extsize = data_todo;
-	}
-	else if (VARATT_IS_COMPRESSED(dval))
-	{
-		data_p = VARDATA(dval);
-		data_todo = VARSIZE(dval) - VARHDRSZ;
-		/* rawsize in a compressed datum is just the size of the payload */
-		toast_pointer.va_rawsize = VARRAWSIZE_4B_C(dval) + VARHDRSZ;
-		toast_pointer.va_extsize = data_todo;
-		/* Assert that the numbers look like it's compressed */
-		Assert(VARATT_EXTERNAL_IS_COMPRESSED(toast_pointer));
-	}
-	else
-	{
-		data_p = VARDATA(dval);
-		data_todo = VARSIZE(dval) - VARHDRSZ;
-		toast_pointer.va_rawsize = VARSIZE(dval);
-		toast_pointer.va_extsize = data_todo;
-	}
-
-	/*
-	 * Insert the correct table OID into the result TOAST pointer.
-	 *
-	 * Normally this is the actual OID of the target toast table, but during
-	 * table-rewriting operations such as CLUSTER, we have to insert the OID
-	 * of the table's real permanent toast table instead.  rd_toastoid is set
-	 * if we have to substitute such an OID.
-	 */
-	if (OidIsValid(rel->rd_toastoid))
-		toast_pointer.va_toastrelid = rel->rd_toastoid;
-	else
-		toast_pointer.va_toastrelid = RelationGetRelid(toastrel);
-
-	/*
-	 * Choose an OID to use as the value ID for this toast value.
-	 *
-	 * Normally we just choose an unused OID within the toast table.  But
-	 * during table-rewriting operations where we are preserving an existing
-	 * toast table OID, we want to preserve toast value OIDs too.  So, if
-	 * rd_toastoid is set and we had a prior external value from that same
-	 * toast table, re-use its value ID.  If we didn't have a prior external
-	 * value (which is a corner case, but possible if the table's attstorage
-	 * options have been changed), we have to pick a value ID that doesn't
-	 * conflict with either new or existing toast value OIDs.
-	 */
-	if (!OidIsValid(rel->rd_toastoid))
-	{
-		/* normal case: just choose an unused OID */
-		toast_pointer.va_valueid =
-			GetNewOidWithIndex(toastrel,
-							   RelationGetRelid(toastidxs[validIndex]),
-							   (AttrNumber) 1);
-	}
-	else
-	{
-		/* rewrite case: check to see if value was in old toast table */
-		toast_pointer.va_valueid = InvalidOid;
-		if (oldexternal != NULL)
-		{
-			struct varatt_external old_toast_pointer;
-
-			Assert(VARATT_IS_EXTERNAL_ONDISK(oldexternal));
-			/* Must copy to access aligned fields */
-			VARATT_EXTERNAL_GET_POINTER(old_toast_pointer, oldexternal);
-			if (old_toast_pointer.va_toastrelid == rel->rd_toastoid)
-			{
-				/* This value came from the old toast table; reuse its OID */
-				toast_pointer.va_valueid = old_toast_pointer.va_valueid;
-
-				/*
-				 * There is a corner case here: the table rewrite might have
-				 * to copy both live and recently-dead versions of a row, and
-				 * those versions could easily reference the same toast value.
-				 * When we copy the second or later version of such a row,
-				 * reusing the OID will mean we select an OID that's already
-				 * in the new toast table.  Check for that, and if so, just
-				 * fall through without writing the data again.
-				 *
-				 * While annoying and ugly-looking, this is a good thing
-				 * because it ensures that we wind up with only one copy of
-				 * the toast value when there is only one copy in the old
-				 * toast table.  Before we detected this case, we'd have made
-				 * multiple copies, wasting space; and what's worse, the
-				 * copies belonging to already-deleted heap tuples would not
-				 * be reclaimed by VACUUM.
-				 */
-				if (toastrel_valueid_exists(toastrel,
-											toast_pointer.va_valueid))
-				{
-					/* Match, so short-circuit the data storage loop below */
-					data_todo = 0;
-				}
-			}
-		}
-		if (toast_pointer.va_valueid == InvalidOid)
-		{
-			/*
-			 * new value; must choose an OID that doesn't conflict in either
-			 * old or new toast table
-			 */
-			do
-			{
-				toast_pointer.va_valueid =
-					GetNewOidWithIndex(toastrel,
-									   RelationGetRelid(toastidxs[validIndex]),
-									   (AttrNumber) 1);
-			} while (toastid_valueid_exists(rel->rd_toastoid,
-											toast_pointer.va_valueid));
-		}
-	}
-
-	/*
-	 * Initialize constant parts of the tuple data
-	 */
-	t_values[0] = ObjectIdGetDatum(toast_pointer.va_valueid);
-	t_values[2] = PointerGetDatum(&chunk_data);
-	t_isnull[0] = false;
-	t_isnull[1] = false;
-	t_isnull[2] = false;
-
-	/*
-	 * Split up the item into chunks
-	 */
-	while (data_todo > 0)
-	{
-		int			i;
-
-		CHECK_FOR_INTERRUPTS();
-
-		/*
-		 * Calculate the size of this chunk
-		 */
-		chunk_size = Min(TOAST_MAX_CHUNK_SIZE, data_todo);
-
-		/*
-		 * Build a tuple and store it
-		 */
-		t_values[1] = Int32GetDatum(chunk_seq++);
-		SET_VARSIZE(&chunk_data, chunk_size + VARHDRSZ);
-		memcpy(VARDATA(&chunk_data), data_p, chunk_size);
-		toasttup = heap_form_tuple(toasttupDesc, t_values, t_isnull);
-
-		heap_insert(toastrel, toasttup, mycid, options, NULL);
-
-		/*
-		 * Create the index entry.  We cheat a little here by not using
-		 * FormIndexDatum: this relies on the knowledge that the index columns
-		 * are the same as the initial columns of the table for all the
-		 * indexes.  We also cheat by not providing an IndexInfo: this is okay
-		 * for now because btree doesn't need one, but we might have to be
-		 * more honest someday.
-		 *
-		 * Note also that there had better not be any user-created index on
-		 * the TOAST table, since we don't bother to update anything else.
-		 */
-		for (i = 0; i < num_indexes; i++)
-		{
-			/* Only index relations marked as ready can be updated */
-			if (toastidxs[i]->rd_index->indisready)
-				index_insert(toastidxs[i], t_values, t_isnull,
-							 &(toasttup->t_self),
-							 toastrel,
-							 toastidxs[i]->rd_index->indisunique ?
-							 UNIQUE_CHECK_YES : UNIQUE_CHECK_NO,
-							 NULL);
-		}
-
-		/*
-		 * Free memory
-		 */
-		heap_freetuple(toasttup);
-
-		/*
-		 * Move on to next chunk
-		 */
-		data_todo -= chunk_size;
-		data_p += chunk_size;
-	}
-
-	/*
-	 * Done - close toast relation and its indexes
-	 */
-	toast_close_indexes(toastidxs, num_indexes, RowExclusiveLock);
-	table_close(toastrel, RowExclusiveLock);
-
-	/*
-	 * Create the TOAST pointer value that we'll return
-	 */
-	result = (struct varlena *) palloc(TOAST_POINTER_SIZE);
-	SET_VARTAG_EXTERNAL(result, VARTAG_ONDISK);
-	memcpy(VARDATA_EXTERNAL(result), &toast_pointer, sizeof(toast_pointer));
-
-	return PointerGetDatum(result);
-}
-
-
-/* ----------
- * toast_delete_datum -
- *
- *	Delete a single external stored value.
- * ----------
- */
-static void
-toast_delete_datum(Relation rel, Datum value, bool is_speculative)
-{
-	struct varlena *attr = (struct varlena *) DatumGetPointer(value);
-	struct varatt_external toast_pointer;
-	Relation	toastrel;
-	Relation   *toastidxs;
-	ScanKeyData toastkey;
-	SysScanDesc toastscan;
-	HeapTuple	toasttup;
-	int			num_indexes;
-	int			validIndex;
-	SnapshotData SnapshotToast;
-
-	if (!VARATT_IS_EXTERNAL_ONDISK(attr))
-		return;
-
-	/* Must copy to access aligned fields */
-	VARATT_EXTERNAL_GET_POINTER(toast_pointer, attr);
-
-	/*
-	 * Open the toast relation and its indexes
-	 */
-	toastrel = table_open(toast_pointer.va_toastrelid, RowExclusiveLock);
-
-	/* Fetch valid relation used for process */
-	validIndex = toast_open_indexes(toastrel,
-									RowExclusiveLock,
-									&toastidxs,
-									&num_indexes);
-
-	/*
-	 * Setup a scan key to find chunks with matching va_valueid
-	 */
-	ScanKeyInit(&toastkey,
-				(AttrNumber) 1,
-				BTEqualStrategyNumber, F_OIDEQ,
-				ObjectIdGetDatum(toast_pointer.va_valueid));
-
-	/*
-	 * Find all the chunks.  (We don't actually care whether we see them in
-	 * sequence or not, but since we've already locked the index we might as
-	 * well use systable_beginscan_ordered.)
-	 */
-	init_toast_snapshot(&SnapshotToast);
-	toastscan = systable_beginscan_ordered(toastrel, toastidxs[validIndex],
-										   &SnapshotToast, 1, &toastkey);
-	while ((toasttup = systable_getnext_ordered(toastscan, ForwardScanDirection)) != NULL)
-	{
-		/*
-		 * Have a chunk, delete it
-		 */
-		if (is_speculative)
-			heap_abort_speculative(toastrel, &toasttup->t_self);
-		else
-			simple_heap_delete(toastrel, &toasttup->t_self);
-	}
-
-	/*
-	 * End scan and close relations
-	 */
-	systable_endscan_ordered(toastscan);
-	toast_close_indexes(toastidxs, num_indexes, RowExclusiveLock);
-	table_close(toastrel, RowExclusiveLock);
-}
-
-
-/* ----------
- * toastrel_valueid_exists -
- *
- *	Test whether a toast value with the given ID exists in the toast relation.
- *	For safety, we consider a value to exist if there are either live or dead
- *	toast rows with that ID; see notes for GetNewOidWithIndex().
- * ----------
- */
-static bool
-toastrel_valueid_exists(Relation toastrel, Oid valueid)
-{
-	bool		result = false;
-	ScanKeyData toastkey;
-	SysScanDesc toastscan;
-	int			num_indexes;
-	int			validIndex;
-	Relation   *toastidxs;
-
-	/* Fetch a valid index relation */
-	validIndex = toast_open_indexes(toastrel,
-									RowExclusiveLock,
-									&toastidxs,
-									&num_indexes);
-
-	/*
-	 * Setup a scan key to find chunks with matching va_valueid
-	 */
-	ScanKeyInit(&toastkey,
-				(AttrNumber) 1,
-				BTEqualStrategyNumber, F_OIDEQ,
-				ObjectIdGetDatum(valueid));
-
-	/*
-	 * Is there any such chunk?
-	 */
-	toastscan = systable_beginscan(toastrel,
-								   RelationGetRelid(toastidxs[validIndex]),
-								   true, SnapshotAny, 1, &toastkey);
-
-	if (systable_getnext(toastscan) != NULL)
-		result = true;
-
-	systable_endscan(toastscan);
-
-	/* Clean up */
-	toast_close_indexes(toastidxs, num_indexes, RowExclusiveLock);
-
-	return result;
-}
-
-/* ----------
- * toastid_valueid_exists -
- *
- *	As above, but work from toast rel's OID not an open relation
- * ----------
- */
-static bool
-toastid_valueid_exists(Oid toastrelid, Oid valueid)
-{
-	bool		result;
-	Relation	toastrel;
-
-	toastrel = table_open(toastrelid, AccessShareLock);
-
-	result = toastrel_valueid_exists(toastrel, valueid);
-
-	table_close(toastrel, AccessShareLock);
-
-	return result;
-}
-
-
-/* ----------
- * toast_fetch_datum -
- *
- *	Reconstruct an in memory Datum from the chunks saved
- *	in the toast relation
- * ----------
- */
-static struct varlena *
-toast_fetch_datum(struct varlena *attr)
-{
-	Relation	toastrel;
-	Relation   *toastidxs;
-	ScanKeyData toastkey;
-	SysScanDesc toastscan;
-	HeapTuple	ttup;
-	TupleDesc	toasttupDesc;
-	struct varlena *result;
-	struct varatt_external toast_pointer;
-	int32		ressize;
-	int32		residx,
-				nextidx;
-	int32		numchunks;
-	Pointer		chunk;
-	bool		isnull;
-	char	   *chunkdata;
-	int32		chunksize;
-	int			num_indexes;
-	int			validIndex;
-	SnapshotData SnapshotToast;
-
-	if (!VARATT_IS_EXTERNAL_ONDISK(attr))
-		elog(ERROR, "toast_fetch_datum shouldn't be called for non-ondisk datums");
-
-	/* Must copy to access aligned fields */
-	VARATT_EXTERNAL_GET_POINTER(toast_pointer, attr);
-
-	ressize = toast_pointer.va_extsize;
-	numchunks = ((ressize - 1) / TOAST_MAX_CHUNK_SIZE) + 1;
-
-	result = (struct varlena *) palloc(ressize + VARHDRSZ);
-
-	if (VARATT_EXTERNAL_IS_COMPRESSED(toast_pointer))
-		SET_VARSIZE_COMPRESSED(result, ressize + VARHDRSZ);
-	else
-		SET_VARSIZE(result, ressize + VARHDRSZ);
-
-	/*
-	 * Open the toast relation and its indexes
-	 */
-	toastrel = table_open(toast_pointer.va_toastrelid, AccessShareLock);
-	toasttupDesc = toastrel->rd_att;
-
-	/* Look for the valid index of the toast relation */
-	validIndex = toast_open_indexes(toastrel,
-									AccessShareLock,
-									&toastidxs,
-									&num_indexes);
-
-	/*
-	 * Setup a scan key to fetch from the index by va_valueid
-	 */
-	ScanKeyInit(&toastkey,
-				(AttrNumber) 1,
-				BTEqualStrategyNumber, F_OIDEQ,
-				ObjectIdGetDatum(toast_pointer.va_valueid));
-
-	/*
-	 * Read the chunks by index
-	 *
-	 * Note that because the index is actually on (valueid, chunkidx) we will
-	 * see the chunks in chunkidx order, even though we didn't explicitly ask
-	 * for it.
-	 */
-	nextidx = 0;
-
-	init_toast_snapshot(&SnapshotToast);
-	toastscan = systable_beginscan_ordered(toastrel, toastidxs[validIndex],
-										   &SnapshotToast, 1, &toastkey);
-	while ((ttup = systable_getnext_ordered(toastscan, ForwardScanDirection)) != NULL)
-	{
-		/*
-		 * Have a chunk, extract the sequence number and the data
-		 */
-		residx = DatumGetInt32(fastgetattr(ttup, 2, toasttupDesc, &isnull));
-		Assert(!isnull);
-		chunk = DatumGetPointer(fastgetattr(ttup, 3, toasttupDesc, &isnull));
-		Assert(!isnull);
-		if (!VARATT_IS_EXTENDED(chunk))
-		{
-			chunksize = VARSIZE(chunk) - VARHDRSZ;
-			chunkdata = VARDATA(chunk);
-		}
-		else if (VARATT_IS_SHORT(chunk))
-		{
-			/* could happen due to heap_form_tuple doing its thing */
-			chunksize = VARSIZE_SHORT(chunk) - VARHDRSZ_SHORT;
-			chunkdata = VARDATA_SHORT(chunk);
-		}
-		else
-		{
-			/* should never happen */
-			elog(ERROR, "found toasted toast chunk for toast value %u in %s",
-				 toast_pointer.va_valueid,
-				 RelationGetRelationName(toastrel));
-			chunksize = 0;		/* keep compiler quiet */
-			chunkdata = NULL;
-		}
-
-		/*
-		 * Some checks on the data we've found
-		 */
-		if (residx != nextidx)
-			elog(ERROR, "unexpected chunk number %d (expected %d) for toast value %u in %s",
-				 residx, nextidx,
-				 toast_pointer.va_valueid,
-				 RelationGetRelationName(toastrel));
-		if (residx < numchunks - 1)
-		{
-			if (chunksize != TOAST_MAX_CHUNK_SIZE)
-				elog(ERROR, "unexpected chunk size %d (expected %d) in chunk %d of %d for toast value %u in %s",
-					 chunksize, (int) TOAST_MAX_CHUNK_SIZE,
-					 residx, numchunks,
-					 toast_pointer.va_valueid,
-					 RelationGetRelationName(toastrel));
-		}
-		else if (residx == numchunks - 1)
-		{
-			if ((residx * TOAST_MAX_CHUNK_SIZE + chunksize) != ressize)
-				elog(ERROR, "unexpected chunk size %d (expected %d) in final chunk %d for toast value %u in %s",
-					 chunksize,
-					 (int) (ressize - residx * TOAST_MAX_CHUNK_SIZE),
-					 residx,
-					 toast_pointer.va_valueid,
-					 RelationGetRelationName(toastrel));
-		}
-		else
-			elog(ERROR, "unexpected chunk number %d (out of range %d..%d) for toast value %u in %s",
-				 residx,
-				 0, numchunks - 1,
-				 toast_pointer.va_valueid,
-				 RelationGetRelationName(toastrel));
-
-		/*
-		 * Copy the data into proper place in our result
-		 */
-		memcpy(VARDATA(result) + residx * TOAST_MAX_CHUNK_SIZE,
-			   chunkdata,
-			   chunksize);
-
-		nextidx++;
-	}
-
-	/*
-	 * Final checks that we successfully fetched the datum
-	 */
-	if (nextidx != numchunks)
-		elog(ERROR, "missing chunk number %d for toast value %u in %s",
-			 nextidx,
-			 toast_pointer.va_valueid,
-			 RelationGetRelationName(toastrel));
-
-	/*
-	 * End scan and close relations
-	 */
-	systable_endscan_ordered(toastscan);
-	toast_close_indexes(toastidxs, num_indexes, AccessShareLock);
-	table_close(toastrel, AccessShareLock);
-
-	return result;
-}
-
-/* ----------
- * toast_fetch_datum_slice -
- *
- *	Reconstruct a segment of a Datum from the chunks saved
- *	in the toast relation
- *
- *	Note that this function only supports non-compressed external datums.
- * ----------
- */
-static struct varlena *
-toast_fetch_datum_slice(struct varlena *attr, int32 sliceoffset, int32 length)
-{
-	Relation	toastrel;
-	Relation   *toastidxs;
-	ScanKeyData toastkey[3];
-	int			nscankeys;
-	SysScanDesc toastscan;
-	HeapTuple	ttup;
-	TupleDesc	toasttupDesc;
-	struct varlena *result;
-	struct varatt_external toast_pointer;
-	int32		attrsize;
-	int32		residx;
-	int32		nextidx;
-	int			numchunks;
-	int			startchunk;
-	int			endchunk;
-	int32		startoffset;
-	int32		endoffset;
-	int			totalchunks;
-	Pointer		chunk;
-	bool		isnull;
-	char	   *chunkdata;
-	int32		chunksize;
-	int32		chcpystrt;
-	int32		chcpyend;
-	int			num_indexes;
-	int			validIndex;
-	SnapshotData SnapshotToast;
-
-	if (!VARATT_IS_EXTERNAL_ONDISK(attr))
-		elog(ERROR, "toast_fetch_datum_slice shouldn't be called for non-ondisk datums");
-
-	/* Must copy to access aligned fields */
-	VARATT_EXTERNAL_GET_POINTER(toast_pointer, attr);
-
-	/*
-	 * It's nonsense to fetch slices of a compressed datum -- this isn't lo_*
-	 * we can't return a compressed datum which is meaningful to toast later
-	 */
-	Assert(!VARATT_EXTERNAL_IS_COMPRESSED(toast_pointer));
-
-	attrsize = toast_pointer.va_extsize;
-	totalchunks = ((attrsize - 1) / TOAST_MAX_CHUNK_SIZE) + 1;
-
-	if (sliceoffset >= attrsize)
-	{
-		sliceoffset = 0;
-		length = 0;
-	}
-
-	if (((sliceoffset + length) > attrsize) || length < 0)
-		length = attrsize - sliceoffset;
-
-	result = (struct varlena *) palloc(length + VARHDRSZ);
-
-	SET_VARSIZE(result, length + VARHDRSZ);
-
-	if (length == 0)
-		return result;			/* Can save a lot of work at this point! */
-
-	startchunk = sliceoffset / TOAST_MAX_CHUNK_SIZE;
-	endchunk = (sliceoffset + length - 1) / TOAST_MAX_CHUNK_SIZE;
-	numchunks = (endchunk - startchunk) + 1;
-
-	startoffset = sliceoffset % TOAST_MAX_CHUNK_SIZE;
-	endoffset = (sliceoffset + length - 1) % TOAST_MAX_CHUNK_SIZE;
-
-	/*
-	 * Open the toast relation and its indexes
-	 */
-	toastrel = table_open(toast_pointer.va_toastrelid, AccessShareLock);
-	toasttupDesc = toastrel->rd_att;
-
-	/* Look for the valid index of toast relation */
-	validIndex = toast_open_indexes(toastrel,
-									AccessShareLock,
-									&toastidxs,
-									&num_indexes);
-
-	/*
-	 * Setup a scan key to fetch from the index. This is either two keys or
-	 * three depending on the number of chunks.
-	 */
-	ScanKeyInit(&toastkey[0],
-				(AttrNumber) 1,
-				BTEqualStrategyNumber, F_OIDEQ,
-				ObjectIdGetDatum(toast_pointer.va_valueid));
-
-	/*
-	 * Use equality condition for one chunk, a range condition otherwise:
-	 */
-	if (numchunks == 1)
-	{
-		ScanKeyInit(&toastkey[1],
-					(AttrNumber) 2,
-					BTEqualStrategyNumber, F_INT4EQ,
-					Int32GetDatum(startchunk));
-		nscankeys = 2;
-	}
-	else
-	{
-		ScanKeyInit(&toastkey[1],
-					(AttrNumber) 2,
-					BTGreaterEqualStrategyNumber, F_INT4GE,
-					Int32GetDatum(startchunk));
-		ScanKeyInit(&toastkey[2],
-					(AttrNumber) 2,
-					BTLessEqualStrategyNumber, F_INT4LE,
-					Int32GetDatum(endchunk));
-		nscankeys = 3;
-	}
-
-	/*
-	 * Read the chunks by index
-	 *
-	 * The index is on (valueid, chunkidx) so they will come in order
-	 */
-	init_toast_snapshot(&SnapshotToast);
-	nextidx = startchunk;
-	toastscan = systable_beginscan_ordered(toastrel, toastidxs[validIndex],
-										   &SnapshotToast, nscankeys, toastkey);
-	while ((ttup = systable_getnext_ordered(toastscan, ForwardScanDirection)) != NULL)
-	{
-		/*
-		 * Have a chunk, extract the sequence number and the data
-		 */
-		residx = DatumGetInt32(fastgetattr(ttup, 2, toasttupDesc, &isnull));
-		Assert(!isnull);
-		chunk = DatumGetPointer(fastgetattr(ttup, 3, toasttupDesc, &isnull));
-		Assert(!isnull);
-		if (!VARATT_IS_EXTENDED(chunk))
-		{
-			chunksize = VARSIZE(chunk) - VARHDRSZ;
-			chunkdata = VARDATA(chunk);
-		}
-		else if (VARATT_IS_SHORT(chunk))
-		{
-			/* could happen due to heap_form_tuple doing its thing */
-			chunksize = VARSIZE_SHORT(chunk) - VARHDRSZ_SHORT;
-			chunkdata = VARDATA_SHORT(chunk);
-		}
-		else
-		{
-			/* should never happen */
-			elog(ERROR, "found toasted toast chunk for toast value %u in %s",
-				 toast_pointer.va_valueid,
-				 RelationGetRelationName(toastrel));
-			chunksize = 0;		/* keep compiler quiet */
-			chunkdata = NULL;
-		}
-
-		/*
-		 * Some checks on the data we've found
-		 */
-		if ((residx != nextidx) || (residx > endchunk) || (residx < startchunk))
-			elog(ERROR, "unexpected chunk number %d (expected %d) for toast value %u in %s",
-				 residx, nextidx,
-				 toast_pointer.va_valueid,
-				 RelationGetRelationName(toastrel));
-		if (residx < totalchunks - 1)
-		{
-			if (chunksize != TOAST_MAX_CHUNK_SIZE)
-				elog(ERROR, "unexpected chunk size %d (expected %d) in chunk %d of %d for toast value %u in %s when fetching slice",
-					 chunksize, (int) TOAST_MAX_CHUNK_SIZE,
-					 residx, totalchunks,
-					 toast_pointer.va_valueid,
-					 RelationGetRelationName(toastrel));
-		}
-		else if (residx == totalchunks - 1)
-		{
-			if ((residx * TOAST_MAX_CHUNK_SIZE + chunksize) != attrsize)
-				elog(ERROR, "unexpected chunk size %d (expected %d) in final chunk %d for toast value %u in %s when fetching slice",
-					 chunksize,
-					 (int) (attrsize - residx * TOAST_MAX_CHUNK_SIZE),
-					 residx,
-					 toast_pointer.va_valueid,
-					 RelationGetRelationName(toastrel));
-		}
-		else
-			elog(ERROR, "unexpected chunk number %d (out of range %d..%d) for toast value %u in %s",
-				 residx,
-				 0, totalchunks - 1,
-				 toast_pointer.va_valueid,
-				 RelationGetRelationName(toastrel));
-
-		/*
-		 * Copy the data into proper place in our result
-		 */
-		chcpystrt = 0;
-		chcpyend = chunksize - 1;
-		if (residx == startchunk)
-			chcpystrt = startoffset;
-		if (residx == endchunk)
-			chcpyend = endoffset;
-
-		memcpy(VARDATA(result) +
-			   (residx * TOAST_MAX_CHUNK_SIZE - sliceoffset) + chcpystrt,
-			   chunkdata + chcpystrt,
-			   (chcpyend - chcpystrt) + 1);
-
-		nextidx++;
-	}
-
-	/*
-	 * Final checks that we successfully fetched the datum
-	 */
-	if (nextidx != (endchunk + 1))
-		elog(ERROR, "missing chunk number %d for toast value %u in %s",
-			 nextidx,
-			 toast_pointer.va_valueid,
-			 RelationGetRelationName(toastrel));
-
-	/*
-	 * End scan and close relations
-	 */
-	systable_endscan_ordered(toastscan);
-	toast_close_indexes(toastidxs, num_indexes, AccessShareLock);
-	table_close(toastrel, AccessShareLock);
-
-	return result;
-}
-
-/* ----------
- * toast_decompress_datum -
- *
- * Decompress a compressed version of a varlena datum
- */
-static struct varlena *
-toast_decompress_datum(struct varlena *attr)
-{
-	struct varlena *result;
-
-	Assert(VARATT_IS_COMPRESSED(attr));
-
-	result = (struct varlena *)
-		palloc(TOAST_COMPRESS_RAWSIZE(attr) + VARHDRSZ);
-	SET_VARSIZE(result, TOAST_COMPRESS_RAWSIZE(attr) + VARHDRSZ);
-
-	if (pglz_decompress(TOAST_COMPRESS_RAWDATA(attr),
-						VARSIZE(attr) - TOAST_COMPRESS_HDRSZ,
-						VARDATA(result),
-						TOAST_COMPRESS_RAWSIZE(attr), true) < 0)
-		elog(ERROR, "compressed data is corrupted");
-
-	return result;
-}
-
-
-/* ----------
- * toast_decompress_datum_slice -
- *
- * Decompress the front of a compressed version of a varlena datum.
- * offset handling happens in heap_tuple_untoast_attr_slice.
- * Here we just decompress a slice from the front.
- */
-static struct varlena *
-toast_decompress_datum_slice(struct varlena *attr, int32 slicelength)
-{
-	struct varlena *result;
-	int32		rawsize;
-
-	Assert(VARATT_IS_COMPRESSED(attr));
-
-	result = (struct varlena *) palloc(slicelength + VARHDRSZ);
-
-	rawsize = pglz_decompress(TOAST_COMPRESS_RAWDATA(attr),
-							  VARSIZE(attr) - TOAST_COMPRESS_HDRSZ,
-							  VARDATA(result),
-							  slicelength, false);
-	if (rawsize < 0)
-		elog(ERROR, "compressed data is corrupted");
-
-	SET_VARSIZE(result, rawsize + VARHDRSZ);
-	return result;
-}
-
-
-/* ----------
- * toast_open_indexes
- *
- *	Get an array of the indexes associated to the given toast relation
- *	and return as well the position of the valid index used by the toast
- *	relation in this array. It is the responsibility of the caller of this
- *	function to close the indexes as well as free them.
- */
-static int
-toast_open_indexes(Relation toastrel,
-				   LOCKMODE lock,
-				   Relation **toastidxs,
-				   int *num_indexes)
-{
-	int			i = 0;
-	int			res = 0;
-	bool		found = false;
-	List	   *indexlist;
-	ListCell   *lc;
-
-	/* Get index list of the toast relation */
-	indexlist = RelationGetIndexList(toastrel);
-	Assert(indexlist != NIL);
-
-	*num_indexes = list_length(indexlist);
-
-	/* Open all the index relations */
-	*toastidxs = (Relation *) palloc(*num_indexes * sizeof(Relation));
-	foreach(lc, indexlist)
-		(*toastidxs)[i++] = index_open(lfirst_oid(lc), lock);
-
-	/* Fetch the first valid index in list */
-	for (i = 0; i < *num_indexes; i++)
-	{
-		Relation	toastidx = (*toastidxs)[i];
-
-		if (toastidx->rd_index->indisvalid)
-		{
-			res = i;
-			found = true;
-			break;
-		}
-	}
-
-	/*
-	 * Free index list, not necessary anymore as relations are opened and a
-	 * valid index has been found.
-	 */
-	list_free(indexlist);
-
-	/*
-	 * The toast relation should have one valid index, so something is going
-	 * wrong if there is nothing.
-	 */
-	if (!found)
-		elog(ERROR, "no valid index found for toast relation with Oid %u",
-			 RelationGetRelid(toastrel));
-
-	return res;
-}
-
-/* ----------
- * toast_close_indexes
- *
- *	Close an array of indexes for a toast relation and free it. This should
- *	be called for a set of indexes opened previously with toast_open_indexes.
- */
-static void
-toast_close_indexes(Relation *toastidxs, int num_indexes, LOCKMODE lock)
-{
-	int			i;
-
-	/* Close relations and clean up things */
-	for (i = 0; i < num_indexes; i++)
-		index_close(toastidxs[i], lock);
-	pfree(toastidxs);
-}
-
-/* ----------
- * init_toast_snapshot
- *
- *	Initialize an appropriate TOAST snapshot.  We must use an MVCC snapshot
- *	to initialize the TOAST snapshot; since we don't know which one to use,
- *	just use the oldest one.  This is safe: at worst, we will get a "snapshot
- *	too old" error that might have been avoided otherwise.
- */
-static void
-init_toast_snapshot(Snapshot toast_snapshot)
-{
-	Snapshot	snapshot = GetOldestSnapshot();
-
-	if (snapshot == NULL)
-		elog(ERROR, "no known snapshots");
-
-	InitToastSnapshot(*toast_snapshot, snapshot->lsn, snapshot->whenTaken);
-}
diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c
index b6c9353cbd..aca6accb3d 100644
--- a/src/backend/access/transam/xlog.c
+++ b/src/backend/access/transam/xlog.c
@@ -24,12 +24,12 @@
 
 #include "access/clog.h"
 #include "access/commit_ts.h"
+#include "access/heaptoast.h"
 #include "access/multixact.h"
 #include "access/rewriteheap.h"
 #include "access/subtrans.h"
 #include "access/timeline.h"
 #include "access/transam.h"
-#include "access/tuptoaster.h"
 #include "access/twophase.h"
 #include "access/xact.h"
 #include "access/xlog_internal.h"
diff --git a/src/backend/commands/analyze.c b/src/backend/commands/analyze.c
index d7004e5313..6b7752788e 100644
--- a/src/backend/commands/analyze.c
+++ b/src/backend/commands/analyze.c
@@ -16,6 +16,7 @@
 
 #include <math.h>
 
+#include "access/detoast.h"
 #include "access/genam.h"
 #include "access/multixact.h"
 #include "access/relation.h"
@@ -24,7 +25,6 @@
 #include "access/tableam.h"
 #include "access/transam.h"
 #include "access/tupconvert.h"
-#include "access/tuptoaster.h"
 #include "access/visibilitymap.h"
 #include "access/xact.h"
 #include "catalog/catalog.h"
diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c
index ebaec4f8dd..7b383499e9 100644
--- a/src/backend/commands/cluster.c
+++ b/src/backend/commands/cluster.c
@@ -23,7 +23,7 @@
 #include "access/relscan.h"
 #include "access/tableam.h"
 #include "access/transam.h"
-#include "access/tuptoaster.h"
+#include "access/toast_internals.h"
 #include "access/xact.h"
 #include "access/xlog.h"
 #include "catalog/pg_am.h"
diff --git a/src/backend/executor/execExprInterp.c b/src/backend/executor/execExprInterp.c
index 66a67c72b2..cfd3aa1fb8 100644
--- a/src/backend/executor/execExprInterp.c
+++ b/src/backend/executor/execExprInterp.c
@@ -56,7 +56,7 @@
  */
 #include "postgres.h"
 
-#include "access/tuptoaster.h"
+#include "access/heaptoast.h"
 #include "catalog/pg_type.h"
 #include "commands/sequence.h"
 #include "executor/execExpr.h"
diff --git a/src/backend/executor/execTuples.c b/src/backend/executor/execTuples.c
index 5ee2a464bb..82b69456ad 100644
--- a/src/backend/executor/execTuples.c
+++ b/src/backend/executor/execTuples.c
@@ -57,9 +57,9 @@
  */
 #include "postgres.h"
 
+#include "access/heaptoast.h"
 #include "access/htup_details.h"
 #include "access/tupdesc_details.h"
-#include "access/tuptoaster.h"
 #include "funcapi.h"
 #include "catalog/pg_type.h"
 #include "nodes/nodeFuncs.h"
diff --git a/src/backend/executor/tstoreReceiver.c b/src/backend/executor/tstoreReceiver.c
index cf79feb6bd..c0c81c82da 100644
--- a/src/backend/executor/tstoreReceiver.c
+++ b/src/backend/executor/tstoreReceiver.c
@@ -20,7 +20,7 @@
 
 #include "postgres.h"
 
-#include "access/tuptoaster.h"
+#include "access/detoast.h"
 #include "executor/tstoreReceiver.h"
 
 
diff --git a/src/backend/replication/logical/reorderbuffer.c b/src/backend/replication/logical/reorderbuffer.c
index 591377d2cd..5c506386f9 100644
--- a/src/backend/replication/logical/reorderbuffer.c
+++ b/src/backend/replication/logical/reorderbuffer.c
@@ -56,10 +56,10 @@
 #include <unistd.h>
 #include <sys/stat.h>
 
+#include "access/detoast.h"
 #include "access/heapam.h"
 #include "access/rewriteheap.h"
 #include "access/transam.h"
-#include "access/tuptoaster.h"
 #include "access/xact.h"
 #include "access/xlog_internal.h"
 #include "catalog/catalog.h"
diff --git a/src/backend/statistics/extended_stats.c b/src/backend/statistics/extended_stats.c
index c56ed48270..6167f79568 100644
--- a/src/backend/statistics/extended_stats.c
+++ b/src/backend/statistics/extended_stats.c
@@ -16,10 +16,10 @@
  */
 #include "postgres.h"
 
+#include "access/detoast.h"
 #include "access/genam.h"
 #include "access/htup_details.h"
 #include "access/table.h"
-#include "access/tuptoaster.h"
 #include "catalog/indexing.h"
 #include "catalog/pg_collation.h"
 #include "catalog/pg_statistic_ext.h"
diff --git a/src/backend/storage/large_object/inv_api.c b/src/backend/storage/large_object/inv_api.c
index a477cb9200..e591236343 100644
--- a/src/backend/storage/large_object/inv_api.c
+++ b/src/backend/storage/large_object/inv_api.c
@@ -32,10 +32,11 @@
 
 #include <limits.h>
 
+#include "access/detoast.h"
 #include "access/genam.h"
+#include "access/htup_details.h"
 #include "access/sysattr.h"
 #include "access/table.h"
-#include "access/tuptoaster.h"
 #include "access/xact.h"
 #include "catalog/dependency.h"
 #include "catalog/indexing.h"
diff --git a/src/backend/utils/adt/array_typanalyze.c b/src/backend/utils/adt/array_typanalyze.c
index eafb94b697..54f5849629 100644
--- a/src/backend/utils/adt/array_typanalyze.c
+++ b/src/backend/utils/adt/array_typanalyze.c
@@ -14,7 +14,7 @@
  */
 #include "postgres.h"
 
-#include "access/tuptoaster.h"
+#include "access/detoast.h"
 #include "commands/vacuum.h"
 #include "utils/array.h"
 #include "utils/builtins.h"
diff --git a/src/backend/utils/adt/datum.c b/src/backend/utils/adt/datum.c
index 81ea5a48e5..1568658bc9 100644
--- a/src/backend/utils/adt/datum.c
+++ b/src/backend/utils/adt/datum.c
@@ -42,7 +42,7 @@
 
 #include "postgres.h"
 
-#include "access/tuptoaster.h"
+#include "access/detoast.h"
 #include "fmgr.h"
 #include "utils/datum.h"
 #include "utils/expandeddatum.h"
diff --git a/src/backend/utils/adt/expandedrecord.c b/src/backend/utils/adt/expandedrecord.c
index 166c863026..369432d53c 100644
--- a/src/backend/utils/adt/expandedrecord.c
+++ b/src/backend/utils/adt/expandedrecord.c
@@ -18,8 +18,9 @@
  */
 #include "postgres.h"
 
+#include "access/detoast.h"
+#include "access/heaptoast.h"
 #include "access/htup_details.h"
-#include "access/tuptoaster.h"
 #include "catalog/heap.h"
 #include "catalog/pg_type.h"
 #include "utils/builtins.h"
diff --git a/src/backend/utils/adt/rowtypes.c b/src/backend/utils/adt/rowtypes.c
index aa7ec8735c..ea3e40a369 100644
--- a/src/backend/utils/adt/rowtypes.c
+++ b/src/backend/utils/adt/rowtypes.c
@@ -16,8 +16,8 @@
 
 #include <ctype.h>
 
+#include "access/detoast.h"
 #include "access/htup_details.h"
-#include "access/tuptoaster.h"
 #include "catalog/pg_type.h"
 #include "funcapi.h"
 #include "libpq/pqformat.h"
diff --git a/src/backend/utils/adt/tsgistidx.c b/src/backend/utils/adt/tsgistidx.c
index 4f256260fd..6ff71a49b8 100644
--- a/src/backend/utils/adt/tsgistidx.c
+++ b/src/backend/utils/adt/tsgistidx.c
@@ -15,7 +15,7 @@
 #include "postgres.h"
 
 #include "access/gist.h"
-#include "access/tuptoaster.h"
+#include "access/heaptoast.h"
 #include "port/pg_bitutils.h"
 #include "tsearch/ts_utils.h"
 #include "utils/builtins.h"
diff --git a/src/backend/utils/adt/varchar.c b/src/backend/utils/adt/varchar.c
index 332dc860c4..9d94399323 100644
--- a/src/backend/utils/adt/varchar.c
+++ b/src/backend/utils/adt/varchar.c
@@ -14,7 +14,7 @@
  */
 #include "postgres.h"
 
-#include "access/tuptoaster.h"
+#include "access/detoast.h"
 #include "catalog/pg_collation.h"
 #include "catalog/pg_type.h"
 #include "libpq/pqformat.h"
diff --git a/src/backend/utils/adt/varlena.c b/src/backend/utils/adt/varlena.c
index 0864838867..3685223922 100644
--- a/src/backend/utils/adt/varlena.c
+++ b/src/backend/utils/adt/varlena.c
@@ -17,7 +17,7 @@
 #include <ctype.h>
 #include <limits.h>
 
-#include "access/tuptoaster.h"
+#include "access/detoast.h"
 #include "catalog/pg_collation.h"
 #include "catalog/pg_type.h"
 #include "common/int.h"
diff --git a/src/backend/utils/cache/catcache.c b/src/backend/utils/cache/catcache.c
index 00def27881..c3e7d94aa5 100644
--- a/src/backend/utils/cache/catcache.c
+++ b/src/backend/utils/cache/catcache.c
@@ -15,10 +15,10 @@
 #include "postgres.h"
 
 #include "access/genam.h"
+#include "access/heaptoast.h"
 #include "access/relscan.h"
 #include "access/sysattr.h"
 #include "access/table.h"
-#include "access/tuptoaster.h"
 #include "access/valid.h"
 #include "access/xact.h"
 #include "catalog/pg_collation.h"
diff --git a/src/backend/utils/fmgr/fmgr.c b/src/backend/utils/fmgr/fmgr.c
index 9b640ccd40..74e36e62d3 100644
--- a/src/backend/utils/fmgr/fmgr.c
+++ b/src/backend/utils/fmgr/fmgr.c
@@ -15,7 +15,7 @@
 
 #include "postgres.h"
 
-#include "access/tuptoaster.h"
+#include "access/detoast.h"
 #include "catalog/pg_language.h"
 #include "catalog/pg_proc.h"
 #include "executor/functions.h"
diff --git a/src/bin/pg_resetwal/pg_resetwal.c b/src/bin/pg_resetwal/pg_resetwal.c
index ff0f8ea5e7..daed66ad49 100644
--- a/src/bin/pg_resetwal/pg_resetwal.c
+++ b/src/bin/pg_resetwal/pg_resetwal.c
@@ -45,7 +45,7 @@
 #include <unistd.h>
 
 #include "access/transam.h"
-#include "access/tuptoaster.h"
+#include "access/heaptoast.h"
 #include "access/multixact.h"
 #include "access/xlog.h"
 #include "access/xlog_internal.h"
diff --git a/src/include/access/detoast.h b/src/include/access/detoast.h
new file mode 100644
index 0000000000..582af147ea
--- /dev/null
+++ b/src/include/access/detoast.h
@@ -0,0 +1,92 @@
+/*-------------------------------------------------------------------------
+ *
+ * detoast.h
+ *	  Access to compressed and external varlena values.
+ *
+ * Copyright (c) 2000-2019, PostgreSQL Global Development Group
+ *
+ * src/include/access/detoast.h
+ *
+ *-------------------------------------------------------------------------
+ */
+#ifndef DETOAST_H 
+#define DETOAST_H
+
+/*
+ * Testing whether an externally-stored value is compressed now requires
+ * comparing extsize (the actual length of the external data) to rawsize
+ * (the original uncompressed datum's size).  The latter includes VARHDRSZ
+ * overhead, the former doesn't.  We never use compression unless it actually
+ * saves space, so we expect either equality or less-than.
+ */
+#define VARATT_EXTERNAL_IS_COMPRESSED(toast_pointer) \
+	((toast_pointer).va_extsize < (toast_pointer).va_rawsize - VARHDRSZ)
+
+/*
+ * Macro to fetch the possibly-unaligned contents of an EXTERNAL datum
+ * into a local "struct varatt_external" toast pointer.  This should be
+ * just a memcpy, but some versions of gcc seem to produce broken code
+ * that assumes the datum contents are aligned.  Introducing an explicit
+ * intermediate "varattrib_1b_e *" variable seems to fix it.
+ */
+#define VARATT_EXTERNAL_GET_POINTER(toast_pointer, attr) \
+do { \
+	varattrib_1b_e *attre = (varattrib_1b_e *) (attr); \
+	Assert(VARATT_IS_EXTERNAL(attre)); \
+	Assert(VARSIZE_EXTERNAL(attre) == sizeof(toast_pointer) + VARHDRSZ_EXTERNAL); \
+	memcpy(&(toast_pointer), VARDATA_EXTERNAL(attre), sizeof(toast_pointer)); \
+} while (0)
+
+/* Size of an EXTERNAL datum that contains a standard TOAST pointer */
+#define TOAST_POINTER_SIZE (VARHDRSZ_EXTERNAL + sizeof(varatt_external))
+
+/* Size of an EXTERNAL datum that contains an indirection pointer */
+#define INDIRECT_POINTER_SIZE (VARHDRSZ_EXTERNAL + sizeof(varatt_indirect))
+
+/* ----------
+ * heap_tuple_fetch_attr() -
+ *
+ *		Fetches an external stored attribute from the toast
+ *		relation. Does NOT decompress it, if stored external
+ *		in compressed format.
+ * ----------
+ */
+extern struct varlena *heap_tuple_fetch_attr(struct varlena *attr);
+
+/* ----------
+ * heap_tuple_untoast_attr() -
+ *
+ *		Fully detoasts one attribute, fetching and/or decompressing
+ *		it as needed.
+ * ----------
+ */
+extern struct varlena *heap_tuple_untoast_attr(struct varlena *attr);
+
+/* ----------
+ * heap_tuple_untoast_attr_slice() -
+ *
+ *		Fetches only the specified portion of an attribute.
+ *		(Handles all cases for attribute storage)
+ * ----------
+ */
+extern struct varlena *heap_tuple_untoast_attr_slice(struct varlena *attr,
+							  int32 sliceoffset,
+							  int32 slicelength);
+
+/* ----------
+ * toast_raw_datum_size -
+ *
+ *	Return the raw (detoasted) size of a varlena datum
+ * ----------
+ */
+extern Size toast_raw_datum_size(Datum value);
+
+/* ----------
+ * toast_datum_size -
+ *
+ *	Return the storage size of a varlena datum
+ * ----------
+ */
+extern Size toast_datum_size(Datum value);
+
+#endif							/* DETOAST_H */
diff --git a/src/include/access/tuptoaster.h b/src/include/access/heaptoast.h
similarity index 57%
rename from src/include/access/tuptoaster.h
rename to src/include/access/heaptoast.h
index f0aea2496b..bf02d2c600 100644
--- a/src/include/access/tuptoaster.h
+++ b/src/include/access/heaptoast.h
@@ -1,29 +1,22 @@
 /*-------------------------------------------------------------------------
  *
- * tuptoaster.h
- *	  POSTGRES definitions for external and compressed storage
+ * heaptoast.h
+ *	  Heap-specific definitions for external and compressed storage
  *	  of variable size attributes.
  *
  * Copyright (c) 2000-2019, PostgreSQL Global Development Group
  *
- * src/include/access/tuptoaster.h
+ * src/include/access/heaptoast.h
  *
  *-------------------------------------------------------------------------
  */
-#ifndef TUPTOASTER_H
-#define TUPTOASTER_H
+#ifndef HEAPTOAST_H
+#define HEAPTOAST_H
 
 #include "access/htup_details.h"
 #include "storage/lockdefs.h"
 #include "utils/relcache.h"
 
-/*
- * This enables de-toasting of index entries.  Needed until VACUUM is
- * smart enough to rebuild indexes from scratch.
- */
-#define TOAST_INDEX_HACK
-
-
 /*
  * Find the maximum size of a tuple if there are to be N tuples per page.
  */
@@ -95,37 +88,6 @@
 	 sizeof(int32) -									\
 	 VARHDRSZ)
 
-/* Size of an EXTERNAL datum that contains a standard TOAST pointer */
-#define TOAST_POINTER_SIZE (VARHDRSZ_EXTERNAL + sizeof(varatt_external))
-
-/* Size of an EXTERNAL datum that contains an indirection pointer */
-#define INDIRECT_POINTER_SIZE (VARHDRSZ_EXTERNAL + sizeof(varatt_indirect))
-
-/*
- * Testing whether an externally-stored value is compressed now requires
- * comparing extsize (the actual length of the external data) to rawsize
- * (the original uncompressed datum's size).  The latter includes VARHDRSZ
- * overhead, the former doesn't.  We never use compression unless it actually
- * saves space, so we expect either equality or less-than.
- */
-#define VARATT_EXTERNAL_IS_COMPRESSED(toast_pointer) \
-	((toast_pointer).va_extsize < (toast_pointer).va_rawsize - VARHDRSZ)
-
-/*
- * Macro to fetch the possibly-unaligned contents of an EXTERNAL datum
- * into a local "struct varatt_external" toast pointer.  This should be
- * just a memcpy, but some versions of gcc seem to produce broken code
- * that assumes the datum contents are aligned.  Introducing an explicit
- * intermediate "varattrib_1b_e *" variable seems to fix it.
- */
-#define VARATT_EXTERNAL_GET_POINTER(toast_pointer, attr) \
-do { \
-	varattrib_1b_e *attre = (varattrib_1b_e *) (attr); \
-	Assert(VARATT_IS_EXTERNAL(attre)); \
-	Assert(VARSIZE_EXTERNAL(attre) == sizeof(toast_pointer) + VARHDRSZ_EXTERNAL); \
-	memcpy(&(toast_pointer), VARDATA_EXTERNAL(attre), sizeof(toast_pointer)); \
-} while (0)
-
 /* ----------
  * toast_insert_or_update -
  *
@@ -144,36 +106,6 @@ extern HeapTuple toast_insert_or_update(Relation rel,
  */
 extern void toast_delete(Relation rel, HeapTuple oldtup, bool is_speculative);
 
-/* ----------
- * heap_tuple_fetch_attr() -
- *
- *		Fetches an external stored attribute from the toast
- *		relation. Does NOT decompress it, if stored external
- *		in compressed format.
- * ----------
- */
-extern struct varlena *heap_tuple_fetch_attr(struct varlena *attr);
-
-/* ----------
- * heap_tuple_untoast_attr() -
- *
- *		Fully detoasts one attribute, fetching and/or decompressing
- *		it as needed.
- * ----------
- */
-extern struct varlena *heap_tuple_untoast_attr(struct varlena *attr);
-
-/* ----------
- * heap_tuple_untoast_attr_slice() -
- *
- *		Fetches only the specified portion of an attribute.
- *		(Handles all cases for attribute storage)
- * ----------
- */
-extern struct varlena *heap_tuple_untoast_attr_slice(struct varlena *attr,
-													 int32 sliceoffset,
-													 int32 slicelength);
-
 /* ----------
  * toast_flatten_tuple -
  *
@@ -204,36 +136,4 @@ extern HeapTuple toast_build_flattened_tuple(TupleDesc tupleDesc,
 											 Datum *values,
 											 bool *isnull);
 
-/* ----------
- * toast_compress_datum -
- *
- *	Create a compressed version of a varlena datum, if possible
- * ----------
- */
-extern Datum toast_compress_datum(Datum value);
-
-/* ----------
- * toast_raw_datum_size -
- *
- *	Return the raw (detoasted) size of a varlena datum
- * ----------
- */
-extern Size toast_raw_datum_size(Datum value);
-
-/* ----------
- * toast_datum_size -
- *
- *	Return the storage size of a varlena datum
- * ----------
- */
-extern Size toast_datum_size(Datum value);
-
-/* ----------
- * toast_get_valid_index -
- *
- *	Return OID of valid index associated to a toast relation
- * ----------
- */
-extern Oid	toast_get_valid_index(Oid toastoid, LOCKMODE lock);
-
-#endif							/* TUPTOASTER_H */
+#endif							/* HEAPTOAST_H */
diff --git a/src/include/access/toast_internals.h b/src/include/access/toast_internals.h
new file mode 100644
index 0000000000..494b07a4b1
--- /dev/null
+++ b/src/include/access/toast_internals.h
@@ -0,0 +1,54 @@
+/*-------------------------------------------------------------------------
+ *
+ * toast_internals.h
+ *	  Internal definitions for the TOAST system.
+ *
+ * Copyright (c) 2000-2019, PostgreSQL Global Development Group
+ *
+ * src/include/access/toast_internals.h
+ *
+ *-------------------------------------------------------------------------
+ */
+#ifndef TOAST_INTERNALS_H
+#define TOAST_INTERNALS_H
+
+#include "storage/lockdefs.h"
+#include "utils/relcache.h"
+#include "utils/snapshot.h"
+
+/*
+ *	The information at the start of the compressed toast data.
+ */
+typedef struct toast_compress_header
+{
+	int32		vl_len_;		/* varlena header (do not touch directly!) */
+	int32		rawsize;
+} toast_compress_header;
+
+/*
+ * Utilities for manipulation of header information for compressed
+ * toast entries.
+ */
+#define TOAST_COMPRESS_HDRSZ		((int32) sizeof(toast_compress_header))
+#define TOAST_COMPRESS_RAWSIZE(ptr) (((toast_compress_header *) (ptr))->rawsize)
+#define TOAST_COMPRESS_RAWDATA(ptr) \
+	(((char *) (ptr)) + TOAST_COMPRESS_HDRSZ)
+#define TOAST_COMPRESS_SET_RAWSIZE(ptr, len) \
+	(((toast_compress_header *) (ptr))->rawsize = (len))
+
+extern Datum toast_compress_datum(Datum value);
+extern Oid	toast_get_valid_index(Oid toastoid, LOCKMODE lock);
+
+extern void toast_delete_datum(Relation rel, Datum value, bool is_speculative);
+extern Datum toast_save_datum(Relation rel, Datum value,
+							  struct varlena *oldexternal, int options);
+
+extern int	toast_open_indexes(Relation toastrel,
+							   LOCKMODE lock,
+							   Relation **toastidxs,
+							   int *num_indexes);
+extern void toast_close_indexes(Relation *toastidxs, int num_indexes,
+								LOCKMODE lock);
+extern void init_toast_snapshot(Snapshot toast_snapshot);
+
+#endif							/* TOAST_INTERNALS_H */
diff --git a/src/pl/plpgsql/src/pl_exec.c b/src/pl/plpgsql/src/pl_exec.c
index a718bccc24..3479fbd550 100644
--- a/src/pl/plpgsql/src/pl_exec.c
+++ b/src/pl/plpgsql/src/pl_exec.c
@@ -17,10 +17,10 @@
 
 #include <ctype.h>
 
+#include "access/detoast.h"
 #include "access/htup_details.h"
 #include "access/transam.h"
 #include "access/tupconvert.h"
-#include "access/tuptoaster.h"
 #include "catalog/pg_proc.h"
 #include "catalog/pg_type.h"
 #include "commands/defrem.h"
diff --git a/src/test/regress/regress.c b/src/test/regress/regress.c
index 7f03b7e857..826556eb29 100644
--- a/src/test/regress/regress.c
+++ b/src/test/regress/regress.c
@@ -19,9 +19,9 @@
 #include <math.h>
 #include <signal.h>
 
+#include "access/detoast.h"
 #include "access/htup_details.h"
 #include "access/transam.h"
-#include "access/tuptoaster.h"
 #include "access/xact.h"
 #include "catalog/pg_operator.h"
 #include "catalog/pg_type.h"
-- 
2.17.2 (Apple Git-113)

From bd43f06a3fadc75a54248a5a54941b9dff3fc576 Mon Sep 17 00:00:00 2001
From: Robert Haas <rhaas@postgresql.org>
Date: Mon, 8 Jul 2019 12:34:37 -0400
Subject: [PATCH 4/4] Rename attribute-detoasting functions.

The old names included the word "heap," which seems outdated now that
the heap is only one of potentially many table access methods.

Discussion: http://postgr.es/m/CA+TgmoZv-=2iWM4jcw5ZhJeL18HF96+W1yJeYrnGMYdkFFnEpQ@mail.gmail.com
---
 src/backend/access/common/detoast.c        | 26 +++++++++++-----------
 src/backend/access/common/indextuple.c     |  2 +-
 src/backend/access/heap/heaptoast.c        |  6 ++---
 src/backend/access/table/toast_helper.c    |  4 ++--
 src/backend/executor/tstoreReceiver.c      |  2 +-
 src/backend/storage/large_object/inv_api.c |  2 +-
 src/backend/utils/adt/expandedrecord.c     |  4 ++--
 src/backend/utils/fmgr/fmgr.c              |  8 +++----
 src/include/access/detoast.h               | 16 ++++++-------
 src/pl/plpgsql/src/pl_exec.c               |  2 +-
 src/test/regress/regress.c                 |  2 +-
 11 files changed, 37 insertions(+), 37 deletions(-)

diff --git a/src/backend/access/common/detoast.c b/src/backend/access/common/detoast.c
index 36b68e35fb..78256f91ca 100644
--- a/src/backend/access/common/detoast.c
+++ b/src/backend/access/common/detoast.c
@@ -31,7 +31,7 @@ static struct varlena *toast_decompress_datum(struct varlena *attr);
 static struct varlena *toast_decompress_datum_slice(struct varlena *attr, int32 slicelength);
 
 /* ----------
- * heap_tuple_fetch_attr -
+ * detoast_external_attr -
  *
  *	Public entry point to get back a toasted value from
  *	external source (possibly still in compressed format).
@@ -43,7 +43,7 @@ static struct varlena *toast_decompress_datum_slice(struct varlena *attr, int32
  * ----------
  */
 struct varlena *
-heap_tuple_fetch_attr(struct varlena *attr)
+detoast_external_attr(struct varlena *attr)
 {
 	struct varlena *result;
 
@@ -69,7 +69,7 @@ heap_tuple_fetch_attr(struct varlena *attr)
 
 		/* recurse if value is still external in some other way */
 		if (VARATT_IS_EXTERNAL(attr))
-			return heap_tuple_fetch_attr(attr);
+			return detoast_external_attr(attr);
 
 		/*
 		 * Copy into the caller's memory context, in case caller tries to
@@ -104,7 +104,7 @@ heap_tuple_fetch_attr(struct varlena *attr)
 
 
 /* ----------
- * heap_tuple_untoast_attr -
+ * detoast_attr -
  *
  *	Public entry point to get back a toasted value from compression
  *	or external storage.  The result is always non-extended varlena form.
@@ -114,7 +114,7 @@ heap_tuple_fetch_attr(struct varlena *attr)
  * ----------
  */
 struct varlena *
-heap_tuple_untoast_attr(struct varlena *attr)
+detoast_attr(struct varlena *attr)
 {
 	if (VARATT_IS_EXTERNAL_ONDISK(attr))
 	{
@@ -145,7 +145,7 @@ heap_tuple_untoast_attr(struct varlena *attr)
 		Assert(!VARATT_IS_EXTERNAL_INDIRECT(attr));
 
 		/* recurse in case value is still extended in some other way */
-		attr = heap_tuple_untoast_attr(attr);
+		attr = detoast_attr(attr);
 
 		/* if it isn't, we'd better copy it */
 		if (attr == (struct varlena *) redirect.pointer)
@@ -162,7 +162,7 @@ heap_tuple_untoast_attr(struct varlena *attr)
 		/*
 		 * This is an expanded-object pointer --- get flat format
 		 */
-		attr = heap_tuple_fetch_attr(attr);
+		attr = detoast_external_attr(attr);
 		/* flatteners are not allowed to produce compressed/short output */
 		Assert(!VARATT_IS_EXTENDED(attr));
 	}
@@ -193,14 +193,14 @@ heap_tuple_untoast_attr(struct varlena *attr)
 
 
 /* ----------
- * heap_tuple_untoast_attr_slice -
+ * detoast_attr_slice -
  *
  *		Public entry point to get back part of a toasted value
  *		from compression or external storage.
  * ----------
  */
 struct varlena *
-heap_tuple_untoast_attr_slice(struct varlena *attr,
+detoast_attr_slice(struct varlena *attr,
 							  int32 sliceoffset, int32 slicelength)
 {
 	struct varlena *preslice;
@@ -230,13 +230,13 @@ heap_tuple_untoast_attr_slice(struct varlena *attr,
 		/* nested indirect Datums aren't allowed */
 		Assert(!VARATT_IS_EXTERNAL_INDIRECT(redirect.pointer));
 
-		return heap_tuple_untoast_attr_slice(redirect.pointer,
+		return detoast_attr_slice(redirect.pointer,
 											 sliceoffset, slicelength);
 	}
 	else if (VARATT_IS_EXTERNAL_EXPANDED(attr))
 	{
-		/* pass it off to heap_tuple_fetch_attr to flatten */
-		preslice = heap_tuple_fetch_attr(attr);
+		/* pass it off to detoast_external_attr to flatten */
+		preslice = detoast_external_attr(attr);
 	}
 	else
 		preslice = attr;
@@ -737,7 +737,7 @@ toast_decompress_datum(struct varlena *attr)
  * toast_decompress_datum_slice -
  *
  * Decompress the front of a compressed version of a varlena datum.
- * offset handling happens in heap_tuple_untoast_attr_slice.
+ * offset handling happens in detoast_attr_slice.
  * Here we just decompress a slice from the front.
  */
 static struct varlena *
diff --git a/src/backend/access/common/indextuple.c b/src/backend/access/common/indextuple.c
index 07586201b9..8a5f5227a3 100644
--- a/src/backend/access/common/indextuple.c
+++ b/src/backend/access/common/indextuple.c
@@ -89,7 +89,7 @@ index_form_tuple(TupleDesc tupleDescriptor,
 		if (VARATT_IS_EXTERNAL(DatumGetPointer(values[i])))
 		{
 			untoasted_values[i] =
-				PointerGetDatum(heap_tuple_fetch_attr((struct varlena *)
+				PointerGetDatum(detoast_external_attr((struct varlena *)
 													  DatumGetPointer(values[i])));
 			untoasted_free[i] = true;
 		}
diff --git a/src/backend/access/heap/heaptoast.c b/src/backend/access/heap/heaptoast.c
index c0acefc97e..9221dc71d7 100644
--- a/src/backend/access/heap/heaptoast.c
+++ b/src/backend/access/heap/heaptoast.c
@@ -376,7 +376,7 @@ toast_flatten_tuple(HeapTuple tup, TupleDesc tupleDesc)
 			new_value = (struct varlena *) DatumGetPointer(toast_values[i]);
 			if (VARATT_IS_EXTERNAL(new_value))
 			{
-				new_value = heap_tuple_fetch_attr(new_value);
+				new_value = detoast_external_attr(new_value);
 				toast_values[i] = PointerGetDatum(new_value);
 				toast_free[i] = true;
 			}
@@ -491,7 +491,7 @@ toast_flatten_tuple_to_datum(HeapTupleHeader tup,
 			if (VARATT_IS_EXTERNAL(new_value) ||
 				VARATT_IS_COMPRESSED(new_value))
 			{
-				new_value = heap_tuple_untoast_attr(new_value);
+				new_value = detoast_attr(new_value);
 				toast_values[i] = PointerGetDatum(new_value);
 				toast_free[i] = true;
 			}
@@ -590,7 +590,7 @@ toast_build_flattened_tuple(TupleDesc tupleDesc,
 			new_value = (struct varlena *) DatumGetPointer(new_values[i]);
 			if (VARATT_IS_EXTERNAL(new_value))
 			{
-				new_value = heap_tuple_fetch_attr(new_value);
+				new_value = detoast_external_attr(new_value);
 				new_values[i] = PointerGetDatum(new_value);
 				freeable_values[num_to_free++] = (Pointer) new_value;
 			}
diff --git a/src/backend/access/table/toast_helper.c b/src/backend/access/table/toast_helper.c
index e33918a7f4..dedc123e31 100644
--- a/src/backend/access/table/toast_helper.c
+++ b/src/backend/access/table/toast_helper.c
@@ -136,9 +136,9 @@ toast_tuple_init(ToastTupleContext *ttc)
 			{
 				ttc->ttc_attr[i].tai_oldexternal = new_value;
 				if (att->attstorage == 'p')
-					new_value = heap_tuple_untoast_attr(new_value);
+					new_value = detoast_attr(new_value);
 				else
-					new_value = heap_tuple_fetch_attr(new_value);
+					new_value = detoast_external_attr(new_value);
 				ttc->ttc_values[i] = PointerGetDatum(new_value);
 				ttc->ttc_attr[i].tai_colflags |= TOASTCOL_NEEDS_FREE;
 				ttc->ttc_flags |= (TOAST_NEEDS_CHANGE | TOAST_NEEDS_FREE);
diff --git a/src/backend/executor/tstoreReceiver.c b/src/backend/executor/tstoreReceiver.c
index c0c81c82da..6306b7d0bd 100644
--- a/src/backend/executor/tstoreReceiver.c
+++ b/src/backend/executor/tstoreReceiver.c
@@ -133,7 +133,7 @@ tstoreReceiveSlot_detoast(TupleTableSlot *slot, DestReceiver *self)
 		{
 			if (VARATT_IS_EXTERNAL(DatumGetPointer(val)))
 			{
-				val = PointerGetDatum(heap_tuple_fetch_attr((struct varlena *)
+				val = PointerGetDatum(detoast_external_attr((struct varlena *)
 															DatumGetPointer(val)));
 				myState->tofree[nfree++] = val;
 			}
diff --git a/src/backend/storage/large_object/inv_api.c b/src/backend/storage/large_object/inv_api.c
index e591236343..263d5be12e 100644
--- a/src/backend/storage/large_object/inv_api.c
+++ b/src/backend/storage/large_object/inv_api.c
@@ -180,7 +180,7 @@ getdatafield(Form_pg_largeobject tuple,
 	if (VARATT_IS_EXTENDED(datafield))
 	{
 		datafield = (bytea *)
-			heap_tuple_untoast_attr((struct varlena *) datafield);
+			detoast_attr((struct varlena *) datafield);
 		freeit = true;
 	}
 	len = VARSIZE(datafield) - VARHDRSZ;
diff --git a/src/backend/utils/adt/expandedrecord.c b/src/backend/utils/adt/expandedrecord.c
index 369432d53c..d99d370b17 100644
--- a/src/backend/utils/adt/expandedrecord.c
+++ b/src/backend/utils/adt/expandedrecord.c
@@ -1159,7 +1159,7 @@ expanded_record_set_field_internal(ExpandedRecordHeader *erh, int fnumber,
 			{
 				/* Detoasting should be done in short-lived context. */
 				oldcxt = MemoryContextSwitchTo(get_short_term_cxt(erh));
-				newValue = PointerGetDatum(heap_tuple_fetch_attr((struct varlena *) DatumGetPointer(newValue)));
+				newValue = PointerGetDatum(detoast_external_attr((struct varlena *) DatumGetPointer(newValue)));
 				MemoryContextSwitchTo(oldcxt);
 			}
 			else
@@ -1305,7 +1305,7 @@ expanded_record_set_fields(ExpandedRecordHeader *erh,
 					if (expand_external)
 					{
 						/* Detoast as requested while copying the value */
-						newValue = PointerGetDatum(heap_tuple_fetch_attr((struct varlena *) DatumGetPointer(newValue)));
+						newValue = PointerGetDatum(detoast_external_attr((struct varlena *) DatumGetPointer(newValue)));
 					}
 					else
 					{
diff --git a/src/backend/utils/fmgr/fmgr.c b/src/backend/utils/fmgr/fmgr.c
index 0484adb984..099ebd779b 100644
--- a/src/backend/utils/fmgr/fmgr.c
+++ b/src/backend/utils/fmgr/fmgr.c
@@ -1739,7 +1739,7 @@ struct varlena *
 pg_detoast_datum(struct varlena *datum)
 {
 	if (VARATT_IS_EXTENDED(datum))
-		return heap_tuple_untoast_attr(datum);
+		return detoast_attr(datum);
 	else
 		return datum;
 }
@@ -1748,7 +1748,7 @@ struct varlena *
 pg_detoast_datum_copy(struct varlena *datum)
 {
 	if (VARATT_IS_EXTENDED(datum))
-		return heap_tuple_untoast_attr(datum);
+		return detoast_attr(datum);
 	else
 	{
 		/* Make a modifiable copy of the varlena object */
@@ -1764,14 +1764,14 @@ struct varlena *
 pg_detoast_datum_slice(struct varlena *datum, int32 first, int32 count)
 {
 	/* Only get the specified portion from the toast rel */
-	return heap_tuple_untoast_attr_slice(datum, first, count);
+	return detoast_attr_slice(datum, first, count);
 }
 
 struct varlena *
 pg_detoast_datum_packed(struct varlena *datum)
 {
 	if (VARATT_IS_COMPRESSED(datum) || VARATT_IS_EXTERNAL(datum))
-		return heap_tuple_untoast_attr(datum);
+		return detoast_attr(datum);
 	else
 		return datum;
 }
diff --git a/src/include/access/detoast.h b/src/include/access/detoast.h
index 582af147ea..8c07124b76 100644
--- a/src/include/access/detoast.h
+++ b/src/include/access/detoast.h
@@ -44,34 +44,34 @@ do { \
 #define INDIRECT_POINTER_SIZE (VARHDRSZ_EXTERNAL + sizeof(varatt_indirect))
 
 /* ----------
- * heap_tuple_fetch_attr() -
+ * detoast_external_attr() -
  *
  *		Fetches an external stored attribute from the toast
  *		relation. Does NOT decompress it, if stored external
  *		in compressed format.
  * ----------
  */
-extern struct varlena *heap_tuple_fetch_attr(struct varlena *attr);
+extern struct varlena *detoast_external_attr(struct varlena *attr);
 
 /* ----------
- * heap_tuple_untoast_attr() -
+ * detoast_attr() -
  *
  *		Fully detoasts one attribute, fetching and/or decompressing
  *		it as needed.
  * ----------
  */
-extern struct varlena *heap_tuple_untoast_attr(struct varlena *attr);
+extern struct varlena *detoast_attr(struct varlena *attr);
 
 /* ----------
- * heap_tuple_untoast_attr_slice() -
+ * detoast_attr_slice() -
  *
  *		Fetches only the specified portion of an attribute.
  *		(Handles all cases for attribute storage)
  * ----------
  */
-extern struct varlena *heap_tuple_untoast_attr_slice(struct varlena *attr,
-							  int32 sliceoffset,
-							  int32 slicelength);
+extern struct varlena *detoast_attr_slice(struct varlena *attr,
+										  int32 sliceoffset,
+										  int32 slicelength);
 
 /* ----------
  * toast_raw_datum_size -
diff --git a/src/pl/plpgsql/src/pl_exec.c b/src/pl/plpgsql/src/pl_exec.c
index db2eff1bbb..870818287a 100644
--- a/src/pl/plpgsql/src/pl_exec.c
+++ b/src/pl/plpgsql/src/pl_exec.c
@@ -8267,7 +8267,7 @@ assign_simple_var(PLpgSQL_execstate *estate, PLpgSQL_var *var,
 		 * pain, but there's little choice.
 		 */
 		oldcxt = MemoryContextSwitchTo(get_eval_mcontext(estate));
-		detoasted = PointerGetDatum(heap_tuple_fetch_attr((struct varlena *) DatumGetPointer(newvalue)));
+		detoasted = PointerGetDatum(detoast_external_attr((struct varlena *) DatumGetPointer(newvalue)));
 		MemoryContextSwitchTo(oldcxt);
 		/* Now's a good time to not leak the input value if it's freeable */
 		if (freeable)
diff --git a/src/test/regress/regress.c b/src/test/regress/regress.c
index 826556eb29..2bbeaa0460 100644
--- a/src/test/regress/regress.c
+++ b/src/test/regress/regress.c
@@ -558,7 +558,7 @@ make_tuple_indirect(PG_FUNCTION_ARGS)
 
 		/* copy datum, so it still lives later */
 		if (VARATT_IS_EXTERNAL_ONDISK(attr))
-			attr = heap_tuple_fetch_attr(attr);
+			attr = detoast_external_attr(attr);
 		else
 		{
 			struct varlena *oldattr = attr;
-- 
2.17.2 (Apple Git-113)

From a1b61ddbc1976b079253eb6e0560913bd6259f65 Mon Sep 17 00:00:00 2001
From: Robert Haas <rhaas@postgresql.org>
Date: Mon, 8 Jul 2019 12:02:16 -0400
Subject: [PATCH 2/4] Create an API for inserting and deleting rows in TOAST
 tables.

This moves much of the non-heap-specific logic from toast_delete and
toast_insert_or_update into a helper functions accessible via a new
header, toast_helper.h.  Using the functions in this module, a table
AM can implement creation and deletion of TOAST table rows with
much less code duplication than was possible heretofore.  Some
table AMs won't want to use the TOAST logic at all, but for those
that do this will make that easier.

Discussion: http://postgr.es/m/CA+TgmoZv-=2iWM4jcw5ZhJeL18HF96+W1yJeYrnGMYdkFFnEpQ@mail.gmail.com
---
 src/backend/access/heap/heaptoast.c     | 400 +++---------------------
 src/backend/access/table/Makefile       |   2 +-
 src/backend/access/table/toast_helper.c | 331 ++++++++++++++++++++
 src/include/access/toast_helper.h       | 115 +++++++
 src/tools/pgindent/typedefs.list        |   2 +
 5 files changed, 493 insertions(+), 357 deletions(-)
 create mode 100644 src/backend/access/table/toast_helper.c
 create mode 100644 src/include/access/toast_helper.h

diff --git a/src/backend/access/heap/heaptoast.c b/src/backend/access/heap/heaptoast.c
index 5d105e3517..fbf9294598 100644
--- a/src/backend/access/heap/heaptoast.c
+++ b/src/backend/access/heap/heaptoast.c
@@ -27,6 +27,7 @@
 #include "access/detoast.h"
 #include "access/heapam.h"
 #include "access/heaptoast.h"
+#include "access/toast_helper.h"
 #include "access/toast_internals.h"
 
 
@@ -40,8 +41,6 @@ void
 toast_delete(Relation rel, HeapTuple oldtup, bool is_speculative)
 {
 	TupleDesc	tupleDesc;
-	int			numAttrs;
-	int			i;
 	Datum		toast_values[MaxHeapAttributeNumber];
 	bool		toast_isnull[MaxHeapAttributeNumber];
 
@@ -64,27 +63,12 @@ toast_delete(Relation rel, HeapTuple oldtup, bool is_speculative)
 	 * least one varlena column, by the way.)
 	 */
 	tupleDesc = rel->rd_att;
-	numAttrs = tupleDesc->natts;
 
-	Assert(numAttrs <= MaxHeapAttributeNumber);
+	Assert(tupleDesc->natts <= MaxHeapAttributeNumber);
 	heap_deform_tuple(oldtup, tupleDesc, toast_values, toast_isnull);
 
-	/*
-	 * Check for external stored attributes and delete them from the secondary
-	 * relation.
-	 */
-	for (i = 0; i < numAttrs; i++)
-	{
-		if (TupleDescAttr(tupleDesc, i)->attlen == -1)
-		{
-			Datum		value = toast_values[i];
-
-			if (toast_isnull[i])
-				continue;
-			else if (VARATT_IS_EXTERNAL_ONDISK(PointerGetDatum(value)))
-				toast_delete_datum(rel, value, is_speculative);
-		}
-	}
+	/* Do the real work. */
+	toast_delete_external(rel, toast_values, toast_isnull, is_speculative);
 }
 
 
@@ -113,25 +97,16 @@ toast_insert_or_update(Relation rel, HeapTuple newtup, HeapTuple oldtup,
 	HeapTuple	result_tuple;
 	TupleDesc	tupleDesc;
 	int			numAttrs;
-	int			i;
-
-	bool		need_change = false;
-	bool		need_free = false;
-	bool		need_delold = false;
-	bool		has_nulls = false;
 
 	Size		maxDataLen;
 	Size		hoff;
 
-	char		toast_action[MaxHeapAttributeNumber];
 	bool		toast_isnull[MaxHeapAttributeNumber];
 	bool		toast_oldisnull[MaxHeapAttributeNumber];
 	Datum		toast_values[MaxHeapAttributeNumber];
 	Datum		toast_oldvalues[MaxHeapAttributeNumber];
-	struct varlena *toast_oldexternal[MaxHeapAttributeNumber];
-	int32		toast_sizes[MaxHeapAttributeNumber];
-	bool		toast_free[MaxHeapAttributeNumber];
-	bool		toast_delold[MaxHeapAttributeNumber];
+	ToastAttrInfo toast_attr[MaxHeapAttributeNumber];
+	ToastTupleContext ttc;
 
 	/*
 	 * Ignore the INSERT_SPECULATIVE option. Speculative insertions/super
@@ -160,129 +135,24 @@ toast_insert_or_update(Relation rel, HeapTuple newtup, HeapTuple oldtup,
 		heap_deform_tuple(oldtup, tupleDesc, toast_oldvalues, toast_oldisnull);
 
 	/* ----------
-	 * Then collect information about the values given
-	 *
-	 * NOTE: toast_action[i] can have these values:
-	 *		' '		default handling
-	 *		'p'		already processed --- don't touch it
-	 *		'x'		incompressible, but OK to move off
-	 *
-	 * NOTE: toast_sizes[i] is only made valid for varlena attributes with
-	 *		toast_action[i] different from 'p'.
+	 * Prepare for toasting
 	 * ----------
 	 */
-	memset(toast_action, ' ', numAttrs * sizeof(char));
-	memset(toast_oldexternal, 0, numAttrs * sizeof(struct varlena *));
-	memset(toast_free, 0, numAttrs * sizeof(bool));
-	memset(toast_delold, 0, numAttrs * sizeof(bool));
-
-	for (i = 0; i < numAttrs; i++)
+	ttc.ttc_rel = rel;
+	ttc.ttc_values = toast_values;
+	ttc.ttc_isnull = toast_isnull;
+	if (oldtup == NULL)
 	{
-		Form_pg_attribute att = TupleDescAttr(tupleDesc, i);
-		struct varlena *old_value;
-		struct varlena *new_value;
-
-		if (oldtup != NULL)
-		{
-			/*
-			 * For UPDATE get the old and new values of this attribute
-			 */
-			old_value = (struct varlena *) DatumGetPointer(toast_oldvalues[i]);
-			new_value = (struct varlena *) DatumGetPointer(toast_values[i]);
-
-			/*
-			 * If the old value is stored on disk, check if it has changed so
-			 * we have to delete it later.
-			 */
-			if (att->attlen == -1 && !toast_oldisnull[i] &&
-				VARATT_IS_EXTERNAL_ONDISK(old_value))
-			{
-				if (toast_isnull[i] || !VARATT_IS_EXTERNAL_ONDISK(new_value) ||
-					memcmp((char *) old_value, (char *) new_value,
-						   VARSIZE_EXTERNAL(old_value)) != 0)
-				{
-					/*
-					 * The old external stored value isn't needed any more
-					 * after the update
-					 */
-					toast_delold[i] = true;
-					need_delold = true;
-				}
-				else
-				{
-					/*
-					 * This attribute isn't changed by this update so we reuse
-					 * the original reference to the old value in the new
-					 * tuple.
-					 */
-					toast_action[i] = 'p';
-					continue;
-				}
-			}
-		}
-		else
-		{
-			/*
-			 * For INSERT simply get the new value
-			 */
-			new_value = (struct varlena *) DatumGetPointer(toast_values[i]);
-		}
-
-		/*
-		 * Handle NULL attributes
-		 */
-		if (toast_isnull[i])
-		{
-			toast_action[i] = 'p';
-			has_nulls = true;
-			continue;
-		}
-
-		/*
-		 * Now look at varlena attributes
-		 */
-		if (att->attlen == -1)
-		{
-			/*
-			 * If the table's attribute says PLAIN always, force it so.
-			 */
-			if (att->attstorage == 'p')
-				toast_action[i] = 'p';
-
-			/*
-			 * We took care of UPDATE above, so any external value we find
-			 * still in the tuple must be someone else's that we cannot reuse
-			 * (this includes the case of an out-of-line in-memory datum).
-			 * Fetch it back (without decompression, unless we are forcing
-			 * PLAIN storage).  If necessary, we'll push it out as a new
-			 * external value below.
-			 */
-			if (VARATT_IS_EXTERNAL(new_value))
-			{
-				toast_oldexternal[i] = new_value;
-				if (att->attstorage == 'p')
-					new_value = heap_tuple_untoast_attr(new_value);
-				else
-					new_value = heap_tuple_fetch_attr(new_value);
-				toast_values[i] = PointerGetDatum(new_value);
-				toast_free[i] = true;
-				need_change = true;
-				need_free = true;
-			}
-
-			/*
-			 * Remember the size of this attribute
-			 */
-			toast_sizes[i] = VARSIZE_ANY(new_value);
-		}
-		else
-		{
-			/*
-			 * Not a varlena attribute, plain storage always
-			 */
-			toast_action[i] = 'p';
-		}
+		ttc.ttc_oldvalues = NULL;
+		ttc.ttc_oldisnull = NULL;
 	}
+	else
+	{
+		ttc.ttc_oldvalues = toast_oldvalues;
+		ttc.ttc_oldisnull = toast_oldisnull;
+	}
+	ttc.ttc_attr = toast_attr;
+	toast_tuple_init(&ttc);
 
 	/* ----------
 	 * Compress and/or save external until data fits into target length
@@ -297,7 +167,7 @@ toast_insert_or_update(Relation rel, HeapTuple newtup, HeapTuple oldtup,
 
 	/* compute header overhead --- this should match heap_form_tuple() */
 	hoff = SizeofHeapTupleHeader;
-	if (has_nulls)
+	if ((ttc.ttc_flags & TOAST_HAS_NULLS) != 0)
 		hoff += BITMAPLEN(numAttrs);
 	hoff = MAXALIGN(hoff);
 	/* now convert to a limit on the tuple data size */
@@ -310,66 +180,21 @@ toast_insert_or_update(Relation rel, HeapTuple newtup, HeapTuple oldtup,
 	while (heap_compute_data_size(tupleDesc,
 								  toast_values, toast_isnull) > maxDataLen)
 	{
-		int			biggest_attno = -1;
-		int32		biggest_size = MAXALIGN(TOAST_POINTER_SIZE);
-		Datum		old_value;
-		Datum		new_value;
-
-		/*
-		 * Search for the biggest yet unprocessed internal attribute
-		 */
-		for (i = 0; i < numAttrs; i++)
-		{
-			Form_pg_attribute att = TupleDescAttr(tupleDesc, i);
-
-			if (toast_action[i] != ' ')
-				continue;
-			if (VARATT_IS_EXTERNAL(DatumGetPointer(toast_values[i])))
-				continue;		/* can't happen, toast_action would be 'p' */
-			if (VARATT_IS_COMPRESSED(DatumGetPointer(toast_values[i])))
-				continue;
-			if (att->attstorage != 'x' && att->attstorage != 'e')
-				continue;
-			if (toast_sizes[i] > biggest_size)
-			{
-				biggest_attno = i;
-				biggest_size = toast_sizes[i];
-			}
-		}
+		int			biggest_attno;
 
+		biggest_attno = toast_tuple_find_biggest_attribute(&ttc, true, false);
 		if (biggest_attno < 0)
 			break;
 
 		/*
 		 * Attempt to compress it inline, if it has attstorage 'x'
 		 */
-		i = biggest_attno;
-		if (TupleDescAttr(tupleDesc, i)->attstorage == 'x')
-		{
-			old_value = toast_values[i];
-			new_value = toast_compress_datum(old_value);
-
-			if (DatumGetPointer(new_value) != NULL)
-			{
-				/* successful compression */
-				if (toast_free[i])
-					pfree(DatumGetPointer(old_value));
-				toast_values[i] = new_value;
-				toast_free[i] = true;
-				toast_sizes[i] = VARSIZE(DatumGetPointer(toast_values[i]));
-				need_change = true;
-				need_free = true;
-			}
-			else
-			{
-				/* incompressible, ignore on subsequent compression passes */
-				toast_action[i] = 'x';
-			}
-		}
+		if (TupleDescAttr(tupleDesc, biggest_attno)->attstorage == 'x')
+			toast_tuple_try_compression(&ttc, biggest_attno);
 		else
 		{
 			/* has attstorage 'e', ignore on subsequent compression passes */
-			toast_action[i] = 'x';
+			toast_attr[biggest_attno].tai_colflags |= TOASTCOL_INCOMPRESSIBLE;
 		}
 
 		/*
@@ -380,72 +205,26 @@ toast_insert_or_update(Relation rel, HeapTuple newtup, HeapTuple oldtup,
 		 *
 		 * XXX maybe the threshold should be less than maxDataLen?
 		 */
-		if (toast_sizes[i] > maxDataLen &&
+		if (toast_attr[biggest_attno].tai_size > maxDataLen &&
 			rel->rd_rel->reltoastrelid != InvalidOid)
-		{
-			old_value = toast_values[i];
-			toast_action[i] = 'p';
-			toast_values[i] = toast_save_datum(rel, toast_values[i],
-											   toast_oldexternal[i], options);
-			if (toast_free[i])
-				pfree(DatumGetPointer(old_value));
-			toast_free[i] = true;
-			need_change = true;
-			need_free = true;
-		}
+			toast_tuple_externalize(&ttc, biggest_attno, options);
 	}
 
 	/*
 	 * Second we look for attributes of attstorage 'x' or 'e' that are still
-	 * inline.  But skip this if there's no toast table to push them to.
+	 * inline, and make them external.  But skip this if there's no toast
+	 * table to push them to.
 	 */
 	while (heap_compute_data_size(tupleDesc,
 								  toast_values, toast_isnull) > maxDataLen &&
 		   rel->rd_rel->reltoastrelid != InvalidOid)
 	{
-		int			biggest_attno = -1;
-		int32		biggest_size = MAXALIGN(TOAST_POINTER_SIZE);
-		Datum		old_value;
-
-		/*------
-		 * Search for the biggest yet inlined attribute with
-		 * attstorage equals 'x' or 'e'
-		 *------
-		 */
-		for (i = 0; i < numAttrs; i++)
-		{
-			Form_pg_attribute att = TupleDescAttr(tupleDesc, i);
-
-			if (toast_action[i] == 'p')
-				continue;
-			if (VARATT_IS_EXTERNAL(DatumGetPointer(toast_values[i])))
-				continue;		/* can't happen, toast_action would be 'p' */
-			if (att->attstorage != 'x' && att->attstorage != 'e')
-				continue;
-			if (toast_sizes[i] > biggest_size)
-			{
-				biggest_attno = i;
-				biggest_size = toast_sizes[i];
-			}
-		}
+		int			biggest_attno;
 
+		biggest_attno = toast_tuple_find_biggest_attribute(&ttc, false, false);
 		if (biggest_attno < 0)
 			break;
-
-		/*
-		 * Store this external
-		 */
-		i = biggest_attno;
-		old_value = toast_values[i];
-		toast_action[i] = 'p';
-		toast_values[i] = toast_save_datum(rel, toast_values[i],
-										   toast_oldexternal[i], options);
-		if (toast_free[i])
-			pfree(DatumGetPointer(old_value));
-		toast_free[i] = true;
-
-		need_change = true;
-		need_free = true;
+		toast_tuple_externalize(&ttc, biggest_attno, options);
 	}
 
 	/*
@@ -455,57 +234,13 @@ toast_insert_or_update(Relation rel, HeapTuple newtup, HeapTuple oldtup,
 	while (heap_compute_data_size(tupleDesc,
 								  toast_values, toast_isnull) > maxDataLen)
 	{
-		int			biggest_attno = -1;
-		int32		biggest_size = MAXALIGN(TOAST_POINTER_SIZE);
-		Datum		old_value;
-		Datum		new_value;
-
-		/*
-		 * Search for the biggest yet uncompressed internal attribute
-		 */
-		for (i = 0; i < numAttrs; i++)
-		{
-			if (toast_action[i] != ' ')
-				continue;
-			if (VARATT_IS_EXTERNAL(DatumGetPointer(toast_values[i])))
-				continue;		/* can't happen, toast_action would be 'p' */
-			if (VARATT_IS_COMPRESSED(DatumGetPointer(toast_values[i])))
-				continue;
-			if (TupleDescAttr(tupleDesc, i)->attstorage != 'm')
-				continue;
-			if (toast_sizes[i] > biggest_size)
-			{
-				biggest_attno = i;
-				biggest_size = toast_sizes[i];
-			}
-		}
+		int			biggest_attno;
 
+		biggest_attno = toast_tuple_find_biggest_attribute(&ttc, true, true);
 		if (biggest_attno < 0)
 			break;
 
-		/*
-		 * Attempt to compress it inline
-		 */
-		i = biggest_attno;
-		old_value = toast_values[i];
-		new_value = toast_compress_datum(old_value);
-
-		if (DatumGetPointer(new_value) != NULL)
-		{
-			/* successful compression */
-			if (toast_free[i])
-				pfree(DatumGetPointer(old_value));
-			toast_values[i] = new_value;
-			toast_free[i] = true;
-			toast_sizes[i] = VARSIZE(DatumGetPointer(toast_values[i]));
-			need_change = true;
-			need_free = true;
-		}
-		else
-		{
-			/* incompressible, ignore on subsequent compression passes */
-			toast_action[i] = 'x';
-		}
+		toast_tuple_try_compression(&ttc, biggest_attno);
 	}
 
 	/*
@@ -519,54 +254,20 @@ toast_insert_or_update(Relation rel, HeapTuple newtup, HeapTuple oldtup,
 								  toast_values, toast_isnull) > maxDataLen &&
 		   rel->rd_rel->reltoastrelid != InvalidOid)
 	{
-		int			biggest_attno = -1;
-		int32		biggest_size = MAXALIGN(TOAST_POINTER_SIZE);
-		Datum		old_value;
-
-		/*--------
-		 * Search for the biggest yet inlined attribute with
-		 * attstorage = 'm'
-		 *--------
-		 */
-		for (i = 0; i < numAttrs; i++)
-		{
-			if (toast_action[i] == 'p')
-				continue;
-			if (VARATT_IS_EXTERNAL(DatumGetPointer(toast_values[i])))
-				continue;		/* can't happen, toast_action would be 'p' */
-			if (TupleDescAttr(tupleDesc, i)->attstorage != 'm')
-				continue;
-			if (toast_sizes[i] > biggest_size)
-			{
-				biggest_attno = i;
-				biggest_size = toast_sizes[i];
-			}
-		}
+		int			biggest_attno;
 
+		biggest_attno = toast_tuple_find_biggest_attribute(&ttc, false, true);
 		if (biggest_attno < 0)
 			break;
 
-		/*
-		 * Store this external
-		 */
-		i = biggest_attno;
-		old_value = toast_values[i];
-		toast_action[i] = 'p';
-		toast_values[i] = toast_save_datum(rel, toast_values[i],
-										   toast_oldexternal[i], options);
-		if (toast_free[i])
-			pfree(DatumGetPointer(old_value));
-		toast_free[i] = true;
-
-		need_change = true;
-		need_free = true;
+		toast_tuple_externalize(&ttc, biggest_attno, options);
 	}
 
 	/*
 	 * In the case we toasted any values, we need to build a new heap tuple
 	 * with the changed values.
 	 */
-	if (need_change)
+	if ((ttc.ttc_flags & TOAST_NEEDS_CHANGE) != 0)
 	{
 		HeapTupleHeader olddata = newtup->t_data;
 		HeapTupleHeader new_data;
@@ -585,7 +286,7 @@ toast_insert_or_update(Relation rel, HeapTuple newtup, HeapTuple oldtup,
 		 * whether there needs to be one at all.
 		 */
 		new_header_len = SizeofHeapTupleHeader;
-		if (has_nulls)
+		if ((ttc.ttc_flags & TOAST_HAS_NULLS) != 0)
 			new_header_len += BITMAPLEN(numAttrs);
 		new_header_len = MAXALIGN(new_header_len);
 		new_data_len = heap_compute_data_size(tupleDesc,
@@ -616,26 +317,13 @@ toast_insert_or_update(Relation rel, HeapTuple newtup, HeapTuple oldtup,
 						(char *) new_data + new_header_len,
 						new_data_len,
 						&(new_data->t_infomask),
-						has_nulls ? new_data->t_bits : NULL);
+						((ttc.ttc_flags & TOAST_HAS_NULLS) != 0) ?
+						new_data->t_bits : NULL);
 	}
 	else
 		result_tuple = newtup;
 
-	/*
-	 * Free allocated temp values
-	 */
-	if (need_free)
-		for (i = 0; i < numAttrs; i++)
-			if (toast_free[i])
-				pfree(DatumGetPointer(toast_values[i]));
-
-	/*
-	 * Delete external values from the old tuple
-	 */
-	if (need_delold)
-		for (i = 0; i < numAttrs; i++)
-			if (toast_delold[i])
-				toast_delete_datum(rel, toast_oldvalues[i], false);
+	toast_tuple_cleanup(&ttc);
 
 	return result_tuple;
 }
diff --git a/src/backend/access/table/Makefile b/src/backend/access/table/Makefile
index 55a0e5efad..b29df3f333 100644
--- a/src/backend/access/table/Makefile
+++ b/src/backend/access/table/Makefile
@@ -12,6 +12,6 @@ subdir = src/backend/access/table
 top_builddir = ../../../..
 include $(top_builddir)/src/Makefile.global
 
-OBJS = table.o tableam.o tableamapi.o
+OBJS = table.o tableam.o tableamapi.o toast_helper.o
 
 include $(top_srcdir)/src/backend/common.mk
diff --git a/src/backend/access/table/toast_helper.c b/src/backend/access/table/toast_helper.c
new file mode 100644
index 0000000000..7532b4f865
--- /dev/null
+++ b/src/backend/access/table/toast_helper.c
@@ -0,0 +1,331 @@
+/*-------------------------------------------------------------------------
+ *
+ * toast_helper.c
+ *	  Helper functions for table AMs implementing compressed or
+ *    out-of-line storage of varlena attributes.
+ *
+ * Copyright (c) 2000-2019, PostgreSQL Global Development Group
+ *
+ * IDENTIFICATION
+ *	  src/backend/access/common/toast_helper.c
+ *
+ *-------------------------------------------------------------------------
+ */
+
+#include "postgres.h"
+
+#include "access/detoast.h"
+#include "access/table.h"
+#include "access/toast_helper.h"
+#include "access/toast_internals.h"
+
+/*
+ * Prepare to TOAST a tuple.
+ *
+ * tupleDesc, toast_values, and toast_isnull are required parameters; they
+ * provide the necessary details about the tuple to be toasted.
+ *
+ * toast_oldvalues and toast_oldisnull should be NULL for a newly-inserted
+ * tuple; for an update, they should describe the existing tuple.
+ *
+ * All of these arrays should have a length equal to tupleDesc->natts.
+ *
+ * On return, toast_flags and toast_attr will have been initialized.
+ * toast_flags is just a single uint8, but toast_attr is an caller-provided
+ * array with a length equal to tupleDesc->natts.  The caller need not
+ * perform any initialization of the array before calling this function.
+ */
+void
+toast_tuple_init(ToastTupleContext *ttc)
+{
+	TupleDesc	tupleDesc = ttc->ttc_rel->rd_att;
+	int			numAttrs = tupleDesc->natts;
+	int			i;
+
+	ttc->ttc_flags = 0;
+
+	for (i = 0; i < numAttrs; i++)
+	{
+		Form_pg_attribute att = TupleDescAttr(tupleDesc, i);
+		struct varlena *old_value;
+		struct varlena *new_value;
+
+		ttc->ttc_attr[i].tai_colflags = 0;
+		ttc->ttc_attr[i].tai_oldexternal = NULL;
+
+		if (ttc->ttc_oldvalues != NULL)
+		{
+			/*
+			 * For UPDATE get the old and new values of this attribute
+			 */
+			old_value =
+				(struct varlena *) DatumGetPointer(ttc->ttc_oldvalues[i]);
+			new_value =
+				(struct varlena *) DatumGetPointer(ttc->ttc_values[i]);
+
+			/*
+			 * If the old value is stored on disk, check if it has changed so
+			 * we have to delete it later.
+			 */
+			if (att->attlen == -1 && !ttc->ttc_oldisnull[i] &&
+				VARATT_IS_EXTERNAL_ONDISK(old_value))
+			{
+				if (ttc->ttc_isnull[i] ||
+					!VARATT_IS_EXTERNAL_ONDISK(new_value) ||
+					memcmp((char *) old_value, (char *) new_value,
+						   VARSIZE_EXTERNAL(old_value)) != 0)
+				{
+					/*
+					 * The old external stored value isn't needed any more
+					 * after the update
+					 */
+					ttc->ttc_attr[i].tai_colflags |= TOASTCOL_NEEDS_DELETE_OLD;
+					ttc->ttc_flags |= TOAST_NEEDS_DELETE_OLD;
+				}
+				else
+				{
+					/*
+					 * This attribute isn't changed by this update so we reuse
+					 * the original reference to the old value in the new
+					 * tuple.
+					 */
+					ttc->ttc_attr[i].tai_colflags |= TOASTCOL_IGNORE;
+					continue;
+				}
+			}
+		}
+		else
+		{
+			/*
+			 * For INSERT simply get the new value
+			 */
+			new_value = (struct varlena *) DatumGetPointer(ttc->ttc_values[i]);
+		}
+
+		/*
+		 * Handle NULL attributes
+		 */
+		if (ttc->ttc_isnull[i])
+		{
+			ttc->ttc_attr[i].tai_colflags |= TOASTCOL_IGNORE;
+			ttc->ttc_flags |= TOAST_HAS_NULLS;
+			continue;
+		}
+
+		/*
+		 * Now look at varlena attributes
+		 */
+		if (att->attlen == -1)
+		{
+			/*
+			 * If the table's attribute says PLAIN always, force it so.
+			 */
+			if (att->attstorage == 'p')
+				ttc->ttc_attr[i].tai_colflags |= TOASTCOL_IGNORE;
+
+			/*
+			 * We took care of UPDATE above, so any external value we find
+			 * still in the tuple must be someone else's that we cannot reuse
+			 * (this includes the case of an out-of-line in-memory datum).
+			 * Fetch it back (without decompression, unless we are forcing
+			 * PLAIN storage).  If necessary, we'll push it out as a new
+			 * external value below.
+			 */
+			if (VARATT_IS_EXTERNAL(new_value))
+			{
+				ttc->ttc_attr[i].tai_oldexternal = new_value;
+				if (att->attstorage == 'p')
+					new_value = heap_tuple_untoast_attr(new_value);
+				else
+					new_value = heap_tuple_fetch_attr(new_value);
+				ttc->ttc_values[i] = PointerGetDatum(new_value);
+				ttc->ttc_attr[i].tai_colflags |= TOASTCOL_NEEDS_FREE;
+				ttc->ttc_flags |= (TOAST_NEEDS_CHANGE | TOAST_NEEDS_FREE);
+			}
+
+			/*
+			 * Remember the size of this attribute
+			 */
+			ttc->ttc_attr[i].tai_size = VARSIZE_ANY(new_value);
+		}
+		else
+		{
+			/*
+			 * Not a varlena attribute, plain storage always
+			 */
+			ttc->ttc_attr[i].tai_colflags |= TOASTCOL_IGNORE;
+		}
+	}
+}
+
+/*
+ * Find the largest varlena attribute that satisfies certain criteria.
+ *
+ * The relevant column must not be marked TOASTCOL_IGNORE, and if the
+ * for_compression flag is passed as true, it must also not be marked
+ * TOASTCOL_INCOMPRESSIBLE.
+ *
+ * The column must have attstorage 'e' or 'x' if check_main is false, and
+ * must have attstorage 'm' if check_main is true.
+ *
+ * The column must have a minimum size of MAXALIGN(TOAST_POINTER_SIZE);
+ * if not, no benefit is to be expected by compressing it.
+ *
+ * The return value is the index of the biggest suitable column, or
+ * -1 if there is none.
+ */
+int
+toast_tuple_find_biggest_attribute(ToastTupleContext *ttc,
+								   bool for_compression, bool check_main)
+{
+	TupleDesc	tupleDesc = ttc->ttc_rel->rd_att;
+	int			numAttrs = tupleDesc->natts;
+	int			biggest_attno = -1;
+	int32		biggest_size = MAXALIGN(TOAST_POINTER_SIZE);
+	int32		skip_colflags = TOASTCOL_IGNORE;
+	int			i;
+
+	if (for_compression)
+		skip_colflags |= TOASTCOL_INCOMPRESSIBLE;
+
+	for (i = 0; i < numAttrs; i++)
+	{
+		Form_pg_attribute att = TupleDescAttr(tupleDesc, i);
+
+		if ((ttc->ttc_attr[i].tai_colflags & skip_colflags) != 0)
+			continue;
+		if (VARATT_IS_EXTERNAL(DatumGetPointer(ttc->ttc_values[i])))
+			continue;			/* can't happen, toast_action would be 'p' */
+		if (for_compression &&
+			VARATT_IS_COMPRESSED(DatumGetPointer(ttc->ttc_values[i])))
+			continue;
+		if (check_main && att->attstorage != 'm')
+			continue;
+		if (!check_main && att->attstorage != 'x' && att->attstorage != 'e')
+			continue;
+
+		if (ttc->ttc_attr[i].tai_size > biggest_size)
+		{
+			biggest_attno = i;
+			biggest_size = ttc->ttc_attr[i].tai_size;
+		}
+	}
+
+	return biggest_attno;
+}
+
+/*
+ * Try compression for an attribute.
+ *
+ * If we find that the attribute is not compressible, mark it so.
+ */
+void
+toast_tuple_try_compression(ToastTupleContext *ttc, int attribute)
+{
+	Datum	   *value = &ttc->ttc_values[attribute];
+	Datum		new_value = toast_compress_datum(*value);
+	ToastAttrInfo *attr = &ttc->ttc_attr[attribute];
+
+	if (DatumGetPointer(new_value) != NULL)
+	{
+		/* successful compression */
+		if ((attr->tai_colflags & TOASTCOL_NEEDS_FREE) != 0)
+			pfree(DatumGetPointer(*value));
+		*value = new_value;
+		attr->tai_colflags |= TOASTCOL_NEEDS_FREE;
+		attr->tai_size = VARSIZE(DatumGetPointer(*value));
+		ttc->ttc_flags |= (TOAST_NEEDS_CHANGE | TOAST_NEEDS_FREE);
+	}
+	else
+	{
+		/* incompressible, ignore on subsequent compression passes */
+		attr->tai_colflags |= TOASTCOL_INCOMPRESSIBLE;
+	}
+}
+
+/*
+ * Move an attribute to external storage.
+ */
+void
+toast_tuple_externalize(ToastTupleContext *ttc, int attribute, int options)
+{
+	Datum	   *value = &ttc->ttc_values[attribute];
+	Datum		old_value = *value;
+	ToastAttrInfo *attr = &ttc->ttc_attr[attribute];
+
+	attr->tai_colflags |= TOASTCOL_IGNORE;
+	*value = toast_save_datum(ttc->ttc_rel, old_value, attr->tai_oldexternal,
+							  options);
+	if ((attr->tai_colflags & TOASTCOL_NEEDS_FREE) != 0)
+		pfree(DatumGetPointer(old_value));
+	attr->tai_colflags |= TOASTCOL_NEEDS_FREE;
+	ttc->ttc_flags |= (TOAST_NEEDS_CHANGE | TOAST_NEEDS_FREE);
+}
+
+/*
+ * Perform appropriate cleanup after one tuple has been subjected to TOAST.
+ */
+void
+toast_tuple_cleanup(ToastTupleContext *ttc)
+{
+	TupleDesc	tupleDesc = ttc->ttc_rel->rd_att;
+	int			numAttrs = tupleDesc->natts;
+
+	/*
+	 * Free allocated temp values
+	 */
+	if ((ttc->ttc_flags & TOAST_NEEDS_FREE) != 0)
+	{
+		int			i;
+
+		for (i = 0; i < numAttrs; i++)
+		{
+			ToastAttrInfo *attr = &ttc->ttc_attr[i];
+
+			if ((attr->tai_colflags & TOASTCOL_NEEDS_FREE) != 0)
+				pfree(DatumGetPointer(ttc->ttc_values[i]));
+		}
+	}
+
+	/*
+	 * Delete external values from the old tuple
+	 */
+	if ((ttc->ttc_flags & TOAST_NEEDS_DELETE_OLD) != 0)
+	{
+		int			i;
+
+		for (i = 0; i < numAttrs; i++)
+		{
+			ToastAttrInfo *attr = &ttc->ttc_attr[i];
+
+			if ((attr->tai_colflags & TOASTCOL_NEEDS_DELETE_OLD) != 0)
+				toast_delete_datum(ttc->ttc_rel, ttc->ttc_oldvalues[i], false);
+		}
+	}
+}
+
+/*
+ * Check for external stored attributes and delete them from the secondary
+ * relation.
+ */
+void
+toast_delete_external(Relation rel, Datum *values, bool *isnull,
+					  bool is_speculative)
+{
+	TupleDesc	tupleDesc = rel->rd_att;
+	int			numAttrs = tupleDesc->natts;
+	int			i;
+
+	for (i = 0; i < numAttrs; i++)
+	{
+		if (TupleDescAttr(tupleDesc, i)->attlen == -1)
+		{
+			Datum		value = values[i];
+
+			if (isnull[i])
+				continue;
+			else if (VARATT_IS_EXTERNAL_ONDISK(PointerGetDatum(value)))
+				toast_delete_datum(rel, value, is_speculative);
+		}
+	}
+}
diff --git a/src/include/access/toast_helper.h b/src/include/access/toast_helper.h
new file mode 100644
index 0000000000..7cefacb0ea
--- /dev/null
+++ b/src/include/access/toast_helper.h
@@ -0,0 +1,115 @@
+/*-------------------------------------------------------------------------
+ *
+ * toast_helper.h
+ *	  Helper functions for table AMs implementing compressed or
+ *    out-of-line storage of varlena attributes.
+ *
+ * Copyright (c) 2000-2019, PostgreSQL Global Development Group
+ *
+ * src/include/access/toast_helper.h
+ *
+ *-------------------------------------------------------------------------
+ */
+
+#ifndef TOAST_HELPER_H
+#define TOAST_HELPER_H
+
+#include "utils/rel.h"
+
+/*
+ * Information about one column of a tuple being toasted.
+ *
+ * NOTE: toast_action[i] can have these values:
+ *		' '		default handling
+ *		'p'		already processed --- don't touch it
+ *		'x'		incompressible, but OK to move off
+ *
+ * NOTE: toast_attr[i].tai_size is only made valid for varlena attributes with
+ * toast_action[i] different from 'p'.
+ */
+typedef struct
+{
+	struct varlena *tai_oldexternal;
+	int32		tai_size;
+	uint8		tai_colflags;
+} ToastAttrInfo;
+
+/*
+ * Information about one tuple being toasted.
+ */
+typedef struct
+{
+	/*
+	 * Before calling toast_tuple_init, the caller must initialize the
+	 * following fields.  Each array must have a length equal to
+	 * ttc_rel->rd_att->natts.  The tts_oldvalues and tts_oldisnull fields
+	 * should be NULL in the case of an insert.
+	 */
+	Relation	ttc_rel;		/* the relation that contains the tuple */
+	Datum	   *ttc_values;		/* values from the tuple columns */
+	bool	   *ttc_isnull;		/* null flags for the tuple columns */
+	Datum	   *ttc_oldvalues;	/* values from previous tuple */
+	bool	   *ttc_oldisnull;	/* null flags from previous tuple */
+
+	/*
+	 * Before calling toast_tuple_init, the caller should set tts_attr to
+	 * point to an array of ToastAttrInfo structures of a length equal to
+	 * tts_rel->rd_att->natts.  The contents of the array need not be
+	 * initialized.  ttc_flags also does not need to be initialized.
+	 */
+	uint8		ttc_flags;
+	ToastAttrInfo *ttc_attr;
+} ToastTupleContext;
+
+/*
+ * Flags indicating the overall state of a TOAST operation.
+ *
+ * TOAST_NEEDS_DELETE_OLD indicates that one or more old TOAST datums need
+ * to be deleted.
+ *
+ * TOAST_NEEDS_FREE indicates that one or more TOAST values need to be freed.
+ *
+ * TOAST_HAS_NULLS indicates that nulls were found in the tuple being toasted.
+ *
+ * TOAST_NEEDS_CHANGE indicates that a new tuple needs to built; in other
+ * words, the toaster did something.
+ */
+#define TOAST_NEEDS_DELETE_OLD				0x0001
+#define TOAST_NEEDS_FREE					0x0002
+#define TOAST_HAS_NULLS						0x0004
+#define TOAST_NEEDS_CHANGE					0x0008
+
+/*
+ * Flags indicating the status of a TOAST operation with respect to a
+ * particular column.
+ *
+ * TOASTCOL_NEEDS_DELETE_OLD indicates that the old TOAST datums for this
+ * column need to be deleted.
+ *
+ * TOASTCOL_NEEDS_FREE indicates that the value for this column needs to
+ * be freed.
+ *
+ * TOASTCOL_IGNORE indicates that the toaster should not further process
+ * this column.
+ *
+ * TOASTCOL_INCOMPRESSIBLE indicates that this column has been found to
+ * be incompressible, but could be moved out-of-line.
+ */
+#define TOASTCOL_NEEDS_DELETE_OLD			TOAST_NEEDS_DELETE_OLD
+#define TOASTCOL_NEEDS_FREE					TOAST_NEEDS_FREE
+#define TOASTCOL_IGNORE						0x0010
+#define TOASTCOL_INCOMPRESSIBLE				0x0020
+
+extern void toast_tuple_init(ToastTupleContext *ttc);
+extern int	toast_tuple_find_biggest_attribute(ToastTupleContext *ttc,
+											   bool for_compression,
+											   bool check_main);
+extern void toast_tuple_try_compression(ToastTupleContext *ttc, int attribute);
+extern void toast_tuple_externalize(ToastTupleContext *ttc, int attribute,
+									int options);
+extern void toast_tuple_cleanup(ToastTupleContext *ttc);
+
+extern void toast_delete_external(Relation rel, Datum *values, bool *isnull,
+								  bool is_speculative);
+
+#endif
diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list
index 432d2d812e..f3cdfa8a22 100644
--- a/src/tools/pgindent/typedefs.list
+++ b/src/tools/pgindent/typedefs.list
@@ -2349,6 +2349,8 @@ TBlockState
 TIDBitmap
 TM_FailureData
 TM_Result
+ToastAttrInfo
+ToastTupleContext
 TOKEN_DEFAULT_DACL
 TOKEN_INFORMATION_CLASS
 TOKEN_PRIVILEGES
-- 
2.17.2 (Apple Git-113)

From 505989b10c29ea82313dedd1023d24b1d695f642 Mon Sep 17 00:00:00 2001
From: Robert Haas <rhaas@postgresql.org>
Date: Thu, 1 Aug 2019 10:37:02 -0400
Subject: [PATCH 3/4] Allow TOAST tables to be implemented using table AMs
 other than heap.

toast_fetch_datum, toast_save_datum, and toast_delete_datum are
adjusted to use tableam rather than heap-specific functions.  This
might have some performance impact, but this patch attempts to
mitigate that by restructuring things so that we don't open and close
the toast table and indexes multiple times per tuple.

tableam now exposes an integer value (not a callback) for the
maximum TOAST chunk size, and has a new callback allowing table
AMs to specify the AM that should be used to implement the TOAST
table. Previously, the toast AM was always the same as the table AM.

Patch by me, tested by Prabhat Sabu.

Discussion: http://postgr.es/m/CA+TgmoZv-=2iWM4jcw5ZhJeL18HF96+W1yJeYrnGMYdkFFnEpQ@mail.gmail.com
---
 src/backend/access/common/detoast.c         |  62 +++++-----
 src/backend/access/common/toast_internals.c | 127 +++++++-------------
 src/backend/access/heap/heapam.c            |   6 +-
 src/backend/access/heap/heapam_handler.c    |  14 ++-
 src/backend/access/heap/heaptoast.c         |  19 ++-
 src/backend/access/index/genam.c            |  20 +++
 src/backend/access/table/toast_helper.c     | 107 ++++++++++++++---
 src/backend/catalog/toasting.c              |   2 +-
 src/include/access/genam.h                  |   5 +-
 src/include/access/heapam.h                 |   3 +-
 src/include/access/heaptoast.h              |   3 +-
 src/include/access/tableam.h                |  31 +++++
 src/include/access/toast_helper.h           |  18 ++-
 src/include/access/toast_internals.h        |  15 ++-
 14 files changed, 284 insertions(+), 148 deletions(-)

diff --git a/src/backend/access/common/detoast.c b/src/backend/access/common/detoast.c
index c8b49d6a12..36b68e35fb 100644
--- a/src/backend/access/common/detoast.c
+++ b/src/backend/access/common/detoast.c
@@ -15,10 +15,11 @@
 
 #include "access/detoast.h"
 #include "access/genam.h"
-#include "access/heaptoast.h"
 #include "access/table.h"
 #include "access/toast_internals.h"
+#include "access/tableam.h"
 #include "common/pg_lzcompress.h"
+#include "executor/tuptable.h"
 #include "utils/expandeddatum.h"
 #include "utils/fmgroids.h"
 #include "utils/rel.h"
@@ -303,8 +304,7 @@ toast_fetch_datum(struct varlena *attr)
 	Relation   *toastidxs;
 	ScanKeyData toastkey;
 	SysScanDesc toastscan;
-	HeapTuple	ttup;
-	TupleDesc	toasttupDesc;
+	TupleTableSlot *slot;
 	struct varlena *result;
 	struct varatt_external toast_pointer;
 	int32		ressize;
@@ -312,11 +312,11 @@ toast_fetch_datum(struct varlena *attr)
 				nextidx;
 	int32		numchunks;
 	Pointer		chunk;
-	bool		isnull;
 	char	   *chunkdata;
 	int32		chunksize;
 	int			num_indexes;
 	int			validIndex;
+	int			max_chunk_size;
 	SnapshotData SnapshotToast;
 
 	if (!VARATT_IS_EXTERNAL_ONDISK(attr))
@@ -326,7 +326,6 @@ toast_fetch_datum(struct varlena *attr)
 	VARATT_EXTERNAL_GET_POINTER(toast_pointer, attr);
 
 	ressize = toast_pointer.va_extsize;
-	numchunks = ((ressize - 1) / TOAST_MAX_CHUNK_SIZE) + 1;
 
 	result = (struct varlena *) palloc(ressize + VARHDRSZ);
 
@@ -339,7 +338,9 @@ toast_fetch_datum(struct varlena *attr)
 	 * Open the toast relation and its indexes
 	 */
 	toastrel = table_open(toast_pointer.va_toastrelid, AccessShareLock);
-	toasttupDesc = toastrel->rd_att;
+
+	max_chunk_size = toastrel->rd_tableam->toast_max_chunk_size;
+	numchunks = ((ressize - 1) / max_chunk_size) + 1;
 
 	/* Look for the valid index of the toast relation */
 	validIndex = toast_open_indexes(toastrel,
@@ -367,15 +368,15 @@ toast_fetch_datum(struct varlena *attr)
 	init_toast_snapshot(&SnapshotToast);
 	toastscan = systable_beginscan_ordered(toastrel, toastidxs[validIndex],
 										   &SnapshotToast, 1, &toastkey);
-	while ((ttup = systable_getnext_ordered(toastscan, ForwardScanDirection)) != NULL)
+	while ((slot = systable_getnextslot_ordered(toastscan, ForwardScanDirection)) != NULL)
 	{
 		/*
 		 * Have a chunk, extract the sequence number and the data
 		 */
-		residx = DatumGetInt32(fastgetattr(ttup, 2, toasttupDesc, &isnull));
-		Assert(!isnull);
-		chunk = DatumGetPointer(fastgetattr(ttup, 3, toasttupDesc, &isnull));
-		Assert(!isnull);
+		slot_getsomeattrs(slot, 3);
+		Assert(!slot->tts_isnull[1] && !slot->tts_isnull[2]);
+		residx = DatumGetInt32(slot->tts_values[1]);
+		chunk = DatumGetPointer(slot->tts_values[2]);
 		if (!VARATT_IS_EXTENDED(chunk))
 		{
 			chunksize = VARSIZE(chunk) - VARHDRSZ;
@@ -409,23 +410,23 @@ toast_fetch_datum(struct varlena *attr)
 									 RelationGetRelationName(toastrel))));
 		if (residx < numchunks - 1)
 		{
-			if (chunksize != TOAST_MAX_CHUNK_SIZE)
+			if (chunksize != max_chunk_size)
 				ereport(ERROR,
 						(errcode(ERRCODE_DATA_CORRUPTED),
 						 errmsg_internal("unexpected chunk size %d (expected %d) in chunk %d of %d for toast value %u in %s",
-										 chunksize, (int) TOAST_MAX_CHUNK_SIZE,
+										 chunksize, max_chunk_size,
 										 residx, numchunks,
 										 toast_pointer.va_valueid,
 										 RelationGetRelationName(toastrel))));
 		}
 		else if (residx == numchunks - 1)
 		{
-			if ((residx * TOAST_MAX_CHUNK_SIZE + chunksize) != ressize)
+			if ((residx * max_chunk_size + chunksize) != ressize)
 				ereport(ERROR,
 						(errcode(ERRCODE_DATA_CORRUPTED),
 						 errmsg_internal("unexpected chunk size %d (expected %d) in final chunk %d for toast value %u in %s",
 										 chunksize,
-										 (int) (ressize - residx * TOAST_MAX_CHUNK_SIZE),
+										 (int) (ressize - residx * max_chunk_size),
 										 residx,
 										 toast_pointer.va_valueid,
 										 RelationGetRelationName(toastrel))));
@@ -442,7 +443,7 @@ toast_fetch_datum(struct varlena *attr)
 		/*
 		 * Copy the data into proper place in our result
 		 */
-		memcpy(VARDATA(result) + residx * TOAST_MAX_CHUNK_SIZE,
+		memcpy(VARDATA(result) + residx * max_chunk_size,
 			   chunkdata,
 			   chunksize);
 
@@ -508,6 +509,7 @@ toast_fetch_datum_slice(struct varlena *attr, int32 sliceoffset, int32 length)
 	int32		chcpyend;
 	int			num_indexes;
 	int			validIndex;
+	int			max_chunk_size;
 	SnapshotData SnapshotToast;
 
 	if (!VARATT_IS_EXTERNAL_ONDISK(attr))
@@ -523,7 +525,6 @@ toast_fetch_datum_slice(struct varlena *attr, int32 sliceoffset, int32 length)
 	Assert(!VARATT_EXTERNAL_IS_COMPRESSED(toast_pointer));
 
 	attrsize = toast_pointer.va_extsize;
-	totalchunks = ((attrsize - 1) / TOAST_MAX_CHUNK_SIZE) + 1;
 
 	if (sliceoffset >= attrsize)
 	{
@@ -541,19 +542,22 @@ toast_fetch_datum_slice(struct varlena *attr, int32 sliceoffset, int32 length)
 	if (length == 0)
 		return result;			/* Can save a lot of work at this point! */
 
-	startchunk = sliceoffset / TOAST_MAX_CHUNK_SIZE;
-	endchunk = (sliceoffset + length - 1) / TOAST_MAX_CHUNK_SIZE;
-	numchunks = (endchunk - startchunk) + 1;
-
-	startoffset = sliceoffset % TOAST_MAX_CHUNK_SIZE;
-	endoffset = (sliceoffset + length - 1) % TOAST_MAX_CHUNK_SIZE;
-
 	/*
 	 * Open the toast relation and its indexes
 	 */
 	toastrel = table_open(toast_pointer.va_toastrelid, AccessShareLock);
 	toasttupDesc = toastrel->rd_att;
 
+	max_chunk_size = toastrel->rd_tableam->toast_max_chunk_size;
+	totalchunks = ((attrsize - 1) / max_chunk_size) + 1;
+
+	startchunk = sliceoffset / max_chunk_size;
+	endchunk = (sliceoffset + length - 1) / max_chunk_size;
+	numchunks = (endchunk - startchunk) + 1;
+
+	startoffset = sliceoffset % max_chunk_size;
+	endoffset = (sliceoffset + length - 1) % max_chunk_size;
+
 	/* Look for the valid index of toast relation */
 	validIndex = toast_open_indexes(toastrel,
 									AccessShareLock,
@@ -642,19 +646,19 @@ toast_fetch_datum_slice(struct varlena *attr, int32 sliceoffset, int32 length)
 				 RelationGetRelationName(toastrel));
 		if (residx < totalchunks - 1)
 		{
-			if (chunksize != TOAST_MAX_CHUNK_SIZE)
+			if (chunksize != max_chunk_size)
 				elog(ERROR, "unexpected chunk size %d (expected %d) in chunk %d of %d for toast value %u in %s when fetching slice",
-					 chunksize, (int) TOAST_MAX_CHUNK_SIZE,
+					 chunksize, max_chunk_size,
 					 residx, totalchunks,
 					 toast_pointer.va_valueid,
 					 RelationGetRelationName(toastrel));
 		}
 		else if (residx == totalchunks - 1)
 		{
-			if ((residx * TOAST_MAX_CHUNK_SIZE + chunksize) != attrsize)
+			if ((residx * max_chunk_size + chunksize) != attrsize)
 				elog(ERROR, "unexpected chunk size %d (expected %d) in final chunk %d for toast value %u in %s when fetching slice",
 					 chunksize,
-					 (int) (attrsize - residx * TOAST_MAX_CHUNK_SIZE),
+					 (int) (attrsize - residx * max_chunk_size),
 					 residx,
 					 toast_pointer.va_valueid,
 					 RelationGetRelationName(toastrel));
@@ -677,7 +681,7 @@ toast_fetch_datum_slice(struct varlena *attr, int32 sliceoffset, int32 length)
 			chcpyend = endoffset;
 
 		memcpy(VARDATA(result) +
-			   (residx * TOAST_MAX_CHUNK_SIZE - sliceoffset) + chcpystrt,
+			   (residx * max_chunk_size - sliceoffset) + chcpystrt,
 			   chunkdata + chcpystrt,
 			   (chcpyend - chcpystrt) + 1);
 
diff --git a/src/backend/access/common/toast_internals.c b/src/backend/access/common/toast_internals.c
index a971242490..beb303034d 100644
--- a/src/backend/access/common/toast_internals.c
+++ b/src/backend/access/common/toast_internals.c
@@ -15,9 +15,8 @@
 
 #include "access/detoast.h"
 #include "access/genam.h"
-#include "access/heapam.h"
-#include "access/heaptoast.h"
 #include "access/table.h"
+#include "access/tableam.h"
 #include "access/toast_internals.h"
 #include "access/xact.h"
 #include "catalog/catalog.h"
@@ -100,22 +99,21 @@ toast_compress_datum(Datum value)
  *	Save one single datum into the secondary relation and return
  *	a Datum reference for it.
  *
- * rel: the main relation we're working with (not the toast rel!)
+ * toastrel: the TOAST relation we're working with (not the main rel!)
+ * toastslot: a slot corresponding to 'toastrel'
+ * num_indexes, toastidxs, validIndex: as returned by toast_open_indexes
+ * toastoid: the toast OID that should be inserted into the new TOAST pointer
  * value: datum to be pushed to toast storage
  * oldexternal: if not NULL, toast pointer previously representing the datum
- * options: options to be passed to heap_insert() for toast rows
+ * options: options to be passed to table_tuple_insert() for toast rows
  * ----------
  */
 Datum
-toast_save_datum(Relation rel, Datum value,
-				 struct varlena *oldexternal, int options)
+toast_save_datum(Relation toastrel, TupleTableSlot *toastslot,
+				 int num_indexes, Relation *toastidxs, int validIndex,
+				 Oid toastoid, Datum value, struct varlena *oldexternal,
+				 int options, int max_chunk_size)
 {
-	Relation	toastrel;
-	Relation   *toastidxs;
-	HeapTuple	toasttup;
-	TupleDesc	toasttupDesc;
-	Datum		t_values[3];
-	bool		t_isnull[3];
 	CommandId	mycid = GetCurrentCommandId(true);
 	struct varlena *result;
 	struct varatt_external toast_pointer;
@@ -123,7 +121,7 @@ toast_save_datum(Relation rel, Datum value,
 	{
 		struct varlena hdr;
 		/* this is to make the union big enough for a chunk: */
-		char		data[TOAST_MAX_CHUNK_SIZE + VARHDRSZ];
+		char		data[BLCKSZ + VARHDRSZ];
 		/* ensure union is aligned well enough: */
 		int32		align_it;
 	}			chunk_data;
@@ -132,24 +130,9 @@ toast_save_datum(Relation rel, Datum value,
 	char	   *data_p;
 	int32		data_todo;
 	Pointer		dval = DatumGetPointer(value);
-	int			num_indexes;
-	int			validIndex;
 
 	Assert(!VARATT_IS_EXTERNAL(value));
-
-	/*
-	 * Open the toast relation and its indexes.  We can use the index to check
-	 * uniqueness of the OID we assign to the toasted item, even though it has
-	 * additional columns besides OID.
-	 */
-	toastrel = table_open(rel->rd_rel->reltoastrelid, RowExclusiveLock);
-	toasttupDesc = toastrel->rd_att;
-
-	/* Open all the toast indexes and look for the valid one */
-	validIndex = toast_open_indexes(toastrel,
-									RowExclusiveLock,
-									&toastidxs,
-									&num_indexes);
+	Assert(max_chunk_size <= BLCKSZ);
 
 	/*
 	 * Get the data pointer and length, and compute va_rawsize and va_extsize.
@@ -189,11 +172,11 @@ toast_save_datum(Relation rel, Datum value,
 	 *
 	 * Normally this is the actual OID of the target toast table, but during
 	 * table-rewriting operations such as CLUSTER, we have to insert the OID
-	 * of the table's real permanent toast table instead.  rd_toastoid is set
+	 * of the table's real permanent toast table instead.  toastoid is set
 	 * if we have to substitute such an OID.
 	 */
-	if (OidIsValid(rel->rd_toastoid))
-		toast_pointer.va_toastrelid = rel->rd_toastoid;
+	if (OidIsValid(toastoid))
+		toast_pointer.va_toastrelid = toastoid;
 	else
 		toast_pointer.va_toastrelid = RelationGetRelid(toastrel);
 
@@ -209,7 +192,7 @@ toast_save_datum(Relation rel, Datum value,
 	 * options have been changed), we have to pick a value ID that doesn't
 	 * conflict with either new or existing toast value OIDs.
 	 */
-	if (!OidIsValid(rel->rd_toastoid))
+	if (!OidIsValid(toastoid))
 	{
 		/* normal case: just choose an unused OID */
 		toast_pointer.va_valueid =
@@ -228,7 +211,7 @@ toast_save_datum(Relation rel, Datum value,
 			Assert(VARATT_IS_EXTERNAL_ONDISK(oldexternal));
 			/* Must copy to access aligned fields */
 			VARATT_EXTERNAL_GET_POINTER(old_toast_pointer, oldexternal);
-			if (old_toast_pointer.va_toastrelid == rel->rd_toastoid)
+			if (old_toast_pointer.va_toastrelid == toastoid)
 			{
 				/* This value came from the old toast table; reuse its OID */
 				toast_pointer.va_valueid = old_toast_pointer.va_valueid;
@@ -270,20 +253,11 @@ toast_save_datum(Relation rel, Datum value,
 					GetNewOidWithIndex(toastrel,
 									   RelationGetRelid(toastidxs[validIndex]),
 									   (AttrNumber) 1);
-			} while (toastid_valueid_exists(rel->rd_toastoid,
+			} while (toastid_valueid_exists(toastoid,
 											toast_pointer.va_valueid));
 		}
 	}
 
-	/*
-	 * Initialize constant parts of the tuple data
-	 */
-	t_values[0] = ObjectIdGetDatum(toast_pointer.va_valueid);
-	t_values[2] = PointerGetDatum(&chunk_data);
-	t_isnull[0] = false;
-	t_isnull[1] = false;
-	t_isnull[2] = false;
-
 	/*
 	 * Split up the item into chunks
 	 */
@@ -296,17 +270,22 @@ toast_save_datum(Relation rel, Datum value,
 		/*
 		 * Calculate the size of this chunk
 		 */
-		chunk_size = Min(TOAST_MAX_CHUNK_SIZE, data_todo);
+		chunk_size = Min(max_chunk_size, data_todo);
 
 		/*
 		 * Build a tuple and store it
 		 */
-		t_values[1] = Int32GetDatum(chunk_seq++);
+		toastslot->tts_values[0] = ObjectIdGetDatum(toast_pointer.va_valueid);
+		toastslot->tts_values[1] = Int32GetDatum(chunk_seq++);
 		SET_VARSIZE(&chunk_data, chunk_size + VARHDRSZ);
 		memcpy(VARDATA(&chunk_data), data_p, chunk_size);
-		toasttup = heap_form_tuple(toasttupDesc, t_values, t_isnull);
+		toastslot->tts_values[2] = PointerGetDatum(&chunk_data);
+		toastslot->tts_isnull[0] = false;
+		toastslot->tts_isnull[1] = false;
+		toastslot->tts_isnull[2] = false;
+		ExecStoreVirtualTuple(toastslot);
 
-		heap_insert(toastrel, toasttup, mycid, options, NULL);
+		table_tuple_insert(toastrel, toastslot, mycid, options, NULL);
 
 		/*
 		 * Create the index entry.  We cheat a little here by not using
@@ -323,8 +302,9 @@ toast_save_datum(Relation rel, Datum value,
 		{
 			/* Only index relations marked as ready can be updated */
 			if (toastidxs[i]->rd_index->indisready)
-				index_insert(toastidxs[i], t_values, t_isnull,
-							 &(toasttup->t_self),
+				index_insert(toastidxs[i], toastslot->tts_values,
+							 toastslot->tts_isnull,
+							 &(toastslot->tts_tid),
 							 toastrel,
 							 toastidxs[i]->rd_index->indisunique ?
 							 UNIQUE_CHECK_YES : UNIQUE_CHECK_NO,
@@ -332,9 +312,9 @@ toast_save_datum(Relation rel, Datum value,
 		}
 
 		/*
-		 * Free memory
+		 * Clear slot
 		 */
-		heap_freetuple(toasttup);
+		ExecClearTuple(toastslot);
 
 		/*
 		 * Move on to next chunk
@@ -343,12 +323,6 @@ toast_save_datum(Relation rel, Datum value,
 		data_p += chunk_size;
 	}
 
-	/*
-	 * Done - close toast relation and its indexes
-	 */
-	toast_close_indexes(toastidxs, num_indexes, RowExclusiveLock);
-	table_close(toastrel, RowExclusiveLock);
-
 	/*
 	 * Create the TOAST pointer value that we'll return
 	 */
@@ -366,35 +340,24 @@ toast_save_datum(Relation rel, Datum value,
  * ----------
  */
 void
-toast_delete_datum(Relation rel, Datum value, bool is_speculative)
+toast_delete_datum(Relation toastrel, int num_indexes, Relation *toastidxs,
+				   int validIndex, Datum value, bool is_speculative,
+				   uint32 specToken)
 {
 	struct varlena *attr = (struct varlena *) DatumGetPointer(value);
 	struct varatt_external toast_pointer;
-	Relation	toastrel;
-	Relation   *toastidxs;
 	ScanKeyData toastkey;
 	SysScanDesc toastscan;
-	HeapTuple	toasttup;
-	int			num_indexes;
-	int			validIndex;
+	TupleTableSlot *slot;
 	SnapshotData SnapshotToast;
 
-	if (!VARATT_IS_EXTERNAL_ONDISK(attr))
-		return;
+	Assert(VARATT_IS_EXTERNAL_ONDISK(attr));
 
 	/* Must copy to access aligned fields */
 	VARATT_EXTERNAL_GET_POINTER(toast_pointer, attr);
 
-	/*
-	 * Open the toast relation and its indexes
-	 */
-	toastrel = table_open(toast_pointer.va_toastrelid, RowExclusiveLock);
-
-	/* Fetch valid relation used for process */
-	validIndex = toast_open_indexes(toastrel,
-									RowExclusiveLock,
-									&toastidxs,
-									&num_indexes);
+	/* Check that caller gave us the correct TOAST relation. */
+	Assert(toast_pointer.va_toastrelid == RelationGetRelid(toastrel));
 
 	/*
 	 * Setup a scan key to find chunks with matching va_valueid
@@ -412,23 +375,19 @@ toast_delete_datum(Relation rel, Datum value, bool is_speculative)
 	init_toast_snapshot(&SnapshotToast);
 	toastscan = systable_beginscan_ordered(toastrel, toastidxs[validIndex],
 										   &SnapshotToast, 1, &toastkey);
-	while ((toasttup = systable_getnext_ordered(toastscan, ForwardScanDirection)) != NULL)
+	while ((slot = systable_getnextslot_ordered(toastscan, ForwardScanDirection)) != NULL)
 	{
 		/*
 		 * Have a chunk, delete it
 		 */
 		if (is_speculative)
-			heap_abort_speculative(toastrel, &toasttup->t_self);
+			table_tuple_complete_speculative(toastrel, slot, specToken, false);
 		else
-			simple_heap_delete(toastrel, &toasttup->t_self);
+			simple_table_tuple_delete(toastrel, &slot->tts_tid, &SnapshotToast);
 	}
 
-	/*
-	 * End scan and close relations
-	 */
+	/* End scan */
 	systable_endscan_ordered(toastscan);
-	toast_close_indexes(toastidxs, num_indexes, RowExclusiveLock);
-	table_close(toastrel, RowExclusiveLock);
 }
 
 /* ----------
diff --git a/src/backend/access/heap/heapam.c b/src/backend/access/heap/heapam.c
index 2c5f58d817..b52e549259 100644
--- a/src/backend/access/heap/heapam.c
+++ b/src/backend/access/heap/heapam.c
@@ -2814,7 +2814,7 @@ l1:
 		Assert(!HeapTupleHasExternal(&tp));
 	}
 	else if (HeapTupleHasExternal(&tp))
-		toast_delete(relation, &tp, false);
+		toast_delete(relation, &tp, false, 0);
 
 	/*
 	 * Mark tuple for invalidation from system caches at next command
@@ -5568,7 +5568,7 @@ heap_finish_speculative(Relation relation, ItemPointer tid)
  * confirmation records.
  */
 void
-heap_abort_speculative(Relation relation, ItemPointer tid)
+heap_abort_speculative(Relation relation, ItemPointer tid, uint32 specToken)
 {
 	TransactionId xid = GetCurrentTransactionId();
 	ItemId		lp;
@@ -5677,7 +5677,7 @@ heap_abort_speculative(Relation relation, ItemPointer tid)
 	if (HeapTupleHasExternal(&tp))
 	{
 		Assert(!IsToastRelation(relation));
-		toast_delete(relation, &tp, true);
+		toast_delete(relation, &tp, true, specToken);
 	}
 
 	/*
diff --git a/src/backend/access/heap/heapam_handler.c b/src/backend/access/heap/heapam_handler.c
index 2dd8821fac..97a7433092 100644
--- a/src/backend/access/heap/heapam_handler.c
+++ b/src/backend/access/heap/heapam_handler.c
@@ -28,6 +28,7 @@
 #include "access/rewriteheap.h"
 #include "access/tableam.h"
 #include "access/tsmapi.h"
+#include "access/heaptoast.h"
 #include "access/xact.h"
 #include "catalog/catalog.h"
 #include "catalog/index.h"
@@ -292,7 +293,7 @@ heapam_tuple_complete_speculative(Relation relation, TupleTableSlot *slot,
 	if (succeeded)
 		heap_finish_speculative(relation, &slot->tts_tid);
 	else
-		heap_abort_speculative(relation, &slot->tts_tid);
+		heap_abort_speculative(relation, &slot->tts_tid, specToken);
 
 	if (shouldFree)
 		pfree(tuple);
@@ -2041,6 +2042,15 @@ heapam_relation_needs_toast_table(Relation rel)
 	return (tuple_length > TOAST_TUPLE_THRESHOLD);
 }
 
+/*
+ * TOAST tables for heap relations are just heap relations.
+ */
+static Oid
+heapam_relation_toast_am(Relation rel)
+{
+	return rel->rd_rel->relam;
+}
+
 
 /* ------------------------------------------------------------------------
  * Planner related callbacks for the heap AM
@@ -2539,6 +2549,8 @@ static const TableAmRoutine heapam_methods = {
 
 	.relation_size = table_block_relation_size,
 	.relation_needs_toast_table = heapam_relation_needs_toast_table,
+	.relation_toast_am = heapam_relation_toast_am,
+	.toast_max_chunk_size = TOAST_MAX_CHUNK_SIZE,
 
 	.relation_estimate_size = heapam_estimate_rel_size,
 
diff --git a/src/backend/access/heap/heaptoast.c b/src/backend/access/heap/heaptoast.c
index fbf9294598..c0acefc97e 100644
--- a/src/backend/access/heap/heaptoast.c
+++ b/src/backend/access/heap/heaptoast.c
@@ -38,7 +38,8 @@
  * ----------
  */
 void
-toast_delete(Relation rel, HeapTuple oldtup, bool is_speculative)
+toast_delete(Relation rel, HeapTuple oldtup, bool is_speculative,
+			 uint32 specToken)
 {
 	TupleDesc	tupleDesc;
 	Datum		toast_values[MaxHeapAttributeNumber];
@@ -68,7 +69,8 @@ toast_delete(Relation rel, HeapTuple oldtup, bool is_speculative)
 	heap_deform_tuple(oldtup, tupleDesc, toast_values, toast_isnull);
 
 	/* Do the real work. */
-	toast_delete_external(rel, toast_values, toast_isnull, is_speculative);
+	toast_delete_external(rel, toast_values, toast_isnull, is_speculative,
+						  specToken);
 }
 
 
@@ -151,6 +153,8 @@ toast_insert_or_update(Relation rel, HeapTuple newtup, HeapTuple oldtup,
 		ttc.ttc_oldvalues = toast_oldvalues;
 		ttc.ttc_oldisnull = toast_oldisnull;
 	}
+	ttc.ttc_toastrel = NULL;
+	ttc.ttc_toastslot = NULL;
 	ttc.ttc_attr = toast_attr;
 	toast_tuple_init(&ttc);
 
@@ -207,7 +211,8 @@ toast_insert_or_update(Relation rel, HeapTuple newtup, HeapTuple oldtup,
 		 */
 		if (toast_attr[biggest_attno].tai_size > maxDataLen &&
 			rel->rd_rel->reltoastrelid != InvalidOid)
-			toast_tuple_externalize(&ttc, biggest_attno, options);
+			toast_tuple_externalize(&ttc, biggest_attno, options,
+									TOAST_MAX_CHUNK_SIZE);
 	}
 
 	/*
@@ -224,7 +229,8 @@ toast_insert_or_update(Relation rel, HeapTuple newtup, HeapTuple oldtup,
 		biggest_attno = toast_tuple_find_biggest_attribute(&ttc, false, false);
 		if (biggest_attno < 0)
 			break;
-		toast_tuple_externalize(&ttc, biggest_attno, options);
+		toast_tuple_externalize(&ttc, biggest_attno, options,
+								TOAST_MAX_CHUNK_SIZE);
 	}
 
 	/*
@@ -260,7 +266,8 @@ toast_insert_or_update(Relation rel, HeapTuple newtup, HeapTuple oldtup,
 		if (biggest_attno < 0)
 			break;
 
-		toast_tuple_externalize(&ttc, biggest_attno, options);
+		toast_tuple_externalize(&ttc, biggest_attno, options,
+								TOAST_MAX_CHUNK_SIZE);
 	}
 
 	/*
@@ -323,7 +330,7 @@ toast_insert_or_update(Relation rel, HeapTuple newtup, HeapTuple oldtup,
 	else
 		result_tuple = newtup;
 
-	toast_tuple_cleanup(&ttc);
+	toast_tuple_cleanup(&ttc, true);
 
 	return result_tuple;
 }
diff --git a/src/backend/access/index/genam.c b/src/backend/access/index/genam.c
index 2599b5d342..233ba24261 100644
--- a/src/backend/access/index/genam.c
+++ b/src/backend/access/index/genam.c
@@ -642,6 +642,26 @@ systable_getnext_ordered(SysScanDesc sysscan, ScanDirection direction)
 	return htup;
 }
 
+/*
+ * systable_getnextslot_ordered
+ *
+ * Return a slot containing the next tuple from an ordered catalog scan,
+ * or NULL if there are no more tuples.
+ */
+TupleTableSlot *
+systable_getnextslot_ordered(SysScanDesc sysscan, ScanDirection direction)
+{
+	Assert(sysscan->irel);
+	if (!index_getnext_slot(sysscan->iscan, direction, sysscan->slot))
+		return NULL;
+
+	/* See notes in systable_getnext */
+	if (sysscan->iscan->xs_recheck)
+		elog(ERROR, "system catalog scans with lossy index conditions are not implemented");
+
+	return sysscan->slot;
+}
+
 /*
  * systable_endscan_ordered --- close scan, release resources
  */
diff --git a/src/backend/access/table/toast_helper.c b/src/backend/access/table/toast_helper.c
index 7532b4f865..e33918a7f4 100644
--- a/src/backend/access/table/toast_helper.c
+++ b/src/backend/access/table/toast_helper.c
@@ -17,6 +17,7 @@
 #include "access/detoast.h"
 #include "access/table.h"
 #include "access/toast_helper.h"
+#include "access/tableam.h"
 #include "access/toast_internals.h"
 
 /*
@@ -247,26 +248,49 @@ toast_tuple_try_compression(ToastTupleContext *ttc, int attribute)
  * Move an attribute to external storage.
  */
 void
-toast_tuple_externalize(ToastTupleContext *ttc, int attribute, int options)
+toast_tuple_externalize(ToastTupleContext *ttc, int attribute, int options,
+						int max_chunk_size)
 {
 	Datum	   *value = &ttc->ttc_values[attribute];
 	Datum		old_value = *value;
 	ToastAttrInfo *attr = &ttc->ttc_attr[attribute];
 
-	attr->tai_colflags |= TOASTCOL_IGNORE;
-	*value = toast_save_datum(ttc->ttc_rel, old_value, attr->tai_oldexternal,
-							  options);
+	/* Initialize for TOAST table access, if not yet done. */
+	if (ttc->ttc_toastrel == NULL)
+	{
+		ttc->ttc_toastrel =
+			table_open(ttc->ttc_rel->rd_rel->reltoastrelid, RowExclusiveLock);
+		ttc->ttc_validtoastidx = toast_open_indexes(ttc->ttc_toastrel,
+													RowExclusiveLock,
+													&ttc->ttc_toastidxs,
+													&ttc->ttc_ntoastidxs);
+	}
+	if (ttc->ttc_toastslot == NULL)
+		ttc->ttc_toastslot = table_slot_create(ttc->ttc_toastrel, NULL);
+
+	/* Do the real work. */
+	*value = toast_save_datum(ttc->ttc_toastrel, ttc->ttc_toastslot,
+							  ttc->ttc_ntoastidxs, ttc->ttc_toastidxs,
+							  ttc->ttc_validtoastidx,
+							  ttc->ttc_rel->rd_toastoid,
+							  old_value, attr->tai_oldexternal,
+							  options, max_chunk_size);
+
+	/* Update bookkeeping information. */
 	if ((attr->tai_colflags & TOASTCOL_NEEDS_FREE) != 0)
 		pfree(DatumGetPointer(old_value));
-	attr->tai_colflags |= TOASTCOL_NEEDS_FREE;
+	attr->tai_colflags |= (TOASTCOL_NEEDS_FREE | TOASTCOL_IGNORE);
 	ttc->ttc_flags |= (TOAST_NEEDS_CHANGE | TOAST_NEEDS_FREE);
 }
 
 /*
  * Perform appropriate cleanup after one tuple has been subjected to TOAST.
+ *
+ * Pass cleanup_toastrel as true to destroy and clear ttc_toastrel and
+ * ttc_toastslot, or false if caller will do it.
  */
 void
-toast_tuple_cleanup(ToastTupleContext *ttc)
+toast_tuple_cleanup(ToastTupleContext *ttc, bool cleanup_toastrel)
 {
 	TupleDesc	tupleDesc = ttc->ttc_rel->rd_att;
 	int			numAttrs = tupleDesc->natts;
@@ -294,14 +318,46 @@ toast_tuple_cleanup(ToastTupleContext *ttc)
 	{
 		int			i;
 
+		/* Initialize for TOAST table access, if not yet done. */
+		if (ttc->ttc_toastrel == NULL)
+		{
+			ttc->ttc_toastrel =
+				table_open(ttc->ttc_rel->rd_rel->reltoastrelid,
+						   RowExclusiveLock);
+			ttc->ttc_validtoastidx = toast_open_indexes(ttc->ttc_toastrel,
+														RowExclusiveLock,
+														&ttc->ttc_toastidxs,
+														&ttc->ttc_ntoastidxs);
+		}
+
+		/* Delete those attributes which require it. */
 		for (i = 0; i < numAttrs; i++)
 		{
 			ToastAttrInfo *attr = &ttc->ttc_attr[i];
 
 			if ((attr->tai_colflags & TOASTCOL_NEEDS_DELETE_OLD) != 0)
-				toast_delete_datum(ttc->ttc_rel, ttc->ttc_oldvalues[i], false);
+				toast_delete_datum(ttc->ttc_toastrel, ttc->ttc_ntoastidxs,
+								   ttc->ttc_toastidxs, ttc->ttc_validtoastidx,
+								   ttc->ttc_oldvalues[i], false, 0);
 		}
 	}
+
+	/*
+	 * Close toast table and indexes and drop slot, if previously done and
+	 * if caller requests it.
+	 */
+	if (cleanup_toastrel && ttc->ttc_toastrel != NULL)
+	{
+		if (ttc->ttc_toastslot != NULL)
+		{
+			ExecDropSingleTupleTableSlot(ttc->ttc_toastslot);
+			ttc->ttc_toastslot = NULL;
+		}
+		toast_close_indexes(ttc->ttc_toastidxs, ttc->ttc_ntoastidxs,
+							RowExclusiveLock);
+		table_close(ttc->ttc_toastrel, RowExclusiveLock);
+		ttc->ttc_toastrel = NULL;
+	}
 }
 
 /*
@@ -310,22 +366,43 @@ toast_tuple_cleanup(ToastTupleContext *ttc)
  */
 void
 toast_delete_external(Relation rel, Datum *values, bool *isnull,
-					  bool is_speculative)
+					  bool is_speculative, uint32 specToken)
 {
 	TupleDesc	tupleDesc = rel->rd_att;
 	int			numAttrs = tupleDesc->natts;
 	int			i;
+	Relation    toastrel = NULL;
+	Relation   *toastidxs;
+	int         num_indexes;
+	int         validIndex;
 
 	for (i = 0; i < numAttrs; i++)
 	{
-		if (TupleDescAttr(tupleDesc, i)->attlen == -1)
-		{
-			Datum		value = values[i];
+		Datum	value;
+
+		if (isnull[i] || TupleDescAttr(tupleDesc, i)->attlen != -1)
+			continue;
+
+		value = values[i];
+		if (!VARATT_IS_EXTERNAL_ONDISK(PointerGetDatum(value)))
+			continue;
 
-			if (isnull[i])
-				continue;
-			else if (VARATT_IS_EXTERNAL_ONDISK(PointerGetDatum(value)))
-				toast_delete_datum(rel, value, is_speculative);
+		/* Initialize for TOAST table access, if not yet done. */
+		if (toastrel == NULL)
+		{
+			toastrel = table_open(rel->rd_rel->reltoastrelid,
+								  RowExclusiveLock);
+			validIndex = toast_open_indexes(toastrel, RowExclusiveLock,
+											&toastidxs, &num_indexes);
 		}
+
+		toast_delete_datum(toastrel, num_indexes, toastidxs, validIndex,
+						   value, is_speculative, specToken);
+	}
+
+	if (toastrel != NULL)
+	{
+		toast_close_indexes(toastidxs, num_indexes, RowExclusiveLock);
+		table_close(toastrel, RowExclusiveLock);
 	}
 }
diff --git a/src/backend/catalog/toasting.c b/src/backend/catalog/toasting.c
index de6282a667..f082463bf6 100644
--- a/src/backend/catalog/toasting.c
+++ b/src/backend/catalog/toasting.c
@@ -258,7 +258,7 @@ create_toast_table(Relation rel, Oid toastOid, Oid toastIndexOid,
 										   toast_typid,
 										   InvalidOid,
 										   rel->rd_rel->relowner,
-										   rel->rd_rel->relam,
+										   table_relation_toast_am(rel),
 										   tupdesc,
 										   NIL,
 										   RELKIND_TOASTVALUE,
diff --git a/src/include/access/genam.h b/src/include/access/genam.h
index 8c053be2ca..a8f5076420 100644
--- a/src/include/access/genam.h
+++ b/src/include/access/genam.h
@@ -21,8 +21,9 @@
 #include "utils/relcache.h"
 #include "utils/snapshot.h"
 
-/* We don't want this file to depend on execnodes.h. */
+/* We don't want this file to depend on execnodes.h or tuptable.h. */
 struct IndexInfo;
+struct TupleTableSlot;
 
 /*
  * Struct for statistics returned by ambuild
@@ -212,6 +213,8 @@ extern SysScanDesc systable_beginscan_ordered(Relation heapRelation,
 											  int nkeys, ScanKey key);
 extern HeapTuple systable_getnext_ordered(SysScanDesc sysscan,
 										  ScanDirection direction);
+extern struct TupleTableSlot *systable_getnextslot_ordered(SysScanDesc sysscan,
+														   ScanDirection direction);
 extern void systable_endscan_ordered(SysScanDesc sysscan);
 
 #endif							/* GENAM_H */
diff --git a/src/include/access/heapam.h b/src/include/access/heapam.h
index 858bcb6bc9..6ee0c6efa7 100644
--- a/src/include/access/heapam.h
+++ b/src/include/access/heapam.h
@@ -143,7 +143,8 @@ extern TM_Result heap_delete(Relation relation, ItemPointer tid,
 							 CommandId cid, Snapshot crosscheck, bool wait,
 							 struct TM_FailureData *tmfd, bool changingPart);
 extern void heap_finish_speculative(Relation relation, ItemPointer tid);
-extern void heap_abort_speculative(Relation relation, ItemPointer tid);
+extern void heap_abort_speculative(Relation relation, ItemPointer tid,
+					   uint32 specToken);
 extern TM_Result heap_update(Relation relation, ItemPointer otid,
 							 HeapTuple newtup,
 							 CommandId cid, Snapshot crosscheck, bool wait,
diff --git a/src/include/access/heaptoast.h b/src/include/access/heaptoast.h
index bf02d2c600..07d36ac968 100644
--- a/src/include/access/heaptoast.h
+++ b/src/include/access/heaptoast.h
@@ -104,7 +104,8 @@ extern HeapTuple toast_insert_or_update(Relation rel,
  *	Called by heap_delete().
  * ----------
  */
-extern void toast_delete(Relation rel, HeapTuple oldtup, bool is_speculative);
+extern void toast_delete(Relation rel, HeapTuple oldtup,
+			 bool is_speculative, uint32 specToken);
 
 /* ----------
  * toast_flatten_tuple -
diff --git a/src/include/access/tableam.h b/src/include/access/tableam.h
index 7f81703b78..521fd6232d 100644
--- a/src/include/access/tableam.h
+++ b/src/include/access/tableam.h
@@ -581,6 +581,27 @@ typedef struct TableAmRoutine
 	 */
 	bool		(*relation_needs_toast_table) (Relation rel);
 
+	/*
+	 * This callback should return the OID of the table AM that implements
+	 * TOAST tables for this AM.  If the relation_needs_toast_table callback
+	 * always returns false, this callback is not required.
+	 */
+	Oid		    (*relation_toast_am) (Relation rel);
+
+	/*
+	 * If this table AM can be used to implement a TOAST table, the following
+	 * field should be set to the maximum number of bytes that can be stored
+	 * in a single TOAST chunk.  It must not be set to a value greater than
+	 * BLCKSZ.  If this table AM is not used to implement a TOAST table, this
+	 * value is ignored.
+	 *
+	 * (Note that there is no requirement that the TOAST table be implemented
+	 * using the same AM as the table to which it is attached.  If this AM
+	 * has TOAST tables but uses some other AM to implement them, this value
+	 * is ignored; it is a property of the TOAST table, not the parent table.)
+	 */
+	int			toast_max_chunk_size;
+
 
 	/* ------------------------------------------------------------------------
 	 * Planner related functions.
@@ -1603,6 +1624,16 @@ table_relation_needs_toast_table(Relation rel)
 	return rel->rd_tableam->relation_needs_toast_table(rel);
 }
 
+/*
+ * Return the OID of the AM that should be used to implement the TOAST table
+ * for this relation.
+ */
+static inline Oid
+table_relation_toast_am(Relation rel)
+{
+	return rel->rd_tableam->relation_toast_am(rel);
+}
+
 
 /* ----------------------------------------------------------------------------
  * Planner related functionality
diff --git a/src/include/access/toast_helper.h b/src/include/access/toast_helper.h
index 7cefacb0ea..cfb4ae0385 100644
--- a/src/include/access/toast_helper.h
+++ b/src/include/access/toast_helper.h
@@ -14,6 +14,7 @@
 #ifndef TOAST_HELPER_H
 #define TOAST_HELPER_H
 
+#include "executor/tuptable.h"
 #include "utils/rel.h"
 
 /*
@@ -51,6 +52,17 @@ typedef struct
 	Datum	   *ttc_oldvalues;	/* values from previous tuple */
 	bool	   *ttc_oldisnull;	/* null flags from previous tuple */
 
+	/*
+	 * Before calling toast_tuple_init, the caller should either initialize
+	 * all of these fields or else set ttc_toastrel and ttc_toastslot to NULL.
+	 * In the latter case, all of the fields will be initialized as required.
+	 */
+	Relation	ttc_toastrel;	/* the toast table for the relation */
+	TupleTableSlot *ttc_toastslot;	/* a slot for the toast table */
+	int			ttc_ntoastidxs; /* # of toast indexes for toast table */
+	Relation   *ttc_toastidxs;	/* array of those toast indexes */
+	int			ttc_validtoastidx;	/* the valid toast index */
+
 	/*
 	 * Before calling toast_tuple_init, the caller should set tts_attr to
 	 * point to an array of ToastAttrInfo structures of a length equal to
@@ -106,10 +118,10 @@ extern int	toast_tuple_find_biggest_attribute(ToastTupleContext *ttc,
 											   bool check_main);
 extern void toast_tuple_try_compression(ToastTupleContext *ttc, int attribute);
 extern void toast_tuple_externalize(ToastTupleContext *ttc, int attribute,
-									int options);
-extern void toast_tuple_cleanup(ToastTupleContext *ttc);
+									int options, int max_chunk_size);
+extern void toast_tuple_cleanup(ToastTupleContext *ttc, bool cleanup_toastrel);
 
 extern void toast_delete_external(Relation rel, Datum *values, bool *isnull,
-								  bool is_speculative);
+								  bool is_speculative, uint32 specToken);
 
 #endif
diff --git a/src/include/access/toast_internals.h b/src/include/access/toast_internals.h
index 494b07a4b1..96f61baf80 100644
--- a/src/include/access/toast_internals.h
+++ b/src/include/access/toast_internals.h
@@ -16,6 +16,8 @@
 #include "utils/relcache.h"
 #include "utils/snapshot.h"
 
+struct TupleTableSlot;
+
 /*
  *	The information at the start of the compressed toast data.
  */
@@ -39,9 +41,16 @@ typedef struct toast_compress_header
 extern Datum toast_compress_datum(Datum value);
 extern Oid	toast_get_valid_index(Oid toastoid, LOCKMODE lock);
 
-extern void toast_delete_datum(Relation rel, Datum value, bool is_speculative);
-extern Datum toast_save_datum(Relation rel, Datum value,
-							  struct varlena *oldexternal, int options);
+extern void toast_delete_datum(Relation toastrel, int num_indexes,
+							   Relation *toastidxs, int validIndex,
+							   Datum value, bool is_speculative,
+							   uint32 specToken);
+extern Datum toast_save_datum(Relation toastrel,
+							  struct TupleTableSlot *toastslot,
+							  int num_indexes, Relation *toastidxs,
+							  int validIndex, Oid toastoid,
+							  Datum value, struct varlena *oldexternal,
+							  int options, int max_chunk_size);
 
 extern int	toast_open_indexes(Relation toastrel,
 							   LOCKMODE lock,
-- 
2.17.2 (Apple Git-113)

From a4c858c75793f0f8aff7914c572a6615ea5babf8 Mon Sep 17 00:00:00 2001
From: Robert Haas <rhaas@postgresql.org>
Date: Mon, 8 Jul 2019 11:58:05 -0400
Subject: [PATCH 1/4] Split tuptoaster.c into three separate files.

detoast.c/h contain functions required to detoast a datum, partially
or completely, plus a few other utility functions for examining the
size of toasted datums.

toast_internals.c/h contain functions that are used internally to the
TOAST subsystem but which (mostly) do not need to be accessed from
outside.

heaptoast.c/h contains code that is intrinsically specific to the
heap AM, either because it operates on HeapTuples or is based on the
layout of a heap page.

detoast.c and toast_internals.c are placed in
src/backend/access/common rather than src/backend/access/heap.  At
present, both files still have dependencies on the heap, but that will
be improved in a future commit.

Discussion: http://postgr.es/m/CA+TgmoZv-=2iWM4jcw5ZhJeL18HF96+W1yJeYrnGMYdkFFnEpQ@mail.gmail.com
---
 doc/src/sgml/storage.sgml                     |    2 +-
 src/backend/access/common/Makefile            |    5 +-
 src/backend/access/common/detoast.c           |  869 ++++++
 src/backend/access/common/heaptuple.c         |    4 +-
 src/backend/access/common/indextuple.c        |    9 +-
 src/backend/access/common/reloptions.c        |    2 +-
 src/backend/access/common/toast_internals.c   |  632 +++++
 src/backend/access/heap/Makefile              |    2 +-
 src/backend/access/heap/heapam.c              |    2 +-
 src/backend/access/heap/heapam_handler.c      |    2 +-
 src/backend/access/heap/heaptoast.c           |  917 +++++++
 src/backend/access/heap/rewriteheap.c         |    2 +-
 src/backend/access/heap/tuptoaster.c          | 2421 -----------------
 src/backend/access/transam/xlog.c             |    2 +-
 src/backend/commands/analyze.c                |    2 +-
 src/backend/commands/cluster.c                |    2 +-
 src/backend/executor/execExprInterp.c         |    2 +-
 src/backend/executor/execTuples.c             |    2 +-
 src/backend/executor/tstoreReceiver.c         |    2 +-
 .../replication/logical/reorderbuffer.c       |    2 +-
 src/backend/statistics/extended_stats.c       |    2 +-
 src/backend/storage/large_object/inv_api.c    |    3 +-
 src/backend/utils/adt/array_typanalyze.c      |    2 +-
 src/backend/utils/adt/datum.c                 |    2 +-
 src/backend/utils/adt/expandedrecord.c        |    3 +-
 src/backend/utils/adt/rowtypes.c              |    2 +-
 src/backend/utils/adt/tsgistidx.c             |    2 +-
 src/backend/utils/adt/varchar.c               |    2 +-
 src/backend/utils/adt/varlena.c               |    2 +-
 src/backend/utils/cache/catcache.c            |    2 +-
 src/backend/utils/fmgr/fmgr.c                 |    2 +-
 src/bin/pg_resetwal/pg_resetwal.c             |    2 +-
 src/include/access/detoast.h                  |   92 +
 .../access/{tuptoaster.h => heaptoast.h}      |  112 +-
 src/include/access/toast_internals.h          |   54 +
 src/pl/plpgsql/src/pl_exec.c                  |    2 +-
 src/test/regress/regress.c                    |    2 +-
 37 files changed, 2612 insertions(+), 2559 deletions(-)
 create mode 100644 src/backend/access/common/detoast.c
 create mode 100644 src/backend/access/common/toast_internals.c
 create mode 100644 src/backend/access/heap/heaptoast.c
 delete mode 100644 src/backend/access/heap/tuptoaster.c
 create mode 100644 src/include/access/detoast.h
 rename src/include/access/{tuptoaster.h => heaptoast.h} (57%)
 create mode 100644 src/include/access/toast_internals.h

diff --git a/doc/src/sgml/storage.sgml b/doc/src/sgml/storage.sgml
index 1047c77a63..78bd030346 100644
--- a/doc/src/sgml/storage.sgml
+++ b/doc/src/sgml/storage.sgml
@@ -382,7 +382,7 @@ The oldest and most common type is a pointer to out-of-line data stored in
 a <firstterm><acronym>TOAST</acronym> table</firstterm> that is separate from, but
 associated with, the table containing the <acronym>TOAST</acronym> pointer datum
 itself.  These <firstterm>on-disk</firstterm> pointer datums are created by the
-<acronym>TOAST</acronym> management code (in <filename>access/heap/tuptoaster.c</filename>)
+<acronym>TOAST</acronym> management code (in <filename>access/common/toast_internals.c</filename>)
 when a tuple to be stored on disk is too large to be stored as-is.
 Further details appear in <xref linkend="storage-toast-ondisk"/>.
 Alternatively, a <acronym>TOAST</acronym> pointer datum can contain a pointer to
diff --git a/src/backend/access/common/Makefile b/src/backend/access/common/Makefile
index d469504337..9ac19d9f9e 100644
--- a/src/backend/access/common/Makefile
+++ b/src/backend/access/common/Makefile
@@ -12,7 +12,8 @@ subdir = src/backend/access/common
 top_builddir = ../../../..
 include $(top_builddir)/src/Makefile.global
 
-OBJS = bufmask.o heaptuple.o indextuple.o printsimple.o printtup.o \
-	relation.o reloptions.o scankey.o session.o tupconvert.o tupdesc.o
+OBJS = bufmask.o detoast.o heaptuple.o indextuple.o printsimple.o \
+	printtup.o relation.o reloptions.o scankey.o session.o toast_internals.o \
+	tupconvert.o tupdesc.o
 
 include $(top_srcdir)/src/backend/common.mk
diff --git a/src/backend/access/common/detoast.c b/src/backend/access/common/detoast.c
new file mode 100644
index 0000000000..c8b49d6a12
--- /dev/null
+++ b/src/backend/access/common/detoast.c
@@ -0,0 +1,869 @@
+/*-------------------------------------------------------------------------
+ *
+ * detoast.c
+ *	  Retrieve compressed or external variable size attributes.
+ *
+ * Copyright (c) 2000-2019, PostgreSQL Global Development Group
+ *
+ * IDENTIFICATION
+ *	  src/backend/access/common/detoast.c
+ *
+ *-------------------------------------------------------------------------
+ */
+
+#include "postgres.h"
+
+#include "access/detoast.h"
+#include "access/genam.h"
+#include "access/heaptoast.h"
+#include "access/table.h"
+#include "access/toast_internals.h"
+#include "common/pg_lzcompress.h"
+#include "utils/expandeddatum.h"
+#include "utils/fmgroids.h"
+#include "utils/rel.h"
+
+static struct varlena *toast_fetch_datum(struct varlena *attr);
+static struct varlena *toast_fetch_datum_slice(struct varlena *attr,
+											   int32 sliceoffset, int32 length);
+static struct varlena *toast_decompress_datum(struct varlena *attr);
+static struct varlena *toast_decompress_datum_slice(struct varlena *attr, int32 slicelength);
+
+/* ----------
+ * heap_tuple_fetch_attr -
+ *
+ *	Public entry point to get back a toasted value from
+ *	external source (possibly still in compressed format).
+ *
+ * This will return a datum that contains all the data internally, ie, not
+ * relying on external storage or memory, but it can still be compressed or
+ * have a short header.  Note some callers assume that if the input is an
+ * EXTERNAL datum, the result will be a pfree'able chunk.
+ * ----------
+ */
+struct varlena *
+heap_tuple_fetch_attr(struct varlena *attr)
+{
+	struct varlena *result;
+
+	if (VARATT_IS_EXTERNAL_ONDISK(attr))
+	{
+		/*
+		 * This is an external stored plain value
+		 */
+		result = toast_fetch_datum(attr);
+	}
+	else if (VARATT_IS_EXTERNAL_INDIRECT(attr))
+	{
+		/*
+		 * This is an indirect pointer --- dereference it
+		 */
+		struct varatt_indirect redirect;
+
+		VARATT_EXTERNAL_GET_POINTER(redirect, attr);
+		attr = (struct varlena *) redirect.pointer;
+
+		/* nested indirect Datums aren't allowed */
+		Assert(!VARATT_IS_EXTERNAL_INDIRECT(attr));
+
+		/* recurse if value is still external in some other way */
+		if (VARATT_IS_EXTERNAL(attr))
+			return heap_tuple_fetch_attr(attr);
+
+		/*
+		 * Copy into the caller's memory context, in case caller tries to
+		 * pfree the result.
+		 */
+		result = (struct varlena *) palloc(VARSIZE_ANY(attr));
+		memcpy(result, attr, VARSIZE_ANY(attr));
+	}
+	else if (VARATT_IS_EXTERNAL_EXPANDED(attr))
+	{
+		/*
+		 * This is an expanded-object pointer --- get flat format
+		 */
+		ExpandedObjectHeader *eoh;
+		Size		resultsize;
+
+		eoh = DatumGetEOHP(PointerGetDatum(attr));
+		resultsize = EOH_get_flat_size(eoh);
+		result = (struct varlena *) palloc(resultsize);
+		EOH_flatten_into(eoh, (void *) result, resultsize);
+	}
+	else
+	{
+		/*
+		 * This is a plain value inside of the main tuple - why am I called?
+		 */
+		result = attr;
+	}
+
+	return result;
+}
+
+
+/* ----------
+ * heap_tuple_untoast_attr -
+ *
+ *	Public entry point to get back a toasted value from compression
+ *	or external storage.  The result is always non-extended varlena form.
+ *
+ * Note some callers assume that if the input is an EXTERNAL or COMPRESSED
+ * datum, the result will be a pfree'able chunk.
+ * ----------
+ */
+struct varlena *
+heap_tuple_untoast_attr(struct varlena *attr)
+{
+	if (VARATT_IS_EXTERNAL_ONDISK(attr))
+	{
+		/*
+		 * This is an externally stored datum --- fetch it back from there
+		 */
+		attr = toast_fetch_datum(attr);
+		/* If it's compressed, decompress it */
+		if (VARATT_IS_COMPRESSED(attr))
+		{
+			struct varlena *tmp = attr;
+
+			attr = toast_decompress_datum(tmp);
+			pfree(tmp);
+		}
+	}
+	else if (VARATT_IS_EXTERNAL_INDIRECT(attr))
+	{
+		/*
+		 * This is an indirect pointer --- dereference it
+		 */
+		struct varatt_indirect redirect;
+
+		VARATT_EXTERNAL_GET_POINTER(redirect, attr);
+		attr = (struct varlena *) redirect.pointer;
+
+		/* nested indirect Datums aren't allowed */
+		Assert(!VARATT_IS_EXTERNAL_INDIRECT(attr));
+
+		/* recurse in case value is still extended in some other way */
+		attr = heap_tuple_untoast_attr(attr);
+
+		/* if it isn't, we'd better copy it */
+		if (attr == (struct varlena *) redirect.pointer)
+		{
+			struct varlena *result;
+
+			result = (struct varlena *) palloc(VARSIZE_ANY(attr));
+			memcpy(result, attr, VARSIZE_ANY(attr));
+			attr = result;
+		}
+	}
+	else if (VARATT_IS_EXTERNAL_EXPANDED(attr))
+	{
+		/*
+		 * This is an expanded-object pointer --- get flat format
+		 */
+		attr = heap_tuple_fetch_attr(attr);
+		/* flatteners are not allowed to produce compressed/short output */
+		Assert(!VARATT_IS_EXTENDED(attr));
+	}
+	else if (VARATT_IS_COMPRESSED(attr))
+	{
+		/*
+		 * This is a compressed value inside of the main tuple
+		 */
+		attr = toast_decompress_datum(attr);
+	}
+	else if (VARATT_IS_SHORT(attr))
+	{
+		/*
+		 * This is a short-header varlena --- convert to 4-byte header format
+		 */
+		Size		data_size = VARSIZE_SHORT(attr) - VARHDRSZ_SHORT;
+		Size		new_size = data_size + VARHDRSZ;
+		struct varlena *new_attr;
+
+		new_attr = (struct varlena *) palloc(new_size);
+		SET_VARSIZE(new_attr, new_size);
+		memcpy(VARDATA(new_attr), VARDATA_SHORT(attr), data_size);
+		attr = new_attr;
+	}
+
+	return attr;
+}
+
+
+/* ----------
+ * heap_tuple_untoast_attr_slice -
+ *
+ *		Public entry point to get back part of a toasted value
+ *		from compression or external storage.
+ * ----------
+ */
+struct varlena *
+heap_tuple_untoast_attr_slice(struct varlena *attr,
+							  int32 sliceoffset, int32 slicelength)
+{
+	struct varlena *preslice;
+	struct varlena *result;
+	char	   *attrdata;
+	int32		attrsize;
+
+	if (VARATT_IS_EXTERNAL_ONDISK(attr))
+	{
+		struct varatt_external toast_pointer;
+
+		VARATT_EXTERNAL_GET_POINTER(toast_pointer, attr);
+
+		/* fast path for non-compressed external datums */
+		if (!VARATT_EXTERNAL_IS_COMPRESSED(toast_pointer))
+			return toast_fetch_datum_slice(attr, sliceoffset, slicelength);
+
+		/* fetch it back (compressed marker will get set automatically) */
+		preslice = toast_fetch_datum(attr);
+	}
+	else if (VARATT_IS_EXTERNAL_INDIRECT(attr))
+	{
+		struct varatt_indirect redirect;
+
+		VARATT_EXTERNAL_GET_POINTER(redirect, attr);
+
+		/* nested indirect Datums aren't allowed */
+		Assert(!VARATT_IS_EXTERNAL_INDIRECT(redirect.pointer));
+
+		return heap_tuple_untoast_attr_slice(redirect.pointer,
+											 sliceoffset, slicelength);
+	}
+	else if (VARATT_IS_EXTERNAL_EXPANDED(attr))
+	{
+		/* pass it off to heap_tuple_fetch_attr to flatten */
+		preslice = heap_tuple_fetch_attr(attr);
+	}
+	else
+		preslice = attr;
+
+	Assert(!VARATT_IS_EXTERNAL(preslice));
+
+	if (VARATT_IS_COMPRESSED(preslice))
+	{
+		struct varlena *tmp = preslice;
+
+		/* Decompress enough to encompass the slice and the offset */
+		if (slicelength > 0 && sliceoffset >= 0)
+			preslice = toast_decompress_datum_slice(tmp, slicelength + sliceoffset);
+		else
+			preslice = toast_decompress_datum(tmp);
+
+		if (tmp != attr)
+			pfree(tmp);
+	}
+
+	if (VARATT_IS_SHORT(preslice))
+	{
+		attrdata = VARDATA_SHORT(preslice);
+		attrsize = VARSIZE_SHORT(preslice) - VARHDRSZ_SHORT;
+	}
+	else
+	{
+		attrdata = VARDATA(preslice);
+		attrsize = VARSIZE(preslice) - VARHDRSZ;
+	}
+
+	/* slicing of datum for compressed cases and plain value */
+
+	if (sliceoffset >= attrsize)
+	{
+		sliceoffset = 0;
+		slicelength = 0;
+	}
+
+	if (((sliceoffset + slicelength) > attrsize) || slicelength < 0)
+		slicelength = attrsize - sliceoffset;
+
+	result = (struct varlena *) palloc(slicelength + VARHDRSZ);
+	SET_VARSIZE(result, slicelength + VARHDRSZ);
+
+	memcpy(VARDATA(result), attrdata + sliceoffset, slicelength);
+
+	if (preslice != attr)
+		pfree(preslice);
+
+	return result;
+}
+
+/* ----------
+ * toast_fetch_datum -
+ *
+ *	Reconstruct an in memory Datum from the chunks saved
+ *	in the toast relation
+ * ----------
+ */
+static struct varlena *
+toast_fetch_datum(struct varlena *attr)
+{
+	Relation	toastrel;
+	Relation   *toastidxs;
+	ScanKeyData toastkey;
+	SysScanDesc toastscan;
+	HeapTuple	ttup;
+	TupleDesc	toasttupDesc;
+	struct varlena *result;
+	struct varatt_external toast_pointer;
+	int32		ressize;
+	int32		residx,
+				nextidx;
+	int32		numchunks;
+	Pointer		chunk;
+	bool		isnull;
+	char	   *chunkdata;
+	int32		chunksize;
+	int			num_indexes;
+	int			validIndex;
+	SnapshotData SnapshotToast;
+
+	if (!VARATT_IS_EXTERNAL_ONDISK(attr))
+		elog(ERROR, "toast_fetch_datum shouldn't be called for non-ondisk datums");
+
+	/* Must copy to access aligned fields */
+	VARATT_EXTERNAL_GET_POINTER(toast_pointer, attr);
+
+	ressize = toast_pointer.va_extsize;
+	numchunks = ((ressize - 1) / TOAST_MAX_CHUNK_SIZE) + 1;
+
+	result = (struct varlena *) palloc(ressize + VARHDRSZ);
+
+	if (VARATT_EXTERNAL_IS_COMPRESSED(toast_pointer))
+		SET_VARSIZE_COMPRESSED(result, ressize + VARHDRSZ);
+	else
+		SET_VARSIZE(result, ressize + VARHDRSZ);
+
+	/*
+	 * Open the toast relation and its indexes
+	 */
+	toastrel = table_open(toast_pointer.va_toastrelid, AccessShareLock);
+	toasttupDesc = toastrel->rd_att;
+
+	/* Look for the valid index of the toast relation */
+	validIndex = toast_open_indexes(toastrel,
+									AccessShareLock,
+									&toastidxs,
+									&num_indexes);
+
+	/*
+	 * Setup a scan key to fetch from the index by va_valueid
+	 */
+	ScanKeyInit(&toastkey,
+				(AttrNumber) 1,
+				BTEqualStrategyNumber, F_OIDEQ,
+				ObjectIdGetDatum(toast_pointer.va_valueid));
+
+	/*
+	 * Read the chunks by index
+	 *
+	 * Note that because the index is actually on (valueid, chunkidx) we will
+	 * see the chunks in chunkidx order, even though we didn't explicitly ask
+	 * for it.
+	 */
+	nextidx = 0;
+
+	init_toast_snapshot(&SnapshotToast);
+	toastscan = systable_beginscan_ordered(toastrel, toastidxs[validIndex],
+										   &SnapshotToast, 1, &toastkey);
+	while ((ttup = systable_getnext_ordered(toastscan, ForwardScanDirection)) != NULL)
+	{
+		/*
+		 * Have a chunk, extract the sequence number and the data
+		 */
+		residx = DatumGetInt32(fastgetattr(ttup, 2, toasttupDesc, &isnull));
+		Assert(!isnull);
+		chunk = DatumGetPointer(fastgetattr(ttup, 3, toasttupDesc, &isnull));
+		Assert(!isnull);
+		if (!VARATT_IS_EXTENDED(chunk))
+		{
+			chunksize = VARSIZE(chunk) - VARHDRSZ;
+			chunkdata = VARDATA(chunk);
+		}
+		else if (VARATT_IS_SHORT(chunk))
+		{
+			/* could happen due to heap_form_tuple doing its thing */
+			chunksize = VARSIZE_SHORT(chunk) - VARHDRSZ_SHORT;
+			chunkdata = VARDATA_SHORT(chunk);
+		}
+		else
+		{
+			/* should never happen */
+			elog(ERROR, "found toasted toast chunk for toast value %u in %s",
+				 toast_pointer.va_valueid,
+				 RelationGetRelationName(toastrel));
+			chunksize = 0;		/* keep compiler quiet */
+			chunkdata = NULL;
+		}
+
+		/*
+		 * Some checks on the data we've found
+		 */
+		if (residx != nextidx)
+			ereport(ERROR,
+					(errcode(ERRCODE_DATA_CORRUPTED),
+					 errmsg_internal("unexpected chunk number %d (expected %d) for toast value %u in %s",
+									 residx, nextidx,
+									 toast_pointer.va_valueid,
+									 RelationGetRelationName(toastrel))));
+		if (residx < numchunks - 1)
+		{
+			if (chunksize != TOAST_MAX_CHUNK_SIZE)
+				ereport(ERROR,
+						(errcode(ERRCODE_DATA_CORRUPTED),
+						 errmsg_internal("unexpected chunk size %d (expected %d) in chunk %d of %d for toast value %u in %s",
+										 chunksize, (int) TOAST_MAX_CHUNK_SIZE,
+										 residx, numchunks,
+										 toast_pointer.va_valueid,
+										 RelationGetRelationName(toastrel))));
+		}
+		else if (residx == numchunks - 1)
+		{
+			if ((residx * TOAST_MAX_CHUNK_SIZE + chunksize) != ressize)
+				ereport(ERROR,
+						(errcode(ERRCODE_DATA_CORRUPTED),
+						 errmsg_internal("unexpected chunk size %d (expected %d) in final chunk %d for toast value %u in %s",
+										 chunksize,
+										 (int) (ressize - residx * TOAST_MAX_CHUNK_SIZE),
+										 residx,
+										 toast_pointer.va_valueid,
+										 RelationGetRelationName(toastrel))));
+		}
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_DATA_CORRUPTED),
+					 errmsg_internal("unexpected chunk number %d (out of range %d..%d) for toast value %u in %s",
+									 residx,
+									 0, numchunks - 1,
+									 toast_pointer.va_valueid,
+									 RelationGetRelationName(toastrel))));
+
+		/*
+		 * Copy the data into proper place in our result
+		 */
+		memcpy(VARDATA(result) + residx * TOAST_MAX_CHUNK_SIZE,
+			   chunkdata,
+			   chunksize);
+
+		nextidx++;
+	}
+
+	/*
+	 * Final checks that we successfully fetched the datum
+	 */
+	if (nextidx != numchunks)
+		ereport(ERROR,
+				(errcode(ERRCODE_DATA_CORRUPTED),
+				 errmsg_internal("missing chunk number %d for toast value %u in %s",
+								 nextidx,
+								 toast_pointer.va_valueid,
+								 RelationGetRelationName(toastrel))));
+
+	/*
+	 * End scan and close relations
+	 */
+	systable_endscan_ordered(toastscan);
+	toast_close_indexes(toastidxs, num_indexes, AccessShareLock);
+	table_close(toastrel, AccessShareLock);
+
+	return result;
+}
+
+/* ----------
+ * toast_fetch_datum_slice -
+ *
+ *	Reconstruct a segment of a Datum from the chunks saved
+ *	in the toast relation
+ *
+ *	Note that this function only supports non-compressed external datums.
+ * ----------
+ */
+static struct varlena *
+toast_fetch_datum_slice(struct varlena *attr, int32 sliceoffset, int32 length)
+{
+	Relation	toastrel;
+	Relation   *toastidxs;
+	ScanKeyData toastkey[3];
+	int			nscankeys;
+	SysScanDesc toastscan;
+	HeapTuple	ttup;
+	TupleDesc	toasttupDesc;
+	struct varlena *result;
+	struct varatt_external toast_pointer;
+	int32		attrsize;
+	int32		residx;
+	int32		nextidx;
+	int			numchunks;
+	int			startchunk;
+	int			endchunk;
+	int32		startoffset;
+	int32		endoffset;
+	int			totalchunks;
+	Pointer		chunk;
+	bool		isnull;
+	char	   *chunkdata;
+	int32		chunksize;
+	int32		chcpystrt;
+	int32		chcpyend;
+	int			num_indexes;
+	int			validIndex;
+	SnapshotData SnapshotToast;
+
+	if (!VARATT_IS_EXTERNAL_ONDISK(attr))
+		elog(ERROR, "toast_fetch_datum_slice shouldn't be called for non-ondisk datums");
+
+	/* Must copy to access aligned fields */
+	VARATT_EXTERNAL_GET_POINTER(toast_pointer, attr);
+
+	/*
+	 * It's nonsense to fetch slices of a compressed datum -- this isn't lo_*
+	 * we can't return a compressed datum which is meaningful to toast later
+	 */
+	Assert(!VARATT_EXTERNAL_IS_COMPRESSED(toast_pointer));
+
+	attrsize = toast_pointer.va_extsize;
+	totalchunks = ((attrsize - 1) / TOAST_MAX_CHUNK_SIZE) + 1;
+
+	if (sliceoffset >= attrsize)
+	{
+		sliceoffset = 0;
+		length = 0;
+	}
+
+	if (((sliceoffset + length) > attrsize) || length < 0)
+		length = attrsize - sliceoffset;
+
+	result = (struct varlena *) palloc(length + VARHDRSZ);
+
+	SET_VARSIZE(result, length + VARHDRSZ);
+
+	if (length == 0)
+		return result;			/* Can save a lot of work at this point! */
+
+	startchunk = sliceoffset / TOAST_MAX_CHUNK_SIZE;
+	endchunk = (sliceoffset + length - 1) / TOAST_MAX_CHUNK_SIZE;
+	numchunks = (endchunk - startchunk) + 1;
+
+	startoffset = sliceoffset % TOAST_MAX_CHUNK_SIZE;
+	endoffset = (sliceoffset + length - 1) % TOAST_MAX_CHUNK_SIZE;
+
+	/*
+	 * Open the toast relation and its indexes
+	 */
+	toastrel = table_open(toast_pointer.va_toastrelid, AccessShareLock);
+	toasttupDesc = toastrel->rd_att;
+
+	/* Look for the valid index of toast relation */
+	validIndex = toast_open_indexes(toastrel,
+									AccessShareLock,
+									&toastidxs,
+									&num_indexes);
+
+	/*
+	 * Setup a scan key to fetch from the index. This is either two keys or
+	 * three depending on the number of chunks.
+	 */
+	ScanKeyInit(&toastkey[0],
+				(AttrNumber) 1,
+				BTEqualStrategyNumber, F_OIDEQ,
+				ObjectIdGetDatum(toast_pointer.va_valueid));
+
+	/*
+	 * Use equality condition for one chunk, a range condition otherwise:
+	 */
+	if (numchunks == 1)
+	{
+		ScanKeyInit(&toastkey[1],
+					(AttrNumber) 2,
+					BTEqualStrategyNumber, F_INT4EQ,
+					Int32GetDatum(startchunk));
+		nscankeys = 2;
+	}
+	else
+	{
+		ScanKeyInit(&toastkey[1],
+					(AttrNumber) 2,
+					BTGreaterEqualStrategyNumber, F_INT4GE,
+					Int32GetDatum(startchunk));
+		ScanKeyInit(&toastkey[2],
+					(AttrNumber) 2,
+					BTLessEqualStrategyNumber, F_INT4LE,
+					Int32GetDatum(endchunk));
+		nscankeys = 3;
+	}
+
+	/*
+	 * Read the chunks by index
+	 *
+	 * The index is on (valueid, chunkidx) so they will come in order
+	 */
+	init_toast_snapshot(&SnapshotToast);
+	nextidx = startchunk;
+	toastscan = systable_beginscan_ordered(toastrel, toastidxs[validIndex],
+										   &SnapshotToast, nscankeys, toastkey);
+	while ((ttup = systable_getnext_ordered(toastscan, ForwardScanDirection)) != NULL)
+	{
+		/*
+		 * Have a chunk, extract the sequence number and the data
+		 */
+		residx = DatumGetInt32(fastgetattr(ttup, 2, toasttupDesc, &isnull));
+		Assert(!isnull);
+		chunk = DatumGetPointer(fastgetattr(ttup, 3, toasttupDesc, &isnull));
+		Assert(!isnull);
+		if (!VARATT_IS_EXTENDED(chunk))
+		{
+			chunksize = VARSIZE(chunk) - VARHDRSZ;
+			chunkdata = VARDATA(chunk);
+		}
+		else if (VARATT_IS_SHORT(chunk))
+		{
+			/* could happen due to heap_form_tuple doing its thing */
+			chunksize = VARSIZE_SHORT(chunk) - VARHDRSZ_SHORT;
+			chunkdata = VARDATA_SHORT(chunk);
+		}
+		else
+		{
+			/* should never happen */
+			elog(ERROR, "found toasted toast chunk for toast value %u in %s",
+				 toast_pointer.va_valueid,
+				 RelationGetRelationName(toastrel));
+			chunksize = 0;		/* keep compiler quiet */
+			chunkdata = NULL;
+		}
+
+		/*
+		 * Some checks on the data we've found
+		 */
+		if ((residx != nextidx) || (residx > endchunk) || (residx < startchunk))
+			elog(ERROR, "unexpected chunk number %d (expected %d) for toast value %u in %s",
+				 residx, nextidx,
+				 toast_pointer.va_valueid,
+				 RelationGetRelationName(toastrel));
+		if (residx < totalchunks - 1)
+		{
+			if (chunksize != TOAST_MAX_CHUNK_SIZE)
+				elog(ERROR, "unexpected chunk size %d (expected %d) in chunk %d of %d for toast value %u in %s when fetching slice",
+					 chunksize, (int) TOAST_MAX_CHUNK_SIZE,
+					 residx, totalchunks,
+					 toast_pointer.va_valueid,
+					 RelationGetRelationName(toastrel));
+		}
+		else if (residx == totalchunks - 1)
+		{
+			if ((residx * TOAST_MAX_CHUNK_SIZE + chunksize) != attrsize)
+				elog(ERROR, "unexpected chunk size %d (expected %d) in final chunk %d for toast value %u in %s when fetching slice",
+					 chunksize,
+					 (int) (attrsize - residx * TOAST_MAX_CHUNK_SIZE),
+					 residx,
+					 toast_pointer.va_valueid,
+					 RelationGetRelationName(toastrel));
+		}
+		else
+			elog(ERROR, "unexpected chunk number %d (out of range %d..%d) for toast value %u in %s",
+				 residx,
+				 0, totalchunks - 1,
+				 toast_pointer.va_valueid,
+				 RelationGetRelationName(toastrel));
+
+		/*
+		 * Copy the data into proper place in our result
+		 */
+		chcpystrt = 0;
+		chcpyend = chunksize - 1;
+		if (residx == startchunk)
+			chcpystrt = startoffset;
+		if (residx == endchunk)
+			chcpyend = endoffset;
+
+		memcpy(VARDATA(result) +
+			   (residx * TOAST_MAX_CHUNK_SIZE - sliceoffset) + chcpystrt,
+			   chunkdata + chcpystrt,
+			   (chcpyend - chcpystrt) + 1);
+
+		nextidx++;
+	}
+
+	/*
+	 * Final checks that we successfully fetched the datum
+	 */
+	if (nextidx != (endchunk + 1))
+		elog(ERROR, "missing chunk number %d for toast value %u in %s",
+			 nextidx,
+			 toast_pointer.va_valueid,
+			 RelationGetRelationName(toastrel));
+
+	/*
+	 * End scan and close relations
+	 */
+	systable_endscan_ordered(toastscan);
+	toast_close_indexes(toastidxs, num_indexes, AccessShareLock);
+	table_close(toastrel, AccessShareLock);
+
+	return result;
+}
+
+/* ----------
+ * toast_decompress_datum -
+ *
+ * Decompress a compressed version of a varlena datum
+ */
+static struct varlena *
+toast_decompress_datum(struct varlena *attr)
+{
+	struct varlena *result;
+
+	Assert(VARATT_IS_COMPRESSED(attr));
+
+	result = (struct varlena *)
+		palloc(TOAST_COMPRESS_RAWSIZE(attr) + VARHDRSZ);
+	SET_VARSIZE(result, TOAST_COMPRESS_RAWSIZE(attr) + VARHDRSZ);
+
+	if (pglz_decompress(TOAST_COMPRESS_RAWDATA(attr),
+						VARSIZE(attr) - TOAST_COMPRESS_HDRSZ,
+						VARDATA(result),
+						TOAST_COMPRESS_RAWSIZE(attr), true) < 0)
+		elog(ERROR, "compressed data is corrupted");
+
+	return result;
+}
+
+
+/* ----------
+ * toast_decompress_datum_slice -
+ *
+ * Decompress the front of a compressed version of a varlena datum.
+ * offset handling happens in heap_tuple_untoast_attr_slice.
+ * Here we just decompress a slice from the front.
+ */
+static struct varlena *
+toast_decompress_datum_slice(struct varlena *attr, int32 slicelength)
+{
+	struct varlena *result;
+	int32		rawsize;
+
+	Assert(VARATT_IS_COMPRESSED(attr));
+
+	result = (struct varlena *) palloc(slicelength + VARHDRSZ);
+
+	rawsize = pglz_decompress(TOAST_COMPRESS_RAWDATA(attr),
+							  VARSIZE(attr) - TOAST_COMPRESS_HDRSZ,
+							  VARDATA(result),
+							  slicelength, false);
+	if (rawsize < 0)
+		elog(ERROR, "compressed data is corrupted");
+
+	SET_VARSIZE(result, rawsize + VARHDRSZ);
+	return result;
+}
+
+/* ----------
+ * toast_raw_datum_size -
+ *
+ *	Return the raw (detoasted) size of a varlena datum
+ *	(including the VARHDRSZ header)
+ * ----------
+ */
+Size
+toast_raw_datum_size(Datum value)
+{
+	struct varlena *attr = (struct varlena *) DatumGetPointer(value);
+	Size		result;
+
+	if (VARATT_IS_EXTERNAL_ONDISK(attr))
+	{
+		/* va_rawsize is the size of the original datum -- including header */
+		struct varatt_external toast_pointer;
+
+		VARATT_EXTERNAL_GET_POINTER(toast_pointer, attr);
+		result = toast_pointer.va_rawsize;
+	}
+	else if (VARATT_IS_EXTERNAL_INDIRECT(attr))
+	{
+		struct varatt_indirect toast_pointer;
+
+		VARATT_EXTERNAL_GET_POINTER(toast_pointer, attr);
+
+		/* nested indirect Datums aren't allowed */
+		Assert(!VARATT_IS_EXTERNAL_INDIRECT(toast_pointer.pointer));
+
+		return toast_raw_datum_size(PointerGetDatum(toast_pointer.pointer));
+	}
+	else if (VARATT_IS_EXTERNAL_EXPANDED(attr))
+	{
+		result = EOH_get_flat_size(DatumGetEOHP(value));
+	}
+	else if (VARATT_IS_COMPRESSED(attr))
+	{
+		/* here, va_rawsize is just the payload size */
+		result = VARRAWSIZE_4B_C(attr) + VARHDRSZ;
+	}
+	else if (VARATT_IS_SHORT(attr))
+	{
+		/*
+		 * we have to normalize the header length to VARHDRSZ or else the
+		 * callers of this function will be confused.
+		 */
+		result = VARSIZE_SHORT(attr) - VARHDRSZ_SHORT + VARHDRSZ;
+	}
+	else
+	{
+		/* plain untoasted datum */
+		result = VARSIZE(attr);
+	}
+	return result;
+}
+
+/* ----------
+ * toast_datum_size
+ *
+ *	Return the physical storage size (possibly compressed) of a varlena datum
+ * ----------
+ */
+Size
+toast_datum_size(Datum value)
+{
+	struct varlena *attr = (struct varlena *) DatumGetPointer(value);
+	Size		result;
+
+	if (VARATT_IS_EXTERNAL_ONDISK(attr))
+	{
+		/*
+		 * Attribute is stored externally - return the extsize whether
+		 * compressed or not.  We do not count the size of the toast pointer
+		 * ... should we?
+		 */
+		struct varatt_external toast_pointer;
+
+		VARATT_EXTERNAL_GET_POINTER(toast_pointer, attr);
+		result = toast_pointer.va_extsize;
+	}
+	else if (VARATT_IS_EXTERNAL_INDIRECT(attr))
+	{
+		struct varatt_indirect toast_pointer;
+
+		VARATT_EXTERNAL_GET_POINTER(toast_pointer, attr);
+
+		/* nested indirect Datums aren't allowed */
+		Assert(!VARATT_IS_EXTERNAL_INDIRECT(attr));
+
+		return toast_datum_size(PointerGetDatum(toast_pointer.pointer));
+	}
+	else if (VARATT_IS_EXTERNAL_EXPANDED(attr))
+	{
+		result = EOH_get_flat_size(DatumGetEOHP(value));
+	}
+	else if (VARATT_IS_SHORT(attr))
+	{
+		result = VARSIZE_SHORT(attr);
+	}
+	else
+	{
+		/*
+		 * Attribute is stored inline either compressed or not, just calculate
+		 * the size of the datum in either case.
+		 */
+		result = VARSIZE(attr);
+	}
+	return result;
+}
diff --git a/src/backend/access/common/heaptuple.c b/src/backend/access/common/heaptuple.c
index a48a6cd757..cc948958d7 100644
--- a/src/backend/access/common/heaptuple.c
+++ b/src/backend/access/common/heaptuple.c
@@ -18,7 +18,7 @@
  * (In performance-critical code paths we can use pg_detoast_datum_packed
  * and the appropriate access macros to avoid that overhead.)  Note that this
  * conversion is performed directly in heap_form_tuple, without invoking
- * tuptoaster.c.
+ * heaptoast.c.
  *
  * This change will break any code that assumes it needn't detoast values
  * that have been put into a tuple but never sent to disk.  Hopefully there
@@ -57,9 +57,9 @@
 
 #include "postgres.h"
 
+#include "access/heaptoast.h"
 #include "access/sysattr.h"
 #include "access/tupdesc_details.h"
-#include "access/tuptoaster.h"
 #include "executor/tuptable.h"
 #include "utils/expandeddatum.h"
 
diff --git a/src/backend/access/common/indextuple.c b/src/backend/access/common/indextuple.c
index cb23be859d..07586201b9 100644
--- a/src/backend/access/common/indextuple.c
+++ b/src/backend/access/common/indextuple.c
@@ -16,10 +16,17 @@
 
 #include "postgres.h"
 
+#include "access/detoast.h"
+#include "access/heaptoast.h"
 #include "access/htup_details.h"
 #include "access/itup.h"
-#include "access/tuptoaster.h"
+#include "access/toast_internals.h"
 
+/*
+ * This enables de-toasting of index entries.  Needed until VACUUM is
+ * smart enough to rebuild indexes from scratch.
+ */
+#define TOAST_INDEX_HACK
 
 /* ----------------------------------------------------------------
  *				  index_ tuple interface routines
diff --git a/src/backend/access/common/reloptions.c b/src/backend/access/common/reloptions.c
index 42647b0526..20f4ed3c38 100644
--- a/src/backend/access/common/reloptions.c
+++ b/src/backend/access/common/reloptions.c
@@ -19,11 +19,11 @@
 
 #include "access/gist_private.h"
 #include "access/hash.h"
+#include "access/heaptoast.h"
 #include "access/htup_details.h"
 #include "access/nbtree.h"
 #include "access/reloptions.h"
 #include "access/spgist.h"
-#include "access/tuptoaster.h"
 #include "catalog/pg_type.h"
 #include "commands/defrem.h"
 #include "commands/tablespace.h"
diff --git a/src/backend/access/common/toast_internals.c b/src/backend/access/common/toast_internals.c
new file mode 100644
index 0000000000..a971242490
--- /dev/null
+++ b/src/backend/access/common/toast_internals.c
@@ -0,0 +1,632 @@
+/*-------------------------------------------------------------------------
+ *
+ * toast_internals.c
+ *	  Functions for internal use by the TOAST system.
+ *
+ * Copyright (c) 2000-2019, PostgreSQL Global Development Group
+ *
+ * IDENTIFICATION
+ *	  src/backend/access/common/toast_internals.c
+ *
+ *-------------------------------------------------------------------------
+ */
+
+#include "postgres.h"
+
+#include "access/detoast.h"
+#include "access/genam.h"
+#include "access/heapam.h"
+#include "access/heaptoast.h"
+#include "access/table.h"
+#include "access/toast_internals.h"
+#include "access/xact.h"
+#include "catalog/catalog.h"
+#include "common/pg_lzcompress.h"
+#include "miscadmin.h"
+#include "utils/fmgroids.h"
+#include "utils/rel.h"
+#include "utils/snapmgr.h"
+
+static bool toastrel_valueid_exists(Relation toastrel, Oid valueid);
+static bool toastid_valueid_exists(Oid toastrelid, Oid valueid);
+
+/* ----------
+ * toast_compress_datum -
+ *
+ *	Create a compressed version of a varlena datum
+ *
+ *	If we fail (ie, compressed result is actually bigger than original)
+ *	then return NULL.  We must not use compressed data if it'd expand
+ *	the tuple!
+ *
+ *	We use VAR{SIZE,DATA}_ANY so we can handle short varlenas here without
+ *	copying them.  But we can't handle external or compressed datums.
+ * ----------
+ */
+Datum
+toast_compress_datum(Datum value)
+{
+	struct varlena *tmp;
+	int32		valsize = VARSIZE_ANY_EXHDR(DatumGetPointer(value));
+	int32		len;
+
+	Assert(!VARATT_IS_EXTERNAL(DatumGetPointer(value)));
+	Assert(!VARATT_IS_COMPRESSED(DatumGetPointer(value)));
+
+	/*
+	 * No point in wasting a palloc cycle if value size is out of the allowed
+	 * range for compression
+	 */
+	if (valsize < PGLZ_strategy_default->min_input_size ||
+		valsize > PGLZ_strategy_default->max_input_size)
+		return PointerGetDatum(NULL);
+
+	tmp = (struct varlena *) palloc(PGLZ_MAX_OUTPUT(valsize) +
+									TOAST_COMPRESS_HDRSZ);
+
+	/*
+	 * We recheck the actual size even if pglz_compress() reports success,
+	 * because it might be satisfied with having saved as little as one byte
+	 * in the compressed data --- which could turn into a net loss once you
+	 * consider header and alignment padding.  Worst case, the compressed
+	 * format might require three padding bytes (plus header, which is
+	 * included in VARSIZE(tmp)), whereas the uncompressed format would take
+	 * only one header byte and no padding if the value is short enough.  So
+	 * we insist on a savings of more than 2 bytes to ensure we have a gain.
+	 */
+	len = pglz_compress(VARDATA_ANY(DatumGetPointer(value)),
+						valsize,
+						TOAST_COMPRESS_RAWDATA(tmp),
+						PGLZ_strategy_default);
+	if (len >= 0 &&
+		len + TOAST_COMPRESS_HDRSZ < valsize - 2)
+	{
+		TOAST_COMPRESS_SET_RAWSIZE(tmp, valsize);
+		SET_VARSIZE_COMPRESSED(tmp, len + TOAST_COMPRESS_HDRSZ);
+		/* successful compression */
+		return PointerGetDatum(tmp);
+	}
+	else
+	{
+		/* incompressible data */
+		pfree(tmp);
+		return PointerGetDatum(NULL);
+	}
+}
+
+/* ----------
+ * toast_save_datum -
+ *
+ *	Save one single datum into the secondary relation and return
+ *	a Datum reference for it.
+ *
+ * rel: the main relation we're working with (not the toast rel!)
+ * value: datum to be pushed to toast storage
+ * oldexternal: if not NULL, toast pointer previously representing the datum
+ * options: options to be passed to heap_insert() for toast rows
+ * ----------
+ */
+Datum
+toast_save_datum(Relation rel, Datum value,
+				 struct varlena *oldexternal, int options)
+{
+	Relation	toastrel;
+	Relation   *toastidxs;
+	HeapTuple	toasttup;
+	TupleDesc	toasttupDesc;
+	Datum		t_values[3];
+	bool		t_isnull[3];
+	CommandId	mycid = GetCurrentCommandId(true);
+	struct varlena *result;
+	struct varatt_external toast_pointer;
+	union
+	{
+		struct varlena hdr;
+		/* this is to make the union big enough for a chunk: */
+		char		data[TOAST_MAX_CHUNK_SIZE + VARHDRSZ];
+		/* ensure union is aligned well enough: */
+		int32		align_it;
+	}			chunk_data;
+	int32		chunk_size;
+	int32		chunk_seq = 0;
+	char	   *data_p;
+	int32		data_todo;
+	Pointer		dval = DatumGetPointer(value);
+	int			num_indexes;
+	int			validIndex;
+
+	Assert(!VARATT_IS_EXTERNAL(value));
+
+	/*
+	 * Open the toast relation and its indexes.  We can use the index to check
+	 * uniqueness of the OID we assign to the toasted item, even though it has
+	 * additional columns besides OID.
+	 */
+	toastrel = table_open(rel->rd_rel->reltoastrelid, RowExclusiveLock);
+	toasttupDesc = toastrel->rd_att;
+
+	/* Open all the toast indexes and look for the valid one */
+	validIndex = toast_open_indexes(toastrel,
+									RowExclusiveLock,
+									&toastidxs,
+									&num_indexes);
+
+	/*
+	 * Get the data pointer and length, and compute va_rawsize and va_extsize.
+	 *
+	 * va_rawsize is the size of the equivalent fully uncompressed datum, so
+	 * we have to adjust for short headers.
+	 *
+	 * va_extsize is the actual size of the data payload in the toast records.
+	 */
+	if (VARATT_IS_SHORT(dval))
+	{
+		data_p = VARDATA_SHORT(dval);
+		data_todo = VARSIZE_SHORT(dval) - VARHDRSZ_SHORT;
+		toast_pointer.va_rawsize = data_todo + VARHDRSZ;	/* as if not short */
+		toast_pointer.va_extsize = data_todo;
+	}
+	else if (VARATT_IS_COMPRESSED(dval))
+	{
+		data_p = VARDATA(dval);
+		data_todo = VARSIZE(dval) - VARHDRSZ;
+		/* rawsize in a compressed datum is just the size of the payload */
+		toast_pointer.va_rawsize = VARRAWSIZE_4B_C(dval) + VARHDRSZ;
+		toast_pointer.va_extsize = data_todo;
+		/* Assert that the numbers look like it's compressed */
+		Assert(VARATT_EXTERNAL_IS_COMPRESSED(toast_pointer));
+	}
+	else
+	{
+		data_p = VARDATA(dval);
+		data_todo = VARSIZE(dval) - VARHDRSZ;
+		toast_pointer.va_rawsize = VARSIZE(dval);
+		toast_pointer.va_extsize = data_todo;
+	}
+
+	/*
+	 * Insert the correct table OID into the result TOAST pointer.
+	 *
+	 * Normally this is the actual OID of the target toast table, but during
+	 * table-rewriting operations such as CLUSTER, we have to insert the OID
+	 * of the table's real permanent toast table instead.  rd_toastoid is set
+	 * if we have to substitute such an OID.
+	 */
+	if (OidIsValid(rel->rd_toastoid))
+		toast_pointer.va_toastrelid = rel->rd_toastoid;
+	else
+		toast_pointer.va_toastrelid = RelationGetRelid(toastrel);
+
+	/*
+	 * Choose an OID to use as the value ID for this toast value.
+	 *
+	 * Normally we just choose an unused OID within the toast table.  But
+	 * during table-rewriting operations where we are preserving an existing
+	 * toast table OID, we want to preserve toast value OIDs too.  So, if
+	 * rd_toastoid is set and we had a prior external value from that same
+	 * toast table, re-use its value ID.  If we didn't have a prior external
+	 * value (which is a corner case, but possible if the table's attstorage
+	 * options have been changed), we have to pick a value ID that doesn't
+	 * conflict with either new or existing toast value OIDs.
+	 */
+	if (!OidIsValid(rel->rd_toastoid))
+	{
+		/* normal case: just choose an unused OID */
+		toast_pointer.va_valueid =
+			GetNewOidWithIndex(toastrel,
+							   RelationGetRelid(toastidxs[validIndex]),
+							   (AttrNumber) 1);
+	}
+	else
+	{
+		/* rewrite case: check to see if value was in old toast table */
+		toast_pointer.va_valueid = InvalidOid;
+		if (oldexternal != NULL)
+		{
+			struct varatt_external old_toast_pointer;
+
+			Assert(VARATT_IS_EXTERNAL_ONDISK(oldexternal));
+			/* Must copy to access aligned fields */
+			VARATT_EXTERNAL_GET_POINTER(old_toast_pointer, oldexternal);
+			if (old_toast_pointer.va_toastrelid == rel->rd_toastoid)
+			{
+				/* This value came from the old toast table; reuse its OID */
+				toast_pointer.va_valueid = old_toast_pointer.va_valueid;
+
+				/*
+				 * There is a corner case here: the table rewrite might have
+				 * to copy both live and recently-dead versions of a row, and
+				 * those versions could easily reference the same toast value.
+				 * When we copy the second or later version of such a row,
+				 * reusing the OID will mean we select an OID that's already
+				 * in the new toast table.  Check for that, and if so, just
+				 * fall through without writing the data again.
+				 *
+				 * While annoying and ugly-looking, this is a good thing
+				 * because it ensures that we wind up with only one copy of
+				 * the toast value when there is only one copy in the old
+				 * toast table.  Before we detected this case, we'd have made
+				 * multiple copies, wasting space; and what's worse, the
+				 * copies belonging to already-deleted heap tuples would not
+				 * be reclaimed by VACUUM.
+				 */
+				if (toastrel_valueid_exists(toastrel,
+											toast_pointer.va_valueid))
+				{
+					/* Match, so short-circuit the data storage loop below */
+					data_todo = 0;
+				}
+			}
+		}
+		if (toast_pointer.va_valueid == InvalidOid)
+		{
+			/*
+			 * new value; must choose an OID that doesn't conflict in either
+			 * old or new toast table
+			 */
+			do
+			{
+				toast_pointer.va_valueid =
+					GetNewOidWithIndex(toastrel,
+									   RelationGetRelid(toastidxs[validIndex]),
+									   (AttrNumber) 1);
+			} while (toastid_valueid_exists(rel->rd_toastoid,
+											toast_pointer.va_valueid));
+		}
+	}
+
+	/*
+	 * Initialize constant parts of the tuple data
+	 */
+	t_values[0] = ObjectIdGetDatum(toast_pointer.va_valueid);
+	t_values[2] = PointerGetDatum(&chunk_data);
+	t_isnull[0] = false;
+	t_isnull[1] = false;
+	t_isnull[2] = false;
+
+	/*
+	 * Split up the item into chunks
+	 */
+	while (data_todo > 0)
+	{
+		int			i;
+
+		CHECK_FOR_INTERRUPTS();
+
+		/*
+		 * Calculate the size of this chunk
+		 */
+		chunk_size = Min(TOAST_MAX_CHUNK_SIZE, data_todo);
+
+		/*
+		 * Build a tuple and store it
+		 */
+		t_values[1] = Int32GetDatum(chunk_seq++);
+		SET_VARSIZE(&chunk_data, chunk_size + VARHDRSZ);
+		memcpy(VARDATA(&chunk_data), data_p, chunk_size);
+		toasttup = heap_form_tuple(toasttupDesc, t_values, t_isnull);
+
+		heap_insert(toastrel, toasttup, mycid, options, NULL);
+
+		/*
+		 * Create the index entry.  We cheat a little here by not using
+		 * FormIndexDatum: this relies on the knowledge that the index columns
+		 * are the same as the initial columns of the table for all the
+		 * indexes.  We also cheat by not providing an IndexInfo: this is okay
+		 * for now because btree doesn't need one, but we might have to be
+		 * more honest someday.
+		 *
+		 * Note also that there had better not be any user-created index on
+		 * the TOAST table, since we don't bother to update anything else.
+		 */
+		for (i = 0; i < num_indexes; i++)
+		{
+			/* Only index relations marked as ready can be updated */
+			if (toastidxs[i]->rd_index->indisready)
+				index_insert(toastidxs[i], t_values, t_isnull,
+							 &(toasttup->t_self),
+							 toastrel,
+							 toastidxs[i]->rd_index->indisunique ?
+							 UNIQUE_CHECK_YES : UNIQUE_CHECK_NO,
+							 NULL);
+		}
+
+		/*
+		 * Free memory
+		 */
+		heap_freetuple(toasttup);
+
+		/*
+		 * Move on to next chunk
+		 */
+		data_todo -= chunk_size;
+		data_p += chunk_size;
+	}
+
+	/*
+	 * Done - close toast relation and its indexes
+	 */
+	toast_close_indexes(toastidxs, num_indexes, RowExclusiveLock);
+	table_close(toastrel, RowExclusiveLock);
+
+	/*
+	 * Create the TOAST pointer value that we'll return
+	 */
+	result = (struct varlena *) palloc(TOAST_POINTER_SIZE);
+	SET_VARTAG_EXTERNAL(result, VARTAG_ONDISK);
+	memcpy(VARDATA_EXTERNAL(result), &toast_pointer, sizeof(toast_pointer));
+
+	return PointerGetDatum(result);
+}
+
+/* ----------
+ * toast_delete_datum -
+ *
+ *	Delete a single external stored value.
+ * ----------
+ */
+void
+toast_delete_datum(Relation rel, Datum value, bool is_speculative)
+{
+	struct varlena *attr = (struct varlena *) DatumGetPointer(value);
+	struct varatt_external toast_pointer;
+	Relation	toastrel;
+	Relation   *toastidxs;
+	ScanKeyData toastkey;
+	SysScanDesc toastscan;
+	HeapTuple	toasttup;
+	int			num_indexes;
+	int			validIndex;
+	SnapshotData SnapshotToast;
+
+	if (!VARATT_IS_EXTERNAL_ONDISK(attr))
+		return;
+
+	/* Must copy to access aligned fields */
+	VARATT_EXTERNAL_GET_POINTER(toast_pointer, attr);
+
+	/*
+	 * Open the toast relation and its indexes
+	 */
+	toastrel = table_open(toast_pointer.va_toastrelid, RowExclusiveLock);
+
+	/* Fetch valid relation used for process */
+	validIndex = toast_open_indexes(toastrel,
+									RowExclusiveLock,
+									&toastidxs,
+									&num_indexes);
+
+	/*
+	 * Setup a scan key to find chunks with matching va_valueid
+	 */
+	ScanKeyInit(&toastkey,
+				(AttrNumber) 1,
+				BTEqualStrategyNumber, F_OIDEQ,
+				ObjectIdGetDatum(toast_pointer.va_valueid));
+
+	/*
+	 * Find all the chunks.  (We don't actually care whether we see them in
+	 * sequence or not, but since we've already locked the index we might as
+	 * well use systable_beginscan_ordered.)
+	 */
+	init_toast_snapshot(&SnapshotToast);
+	toastscan = systable_beginscan_ordered(toastrel, toastidxs[validIndex],
+										   &SnapshotToast, 1, &toastkey);
+	while ((toasttup = systable_getnext_ordered(toastscan, ForwardScanDirection)) != NULL)
+	{
+		/*
+		 * Have a chunk, delete it
+		 */
+		if (is_speculative)
+			heap_abort_speculative(toastrel, &toasttup->t_self);
+		else
+			simple_heap_delete(toastrel, &toasttup->t_self);
+	}
+
+	/*
+	 * End scan and close relations
+	 */
+	systable_endscan_ordered(toastscan);
+	toast_close_indexes(toastidxs, num_indexes, RowExclusiveLock);
+	table_close(toastrel, RowExclusiveLock);
+}
+
+/* ----------
+ * toastrel_valueid_exists -
+ *
+ *	Test whether a toast value with the given ID exists in the toast relation.
+ *	For safety, we consider a value to exist if there are either live or dead
+ *	toast rows with that ID; see notes for GetNewOidWithIndex().
+ * ----------
+ */
+static bool
+toastrel_valueid_exists(Relation toastrel, Oid valueid)
+{
+	bool		result = false;
+	ScanKeyData toastkey;
+	SysScanDesc toastscan;
+	int			num_indexes;
+	int			validIndex;
+	Relation   *toastidxs;
+
+	/* Fetch a valid index relation */
+	validIndex = toast_open_indexes(toastrel,
+									RowExclusiveLock,
+									&toastidxs,
+									&num_indexes);
+
+	/*
+	 * Setup a scan key to find chunks with matching va_valueid
+	 */
+	ScanKeyInit(&toastkey,
+				(AttrNumber) 1,
+				BTEqualStrategyNumber, F_OIDEQ,
+				ObjectIdGetDatum(valueid));
+
+	/*
+	 * Is there any such chunk?
+	 */
+	toastscan = systable_beginscan(toastrel,
+								   RelationGetRelid(toastidxs[validIndex]),
+								   true, SnapshotAny, 1, &toastkey);
+
+	if (systable_getnext(toastscan) != NULL)
+		result = true;
+
+	systable_endscan(toastscan);
+
+	/* Clean up */
+	toast_close_indexes(toastidxs, num_indexes, RowExclusiveLock);
+
+	return result;
+}
+
+/* ----------
+ * toastid_valueid_exists -
+ *
+ *	As above, but work from toast rel's OID not an open relation
+ * ----------
+ */
+static bool
+toastid_valueid_exists(Oid toastrelid, Oid valueid)
+{
+	bool		result;
+	Relation	toastrel;
+
+	toastrel = table_open(toastrelid, AccessShareLock);
+
+	result = toastrel_valueid_exists(toastrel, valueid);
+
+	table_close(toastrel, AccessShareLock);
+
+	return result;
+}
+
+/* ----------
+ * toast_get_valid_index
+ *
+ *	Get OID of valid index associated to given toast relation. A toast
+ *	relation can have only one valid index at the same time.
+ */
+Oid
+toast_get_valid_index(Oid toastoid, LOCKMODE lock)
+{
+	int			num_indexes;
+	int			validIndex;
+	Oid			validIndexOid;
+	Relation   *toastidxs;
+	Relation	toastrel;
+
+	/* Open the toast relation */
+	toastrel = table_open(toastoid, lock);
+
+	/* Look for the valid index of the toast relation */
+	validIndex = toast_open_indexes(toastrel,
+									lock,
+									&toastidxs,
+									&num_indexes);
+	validIndexOid = RelationGetRelid(toastidxs[validIndex]);
+
+	/* Close the toast relation and all its indexes */
+	toast_close_indexes(toastidxs, num_indexes, lock);
+	table_close(toastrel, lock);
+
+	return validIndexOid;
+}
+
+/* ----------
+ * toast_open_indexes
+ *
+ *	Get an array of the indexes associated to the given toast relation
+ *	and return as well the position of the valid index used by the toast
+ *	relation in this array. It is the responsibility of the caller of this
+ *	function to close the indexes as well as free them.
+ */
+int
+toast_open_indexes(Relation toastrel,
+				   LOCKMODE lock,
+				   Relation **toastidxs,
+				   int *num_indexes)
+{
+	int			i = 0;
+	int			res = 0;
+	bool		found = false;
+	List	   *indexlist;
+	ListCell   *lc;
+
+	/* Get index list of the toast relation */
+	indexlist = RelationGetIndexList(toastrel);
+	Assert(indexlist != NIL);
+
+	*num_indexes = list_length(indexlist);
+
+	/* Open all the index relations */
+	*toastidxs = (Relation *) palloc(*num_indexes * sizeof(Relation));
+	foreach(lc, indexlist)
+		(*toastidxs)[i++] = index_open(lfirst_oid(lc), lock);
+
+	/* Fetch the first valid index in list */
+	for (i = 0; i < *num_indexes; i++)
+	{
+		Relation	toastidx = (*toastidxs)[i];
+
+		if (toastidx->rd_index->indisvalid)
+		{
+			res = i;
+			found = true;
+			break;
+		}
+	}
+
+	/*
+	 * Free index list, not necessary anymore as relations are opened and a
+	 * valid index has been found.
+	 */
+	list_free(indexlist);
+
+	/*
+	 * The toast relation should have one valid index, so something is going
+	 * wrong if there is nothing.
+	 */
+	if (!found)
+		elog(ERROR, "no valid index found for toast relation with Oid %u",
+			 RelationGetRelid(toastrel));
+
+	return res;
+}
+
+/* ----------
+ * toast_close_indexes
+ *
+ *	Close an array of indexes for a toast relation and free it. This should
+ *	be called for a set of indexes opened previously with toast_open_indexes.
+ */
+void
+toast_close_indexes(Relation *toastidxs, int num_indexes, LOCKMODE lock)
+{
+	int			i;
+
+	/* Close relations and clean up things */
+	for (i = 0; i < num_indexes; i++)
+		index_close(toastidxs[i], lock);
+	pfree(toastidxs);
+}
+
+/* ----------
+ * init_toast_snapshot
+ *
+ *	Initialize an appropriate TOAST snapshot.  We must use an MVCC snapshot
+ *	to initialize the TOAST snapshot; since we don't know which one to use,
+ *	just use the oldest one.  This is safe: at worst, we will get a "snapshot
+ *	too old" error that might have been avoided otherwise.
+ */
+void
+init_toast_snapshot(Snapshot toast_snapshot)
+{
+	Snapshot	snapshot = GetOldestSnapshot();
+
+	if (snapshot == NULL)
+		elog(ERROR, "no known snapshots");
+
+	InitToastSnapshot(*toast_snapshot, snapshot->lsn, snapshot->whenTaken);
+}
diff --git a/src/backend/access/heap/Makefile b/src/backend/access/heap/Makefile
index b2a017249b..38497b09c0 100644
--- a/src/backend/access/heap/Makefile
+++ b/src/backend/access/heap/Makefile
@@ -13,6 +13,6 @@ top_builddir = ../../../..
 include $(top_builddir)/src/Makefile.global
 
 OBJS = heapam.o heapam_handler.o heapam_visibility.o hio.o pruneheap.o rewriteheap.o \
-	syncscan.o tuptoaster.o vacuumlazy.o visibilitymap.o
+	syncscan.o heaptoast.o vacuumlazy.o visibilitymap.o
 
 include $(top_srcdir)/src/backend/common.mk
diff --git a/src/backend/access/heap/heapam.c b/src/backend/access/heap/heapam.c
index 94309949fa..2c5f58d817 100644
--- a/src/backend/access/heap/heapam.c
+++ b/src/backend/access/heap/heapam.c
@@ -36,6 +36,7 @@
 #include "access/genam.h"
 #include "access/heapam.h"
 #include "access/heapam_xlog.h"
+#include "access/heaptoast.h"
 #include "access/hio.h"
 #include "access/multixact.h"
 #include "access/parallel.h"
@@ -43,7 +44,6 @@
 #include "access/sysattr.h"
 #include "access/tableam.h"
 #include "access/transam.h"
-#include "access/tuptoaster.h"
 #include "access/valid.h"
 #include "access/visibilitymap.h"
 #include "access/xact.h"
diff --git a/src/backend/access/heap/heapam_handler.c b/src/backend/access/heap/heapam_handler.c
index f1ff01e8cb..2dd8821fac 100644
--- a/src/backend/access/heap/heapam_handler.c
+++ b/src/backend/access/heap/heapam_handler.c
@@ -23,11 +23,11 @@
 
 #include "access/genam.h"
 #include "access/heapam.h"
+#include "access/heaptoast.h"
 #include "access/multixact.h"
 #include "access/rewriteheap.h"
 #include "access/tableam.h"
 #include "access/tsmapi.h"
-#include "access/tuptoaster.h"
 #include "access/xact.h"
 #include "catalog/catalog.h"
 #include "catalog/index.h"
diff --git a/src/backend/access/heap/heaptoast.c b/src/backend/access/heap/heaptoast.c
new file mode 100644
index 0000000000..5d105e3517
--- /dev/null
+++ b/src/backend/access/heap/heaptoast.c
@@ -0,0 +1,917 @@
+/*-------------------------------------------------------------------------
+ *
+ * heaptoast.c
+ *	  Heap-specific definitions for external and compressed storage
+ *	  of variable size attributes.
+ *
+ * Copyright (c) 2000-2019, PostgreSQL Global Development Group
+ *
+ *
+ * IDENTIFICATION
+ *	  src/backend/access/heap/heaptoast.c
+ *
+ *
+ * INTERFACE ROUTINES
+ *		toast_insert_or_update -
+ *			Try to make a given tuple fit into one page by compressing
+ *			or moving off attributes
+ *
+ *		toast_delete -
+ *			Reclaim toast storage when a tuple is deleted
+ *
+ *-------------------------------------------------------------------------
+ */
+
+#include "postgres.h"
+
+#include "access/detoast.h"
+#include "access/heapam.h"
+#include "access/heaptoast.h"
+#include "access/toast_internals.h"
+
+
+/* ----------
+ * toast_delete -
+ *
+ *	Cascaded delete toast-entries on DELETE
+ * ----------
+ */
+void
+toast_delete(Relation rel, HeapTuple oldtup, bool is_speculative)
+{
+	TupleDesc	tupleDesc;
+	int			numAttrs;
+	int			i;
+	Datum		toast_values[MaxHeapAttributeNumber];
+	bool		toast_isnull[MaxHeapAttributeNumber];
+
+	/*
+	 * We should only ever be called for tuples of plain relations or
+	 * materialized views --- recursing on a toast rel is bad news.
+	 */
+	Assert(rel->rd_rel->relkind == RELKIND_RELATION ||
+		   rel->rd_rel->relkind == RELKIND_MATVIEW);
+
+	/*
+	 * Get the tuple descriptor and break down the tuple into fields.
+	 *
+	 * NOTE: it's debatable whether to use heap_deform_tuple() here or just
+	 * heap_getattr() only the varlena columns.  The latter could win if there
+	 * are few varlena columns and many non-varlena ones. However,
+	 * heap_deform_tuple costs only O(N) while the heap_getattr way would cost
+	 * O(N^2) if there are many varlena columns, so it seems better to err on
+	 * the side of linear cost.  (We won't even be here unless there's at
+	 * least one varlena column, by the way.)
+	 */
+	tupleDesc = rel->rd_att;
+	numAttrs = tupleDesc->natts;
+
+	Assert(numAttrs <= MaxHeapAttributeNumber);
+	heap_deform_tuple(oldtup, tupleDesc, toast_values, toast_isnull);
+
+	/*
+	 * Check for external stored attributes and delete them from the secondary
+	 * relation.
+	 */
+	for (i = 0; i < numAttrs; i++)
+	{
+		if (TupleDescAttr(tupleDesc, i)->attlen == -1)
+		{
+			Datum		value = toast_values[i];
+
+			if (toast_isnull[i])
+				continue;
+			else if (VARATT_IS_EXTERNAL_ONDISK(PointerGetDatum(value)))
+				toast_delete_datum(rel, value, is_speculative);
+		}
+	}
+}
+
+
+/* ----------
+ * toast_insert_or_update -
+ *
+ *	Delete no-longer-used toast-entries and create new ones to
+ *	make the new tuple fit on INSERT or UPDATE
+ *
+ * Inputs:
+ *	newtup: the candidate new tuple to be inserted
+ *	oldtup: the old row version for UPDATE, or NULL for INSERT
+ *	options: options to be passed to heap_insert() for toast rows
+ * Result:
+ *	either newtup if no toasting is needed, or a palloc'd modified tuple
+ *	that is what should actually get stored
+ *
+ * NOTE: neither newtup nor oldtup will be modified.  This is a change
+ * from the pre-8.1 API of this routine.
+ * ----------
+ */
+HeapTuple
+toast_insert_or_update(Relation rel, HeapTuple newtup, HeapTuple oldtup,
+					   int options)
+{
+	HeapTuple	result_tuple;
+	TupleDesc	tupleDesc;
+	int			numAttrs;
+	int			i;
+
+	bool		need_change = false;
+	bool		need_free = false;
+	bool		need_delold = false;
+	bool		has_nulls = false;
+
+	Size		maxDataLen;
+	Size		hoff;
+
+	char		toast_action[MaxHeapAttributeNumber];
+	bool		toast_isnull[MaxHeapAttributeNumber];
+	bool		toast_oldisnull[MaxHeapAttributeNumber];
+	Datum		toast_values[MaxHeapAttributeNumber];
+	Datum		toast_oldvalues[MaxHeapAttributeNumber];
+	struct varlena *toast_oldexternal[MaxHeapAttributeNumber];
+	int32		toast_sizes[MaxHeapAttributeNumber];
+	bool		toast_free[MaxHeapAttributeNumber];
+	bool		toast_delold[MaxHeapAttributeNumber];
+
+	/*
+	 * Ignore the INSERT_SPECULATIVE option. Speculative insertions/super
+	 * deletions just normally insert/delete the toast values. It seems
+	 * easiest to deal with that here, instead on, potentially, multiple
+	 * callers.
+	 */
+	options &= ~HEAP_INSERT_SPECULATIVE;
+
+	/*
+	 * We should only ever be called for tuples of plain relations or
+	 * materialized views --- recursing on a toast rel is bad news.
+	 */
+	Assert(rel->rd_rel->relkind == RELKIND_RELATION ||
+		   rel->rd_rel->relkind == RELKIND_MATVIEW);
+
+	/*
+	 * Get the tuple descriptor and break down the tuple(s) into fields.
+	 */
+	tupleDesc = rel->rd_att;
+	numAttrs = tupleDesc->natts;
+
+	Assert(numAttrs <= MaxHeapAttributeNumber);
+	heap_deform_tuple(newtup, tupleDesc, toast_values, toast_isnull);
+	if (oldtup != NULL)
+		heap_deform_tuple(oldtup, tupleDesc, toast_oldvalues, toast_oldisnull);
+
+	/* ----------
+	 * Then collect information about the values given
+	 *
+	 * NOTE: toast_action[i] can have these values:
+	 *		' '		default handling
+	 *		'p'		already processed --- don't touch it
+	 *		'x'		incompressible, but OK to move off
+	 *
+	 * NOTE: toast_sizes[i] is only made valid for varlena attributes with
+	 *		toast_action[i] different from 'p'.
+	 * ----------
+	 */
+	memset(toast_action, ' ', numAttrs * sizeof(char));
+	memset(toast_oldexternal, 0, numAttrs * sizeof(struct varlena *));
+	memset(toast_free, 0, numAttrs * sizeof(bool));
+	memset(toast_delold, 0, numAttrs * sizeof(bool));
+
+	for (i = 0; i < numAttrs; i++)
+	{
+		Form_pg_attribute att = TupleDescAttr(tupleDesc, i);
+		struct varlena *old_value;
+		struct varlena *new_value;
+
+		if (oldtup != NULL)
+		{
+			/*
+			 * For UPDATE get the old and new values of this attribute
+			 */
+			old_value = (struct varlena *) DatumGetPointer(toast_oldvalues[i]);
+			new_value = (struct varlena *) DatumGetPointer(toast_values[i]);
+
+			/*
+			 * If the old value is stored on disk, check if it has changed so
+			 * we have to delete it later.
+			 */
+			if (att->attlen == -1 && !toast_oldisnull[i] &&
+				VARATT_IS_EXTERNAL_ONDISK(old_value))
+			{
+				if (toast_isnull[i] || !VARATT_IS_EXTERNAL_ONDISK(new_value) ||
+					memcmp((char *) old_value, (char *) new_value,
+						   VARSIZE_EXTERNAL(old_value)) != 0)
+				{
+					/*
+					 * The old external stored value isn't needed any more
+					 * after the update
+					 */
+					toast_delold[i] = true;
+					need_delold = true;
+				}
+				else
+				{
+					/*
+					 * This attribute isn't changed by this update so we reuse
+					 * the original reference to the old value in the new
+					 * tuple.
+					 */
+					toast_action[i] = 'p';
+					continue;
+				}
+			}
+		}
+		else
+		{
+			/*
+			 * For INSERT simply get the new value
+			 */
+			new_value = (struct varlena *) DatumGetPointer(toast_values[i]);
+		}
+
+		/*
+		 * Handle NULL attributes
+		 */
+		if (toast_isnull[i])
+		{
+			toast_action[i] = 'p';
+			has_nulls = true;
+			continue;
+		}
+
+		/*
+		 * Now look at varlena attributes
+		 */
+		if (att->attlen == -1)
+		{
+			/*
+			 * If the table's attribute says PLAIN always, force it so.
+			 */
+			if (att->attstorage == 'p')
+				toast_action[i] = 'p';
+
+			/*
+			 * We took care of UPDATE above, so any external value we find
+			 * still in the tuple must be someone else's that we cannot reuse
+			 * (this includes the case of an out-of-line in-memory datum).
+			 * Fetch it back (without decompression, unless we are forcing
+			 * PLAIN storage).  If necessary, we'll push it out as a new
+			 * external value below.
+			 */
+			if (VARATT_IS_EXTERNAL(new_value))
+			{
+				toast_oldexternal[i] = new_value;
+				if (att->attstorage == 'p')
+					new_value = heap_tuple_untoast_attr(new_value);
+				else
+					new_value = heap_tuple_fetch_attr(new_value);
+				toast_values[i] = PointerGetDatum(new_value);
+				toast_free[i] = true;
+				need_change = true;
+				need_free = true;
+			}
+
+			/*
+			 * Remember the size of this attribute
+			 */
+			toast_sizes[i] = VARSIZE_ANY(new_value);
+		}
+		else
+		{
+			/*
+			 * Not a varlena attribute, plain storage always
+			 */
+			toast_action[i] = 'p';
+		}
+	}
+
+	/* ----------
+	 * Compress and/or save external until data fits into target length
+	 *
+	 *	1: Inline compress attributes with attstorage 'x', and store very
+	 *	   large attributes with attstorage 'x' or 'e' external immediately
+	 *	2: Store attributes with attstorage 'x' or 'e' external
+	 *	3: Inline compress attributes with attstorage 'm'
+	 *	4: Store attributes with attstorage 'm' external
+	 * ----------
+	 */
+
+	/* compute header overhead --- this should match heap_form_tuple() */
+	hoff = SizeofHeapTupleHeader;
+	if (has_nulls)
+		hoff += BITMAPLEN(numAttrs);
+	hoff = MAXALIGN(hoff);
+	/* now convert to a limit on the tuple data size */
+	maxDataLen = RelationGetToastTupleTarget(rel, TOAST_TUPLE_TARGET) - hoff;
+
+	/*
+	 * Look for attributes with attstorage 'x' to compress.  Also find large
+	 * attributes with attstorage 'x' or 'e', and store them external.
+	 */
+	while (heap_compute_data_size(tupleDesc,
+								  toast_values, toast_isnull) > maxDataLen)
+	{
+		int			biggest_attno = -1;
+		int32		biggest_size = MAXALIGN(TOAST_POINTER_SIZE);
+		Datum		old_value;
+		Datum		new_value;
+
+		/*
+		 * Search for the biggest yet unprocessed internal attribute
+		 */
+		for (i = 0; i < numAttrs; i++)
+		{
+			Form_pg_attribute att = TupleDescAttr(tupleDesc, i);
+
+			if (toast_action[i] != ' ')
+				continue;
+			if (VARATT_IS_EXTERNAL(DatumGetPointer(toast_values[i])))
+				continue;		/* can't happen, toast_action would be 'p' */
+			if (VARATT_IS_COMPRESSED(DatumGetPointer(toast_values[i])))
+				continue;
+			if (att->attstorage != 'x' && att->attstorage != 'e')
+				continue;
+			if (toast_sizes[i] > biggest_size)
+			{
+				biggest_attno = i;
+				biggest_size = toast_sizes[i];
+			}
+		}
+
+		if (biggest_attno < 0)
+			break;
+
+		/*
+		 * Attempt to compress it inline, if it has attstorage 'x'
+		 */
+		i = biggest_attno;
+		if (TupleDescAttr(tupleDesc, i)->attstorage == 'x')
+		{
+			old_value = toast_values[i];
+			new_value = toast_compress_datum(old_value);
+
+			if (DatumGetPointer(new_value) != NULL)
+			{
+				/* successful compression */
+				if (toast_free[i])
+					pfree(DatumGetPointer(old_value));
+				toast_values[i] = new_value;
+				toast_free[i] = true;
+				toast_sizes[i] = VARSIZE(DatumGetPointer(toast_values[i]));
+				need_change = true;
+				need_free = true;
+			}
+			else
+			{
+				/* incompressible, ignore on subsequent compression passes */
+				toast_action[i] = 'x';
+			}
+		}
+		else
+		{
+			/* has attstorage 'e', ignore on subsequent compression passes */
+			toast_action[i] = 'x';
+		}
+
+		/*
+		 * If this value is by itself more than maxDataLen (after compression
+		 * if any), push it out to the toast table immediately, if possible.
+		 * This avoids uselessly compressing other fields in the common case
+		 * where we have one long field and several short ones.
+		 *
+		 * XXX maybe the threshold should be less than maxDataLen?
+		 */
+		if (toast_sizes[i] > maxDataLen &&
+			rel->rd_rel->reltoastrelid != InvalidOid)
+		{
+			old_value = toast_values[i];
+			toast_action[i] = 'p';
+			toast_values[i] = toast_save_datum(rel, toast_values[i],
+											   toast_oldexternal[i], options);
+			if (toast_free[i])
+				pfree(DatumGetPointer(old_value));
+			toast_free[i] = true;
+			need_change = true;
+			need_free = true;
+		}
+	}
+
+	/*
+	 * Second we look for attributes of attstorage 'x' or 'e' that are still
+	 * inline.  But skip this if there's no toast table to push them to.
+	 */
+	while (heap_compute_data_size(tupleDesc,
+								  toast_values, toast_isnull) > maxDataLen &&
+		   rel->rd_rel->reltoastrelid != InvalidOid)
+	{
+		int			biggest_attno = -1;
+		int32		biggest_size = MAXALIGN(TOAST_POINTER_SIZE);
+		Datum		old_value;
+
+		/*------
+		 * Search for the biggest yet inlined attribute with
+		 * attstorage equals 'x' or 'e'
+		 *------
+		 */
+		for (i = 0; i < numAttrs; i++)
+		{
+			Form_pg_attribute att = TupleDescAttr(tupleDesc, i);
+
+			if (toast_action[i] == 'p')
+				continue;
+			if (VARATT_IS_EXTERNAL(DatumGetPointer(toast_values[i])))
+				continue;		/* can't happen, toast_action would be 'p' */
+			if (att->attstorage != 'x' && att->attstorage != 'e')
+				continue;
+			if (toast_sizes[i] > biggest_size)
+			{
+				biggest_attno = i;
+				biggest_size = toast_sizes[i];
+			}
+		}
+
+		if (biggest_attno < 0)
+			break;
+
+		/*
+		 * Store this external
+		 */
+		i = biggest_attno;
+		old_value = toast_values[i];
+		toast_action[i] = 'p';
+		toast_values[i] = toast_save_datum(rel, toast_values[i],
+										   toast_oldexternal[i], options);
+		if (toast_free[i])
+			pfree(DatumGetPointer(old_value));
+		toast_free[i] = true;
+
+		need_change = true;
+		need_free = true;
+	}
+
+	/*
+	 * Round 3 - this time we take attributes with storage 'm' into
+	 * compression
+	 */
+	while (heap_compute_data_size(tupleDesc,
+								  toast_values, toast_isnull) > maxDataLen)
+	{
+		int			biggest_attno = -1;
+		int32		biggest_size = MAXALIGN(TOAST_POINTER_SIZE);
+		Datum		old_value;
+		Datum		new_value;
+
+		/*
+		 * Search for the biggest yet uncompressed internal attribute
+		 */
+		for (i = 0; i < numAttrs; i++)
+		{
+			if (toast_action[i] != ' ')
+				continue;
+			if (VARATT_IS_EXTERNAL(DatumGetPointer(toast_values[i])))
+				continue;		/* can't happen, toast_action would be 'p' */
+			if (VARATT_IS_COMPRESSED(DatumGetPointer(toast_values[i])))
+				continue;
+			if (TupleDescAttr(tupleDesc, i)->attstorage != 'm')
+				continue;
+			if (toast_sizes[i] > biggest_size)
+			{
+				biggest_attno = i;
+				biggest_size = toast_sizes[i];
+			}
+		}
+
+		if (biggest_attno < 0)
+			break;
+
+		/*
+		 * Attempt to compress it inline
+		 */
+		i = biggest_attno;
+		old_value = toast_values[i];
+		new_value = toast_compress_datum(old_value);
+
+		if (DatumGetPointer(new_value) != NULL)
+		{
+			/* successful compression */
+			if (toast_free[i])
+				pfree(DatumGetPointer(old_value));
+			toast_values[i] = new_value;
+			toast_free[i] = true;
+			toast_sizes[i] = VARSIZE(DatumGetPointer(toast_values[i]));
+			need_change = true;
+			need_free = true;
+		}
+		else
+		{
+			/* incompressible, ignore on subsequent compression passes */
+			toast_action[i] = 'x';
+		}
+	}
+
+	/*
+	 * Finally we store attributes of type 'm' externally.  At this point we
+	 * increase the target tuple size, so that 'm' attributes aren't stored
+	 * externally unless really necessary.
+	 */
+	maxDataLen = TOAST_TUPLE_TARGET_MAIN - hoff;
+
+	while (heap_compute_data_size(tupleDesc,
+								  toast_values, toast_isnull) > maxDataLen &&
+		   rel->rd_rel->reltoastrelid != InvalidOid)
+	{
+		int			biggest_attno = -1;
+		int32		biggest_size = MAXALIGN(TOAST_POINTER_SIZE);
+		Datum		old_value;
+
+		/*--------
+		 * Search for the biggest yet inlined attribute with
+		 * attstorage = 'm'
+		 *--------
+		 */
+		for (i = 0; i < numAttrs; i++)
+		{
+			if (toast_action[i] == 'p')
+				continue;
+			if (VARATT_IS_EXTERNAL(DatumGetPointer(toast_values[i])))
+				continue;		/* can't happen, toast_action would be 'p' */
+			if (TupleDescAttr(tupleDesc, i)->attstorage != 'm')
+				continue;
+			if (toast_sizes[i] > biggest_size)
+			{
+				biggest_attno = i;
+				biggest_size = toast_sizes[i];
+			}
+		}
+
+		if (biggest_attno < 0)
+			break;
+
+		/*
+		 * Store this external
+		 */
+		i = biggest_attno;
+		old_value = toast_values[i];
+		toast_action[i] = 'p';
+		toast_values[i] = toast_save_datum(rel, toast_values[i],
+										   toast_oldexternal[i], options);
+		if (toast_free[i])
+			pfree(DatumGetPointer(old_value));
+		toast_free[i] = true;
+
+		need_change = true;
+		need_free = true;
+	}
+
+	/*
+	 * In the case we toasted any values, we need to build a new heap tuple
+	 * with the changed values.
+	 */
+	if (need_change)
+	{
+		HeapTupleHeader olddata = newtup->t_data;
+		HeapTupleHeader new_data;
+		int32		new_header_len;
+		int32		new_data_len;
+		int32		new_tuple_len;
+
+		/*
+		 * Calculate the new size of the tuple.
+		 *
+		 * Note: we used to assume here that the old tuple's t_hoff must equal
+		 * the new_header_len value, but that was incorrect.  The old tuple
+		 * might have a smaller-than-current natts, if there's been an ALTER
+		 * TABLE ADD COLUMN since it was stored; and that would lead to a
+		 * different conclusion about the size of the null bitmap, or even
+		 * whether there needs to be one at all.
+		 */
+		new_header_len = SizeofHeapTupleHeader;
+		if (has_nulls)
+			new_header_len += BITMAPLEN(numAttrs);
+		new_header_len = MAXALIGN(new_header_len);
+		new_data_len = heap_compute_data_size(tupleDesc,
+											  toast_values, toast_isnull);
+		new_tuple_len = new_header_len + new_data_len;
+
+		/*
+		 * Allocate and zero the space needed, and fill HeapTupleData fields.
+		 */
+		result_tuple = (HeapTuple) palloc0(HEAPTUPLESIZE + new_tuple_len);
+		result_tuple->t_len = new_tuple_len;
+		result_tuple->t_self = newtup->t_self;
+		result_tuple->t_tableOid = newtup->t_tableOid;
+		new_data = (HeapTupleHeader) ((char *) result_tuple + HEAPTUPLESIZE);
+		result_tuple->t_data = new_data;
+
+		/*
+		 * Copy the existing tuple header, but adjust natts and t_hoff.
+		 */
+		memcpy(new_data, olddata, SizeofHeapTupleHeader);
+		HeapTupleHeaderSetNatts(new_data, numAttrs);
+		new_data->t_hoff = new_header_len;
+
+		/* Copy over the data, and fill the null bitmap if needed */
+		heap_fill_tuple(tupleDesc,
+						toast_values,
+						toast_isnull,
+						(char *) new_data + new_header_len,
+						new_data_len,
+						&(new_data->t_infomask),
+						has_nulls ? new_data->t_bits : NULL);
+	}
+	else
+		result_tuple = newtup;
+
+	/*
+	 * Free allocated temp values
+	 */
+	if (need_free)
+		for (i = 0; i < numAttrs; i++)
+			if (toast_free[i])
+				pfree(DatumGetPointer(toast_values[i]));
+
+	/*
+	 * Delete external values from the old tuple
+	 */
+	if (need_delold)
+		for (i = 0; i < numAttrs; i++)
+			if (toast_delold[i])
+				toast_delete_datum(rel, toast_oldvalues[i], false);
+
+	return result_tuple;
+}
+
+
+/* ----------
+ * toast_flatten_tuple -
+ *
+ *	"Flatten" a tuple to contain no out-of-line toasted fields.
+ *	(This does not eliminate compressed or short-header datums.)
+ *
+ *	Note: we expect the caller already checked HeapTupleHasExternal(tup),
+ *	so there is no need for a short-circuit path.
+ * ----------
+ */
+HeapTuple
+toast_flatten_tuple(HeapTuple tup, TupleDesc tupleDesc)
+{
+	HeapTuple	new_tuple;
+	int			numAttrs = tupleDesc->natts;
+	int			i;
+	Datum		toast_values[MaxTupleAttributeNumber];
+	bool		toast_isnull[MaxTupleAttributeNumber];
+	bool		toast_free[MaxTupleAttributeNumber];
+
+	/*
+	 * Break down the tuple into fields.
+	 */
+	Assert(numAttrs <= MaxTupleAttributeNumber);
+	heap_deform_tuple(tup, tupleDesc, toast_values, toast_isnull);
+
+	memset(toast_free, 0, numAttrs * sizeof(bool));
+
+	for (i = 0; i < numAttrs; i++)
+	{
+		/*
+		 * Look at non-null varlena attributes
+		 */
+		if (!toast_isnull[i] && TupleDescAttr(tupleDesc, i)->attlen == -1)
+		{
+			struct varlena *new_value;
+
+			new_value = (struct varlena *) DatumGetPointer(toast_values[i]);
+			if (VARATT_IS_EXTERNAL(new_value))
+			{
+				new_value = heap_tuple_fetch_attr(new_value);
+				toast_values[i] = PointerGetDatum(new_value);
+				toast_free[i] = true;
+			}
+		}
+	}
+
+	/*
+	 * Form the reconfigured tuple.
+	 */
+	new_tuple = heap_form_tuple(tupleDesc, toast_values, toast_isnull);
+
+	/*
+	 * Be sure to copy the tuple's identity fields.  We also make a point of
+	 * copying visibility info, just in case anybody looks at those fields in
+	 * a syscache entry.
+	 */
+	new_tuple->t_self = tup->t_self;
+	new_tuple->t_tableOid = tup->t_tableOid;
+
+	new_tuple->t_data->t_choice = tup->t_data->t_choice;
+	new_tuple->t_data->t_ctid = tup->t_data->t_ctid;
+	new_tuple->t_data->t_infomask &= ~HEAP_XACT_MASK;
+	new_tuple->t_data->t_infomask |=
+		tup->t_data->t_infomask & HEAP_XACT_MASK;
+	new_tuple->t_data->t_infomask2 &= ~HEAP2_XACT_MASK;
+	new_tuple->t_data->t_infomask2 |=
+		tup->t_data->t_infomask2 & HEAP2_XACT_MASK;
+
+	/*
+	 * Free allocated temp values
+	 */
+	for (i = 0; i < numAttrs; i++)
+		if (toast_free[i])
+			pfree(DatumGetPointer(toast_values[i]));
+
+	return new_tuple;
+}
+
+
+/* ----------
+ * toast_flatten_tuple_to_datum -
+ *
+ *	"Flatten" a tuple containing out-of-line toasted fields into a Datum.
+ *	The result is always palloc'd in the current memory context.
+ *
+ *	We have a general rule that Datums of container types (rows, arrays,
+ *	ranges, etc) must not contain any external TOAST pointers.  Without
+ *	this rule, we'd have to look inside each Datum when preparing a tuple
+ *	for storage, which would be expensive and would fail to extend cleanly
+ *	to new sorts of container types.
+ *
+ *	However, we don't want to say that tuples represented as HeapTuples
+ *	can't contain toasted fields, so instead this routine should be called
+ *	when such a HeapTuple is being converted into a Datum.
+ *
+ *	While we're at it, we decompress any compressed fields too.  This is not
+ *	necessary for correctness, but reflects an expectation that compression
+ *	will be more effective if applied to the whole tuple not individual
+ *	fields.  We are not so concerned about that that we want to deconstruct
+ *	and reconstruct tuples just to get rid of compressed fields, however.
+ *	So callers typically won't call this unless they see that the tuple has
+ *	at least one external field.
+ *
+ *	On the other hand, in-line short-header varlena fields are left alone.
+ *	If we "untoasted" them here, they'd just get changed back to short-header
+ *	format anyway within heap_fill_tuple.
+ * ----------
+ */
+Datum
+toast_flatten_tuple_to_datum(HeapTupleHeader tup,
+							 uint32 tup_len,
+							 TupleDesc tupleDesc)
+{
+	HeapTupleHeader new_data;
+	int32		new_header_len;
+	int32		new_data_len;
+	int32		new_tuple_len;
+	HeapTupleData tmptup;
+	int			numAttrs = tupleDesc->natts;
+	int			i;
+	bool		has_nulls = false;
+	Datum		toast_values[MaxTupleAttributeNumber];
+	bool		toast_isnull[MaxTupleAttributeNumber];
+	bool		toast_free[MaxTupleAttributeNumber];
+
+	/* Build a temporary HeapTuple control structure */
+	tmptup.t_len = tup_len;
+	ItemPointerSetInvalid(&(tmptup.t_self));
+	tmptup.t_tableOid = InvalidOid;
+	tmptup.t_data = tup;
+
+	/*
+	 * Break down the tuple into fields.
+	 */
+	Assert(numAttrs <= MaxTupleAttributeNumber);
+	heap_deform_tuple(&tmptup, tupleDesc, toast_values, toast_isnull);
+
+	memset(toast_free, 0, numAttrs * sizeof(bool));
+
+	for (i = 0; i < numAttrs; i++)
+	{
+		/*
+		 * Look at non-null varlena attributes
+		 */
+		if (toast_isnull[i])
+			has_nulls = true;
+		else if (TupleDescAttr(tupleDesc, i)->attlen == -1)
+		{
+			struct varlena *new_value;
+
+			new_value = (struct varlena *) DatumGetPointer(toast_values[i]);
+			if (VARATT_IS_EXTERNAL(new_value) ||
+				VARATT_IS_COMPRESSED(new_value))
+			{
+				new_value = heap_tuple_untoast_attr(new_value);
+				toast_values[i] = PointerGetDatum(new_value);
+				toast_free[i] = true;
+			}
+		}
+	}
+
+	/*
+	 * Calculate the new size of the tuple.
+	 *
+	 * This should match the reconstruction code in toast_insert_or_update.
+	 */
+	new_header_len = SizeofHeapTupleHeader;
+	if (has_nulls)
+		new_header_len += BITMAPLEN(numAttrs);
+	new_header_len = MAXALIGN(new_header_len);
+	new_data_len = heap_compute_data_size(tupleDesc,
+										  toast_values, toast_isnull);
+	new_tuple_len = new_header_len + new_data_len;
+
+	new_data = (HeapTupleHeader) palloc0(new_tuple_len);
+
+	/*
+	 * Copy the existing tuple header, but adjust natts and t_hoff.
+	 */
+	memcpy(new_data, tup, SizeofHeapTupleHeader);
+	HeapTupleHeaderSetNatts(new_data, numAttrs);
+	new_data->t_hoff = new_header_len;
+
+	/* Set the composite-Datum header fields correctly */
+	HeapTupleHeaderSetDatumLength(new_data, new_tuple_len);
+	HeapTupleHeaderSetTypeId(new_data, tupleDesc->tdtypeid);
+	HeapTupleHeaderSetTypMod(new_data, tupleDesc->tdtypmod);
+
+	/* Copy over the data, and fill the null bitmap if needed */
+	heap_fill_tuple(tupleDesc,
+					toast_values,
+					toast_isnull,
+					(char *) new_data + new_header_len,
+					new_data_len,
+					&(new_data->t_infomask),
+					has_nulls ? new_data->t_bits : NULL);
+
+	/*
+	 * Free allocated temp values
+	 */
+	for (i = 0; i < numAttrs; i++)
+		if (toast_free[i])
+			pfree(DatumGetPointer(toast_values[i]));
+
+	return PointerGetDatum(new_data);
+}
+
+
+/* ----------
+ * toast_build_flattened_tuple -
+ *
+ *	Build a tuple containing no out-of-line toasted fields.
+ *	(This does not eliminate compressed or short-header datums.)
+ *
+ *	This is essentially just like heap_form_tuple, except that it will
+ *	expand any external-data pointers beforehand.
+ *
+ *	It's not very clear whether it would be preferable to decompress
+ *	in-line compressed datums while at it.  For now, we don't.
+ * ----------
+ */
+HeapTuple
+toast_build_flattened_tuple(TupleDesc tupleDesc,
+							Datum *values,
+							bool *isnull)
+{
+	HeapTuple	new_tuple;
+	int			numAttrs = tupleDesc->natts;
+	int			num_to_free;
+	int			i;
+	Datum		new_values[MaxTupleAttributeNumber];
+	Pointer		freeable_values[MaxTupleAttributeNumber];
+
+	/*
+	 * We can pass the caller's isnull array directly to heap_form_tuple, but
+	 * we potentially need to modify the values array.
+	 */
+	Assert(numAttrs <= MaxTupleAttributeNumber);
+	memcpy(new_values, values, numAttrs * sizeof(Datum));
+
+	num_to_free = 0;
+	for (i = 0; i < numAttrs; i++)
+	{
+		/*
+		 * Look at non-null varlena attributes
+		 */
+		if (!isnull[i] && TupleDescAttr(tupleDesc, i)->attlen == -1)
+		{
+			struct varlena *new_value;
+
+			new_value = (struct varlena *) DatumGetPointer(new_values[i]);
+			if (VARATT_IS_EXTERNAL(new_value))
+			{
+				new_value = heap_tuple_fetch_attr(new_value);
+				new_values[i] = PointerGetDatum(new_value);
+				freeable_values[num_to_free++] = (Pointer) new_value;
+			}
+		}
+	}
+
+	/*
+	 * Form the reconfigured tuple.
+	 */
+	new_tuple = heap_form_tuple(tupleDesc, new_values, isnull);
+
+	/*
+	 * Free allocated temp values
+	 */
+	for (i = 0; i < num_to_free; i++)
+		pfree(freeable_values[i]);
+
+	return new_tuple;
+}
diff --git a/src/backend/access/heap/rewriteheap.c b/src/backend/access/heap/rewriteheap.c
index a17508a82f..0172a13957 100644
--- a/src/backend/access/heap/rewriteheap.c
+++ b/src/backend/access/heap/rewriteheap.c
@@ -109,9 +109,9 @@
 
 #include "access/heapam.h"
 #include "access/heapam_xlog.h"
+#include "access/heaptoast.h"
 #include "access/rewriteheap.h"
 #include "access/transam.h"
-#include "access/tuptoaster.h"
 #include "access/xact.h"
 #include "access/xloginsert.h"
 
diff --git a/src/backend/access/heap/tuptoaster.c b/src/backend/access/heap/tuptoaster.c
deleted file mode 100644
index 74233bb931..0000000000
--- a/src/backend/access/heap/tuptoaster.c
+++ /dev/null
@@ -1,2421 +0,0 @@
-/*-------------------------------------------------------------------------
- *
- * tuptoaster.c
- *	  Support routines for external and compressed storage of
- *	  variable size attributes.
- *
- * Copyright (c) 2000-2019, PostgreSQL Global Development Group
- *
- *
- * IDENTIFICATION
- *	  src/backend/access/heap/tuptoaster.c
- *
- *
- * INTERFACE ROUTINES
- *		toast_insert_or_update -
- *			Try to make a given tuple fit into one page by compressing
- *			or moving off attributes
- *
- *		toast_delete -
- *			Reclaim toast storage when a tuple is deleted
- *
- *		heap_tuple_untoast_attr -
- *			Fetch back a given value from the "secondary" relation
- *
- *-------------------------------------------------------------------------
- */
-
-#include "postgres.h"
-
-#include <unistd.h>
-#include <fcntl.h>
-
-#include "access/genam.h"
-#include "access/heapam.h"
-#include "access/tuptoaster.h"
-#include "access/xact.h"
-#include "catalog/catalog.h"
-#include "common/pg_lzcompress.h"
-#include "miscadmin.h"
-#include "utils/expandeddatum.h"
-#include "utils/fmgroids.h"
-#include "utils/rel.h"
-#include "utils/snapmgr.h"
-#include "utils/typcache.h"
-
-
-#undef TOAST_DEBUG
-
-/*
- *	The information at the start of the compressed toast data.
- */
-typedef struct toast_compress_header
-{
-	int32		vl_len_;		/* varlena header (do not touch directly!) */
-	int32		rawsize;
-} toast_compress_header;
-
-/*
- * Utilities for manipulation of header information for compressed
- * toast entries.
- */
-#define TOAST_COMPRESS_HDRSZ		((int32) sizeof(toast_compress_header))
-#define TOAST_COMPRESS_RAWSIZE(ptr) (((toast_compress_header *) (ptr))->rawsize)
-#define TOAST_COMPRESS_RAWDATA(ptr) \
-	(((char *) (ptr)) + TOAST_COMPRESS_HDRSZ)
-#define TOAST_COMPRESS_SET_RAWSIZE(ptr, len) \
-	(((toast_compress_header *) (ptr))->rawsize = (len))
-
-static void toast_delete_datum(Relation rel, Datum value, bool is_speculative);
-static Datum toast_save_datum(Relation rel, Datum value,
-							  struct varlena *oldexternal, int options);
-static bool toastrel_valueid_exists(Relation toastrel, Oid valueid);
-static bool toastid_valueid_exists(Oid toastrelid, Oid valueid);
-static struct varlena *toast_fetch_datum(struct varlena *attr);
-static struct varlena *toast_fetch_datum_slice(struct varlena *attr,
-											   int32 sliceoffset, int32 length);
-static struct varlena *toast_decompress_datum(struct varlena *attr);
-static struct varlena *toast_decompress_datum_slice(struct varlena *attr, int32 slicelength);
-static int	toast_open_indexes(Relation toastrel,
-							   LOCKMODE lock,
-							   Relation **toastidxs,
-							   int *num_indexes);
-static void toast_close_indexes(Relation *toastidxs, int num_indexes,
-								LOCKMODE lock);
-static void init_toast_snapshot(Snapshot toast_snapshot);
-
-
-/* ----------
- * heap_tuple_fetch_attr -
- *
- *	Public entry point to get back a toasted value from
- *	external source (possibly still in compressed format).
- *
- * This will return a datum that contains all the data internally, ie, not
- * relying on external storage or memory, but it can still be compressed or
- * have a short header.  Note some callers assume that if the input is an
- * EXTERNAL datum, the result will be a pfree'able chunk.
- * ----------
- */
-struct varlena *
-heap_tuple_fetch_attr(struct varlena *attr)
-{
-	struct varlena *result;
-
-	if (VARATT_IS_EXTERNAL_ONDISK(attr))
-	{
-		/*
-		 * This is an external stored plain value
-		 */
-		result = toast_fetch_datum(attr);
-	}
-	else if (VARATT_IS_EXTERNAL_INDIRECT(attr))
-	{
-		/*
-		 * This is an indirect pointer --- dereference it
-		 */
-		struct varatt_indirect redirect;
-
-		VARATT_EXTERNAL_GET_POINTER(redirect, attr);
-		attr = (struct varlena *) redirect.pointer;
-
-		/* nested indirect Datums aren't allowed */
-		Assert(!VARATT_IS_EXTERNAL_INDIRECT(attr));
-
-		/* recurse if value is still external in some other way */
-		if (VARATT_IS_EXTERNAL(attr))
-			return heap_tuple_fetch_attr(attr);
-
-		/*
-		 * Copy into the caller's memory context, in case caller tries to
-		 * pfree the result.
-		 */
-		result = (struct varlena *) palloc(VARSIZE_ANY(attr));
-		memcpy(result, attr, VARSIZE_ANY(attr));
-	}
-	else if (VARATT_IS_EXTERNAL_EXPANDED(attr))
-	{
-		/*
-		 * This is an expanded-object pointer --- get flat format
-		 */
-		ExpandedObjectHeader *eoh;
-		Size		resultsize;
-
-		eoh = DatumGetEOHP(PointerGetDatum(attr));
-		resultsize = EOH_get_flat_size(eoh);
-		result = (struct varlena *) palloc(resultsize);
-		EOH_flatten_into(eoh, (void *) result, resultsize);
-	}
-	else
-	{
-		/*
-		 * This is a plain value inside of the main tuple - why am I called?
-		 */
-		result = attr;
-	}
-
-	return result;
-}
-
-
-/* ----------
- * heap_tuple_untoast_attr -
- *
- *	Public entry point to get back a toasted value from compression
- *	or external storage.  The result is always non-extended varlena form.
- *
- * Note some callers assume that if the input is an EXTERNAL or COMPRESSED
- * datum, the result will be a pfree'able chunk.
- * ----------
- */
-struct varlena *
-heap_tuple_untoast_attr(struct varlena *attr)
-{
-	if (VARATT_IS_EXTERNAL_ONDISK(attr))
-	{
-		/*
-		 * This is an externally stored datum --- fetch it back from there
-		 */
-		attr = toast_fetch_datum(attr);
-		/* If it's compressed, decompress it */
-		if (VARATT_IS_COMPRESSED(attr))
-		{
-			struct varlena *tmp = attr;
-
-			attr = toast_decompress_datum(tmp);
-			pfree(tmp);
-		}
-	}
-	else if (VARATT_IS_EXTERNAL_INDIRECT(attr))
-	{
-		/*
-		 * This is an indirect pointer --- dereference it
-		 */
-		struct varatt_indirect redirect;
-
-		VARATT_EXTERNAL_GET_POINTER(redirect, attr);
-		attr = (struct varlena *) redirect.pointer;
-
-		/* nested indirect Datums aren't allowed */
-		Assert(!VARATT_IS_EXTERNAL_INDIRECT(attr));
-
-		/* recurse in case value is still extended in some other way */
-		attr = heap_tuple_untoast_attr(attr);
-
-		/* if it isn't, we'd better copy it */
-		if (attr == (struct varlena *) redirect.pointer)
-		{
-			struct varlena *result;
-
-			result = (struct varlena *) palloc(VARSIZE_ANY(attr));
-			memcpy(result, attr, VARSIZE_ANY(attr));
-			attr = result;
-		}
-	}
-	else if (VARATT_IS_EXTERNAL_EXPANDED(attr))
-	{
-		/*
-		 * This is an expanded-object pointer --- get flat format
-		 */
-		attr = heap_tuple_fetch_attr(attr);
-		/* flatteners are not allowed to produce compressed/short output */
-		Assert(!VARATT_IS_EXTENDED(attr));
-	}
-	else if (VARATT_IS_COMPRESSED(attr))
-	{
-		/*
-		 * This is a compressed value inside of the main tuple
-		 */
-		attr = toast_decompress_datum(attr);
-	}
-	else if (VARATT_IS_SHORT(attr))
-	{
-		/*
-		 * This is a short-header varlena --- convert to 4-byte header format
-		 */
-		Size		data_size = VARSIZE_SHORT(attr) - VARHDRSZ_SHORT;
-		Size		new_size = data_size + VARHDRSZ;
-		struct varlena *new_attr;
-
-		new_attr = (struct varlena *) palloc(new_size);
-		SET_VARSIZE(new_attr, new_size);
-		memcpy(VARDATA(new_attr), VARDATA_SHORT(attr), data_size);
-		attr = new_attr;
-	}
-
-	return attr;
-}
-
-
-/* ----------
- * heap_tuple_untoast_attr_slice -
- *
- *		Public entry point to get back part of a toasted value
- *		from compression or external storage.
- * ----------
- */
-struct varlena *
-heap_tuple_untoast_attr_slice(struct varlena *attr,
-							  int32 sliceoffset, int32 slicelength)
-{
-	struct varlena *preslice;
-	struct varlena *result;
-	char	   *attrdata;
-	int32		attrsize;
-
-	if (VARATT_IS_EXTERNAL_ONDISK(attr))
-	{
-		struct varatt_external toast_pointer;
-
-		VARATT_EXTERNAL_GET_POINTER(toast_pointer, attr);
-
-		/* fast path for non-compressed external datums */
-		if (!VARATT_EXTERNAL_IS_COMPRESSED(toast_pointer))
-			return toast_fetch_datum_slice(attr, sliceoffset, slicelength);
-
-		/* fetch it back (compressed marker will get set automatically) */
-		preslice = toast_fetch_datum(attr);
-	}
-	else if (VARATT_IS_EXTERNAL_INDIRECT(attr))
-	{
-		struct varatt_indirect redirect;
-
-		VARATT_EXTERNAL_GET_POINTER(redirect, attr);
-
-		/* nested indirect Datums aren't allowed */
-		Assert(!VARATT_IS_EXTERNAL_INDIRECT(redirect.pointer));
-
-		return heap_tuple_untoast_attr_slice(redirect.pointer,
-											 sliceoffset, slicelength);
-	}
-	else if (VARATT_IS_EXTERNAL_EXPANDED(attr))
-	{
-		/* pass it off to heap_tuple_fetch_attr to flatten */
-		preslice = heap_tuple_fetch_attr(attr);
-	}
-	else
-		preslice = attr;
-
-	Assert(!VARATT_IS_EXTERNAL(preslice));
-
-	if (VARATT_IS_COMPRESSED(preslice))
-	{
-		struct varlena *tmp = preslice;
-
-		/* Decompress enough to encompass the slice and the offset */
-		if (slicelength > 0 && sliceoffset >= 0)
-			preslice = toast_decompress_datum_slice(tmp, slicelength + sliceoffset);
-		else
-			preslice = toast_decompress_datum(tmp);
-
-		if (tmp != attr)
-			pfree(tmp);
-	}
-
-	if (VARATT_IS_SHORT(preslice))
-	{
-		attrdata = VARDATA_SHORT(preslice);
-		attrsize = VARSIZE_SHORT(preslice) - VARHDRSZ_SHORT;
-	}
-	else
-	{
-		attrdata = VARDATA(preslice);
-		attrsize = VARSIZE(preslice) - VARHDRSZ;
-	}
-
-	/* slicing of datum for compressed cases and plain value */
-
-	if (sliceoffset >= attrsize)
-	{
-		sliceoffset = 0;
-		slicelength = 0;
-	}
-
-	if (((sliceoffset + slicelength) > attrsize) || slicelength < 0)
-		slicelength = attrsize - sliceoffset;
-
-	result = (struct varlena *) palloc(slicelength + VARHDRSZ);
-	SET_VARSIZE(result, slicelength + VARHDRSZ);
-
-	memcpy(VARDATA(result), attrdata + sliceoffset, slicelength);
-
-	if (preslice != attr)
-		pfree(preslice);
-
-	return result;
-}
-
-
-/* ----------
- * toast_raw_datum_size -
- *
- *	Return the raw (detoasted) size of a varlena datum
- *	(including the VARHDRSZ header)
- * ----------
- */
-Size
-toast_raw_datum_size(Datum value)
-{
-	struct varlena *attr = (struct varlena *) DatumGetPointer(value);
-	Size		result;
-
-	if (VARATT_IS_EXTERNAL_ONDISK(attr))
-	{
-		/* va_rawsize is the size of the original datum -- including header */
-		struct varatt_external toast_pointer;
-
-		VARATT_EXTERNAL_GET_POINTER(toast_pointer, attr);
-		result = toast_pointer.va_rawsize;
-	}
-	else if (VARATT_IS_EXTERNAL_INDIRECT(attr))
-	{
-		struct varatt_indirect toast_pointer;
-
-		VARATT_EXTERNAL_GET_POINTER(toast_pointer, attr);
-
-		/* nested indirect Datums aren't allowed */
-		Assert(!VARATT_IS_EXTERNAL_INDIRECT(toast_pointer.pointer));
-
-		return toast_raw_datum_size(PointerGetDatum(toast_pointer.pointer));
-	}
-	else if (VARATT_IS_EXTERNAL_EXPANDED(attr))
-	{
-		result = EOH_get_flat_size(DatumGetEOHP(value));
-	}
-	else if (VARATT_IS_COMPRESSED(attr))
-	{
-		/* here, va_rawsize is just the payload size */
-		result = VARRAWSIZE_4B_C(attr) + VARHDRSZ;
-	}
-	else if (VARATT_IS_SHORT(attr))
-	{
-		/*
-		 * we have to normalize the header length to VARHDRSZ or else the
-		 * callers of this function will be confused.
-		 */
-		result = VARSIZE_SHORT(attr) - VARHDRSZ_SHORT + VARHDRSZ;
-	}
-	else
-	{
-		/* plain untoasted datum */
-		result = VARSIZE(attr);
-	}
-	return result;
-}
-
-/* ----------
- * toast_datum_size
- *
- *	Return the physical storage size (possibly compressed) of a varlena datum
- * ----------
- */
-Size
-toast_datum_size(Datum value)
-{
-	struct varlena *attr = (struct varlena *) DatumGetPointer(value);
-	Size		result;
-
-	if (VARATT_IS_EXTERNAL_ONDISK(attr))
-	{
-		/*
-		 * Attribute is stored externally - return the extsize whether
-		 * compressed or not.  We do not count the size of the toast pointer
-		 * ... should we?
-		 */
-		struct varatt_external toast_pointer;
-
-		VARATT_EXTERNAL_GET_POINTER(toast_pointer, attr);
-		result = toast_pointer.va_extsize;
-	}
-	else if (VARATT_IS_EXTERNAL_INDIRECT(attr))
-	{
-		struct varatt_indirect toast_pointer;
-
-		VARATT_EXTERNAL_GET_POINTER(toast_pointer, attr);
-
-		/* nested indirect Datums aren't allowed */
-		Assert(!VARATT_IS_EXTERNAL_INDIRECT(attr));
-
-		return toast_datum_size(PointerGetDatum(toast_pointer.pointer));
-	}
-	else if (VARATT_IS_EXTERNAL_EXPANDED(attr))
-	{
-		result = EOH_get_flat_size(DatumGetEOHP(value));
-	}
-	else if (VARATT_IS_SHORT(attr))
-	{
-		result = VARSIZE_SHORT(attr);
-	}
-	else
-	{
-		/*
-		 * Attribute is stored inline either compressed or not, just calculate
-		 * the size of the datum in either case.
-		 */
-		result = VARSIZE(attr);
-	}
-	return result;
-}
-
-
-/* ----------
- * toast_delete -
- *
- *	Cascaded delete toast-entries on DELETE
- * ----------
- */
-void
-toast_delete(Relation rel, HeapTuple oldtup, bool is_speculative)
-{
-	TupleDesc	tupleDesc;
-	int			numAttrs;
-	int			i;
-	Datum		toast_values[MaxHeapAttributeNumber];
-	bool		toast_isnull[MaxHeapAttributeNumber];
-
-	/*
-	 * We should only ever be called for tuples of plain relations or
-	 * materialized views --- recursing on a toast rel is bad news.
-	 */
-	Assert(rel->rd_rel->relkind == RELKIND_RELATION ||
-		   rel->rd_rel->relkind == RELKIND_MATVIEW);
-
-	/*
-	 * Get the tuple descriptor and break down the tuple into fields.
-	 *
-	 * NOTE: it's debatable whether to use heap_deform_tuple() here or just
-	 * heap_getattr() only the varlena columns.  The latter could win if there
-	 * are few varlena columns and many non-varlena ones. However,
-	 * heap_deform_tuple costs only O(N) while the heap_getattr way would cost
-	 * O(N^2) if there are many varlena columns, so it seems better to err on
-	 * the side of linear cost.  (We won't even be here unless there's at
-	 * least one varlena column, by the way.)
-	 */
-	tupleDesc = rel->rd_att;
-	numAttrs = tupleDesc->natts;
-
-	Assert(numAttrs <= MaxHeapAttributeNumber);
-	heap_deform_tuple(oldtup, tupleDesc, toast_values, toast_isnull);
-
-	/*
-	 * Check for external stored attributes and delete them from the secondary
-	 * relation.
-	 */
-	for (i = 0; i < numAttrs; i++)
-	{
-		if (TupleDescAttr(tupleDesc, i)->attlen == -1)
-		{
-			Datum		value = toast_values[i];
-
-			if (toast_isnull[i])
-				continue;
-			else if (VARATT_IS_EXTERNAL_ONDISK(PointerGetDatum(value)))
-				toast_delete_datum(rel, value, is_speculative);
-		}
-	}
-}
-
-
-/* ----------
- * toast_insert_or_update -
- *
- *	Delete no-longer-used toast-entries and create new ones to
- *	make the new tuple fit on INSERT or UPDATE
- *
- * Inputs:
- *	newtup: the candidate new tuple to be inserted
- *	oldtup: the old row version for UPDATE, or NULL for INSERT
- *	options: options to be passed to heap_insert() for toast rows
- * Result:
- *	either newtup if no toasting is needed, or a palloc'd modified tuple
- *	that is what should actually get stored
- *
- * NOTE: neither newtup nor oldtup will be modified.  This is a change
- * from the pre-8.1 API of this routine.
- * ----------
- */
-HeapTuple
-toast_insert_or_update(Relation rel, HeapTuple newtup, HeapTuple oldtup,
-					   int options)
-{
-	HeapTuple	result_tuple;
-	TupleDesc	tupleDesc;
-	int			numAttrs;
-	int			i;
-
-	bool		need_change = false;
-	bool		need_free = false;
-	bool		need_delold = false;
-	bool		has_nulls = false;
-
-	Size		maxDataLen;
-	Size		hoff;
-
-	char		toast_action[MaxHeapAttributeNumber];
-	bool		toast_isnull[MaxHeapAttributeNumber];
-	bool		toast_oldisnull[MaxHeapAttributeNumber];
-	Datum		toast_values[MaxHeapAttributeNumber];
-	Datum		toast_oldvalues[MaxHeapAttributeNumber];
-	struct varlena *toast_oldexternal[MaxHeapAttributeNumber];
-	int32		toast_sizes[MaxHeapAttributeNumber];
-	bool		toast_free[MaxHeapAttributeNumber];
-	bool		toast_delold[MaxHeapAttributeNumber];
-
-	/*
-	 * Ignore the INSERT_SPECULATIVE option. Speculative insertions/super
-	 * deletions just normally insert/delete the toast values. It seems
-	 * easiest to deal with that here, instead on, potentially, multiple
-	 * callers.
-	 */
-	options &= ~HEAP_INSERT_SPECULATIVE;
-
-	/*
-	 * We should only ever be called for tuples of plain relations or
-	 * materialized views --- recursing on a toast rel is bad news.
-	 */
-	Assert(rel->rd_rel->relkind == RELKIND_RELATION ||
-		   rel->rd_rel->relkind == RELKIND_MATVIEW);
-
-	/*
-	 * Get the tuple descriptor and break down the tuple(s) into fields.
-	 */
-	tupleDesc = rel->rd_att;
-	numAttrs = tupleDesc->natts;
-
-	Assert(numAttrs <= MaxHeapAttributeNumber);
-	heap_deform_tuple(newtup, tupleDesc, toast_values, toast_isnull);
-	if (oldtup != NULL)
-		heap_deform_tuple(oldtup, tupleDesc, toast_oldvalues, toast_oldisnull);
-
-	/* ----------
-	 * Then collect information about the values given
-	 *
-	 * NOTE: toast_action[i] can have these values:
-	 *		' '		default handling
-	 *		'p'		already processed --- don't touch it
-	 *		'x'		incompressible, but OK to move off
-	 *
-	 * NOTE: toast_sizes[i] is only made valid for varlena attributes with
-	 *		toast_action[i] different from 'p'.
-	 * ----------
-	 */
-	memset(toast_action, ' ', numAttrs * sizeof(char));
-	memset(toast_oldexternal, 0, numAttrs * sizeof(struct varlena *));
-	memset(toast_free, 0, numAttrs * sizeof(bool));
-	memset(toast_delold, 0, numAttrs * sizeof(bool));
-
-	for (i = 0; i < numAttrs; i++)
-	{
-		Form_pg_attribute att = TupleDescAttr(tupleDesc, i);
-		struct varlena *old_value;
-		struct varlena *new_value;
-
-		if (oldtup != NULL)
-		{
-			/*
-			 * For UPDATE get the old and new values of this attribute
-			 */
-			old_value = (struct varlena *) DatumGetPointer(toast_oldvalues[i]);
-			new_value = (struct varlena *) DatumGetPointer(toast_values[i]);
-
-			/*
-			 * If the old value is stored on disk, check if it has changed so
-			 * we have to delete it later.
-			 */
-			if (att->attlen == -1 && !toast_oldisnull[i] &&
-				VARATT_IS_EXTERNAL_ONDISK(old_value))
-			{
-				if (toast_isnull[i] || !VARATT_IS_EXTERNAL_ONDISK(new_value) ||
-					memcmp((char *) old_value, (char *) new_value,
-						   VARSIZE_EXTERNAL(old_value)) != 0)
-				{
-					/*
-					 * The old external stored value isn't needed any more
-					 * after the update
-					 */
-					toast_delold[i] = true;
-					need_delold = true;
-				}
-				else
-				{
-					/*
-					 * This attribute isn't changed by this update so we reuse
-					 * the original reference to the old value in the new
-					 * tuple.
-					 */
-					toast_action[i] = 'p';
-					continue;
-				}
-			}
-		}
-		else
-		{
-			/*
-			 * For INSERT simply get the new value
-			 */
-			new_value = (struct varlena *) DatumGetPointer(toast_values[i]);
-		}
-
-		/*
-		 * Handle NULL attributes
-		 */
-		if (toast_isnull[i])
-		{
-			toast_action[i] = 'p';
-			has_nulls = true;
-			continue;
-		}
-
-		/*
-		 * Now look at varlena attributes
-		 */
-		if (att->attlen == -1)
-		{
-			/*
-			 * If the table's attribute says PLAIN always, force it so.
-			 */
-			if (att->attstorage == 'p')
-				toast_action[i] = 'p';
-
-			/*
-			 * We took care of UPDATE above, so any external value we find
-			 * still in the tuple must be someone else's that we cannot reuse
-			 * (this includes the case of an out-of-line in-memory datum).
-			 * Fetch it back (without decompression, unless we are forcing
-			 * PLAIN storage).  If necessary, we'll push it out as a new
-			 * external value below.
-			 */
-			if (VARATT_IS_EXTERNAL(new_value))
-			{
-				toast_oldexternal[i] = new_value;
-				if (att->attstorage == 'p')
-					new_value = heap_tuple_untoast_attr(new_value);
-				else
-					new_value = heap_tuple_fetch_attr(new_value);
-				toast_values[i] = PointerGetDatum(new_value);
-				toast_free[i] = true;
-				need_change = true;
-				need_free = true;
-			}
-
-			/*
-			 * Remember the size of this attribute
-			 */
-			toast_sizes[i] = VARSIZE_ANY(new_value);
-		}
-		else
-		{
-			/*
-			 * Not a varlena attribute, plain storage always
-			 */
-			toast_action[i] = 'p';
-		}
-	}
-
-	/* ----------
-	 * Compress and/or save external until data fits into target length
-	 *
-	 *	1: Inline compress attributes with attstorage 'x', and store very
-	 *	   large attributes with attstorage 'x' or 'e' external immediately
-	 *	2: Store attributes with attstorage 'x' or 'e' external
-	 *	3: Inline compress attributes with attstorage 'm'
-	 *	4: Store attributes with attstorage 'm' external
-	 * ----------
-	 */
-
-	/* compute header overhead --- this should match heap_form_tuple() */
-	hoff = SizeofHeapTupleHeader;
-	if (has_nulls)
-		hoff += BITMAPLEN(numAttrs);
-	hoff = MAXALIGN(hoff);
-	/* now convert to a limit on the tuple data size */
-	maxDataLen = RelationGetToastTupleTarget(rel, TOAST_TUPLE_TARGET) - hoff;
-
-	/*
-	 * Look for attributes with attstorage 'x' to compress.  Also find large
-	 * attributes with attstorage 'x' or 'e', and store them external.
-	 */
-	while (heap_compute_data_size(tupleDesc,
-								  toast_values, toast_isnull) > maxDataLen)
-	{
-		int			biggest_attno = -1;
-		int32		biggest_size = MAXALIGN(TOAST_POINTER_SIZE);
-		Datum		old_value;
-		Datum		new_value;
-
-		/*
-		 * Search for the biggest yet unprocessed internal attribute
-		 */
-		for (i = 0; i < numAttrs; i++)
-		{
-			Form_pg_attribute att = TupleDescAttr(tupleDesc, i);
-
-			if (toast_action[i] != ' ')
-				continue;
-			if (VARATT_IS_EXTERNAL(DatumGetPointer(toast_values[i])))
-				continue;		/* can't happen, toast_action would be 'p' */
-			if (VARATT_IS_COMPRESSED(DatumGetPointer(toast_values[i])))
-				continue;
-			if (att->attstorage != 'x' && att->attstorage != 'e')
-				continue;
-			if (toast_sizes[i] > biggest_size)
-			{
-				biggest_attno = i;
-				biggest_size = toast_sizes[i];
-			}
-		}
-
-		if (biggest_attno < 0)
-			break;
-
-		/*
-		 * Attempt to compress it inline, if it has attstorage 'x'
-		 */
-		i = biggest_attno;
-		if (TupleDescAttr(tupleDesc, i)->attstorage == 'x')
-		{
-			old_value = toast_values[i];
-			new_value = toast_compress_datum(old_value);
-
-			if (DatumGetPointer(new_value) != NULL)
-			{
-				/* successful compression */
-				if (toast_free[i])
-					pfree(DatumGetPointer(old_value));
-				toast_values[i] = new_value;
-				toast_free[i] = true;
-				toast_sizes[i] = VARSIZE(DatumGetPointer(toast_values[i]));
-				need_change = true;
-				need_free = true;
-			}
-			else
-			{
-				/* incompressible, ignore on subsequent compression passes */
-				toast_action[i] = 'x';
-			}
-		}
-		else
-		{
-			/* has attstorage 'e', ignore on subsequent compression passes */
-			toast_action[i] = 'x';
-		}
-
-		/*
-		 * If this value is by itself more than maxDataLen (after compression
-		 * if any), push it out to the toast table immediately, if possible.
-		 * This avoids uselessly compressing other fields in the common case
-		 * where we have one long field and several short ones.
-		 *
-		 * XXX maybe the threshold should be less than maxDataLen?
-		 */
-		if (toast_sizes[i] > maxDataLen &&
-			rel->rd_rel->reltoastrelid != InvalidOid)
-		{
-			old_value = toast_values[i];
-			toast_action[i] = 'p';
-			toast_values[i] = toast_save_datum(rel, toast_values[i],
-											   toast_oldexternal[i], options);
-			if (toast_free[i])
-				pfree(DatumGetPointer(old_value));
-			toast_free[i] = true;
-			need_change = true;
-			need_free = true;
-		}
-	}
-
-	/*
-	 * Second we look for attributes of attstorage 'x' or 'e' that are still
-	 * inline.  But skip this if there's no toast table to push them to.
-	 */
-	while (heap_compute_data_size(tupleDesc,
-								  toast_values, toast_isnull) > maxDataLen &&
-		   rel->rd_rel->reltoastrelid != InvalidOid)
-	{
-		int			biggest_attno = -1;
-		int32		biggest_size = MAXALIGN(TOAST_POINTER_SIZE);
-		Datum		old_value;
-
-		/*------
-		 * Search for the biggest yet inlined attribute with
-		 * attstorage equals 'x' or 'e'
-		 *------
-		 */
-		for (i = 0; i < numAttrs; i++)
-		{
-			Form_pg_attribute att = TupleDescAttr(tupleDesc, i);
-
-			if (toast_action[i] == 'p')
-				continue;
-			if (VARATT_IS_EXTERNAL(DatumGetPointer(toast_values[i])))
-				continue;		/* can't happen, toast_action would be 'p' */
-			if (att->attstorage != 'x' && att->attstorage != 'e')
-				continue;
-			if (toast_sizes[i] > biggest_size)
-			{
-				biggest_attno = i;
-				biggest_size = toast_sizes[i];
-			}
-		}
-
-		if (biggest_attno < 0)
-			break;
-
-		/*
-		 * Store this external
-		 */
-		i = biggest_attno;
-		old_value = toast_values[i];
-		toast_action[i] = 'p';
-		toast_values[i] = toast_save_datum(rel, toast_values[i],
-										   toast_oldexternal[i], options);
-		if (toast_free[i])
-			pfree(DatumGetPointer(old_value));
-		toast_free[i] = true;
-
-		need_change = true;
-		need_free = true;
-	}
-
-	/*
-	 * Round 3 - this time we take attributes with storage 'm' into
-	 * compression
-	 */
-	while (heap_compute_data_size(tupleDesc,
-								  toast_values, toast_isnull) > maxDataLen)
-	{
-		int			biggest_attno = -1;
-		int32		biggest_size = MAXALIGN(TOAST_POINTER_SIZE);
-		Datum		old_value;
-		Datum		new_value;
-
-		/*
-		 * Search for the biggest yet uncompressed internal attribute
-		 */
-		for (i = 0; i < numAttrs; i++)
-		{
-			if (toast_action[i] != ' ')
-				continue;
-			if (VARATT_IS_EXTERNAL(DatumGetPointer(toast_values[i])))
-				continue;		/* can't happen, toast_action would be 'p' */
-			if (VARATT_IS_COMPRESSED(DatumGetPointer(toast_values[i])))
-				continue;
-			if (TupleDescAttr(tupleDesc, i)->attstorage != 'm')
-				continue;
-			if (toast_sizes[i] > biggest_size)
-			{
-				biggest_attno = i;
-				biggest_size = toast_sizes[i];
-			}
-		}
-
-		if (biggest_attno < 0)
-			break;
-
-		/*
-		 * Attempt to compress it inline
-		 */
-		i = biggest_attno;
-		old_value = toast_values[i];
-		new_value = toast_compress_datum(old_value);
-
-		if (DatumGetPointer(new_value) != NULL)
-		{
-			/* successful compression */
-			if (toast_free[i])
-				pfree(DatumGetPointer(old_value));
-			toast_values[i] = new_value;
-			toast_free[i] = true;
-			toast_sizes[i] = VARSIZE(DatumGetPointer(toast_values[i]));
-			need_change = true;
-			need_free = true;
-		}
-		else
-		{
-			/* incompressible, ignore on subsequent compression passes */
-			toast_action[i] = 'x';
-		}
-	}
-
-	/*
-	 * Finally we store attributes of type 'm' externally.  At this point we
-	 * increase the target tuple size, so that 'm' attributes aren't stored
-	 * externally unless really necessary.
-	 */
-	maxDataLen = TOAST_TUPLE_TARGET_MAIN - hoff;
-
-	while (heap_compute_data_size(tupleDesc,
-								  toast_values, toast_isnull) > maxDataLen &&
-		   rel->rd_rel->reltoastrelid != InvalidOid)
-	{
-		int			biggest_attno = -1;
-		int32		biggest_size = MAXALIGN(TOAST_POINTER_SIZE);
-		Datum		old_value;
-
-		/*--------
-		 * Search for the biggest yet inlined attribute with
-		 * attstorage = 'm'
-		 *--------
-		 */
-		for (i = 0; i < numAttrs; i++)
-		{
-			if (toast_action[i] == 'p')
-				continue;
-			if (VARATT_IS_EXTERNAL(DatumGetPointer(toast_values[i])))
-				continue;		/* can't happen, toast_action would be 'p' */
-			if (TupleDescAttr(tupleDesc, i)->attstorage != 'm')
-				continue;
-			if (toast_sizes[i] > biggest_size)
-			{
-				biggest_attno = i;
-				biggest_size = toast_sizes[i];
-			}
-		}
-
-		if (biggest_attno < 0)
-			break;
-
-		/*
-		 * Store this external
-		 */
-		i = biggest_attno;
-		old_value = toast_values[i];
-		toast_action[i] = 'p';
-		toast_values[i] = toast_save_datum(rel, toast_values[i],
-										   toast_oldexternal[i], options);
-		if (toast_free[i])
-			pfree(DatumGetPointer(old_value));
-		toast_free[i] = true;
-
-		need_change = true;
-		need_free = true;
-	}
-
-	/*
-	 * In the case we toasted any values, we need to build a new heap tuple
-	 * with the changed values.
-	 */
-	if (need_change)
-	{
-		HeapTupleHeader olddata = newtup->t_data;
-		HeapTupleHeader new_data;
-		int32		new_header_len;
-		int32		new_data_len;
-		int32		new_tuple_len;
-
-		/*
-		 * Calculate the new size of the tuple.
-		 *
-		 * Note: we used to assume here that the old tuple's t_hoff must equal
-		 * the new_header_len value, but that was incorrect.  The old tuple
-		 * might have a smaller-than-current natts, if there's been an ALTER
-		 * TABLE ADD COLUMN since it was stored; and that would lead to a
-		 * different conclusion about the size of the null bitmap, or even
-		 * whether there needs to be one at all.
-		 */
-		new_header_len = SizeofHeapTupleHeader;
-		if (has_nulls)
-			new_header_len += BITMAPLEN(numAttrs);
-		new_header_len = MAXALIGN(new_header_len);
-		new_data_len = heap_compute_data_size(tupleDesc,
-											  toast_values, toast_isnull);
-		new_tuple_len = new_header_len + new_data_len;
-
-		/*
-		 * Allocate and zero the space needed, and fill HeapTupleData fields.
-		 */
-		result_tuple = (HeapTuple) palloc0(HEAPTUPLESIZE + new_tuple_len);
-		result_tuple->t_len = new_tuple_len;
-		result_tuple->t_self = newtup->t_self;
-		result_tuple->t_tableOid = newtup->t_tableOid;
-		new_data = (HeapTupleHeader) ((char *) result_tuple + HEAPTUPLESIZE);
-		result_tuple->t_data = new_data;
-
-		/*
-		 * Copy the existing tuple header, but adjust natts and t_hoff.
-		 */
-		memcpy(new_data, olddata, SizeofHeapTupleHeader);
-		HeapTupleHeaderSetNatts(new_data, numAttrs);
-		new_data->t_hoff = new_header_len;
-
-		/* Copy over the data, and fill the null bitmap if needed */
-		heap_fill_tuple(tupleDesc,
-						toast_values,
-						toast_isnull,
-						(char *) new_data + new_header_len,
-						new_data_len,
-						&(new_data->t_infomask),
-						has_nulls ? new_data->t_bits : NULL);
-	}
-	else
-		result_tuple = newtup;
-
-	/*
-	 * Free allocated temp values
-	 */
-	if (need_free)
-		for (i = 0; i < numAttrs; i++)
-			if (toast_free[i])
-				pfree(DatumGetPointer(toast_values[i]));
-
-	/*
-	 * Delete external values from the old tuple
-	 */
-	if (need_delold)
-		for (i = 0; i < numAttrs; i++)
-			if (toast_delold[i])
-				toast_delete_datum(rel, toast_oldvalues[i], false);
-
-	return result_tuple;
-}
-
-
-/* ----------
- * toast_flatten_tuple -
- *
- *	"Flatten" a tuple to contain no out-of-line toasted fields.
- *	(This does not eliminate compressed or short-header datums.)
- *
- *	Note: we expect the caller already checked HeapTupleHasExternal(tup),
- *	so there is no need for a short-circuit path.
- * ----------
- */
-HeapTuple
-toast_flatten_tuple(HeapTuple tup, TupleDesc tupleDesc)
-{
-	HeapTuple	new_tuple;
-	int			numAttrs = tupleDesc->natts;
-	int			i;
-	Datum		toast_values[MaxTupleAttributeNumber];
-	bool		toast_isnull[MaxTupleAttributeNumber];
-	bool		toast_free[MaxTupleAttributeNumber];
-
-	/*
-	 * Break down the tuple into fields.
-	 */
-	Assert(numAttrs <= MaxTupleAttributeNumber);
-	heap_deform_tuple(tup, tupleDesc, toast_values, toast_isnull);
-
-	memset(toast_free, 0, numAttrs * sizeof(bool));
-
-	for (i = 0; i < numAttrs; i++)
-	{
-		/*
-		 * Look at non-null varlena attributes
-		 */
-		if (!toast_isnull[i] && TupleDescAttr(tupleDesc, i)->attlen == -1)
-		{
-			struct varlena *new_value;
-
-			new_value = (struct varlena *) DatumGetPointer(toast_values[i]);
-			if (VARATT_IS_EXTERNAL(new_value))
-			{
-				new_value = heap_tuple_fetch_attr(new_value);
-				toast_values[i] = PointerGetDatum(new_value);
-				toast_free[i] = true;
-			}
-		}
-	}
-
-	/*
-	 * Form the reconfigured tuple.
-	 */
-	new_tuple = heap_form_tuple(tupleDesc, toast_values, toast_isnull);
-
-	/*
-	 * Be sure to copy the tuple's identity fields.  We also make a point of
-	 * copying visibility info, just in case anybody looks at those fields in
-	 * a syscache entry.
-	 */
-	new_tuple->t_self = tup->t_self;
-	new_tuple->t_tableOid = tup->t_tableOid;
-
-	new_tuple->t_data->t_choice = tup->t_data->t_choice;
-	new_tuple->t_data->t_ctid = tup->t_data->t_ctid;
-	new_tuple->t_data->t_infomask &= ~HEAP_XACT_MASK;
-	new_tuple->t_data->t_infomask |=
-		tup->t_data->t_infomask & HEAP_XACT_MASK;
-	new_tuple->t_data->t_infomask2 &= ~HEAP2_XACT_MASK;
-	new_tuple->t_data->t_infomask2 |=
-		tup->t_data->t_infomask2 & HEAP2_XACT_MASK;
-
-	/*
-	 * Free allocated temp values
-	 */
-	for (i = 0; i < numAttrs; i++)
-		if (toast_free[i])
-			pfree(DatumGetPointer(toast_values[i]));
-
-	return new_tuple;
-}
-
-
-/* ----------
- * toast_flatten_tuple_to_datum -
- *
- *	"Flatten" a tuple containing out-of-line toasted fields into a Datum.
- *	The result is always palloc'd in the current memory context.
- *
- *	We have a general rule that Datums of container types (rows, arrays,
- *	ranges, etc) must not contain any external TOAST pointers.  Without
- *	this rule, we'd have to look inside each Datum when preparing a tuple
- *	for storage, which would be expensive and would fail to extend cleanly
- *	to new sorts of container types.
- *
- *	However, we don't want to say that tuples represented as HeapTuples
- *	can't contain toasted fields, so instead this routine should be called
- *	when such a HeapTuple is being converted into a Datum.
- *
- *	While we're at it, we decompress any compressed fields too.  This is not
- *	necessary for correctness, but reflects an expectation that compression
- *	will be more effective if applied to the whole tuple not individual
- *	fields.  We are not so concerned about that that we want to deconstruct
- *	and reconstruct tuples just to get rid of compressed fields, however.
- *	So callers typically won't call this unless they see that the tuple has
- *	at least one external field.
- *
- *	On the other hand, in-line short-header varlena fields are left alone.
- *	If we "untoasted" them here, they'd just get changed back to short-header
- *	format anyway within heap_fill_tuple.
- * ----------
- */
-Datum
-toast_flatten_tuple_to_datum(HeapTupleHeader tup,
-							 uint32 tup_len,
-							 TupleDesc tupleDesc)
-{
-	HeapTupleHeader new_data;
-	int32		new_header_len;
-	int32		new_data_len;
-	int32		new_tuple_len;
-	HeapTupleData tmptup;
-	int			numAttrs = tupleDesc->natts;
-	int			i;
-	bool		has_nulls = false;
-	Datum		toast_values[MaxTupleAttributeNumber];
-	bool		toast_isnull[MaxTupleAttributeNumber];
-	bool		toast_free[MaxTupleAttributeNumber];
-
-	/* Build a temporary HeapTuple control structure */
-	tmptup.t_len = tup_len;
-	ItemPointerSetInvalid(&(tmptup.t_self));
-	tmptup.t_tableOid = InvalidOid;
-	tmptup.t_data = tup;
-
-	/*
-	 * Break down the tuple into fields.
-	 */
-	Assert(numAttrs <= MaxTupleAttributeNumber);
-	heap_deform_tuple(&tmptup, tupleDesc, toast_values, toast_isnull);
-
-	memset(toast_free, 0, numAttrs * sizeof(bool));
-
-	for (i = 0; i < numAttrs; i++)
-	{
-		/*
-		 * Look at non-null varlena attributes
-		 */
-		if (toast_isnull[i])
-			has_nulls = true;
-		else if (TupleDescAttr(tupleDesc, i)->attlen == -1)
-		{
-			struct varlena *new_value;
-
-			new_value = (struct varlena *) DatumGetPointer(toast_values[i]);
-			if (VARATT_IS_EXTERNAL(new_value) ||
-				VARATT_IS_COMPRESSED(new_value))
-			{
-				new_value = heap_tuple_untoast_attr(new_value);
-				toast_values[i] = PointerGetDatum(new_value);
-				toast_free[i] = true;
-			}
-		}
-	}
-
-	/*
-	 * Calculate the new size of the tuple.
-	 *
-	 * This should match the reconstruction code in toast_insert_or_update.
-	 */
-	new_header_len = SizeofHeapTupleHeader;
-	if (has_nulls)
-		new_header_len += BITMAPLEN(numAttrs);
-	new_header_len = MAXALIGN(new_header_len);
-	new_data_len = heap_compute_data_size(tupleDesc,
-										  toast_values, toast_isnull);
-	new_tuple_len = new_header_len + new_data_len;
-
-	new_data = (HeapTupleHeader) palloc0(new_tuple_len);
-
-	/*
-	 * Copy the existing tuple header, but adjust natts and t_hoff.
-	 */
-	memcpy(new_data, tup, SizeofHeapTupleHeader);
-	HeapTupleHeaderSetNatts(new_data, numAttrs);
-	new_data->t_hoff = new_header_len;
-
-	/* Set the composite-Datum header fields correctly */
-	HeapTupleHeaderSetDatumLength(new_data, new_tuple_len);
-	HeapTupleHeaderSetTypeId(new_data, tupleDesc->tdtypeid);
-	HeapTupleHeaderSetTypMod(new_data, tupleDesc->tdtypmod);
-
-	/* Copy over the data, and fill the null bitmap if needed */
-	heap_fill_tuple(tupleDesc,
-					toast_values,
-					toast_isnull,
-					(char *) new_data + new_header_len,
-					new_data_len,
-					&(new_data->t_infomask),
-					has_nulls ? new_data->t_bits : NULL);
-
-	/*
-	 * Free allocated temp values
-	 */
-	for (i = 0; i < numAttrs; i++)
-		if (toast_free[i])
-			pfree(DatumGetPointer(toast_values[i]));
-
-	return PointerGetDatum(new_data);
-}
-
-
-/* ----------
- * toast_build_flattened_tuple -
- *
- *	Build a tuple containing no out-of-line toasted fields.
- *	(This does not eliminate compressed or short-header datums.)
- *
- *	This is essentially just like heap_form_tuple, except that it will
- *	expand any external-data pointers beforehand.
- *
- *	It's not very clear whether it would be preferable to decompress
- *	in-line compressed datums while at it.  For now, we don't.
- * ----------
- */
-HeapTuple
-toast_build_flattened_tuple(TupleDesc tupleDesc,
-							Datum *values,
-							bool *isnull)
-{
-	HeapTuple	new_tuple;
-	int			numAttrs = tupleDesc->natts;
-	int			num_to_free;
-	int			i;
-	Datum		new_values[MaxTupleAttributeNumber];
-	Pointer		freeable_values[MaxTupleAttributeNumber];
-
-	/*
-	 * We can pass the caller's isnull array directly to heap_form_tuple, but
-	 * we potentially need to modify the values array.
-	 */
-	Assert(numAttrs <= MaxTupleAttributeNumber);
-	memcpy(new_values, values, numAttrs * sizeof(Datum));
-
-	num_to_free = 0;
-	for (i = 0; i < numAttrs; i++)
-	{
-		/*
-		 * Look at non-null varlena attributes
-		 */
-		if (!isnull[i] && TupleDescAttr(tupleDesc, i)->attlen == -1)
-		{
-			struct varlena *new_value;
-
-			new_value = (struct varlena *) DatumGetPointer(new_values[i]);
-			if (VARATT_IS_EXTERNAL(new_value))
-			{
-				new_value = heap_tuple_fetch_attr(new_value);
-				new_values[i] = PointerGetDatum(new_value);
-				freeable_values[num_to_free++] = (Pointer) new_value;
-			}
-		}
-	}
-
-	/*
-	 * Form the reconfigured tuple.
-	 */
-	new_tuple = heap_form_tuple(tupleDesc, new_values, isnull);
-
-	/*
-	 * Free allocated temp values
-	 */
-	for (i = 0; i < num_to_free; i++)
-		pfree(freeable_values[i]);
-
-	return new_tuple;
-}
-
-
-/* ----------
- * toast_compress_datum -
- *
- *	Create a compressed version of a varlena datum
- *
- *	If we fail (ie, compressed result is actually bigger than original)
- *	then return NULL.  We must not use compressed data if it'd expand
- *	the tuple!
- *
- *	We use VAR{SIZE,DATA}_ANY so we can handle short varlenas here without
- *	copying them.  But we can't handle external or compressed datums.
- * ----------
- */
-Datum
-toast_compress_datum(Datum value)
-{
-	struct varlena *tmp;
-	int32		valsize = VARSIZE_ANY_EXHDR(DatumGetPointer(value));
-	int32		len;
-
-	Assert(!VARATT_IS_EXTERNAL(DatumGetPointer(value)));
-	Assert(!VARATT_IS_COMPRESSED(DatumGetPointer(value)));
-
-	/*
-	 * No point in wasting a palloc cycle if value size is out of the allowed
-	 * range for compression
-	 */
-	if (valsize < PGLZ_strategy_default->min_input_size ||
-		valsize > PGLZ_strategy_default->max_input_size)
-		return PointerGetDatum(NULL);
-
-	tmp = (struct varlena *) palloc(PGLZ_MAX_OUTPUT(valsize) +
-									TOAST_COMPRESS_HDRSZ);
-
-	/*
-	 * We recheck the actual size even if pglz_compress() reports success,
-	 * because it might be satisfied with having saved as little as one byte
-	 * in the compressed data --- which could turn into a net loss once you
-	 * consider header and alignment padding.  Worst case, the compressed
-	 * format might require three padding bytes (plus header, which is
-	 * included in VARSIZE(tmp)), whereas the uncompressed format would take
-	 * only one header byte and no padding if the value is short enough.  So
-	 * we insist on a savings of more than 2 bytes to ensure we have a gain.
-	 */
-	len = pglz_compress(VARDATA_ANY(DatumGetPointer(value)),
-						valsize,
-						TOAST_COMPRESS_RAWDATA(tmp),
-						PGLZ_strategy_default);
-	if (len >= 0 &&
-		len + TOAST_COMPRESS_HDRSZ < valsize - 2)
-	{
-		TOAST_COMPRESS_SET_RAWSIZE(tmp, valsize);
-		SET_VARSIZE_COMPRESSED(tmp, len + TOAST_COMPRESS_HDRSZ);
-		/* successful compression */
-		return PointerGetDatum(tmp);
-	}
-	else
-	{
-		/* incompressible data */
-		pfree(tmp);
-		return PointerGetDatum(NULL);
-	}
-}
-
-
-/* ----------
- * toast_get_valid_index
- *
- *	Get OID of valid index associated to given toast relation. A toast
- *	relation can have only one valid index at the same time.
- */
-Oid
-toast_get_valid_index(Oid toastoid, LOCKMODE lock)
-{
-	int			num_indexes;
-	int			validIndex;
-	Oid			validIndexOid;
-	Relation   *toastidxs;
-	Relation	toastrel;
-
-	/* Open the toast relation */
-	toastrel = table_open(toastoid, lock);
-
-	/* Look for the valid index of the toast relation */
-	validIndex = toast_open_indexes(toastrel,
-									lock,
-									&toastidxs,
-									&num_indexes);
-	validIndexOid = RelationGetRelid(toastidxs[validIndex]);
-
-	/* Close the toast relation and all its indexes */
-	toast_close_indexes(toastidxs, num_indexes, lock);
-	table_close(toastrel, lock);
-
-	return validIndexOid;
-}
-
-
-/* ----------
- * toast_save_datum -
- *
- *	Save one single datum into the secondary relation and return
- *	a Datum reference for it.
- *
- * rel: the main relation we're working with (not the toast rel!)
- * value: datum to be pushed to toast storage
- * oldexternal: if not NULL, toast pointer previously representing the datum
- * options: options to be passed to heap_insert() for toast rows
- * ----------
- */
-static Datum
-toast_save_datum(Relation rel, Datum value,
-				 struct varlena *oldexternal, int options)
-{
-	Relation	toastrel;
-	Relation   *toastidxs;
-	HeapTuple	toasttup;
-	TupleDesc	toasttupDesc;
-	Datum		t_values[3];
-	bool		t_isnull[3];
-	CommandId	mycid = GetCurrentCommandId(true);
-	struct varlena *result;
-	struct varatt_external toast_pointer;
-	union
-	{
-		struct varlena hdr;
-		/* this is to make the union big enough for a chunk: */
-		char		data[TOAST_MAX_CHUNK_SIZE + VARHDRSZ];
-		/* ensure union is aligned well enough: */
-		int32		align_it;
-	}			chunk_data;
-	int32		chunk_size;
-	int32		chunk_seq = 0;
-	char	   *data_p;
-	int32		data_todo;
-	Pointer		dval = DatumGetPointer(value);
-	int			num_indexes;
-	int			validIndex;
-
-	Assert(!VARATT_IS_EXTERNAL(value));
-
-	/*
-	 * Open the toast relation and its indexes.  We can use the index to check
-	 * uniqueness of the OID we assign to the toasted item, even though it has
-	 * additional columns besides OID.
-	 */
-	toastrel = table_open(rel->rd_rel->reltoastrelid, RowExclusiveLock);
-	toasttupDesc = toastrel->rd_att;
-
-	/* Open all the toast indexes and look for the valid one */
-	validIndex = toast_open_indexes(toastrel,
-									RowExclusiveLock,
-									&toastidxs,
-									&num_indexes);
-
-	/*
-	 * Get the data pointer and length, and compute va_rawsize and va_extsize.
-	 *
-	 * va_rawsize is the size of the equivalent fully uncompressed datum, so
-	 * we have to adjust for short headers.
-	 *
-	 * va_extsize is the actual size of the data payload in the toast records.
-	 */
-	if (VARATT_IS_SHORT(dval))
-	{
-		data_p = VARDATA_SHORT(dval);
-		data_todo = VARSIZE_SHORT(dval) - VARHDRSZ_SHORT;
-		toast_pointer.va_rawsize = data_todo + VARHDRSZ;	/* as if not short */
-		toast_pointer.va_extsize = data_todo;
-	}
-	else if (VARATT_IS_COMPRESSED(dval))
-	{
-		data_p = VARDATA(dval);
-		data_todo = VARSIZE(dval) - VARHDRSZ;
-		/* rawsize in a compressed datum is just the size of the payload */
-		toast_pointer.va_rawsize = VARRAWSIZE_4B_C(dval) + VARHDRSZ;
-		toast_pointer.va_extsize = data_todo;
-		/* Assert that the numbers look like it's compressed */
-		Assert(VARATT_EXTERNAL_IS_COMPRESSED(toast_pointer));
-	}
-	else
-	{
-		data_p = VARDATA(dval);
-		data_todo = VARSIZE(dval) - VARHDRSZ;
-		toast_pointer.va_rawsize = VARSIZE(dval);
-		toast_pointer.va_extsize = data_todo;
-	}
-
-	/*
-	 * Insert the correct table OID into the result TOAST pointer.
-	 *
-	 * Normally this is the actual OID of the target toast table, but during
-	 * table-rewriting operations such as CLUSTER, we have to insert the OID
-	 * of the table's real permanent toast table instead.  rd_toastoid is set
-	 * if we have to substitute such an OID.
-	 */
-	if (OidIsValid(rel->rd_toastoid))
-		toast_pointer.va_toastrelid = rel->rd_toastoid;
-	else
-		toast_pointer.va_toastrelid = RelationGetRelid(toastrel);
-
-	/*
-	 * Choose an OID to use as the value ID for this toast value.
-	 *
-	 * Normally we just choose an unused OID within the toast table.  But
-	 * during table-rewriting operations where we are preserving an existing
-	 * toast table OID, we want to preserve toast value OIDs too.  So, if
-	 * rd_toastoid is set and we had a prior external value from that same
-	 * toast table, re-use its value ID.  If we didn't have a prior external
-	 * value (which is a corner case, but possible if the table's attstorage
-	 * options have been changed), we have to pick a value ID that doesn't
-	 * conflict with either new or existing toast value OIDs.
-	 */
-	if (!OidIsValid(rel->rd_toastoid))
-	{
-		/* normal case: just choose an unused OID */
-		toast_pointer.va_valueid =
-			GetNewOidWithIndex(toastrel,
-							   RelationGetRelid(toastidxs[validIndex]),
-							   (AttrNumber) 1);
-	}
-	else
-	{
-		/* rewrite case: check to see if value was in old toast table */
-		toast_pointer.va_valueid = InvalidOid;
-		if (oldexternal != NULL)
-		{
-			struct varatt_external old_toast_pointer;
-
-			Assert(VARATT_IS_EXTERNAL_ONDISK(oldexternal));
-			/* Must copy to access aligned fields */
-			VARATT_EXTERNAL_GET_POINTER(old_toast_pointer, oldexternal);
-			if (old_toast_pointer.va_toastrelid == rel->rd_toastoid)
-			{
-				/* This value came from the old toast table; reuse its OID */
-				toast_pointer.va_valueid = old_toast_pointer.va_valueid;
-
-				/*
-				 * There is a corner case here: the table rewrite might have
-				 * to copy both live and recently-dead versions of a row, and
-				 * those versions could easily reference the same toast value.
-				 * When we copy the second or later version of such a row,
-				 * reusing the OID will mean we select an OID that's already
-				 * in the new toast table.  Check for that, and if so, just
-				 * fall through without writing the data again.
-				 *
-				 * While annoying and ugly-looking, this is a good thing
-				 * because it ensures that we wind up with only one copy of
-				 * the toast value when there is only one copy in the old
-				 * toast table.  Before we detected this case, we'd have made
-				 * multiple copies, wasting space; and what's worse, the
-				 * copies belonging to already-deleted heap tuples would not
-				 * be reclaimed by VACUUM.
-				 */
-				if (toastrel_valueid_exists(toastrel,
-											toast_pointer.va_valueid))
-				{
-					/* Match, so short-circuit the data storage loop below */
-					data_todo = 0;
-				}
-			}
-		}
-		if (toast_pointer.va_valueid == InvalidOid)
-		{
-			/*
-			 * new value; must choose an OID that doesn't conflict in either
-			 * old or new toast table
-			 */
-			do
-			{
-				toast_pointer.va_valueid =
-					GetNewOidWithIndex(toastrel,
-									   RelationGetRelid(toastidxs[validIndex]),
-									   (AttrNumber) 1);
-			} while (toastid_valueid_exists(rel->rd_toastoid,
-											toast_pointer.va_valueid));
-		}
-	}
-
-	/*
-	 * Initialize constant parts of the tuple data
-	 */
-	t_values[0] = ObjectIdGetDatum(toast_pointer.va_valueid);
-	t_values[2] = PointerGetDatum(&chunk_data);
-	t_isnull[0] = false;
-	t_isnull[1] = false;
-	t_isnull[2] = false;
-
-	/*
-	 * Split up the item into chunks
-	 */
-	while (data_todo > 0)
-	{
-		int			i;
-
-		CHECK_FOR_INTERRUPTS();
-
-		/*
-		 * Calculate the size of this chunk
-		 */
-		chunk_size = Min(TOAST_MAX_CHUNK_SIZE, data_todo);
-
-		/*
-		 * Build a tuple and store it
-		 */
-		t_values[1] = Int32GetDatum(chunk_seq++);
-		SET_VARSIZE(&chunk_data, chunk_size + VARHDRSZ);
-		memcpy(VARDATA(&chunk_data), data_p, chunk_size);
-		toasttup = heap_form_tuple(toasttupDesc, t_values, t_isnull);
-
-		heap_insert(toastrel, toasttup, mycid, options, NULL);
-
-		/*
-		 * Create the index entry.  We cheat a little here by not using
-		 * FormIndexDatum: this relies on the knowledge that the index columns
-		 * are the same as the initial columns of the table for all the
-		 * indexes.  We also cheat by not providing an IndexInfo: this is okay
-		 * for now because btree doesn't need one, but we might have to be
-		 * more honest someday.
-		 *
-		 * Note also that there had better not be any user-created index on
-		 * the TOAST table, since we don't bother to update anything else.
-		 */
-		for (i = 0; i < num_indexes; i++)
-		{
-			/* Only index relations marked as ready can be updated */
-			if (toastidxs[i]->rd_index->indisready)
-				index_insert(toastidxs[i], t_values, t_isnull,
-							 &(toasttup->t_self),
-							 toastrel,
-							 toastidxs[i]->rd_index->indisunique ?
-							 UNIQUE_CHECK_YES : UNIQUE_CHECK_NO,
-							 NULL);
-		}
-
-		/*
-		 * Free memory
-		 */
-		heap_freetuple(toasttup);
-
-		/*
-		 * Move on to next chunk
-		 */
-		data_todo -= chunk_size;
-		data_p += chunk_size;
-	}
-
-	/*
-	 * Done - close toast relation and its indexes
-	 */
-	toast_close_indexes(toastidxs, num_indexes, RowExclusiveLock);
-	table_close(toastrel, RowExclusiveLock);
-
-	/*
-	 * Create the TOAST pointer value that we'll return
-	 */
-	result = (struct varlena *) palloc(TOAST_POINTER_SIZE);
-	SET_VARTAG_EXTERNAL(result, VARTAG_ONDISK);
-	memcpy(VARDATA_EXTERNAL(result), &toast_pointer, sizeof(toast_pointer));
-
-	return PointerGetDatum(result);
-}
-
-
-/* ----------
- * toast_delete_datum -
- *
- *	Delete a single external stored value.
- * ----------
- */
-static void
-toast_delete_datum(Relation rel, Datum value, bool is_speculative)
-{
-	struct varlena *attr = (struct varlena *) DatumGetPointer(value);
-	struct varatt_external toast_pointer;
-	Relation	toastrel;
-	Relation   *toastidxs;
-	ScanKeyData toastkey;
-	SysScanDesc toastscan;
-	HeapTuple	toasttup;
-	int			num_indexes;
-	int			validIndex;
-	SnapshotData SnapshotToast;
-
-	if (!VARATT_IS_EXTERNAL_ONDISK(attr))
-		return;
-
-	/* Must copy to access aligned fields */
-	VARATT_EXTERNAL_GET_POINTER(toast_pointer, attr);
-
-	/*
-	 * Open the toast relation and its indexes
-	 */
-	toastrel = table_open(toast_pointer.va_toastrelid, RowExclusiveLock);
-
-	/* Fetch valid relation used for process */
-	validIndex = toast_open_indexes(toastrel,
-									RowExclusiveLock,
-									&toastidxs,
-									&num_indexes);
-
-	/*
-	 * Setup a scan key to find chunks with matching va_valueid
-	 */
-	ScanKeyInit(&toastkey,
-				(AttrNumber) 1,
-				BTEqualStrategyNumber, F_OIDEQ,
-				ObjectIdGetDatum(toast_pointer.va_valueid));
-
-	/*
-	 * Find all the chunks.  (We don't actually care whether we see them in
-	 * sequence or not, but since we've already locked the index we might as
-	 * well use systable_beginscan_ordered.)
-	 */
-	init_toast_snapshot(&SnapshotToast);
-	toastscan = systable_beginscan_ordered(toastrel, toastidxs[validIndex],
-										   &SnapshotToast, 1, &toastkey);
-	while ((toasttup = systable_getnext_ordered(toastscan, ForwardScanDirection)) != NULL)
-	{
-		/*
-		 * Have a chunk, delete it
-		 */
-		if (is_speculative)
-			heap_abort_speculative(toastrel, &toasttup->t_self);
-		else
-			simple_heap_delete(toastrel, &toasttup->t_self);
-	}
-
-	/*
-	 * End scan and close relations
-	 */
-	systable_endscan_ordered(toastscan);
-	toast_close_indexes(toastidxs, num_indexes, RowExclusiveLock);
-	table_close(toastrel, RowExclusiveLock);
-}
-
-
-/* ----------
- * toastrel_valueid_exists -
- *
- *	Test whether a toast value with the given ID exists in the toast relation.
- *	For safety, we consider a value to exist if there are either live or dead
- *	toast rows with that ID; see notes for GetNewOidWithIndex().
- * ----------
- */
-static bool
-toastrel_valueid_exists(Relation toastrel, Oid valueid)
-{
-	bool		result = false;
-	ScanKeyData toastkey;
-	SysScanDesc toastscan;
-	int			num_indexes;
-	int			validIndex;
-	Relation   *toastidxs;
-
-	/* Fetch a valid index relation */
-	validIndex = toast_open_indexes(toastrel,
-									RowExclusiveLock,
-									&toastidxs,
-									&num_indexes);
-
-	/*
-	 * Setup a scan key to find chunks with matching va_valueid
-	 */
-	ScanKeyInit(&toastkey,
-				(AttrNumber) 1,
-				BTEqualStrategyNumber, F_OIDEQ,
-				ObjectIdGetDatum(valueid));
-
-	/*
-	 * Is there any such chunk?
-	 */
-	toastscan = systable_beginscan(toastrel,
-								   RelationGetRelid(toastidxs[validIndex]),
-								   true, SnapshotAny, 1, &toastkey);
-
-	if (systable_getnext(toastscan) != NULL)
-		result = true;
-
-	systable_endscan(toastscan);
-
-	/* Clean up */
-	toast_close_indexes(toastidxs, num_indexes, RowExclusiveLock);
-
-	return result;
-}
-
-/* ----------
- * toastid_valueid_exists -
- *
- *	As above, but work from toast rel's OID not an open relation
- * ----------
- */
-static bool
-toastid_valueid_exists(Oid toastrelid, Oid valueid)
-{
-	bool		result;
-	Relation	toastrel;
-
-	toastrel = table_open(toastrelid, AccessShareLock);
-
-	result = toastrel_valueid_exists(toastrel, valueid);
-
-	table_close(toastrel, AccessShareLock);
-
-	return result;
-}
-
-
-/* ----------
- * toast_fetch_datum -
- *
- *	Reconstruct an in memory Datum from the chunks saved
- *	in the toast relation
- * ----------
- */
-static struct varlena *
-toast_fetch_datum(struct varlena *attr)
-{
-	Relation	toastrel;
-	Relation   *toastidxs;
-	ScanKeyData toastkey;
-	SysScanDesc toastscan;
-	HeapTuple	ttup;
-	TupleDesc	toasttupDesc;
-	struct varlena *result;
-	struct varatt_external toast_pointer;
-	int32		ressize;
-	int32		residx,
-				nextidx;
-	int32		numchunks;
-	Pointer		chunk;
-	bool		isnull;
-	char	   *chunkdata;
-	int32		chunksize;
-	int			num_indexes;
-	int			validIndex;
-	SnapshotData SnapshotToast;
-
-	if (!VARATT_IS_EXTERNAL_ONDISK(attr))
-		elog(ERROR, "toast_fetch_datum shouldn't be called for non-ondisk datums");
-
-	/* Must copy to access aligned fields */
-	VARATT_EXTERNAL_GET_POINTER(toast_pointer, attr);
-
-	ressize = toast_pointer.va_extsize;
-	numchunks = ((ressize - 1) / TOAST_MAX_CHUNK_SIZE) + 1;
-
-	result = (struct varlena *) palloc(ressize + VARHDRSZ);
-
-	if (VARATT_EXTERNAL_IS_COMPRESSED(toast_pointer))
-		SET_VARSIZE_COMPRESSED(result, ressize + VARHDRSZ);
-	else
-		SET_VARSIZE(result, ressize + VARHDRSZ);
-
-	/*
-	 * Open the toast relation and its indexes
-	 */
-	toastrel = table_open(toast_pointer.va_toastrelid, AccessShareLock);
-	toasttupDesc = toastrel->rd_att;
-
-	/* Look for the valid index of the toast relation */
-	validIndex = toast_open_indexes(toastrel,
-									AccessShareLock,
-									&toastidxs,
-									&num_indexes);
-
-	/*
-	 * Setup a scan key to fetch from the index by va_valueid
-	 */
-	ScanKeyInit(&toastkey,
-				(AttrNumber) 1,
-				BTEqualStrategyNumber, F_OIDEQ,
-				ObjectIdGetDatum(toast_pointer.va_valueid));
-
-	/*
-	 * Read the chunks by index
-	 *
-	 * Note that because the index is actually on (valueid, chunkidx) we will
-	 * see the chunks in chunkidx order, even though we didn't explicitly ask
-	 * for it.
-	 */
-	nextidx = 0;
-
-	init_toast_snapshot(&SnapshotToast);
-	toastscan = systable_beginscan_ordered(toastrel, toastidxs[validIndex],
-										   &SnapshotToast, 1, &toastkey);
-	while ((ttup = systable_getnext_ordered(toastscan, ForwardScanDirection)) != NULL)
-	{
-		/*
-		 * Have a chunk, extract the sequence number and the data
-		 */
-		residx = DatumGetInt32(fastgetattr(ttup, 2, toasttupDesc, &isnull));
-		Assert(!isnull);
-		chunk = DatumGetPointer(fastgetattr(ttup, 3, toasttupDesc, &isnull));
-		Assert(!isnull);
-		if (!VARATT_IS_EXTENDED(chunk))
-		{
-			chunksize = VARSIZE(chunk) - VARHDRSZ;
-			chunkdata = VARDATA(chunk);
-		}
-		else if (VARATT_IS_SHORT(chunk))
-		{
-			/* could happen due to heap_form_tuple doing its thing */
-			chunksize = VARSIZE_SHORT(chunk) - VARHDRSZ_SHORT;
-			chunkdata = VARDATA_SHORT(chunk);
-		}
-		else
-		{
-			/* should never happen */
-			elog(ERROR, "found toasted toast chunk for toast value %u in %s",
-				 toast_pointer.va_valueid,
-				 RelationGetRelationName(toastrel));
-			chunksize = 0;		/* keep compiler quiet */
-			chunkdata = NULL;
-		}
-
-		/*
-		 * Some checks on the data we've found
-		 */
-		if (residx != nextidx)
-			ereport(ERROR,
-					(errcode(ERRCODE_DATA_CORRUPTED),
-					 errmsg_internal("unexpected chunk number %d (expected %d) for toast value %u in %s",
-									 residx, nextidx,
-									 toast_pointer.va_valueid,
-									 RelationGetRelationName(toastrel))));
-		if (residx < numchunks - 1)
-		{
-			if (chunksize != TOAST_MAX_CHUNK_SIZE)
-				ereport(ERROR,
-						(errcode(ERRCODE_DATA_CORRUPTED),
-						 errmsg_internal("unexpected chunk size %d (expected %d) in chunk %d of %d for toast value %u in %s",
-										 chunksize, (int) TOAST_MAX_CHUNK_SIZE,
-										 residx, numchunks,
-										 toast_pointer.va_valueid,
-										 RelationGetRelationName(toastrel))));
-		}
-		else if (residx == numchunks - 1)
-		{
-			if ((residx * TOAST_MAX_CHUNK_SIZE + chunksize) != ressize)
-				ereport(ERROR,
-						(errcode(ERRCODE_DATA_CORRUPTED),
-						 errmsg_internal("unexpected chunk size %d (expected %d) in final chunk %d for toast value %u in %s",
-										 chunksize,
-										 (int) (ressize - residx * TOAST_MAX_CHUNK_SIZE),
-										 residx,
-										 toast_pointer.va_valueid,
-										 RelationGetRelationName(toastrel))));
-		}
-		else
-			ereport(ERROR,
-					(errcode(ERRCODE_DATA_CORRUPTED),
-					 errmsg_internal("unexpected chunk number %d (out of range %d..%d) for toast value %u in %s",
-									 residx,
-									 0, numchunks - 1,
-									 toast_pointer.va_valueid,
-									 RelationGetRelationName(toastrel))));
-
-		/*
-		 * Copy the data into proper place in our result
-		 */
-		memcpy(VARDATA(result) + residx * TOAST_MAX_CHUNK_SIZE,
-			   chunkdata,
-			   chunksize);
-
-		nextidx++;
-	}
-
-	/*
-	 * Final checks that we successfully fetched the datum
-	 */
-	if (nextidx != numchunks)
-		ereport(ERROR,
-				(errcode(ERRCODE_DATA_CORRUPTED),
-				 errmsg_internal("missing chunk number %d for toast value %u in %s",
-								 nextidx,
-								 toast_pointer.va_valueid,
-								 RelationGetRelationName(toastrel))));
-
-	/*
-	 * End scan and close relations
-	 */
-	systable_endscan_ordered(toastscan);
-	toast_close_indexes(toastidxs, num_indexes, AccessShareLock);
-	table_close(toastrel, AccessShareLock);
-
-	return result;
-}
-
-/* ----------
- * toast_fetch_datum_slice -
- *
- *	Reconstruct a segment of a Datum from the chunks saved
- *	in the toast relation
- *
- *	Note that this function only supports non-compressed external datums.
- * ----------
- */
-static struct varlena *
-toast_fetch_datum_slice(struct varlena *attr, int32 sliceoffset, int32 length)
-{
-	Relation	toastrel;
-	Relation   *toastidxs;
-	ScanKeyData toastkey[3];
-	int			nscankeys;
-	SysScanDesc toastscan;
-	HeapTuple	ttup;
-	TupleDesc	toasttupDesc;
-	struct varlena *result;
-	struct varatt_external toast_pointer;
-	int32		attrsize;
-	int32		residx;
-	int32		nextidx;
-	int			numchunks;
-	int			startchunk;
-	int			endchunk;
-	int32		startoffset;
-	int32		endoffset;
-	int			totalchunks;
-	Pointer		chunk;
-	bool		isnull;
-	char	   *chunkdata;
-	int32		chunksize;
-	int32		chcpystrt;
-	int32		chcpyend;
-	int			num_indexes;
-	int			validIndex;
-	SnapshotData SnapshotToast;
-
-	if (!VARATT_IS_EXTERNAL_ONDISK(attr))
-		elog(ERROR, "toast_fetch_datum_slice shouldn't be called for non-ondisk datums");
-
-	/* Must copy to access aligned fields */
-	VARATT_EXTERNAL_GET_POINTER(toast_pointer, attr);
-
-	/*
-	 * It's nonsense to fetch slices of a compressed datum -- this isn't lo_*
-	 * we can't return a compressed datum which is meaningful to toast later
-	 */
-	Assert(!VARATT_EXTERNAL_IS_COMPRESSED(toast_pointer));
-
-	attrsize = toast_pointer.va_extsize;
-	totalchunks = ((attrsize - 1) / TOAST_MAX_CHUNK_SIZE) + 1;
-
-	if (sliceoffset >= attrsize)
-	{
-		sliceoffset = 0;
-		length = 0;
-	}
-
-	if (((sliceoffset + length) > attrsize) || length < 0)
-		length = attrsize - sliceoffset;
-
-	result = (struct varlena *) palloc(length + VARHDRSZ);
-
-	SET_VARSIZE(result, length + VARHDRSZ);
-
-	if (length == 0)
-		return result;			/* Can save a lot of work at this point! */
-
-	startchunk = sliceoffset / TOAST_MAX_CHUNK_SIZE;
-	endchunk = (sliceoffset + length - 1) / TOAST_MAX_CHUNK_SIZE;
-	numchunks = (endchunk - startchunk) + 1;
-
-	startoffset = sliceoffset % TOAST_MAX_CHUNK_SIZE;
-	endoffset = (sliceoffset + length - 1) % TOAST_MAX_CHUNK_SIZE;
-
-	/*
-	 * Open the toast relation and its indexes
-	 */
-	toastrel = table_open(toast_pointer.va_toastrelid, AccessShareLock);
-	toasttupDesc = toastrel->rd_att;
-
-	/* Look for the valid index of toast relation */
-	validIndex = toast_open_indexes(toastrel,
-									AccessShareLock,
-									&toastidxs,
-									&num_indexes);
-
-	/*
-	 * Setup a scan key to fetch from the index. This is either two keys or
-	 * three depending on the number of chunks.
-	 */
-	ScanKeyInit(&toastkey[0],
-				(AttrNumber) 1,
-				BTEqualStrategyNumber, F_OIDEQ,
-				ObjectIdGetDatum(toast_pointer.va_valueid));
-
-	/*
-	 * Use equality condition for one chunk, a range condition otherwise:
-	 */
-	if (numchunks == 1)
-	{
-		ScanKeyInit(&toastkey[1],
-					(AttrNumber) 2,
-					BTEqualStrategyNumber, F_INT4EQ,
-					Int32GetDatum(startchunk));
-		nscankeys = 2;
-	}
-	else
-	{
-		ScanKeyInit(&toastkey[1],
-					(AttrNumber) 2,
-					BTGreaterEqualStrategyNumber, F_INT4GE,
-					Int32GetDatum(startchunk));
-		ScanKeyInit(&toastkey[2],
-					(AttrNumber) 2,
-					BTLessEqualStrategyNumber, F_INT4LE,
-					Int32GetDatum(endchunk));
-		nscankeys = 3;
-	}
-
-	/*
-	 * Read the chunks by index
-	 *
-	 * The index is on (valueid, chunkidx) so they will come in order
-	 */
-	init_toast_snapshot(&SnapshotToast);
-	nextidx = startchunk;
-	toastscan = systable_beginscan_ordered(toastrel, toastidxs[validIndex],
-										   &SnapshotToast, nscankeys, toastkey);
-	while ((ttup = systable_getnext_ordered(toastscan, ForwardScanDirection)) != NULL)
-	{
-		/*
-		 * Have a chunk, extract the sequence number and the data
-		 */
-		residx = DatumGetInt32(fastgetattr(ttup, 2, toasttupDesc, &isnull));
-		Assert(!isnull);
-		chunk = DatumGetPointer(fastgetattr(ttup, 3, toasttupDesc, &isnull));
-		Assert(!isnull);
-		if (!VARATT_IS_EXTENDED(chunk))
-		{
-			chunksize = VARSIZE(chunk) - VARHDRSZ;
-			chunkdata = VARDATA(chunk);
-		}
-		else if (VARATT_IS_SHORT(chunk))
-		{
-			/* could happen due to heap_form_tuple doing its thing */
-			chunksize = VARSIZE_SHORT(chunk) - VARHDRSZ_SHORT;
-			chunkdata = VARDATA_SHORT(chunk);
-		}
-		else
-		{
-			/* should never happen */
-			elog(ERROR, "found toasted toast chunk for toast value %u in %s",
-				 toast_pointer.va_valueid,
-				 RelationGetRelationName(toastrel));
-			chunksize = 0;		/* keep compiler quiet */
-			chunkdata = NULL;
-		}
-
-		/*
-		 * Some checks on the data we've found
-		 */
-		if ((residx != nextidx) || (residx > endchunk) || (residx < startchunk))
-			elog(ERROR, "unexpected chunk number %d (expected %d) for toast value %u in %s",
-				 residx, nextidx,
-				 toast_pointer.va_valueid,
-				 RelationGetRelationName(toastrel));
-		if (residx < totalchunks - 1)
-		{
-			if (chunksize != TOAST_MAX_CHUNK_SIZE)
-				elog(ERROR, "unexpected chunk size %d (expected %d) in chunk %d of %d for toast value %u in %s when fetching slice",
-					 chunksize, (int) TOAST_MAX_CHUNK_SIZE,
-					 residx, totalchunks,
-					 toast_pointer.va_valueid,
-					 RelationGetRelationName(toastrel));
-		}
-		else if (residx == totalchunks - 1)
-		{
-			if ((residx * TOAST_MAX_CHUNK_SIZE + chunksize) != attrsize)
-				elog(ERROR, "unexpected chunk size %d (expected %d) in final chunk %d for toast value %u in %s when fetching slice",
-					 chunksize,
-					 (int) (attrsize - residx * TOAST_MAX_CHUNK_SIZE),
-					 residx,
-					 toast_pointer.va_valueid,
-					 RelationGetRelationName(toastrel));
-		}
-		else
-			elog(ERROR, "unexpected chunk number %d (out of range %d..%d) for toast value %u in %s",
-				 residx,
-				 0, totalchunks - 1,
-				 toast_pointer.va_valueid,
-				 RelationGetRelationName(toastrel));
-
-		/*
-		 * Copy the data into proper place in our result
-		 */
-		chcpystrt = 0;
-		chcpyend = chunksize - 1;
-		if (residx == startchunk)
-			chcpystrt = startoffset;
-		if (residx == endchunk)
-			chcpyend = endoffset;
-
-		memcpy(VARDATA(result) +
-			   (residx * TOAST_MAX_CHUNK_SIZE - sliceoffset) + chcpystrt,
-			   chunkdata + chcpystrt,
-			   (chcpyend - chcpystrt) + 1);
-
-		nextidx++;
-	}
-
-	/*
-	 * Final checks that we successfully fetched the datum
-	 */
-	if (nextidx != (endchunk + 1))
-		elog(ERROR, "missing chunk number %d for toast value %u in %s",
-			 nextidx,
-			 toast_pointer.va_valueid,
-			 RelationGetRelationName(toastrel));
-
-	/*
-	 * End scan and close relations
-	 */
-	systable_endscan_ordered(toastscan);
-	toast_close_indexes(toastidxs, num_indexes, AccessShareLock);
-	table_close(toastrel, AccessShareLock);
-
-	return result;
-}
-
-/* ----------
- * toast_decompress_datum -
- *
- * Decompress a compressed version of a varlena datum
- */
-static struct varlena *
-toast_decompress_datum(struct varlena *attr)
-{
-	struct varlena *result;
-
-	Assert(VARATT_IS_COMPRESSED(attr));
-
-	result = (struct varlena *)
-		palloc(TOAST_COMPRESS_RAWSIZE(attr) + VARHDRSZ);
-	SET_VARSIZE(result, TOAST_COMPRESS_RAWSIZE(attr) + VARHDRSZ);
-
-	if (pglz_decompress(TOAST_COMPRESS_RAWDATA(attr),
-						VARSIZE(attr) - TOAST_COMPRESS_HDRSZ,
-						VARDATA(result),
-						TOAST_COMPRESS_RAWSIZE(attr), true) < 0)
-		elog(ERROR, "compressed data is corrupted");
-
-	return result;
-}
-
-
-/* ----------
- * toast_decompress_datum_slice -
- *
- * Decompress the front of a compressed version of a varlena datum.
- * offset handling happens in heap_tuple_untoast_attr_slice.
- * Here we just decompress a slice from the front.
- */
-static struct varlena *
-toast_decompress_datum_slice(struct varlena *attr, int32 slicelength)
-{
-	struct varlena *result;
-	int32		rawsize;
-
-	Assert(VARATT_IS_COMPRESSED(attr));
-
-	result = (struct varlena *) palloc(slicelength + VARHDRSZ);
-
-	rawsize = pglz_decompress(TOAST_COMPRESS_RAWDATA(attr),
-							  VARSIZE(attr) - TOAST_COMPRESS_HDRSZ,
-							  VARDATA(result),
-							  slicelength, false);
-	if (rawsize < 0)
-		elog(ERROR, "compressed data is corrupted");
-
-	SET_VARSIZE(result, rawsize + VARHDRSZ);
-	return result;
-}
-
-
-/* ----------
- * toast_open_indexes
- *
- *	Get an array of the indexes associated to the given toast relation
- *	and return as well the position of the valid index used by the toast
- *	relation in this array. It is the responsibility of the caller of this
- *	function to close the indexes as well as free them.
- */
-static int
-toast_open_indexes(Relation toastrel,
-				   LOCKMODE lock,
-				   Relation **toastidxs,
-				   int *num_indexes)
-{
-	int			i = 0;
-	int			res = 0;
-	bool		found = false;
-	List	   *indexlist;
-	ListCell   *lc;
-
-	/* Get index list of the toast relation */
-	indexlist = RelationGetIndexList(toastrel);
-	Assert(indexlist != NIL);
-
-	*num_indexes = list_length(indexlist);
-
-	/* Open all the index relations */
-	*toastidxs = (Relation *) palloc(*num_indexes * sizeof(Relation));
-	foreach(lc, indexlist)
-		(*toastidxs)[i++] = index_open(lfirst_oid(lc), lock);
-
-	/* Fetch the first valid index in list */
-	for (i = 0; i < *num_indexes; i++)
-	{
-		Relation	toastidx = (*toastidxs)[i];
-
-		if (toastidx->rd_index->indisvalid)
-		{
-			res = i;
-			found = true;
-			break;
-		}
-	}
-
-	/*
-	 * Free index list, not necessary anymore as relations are opened and a
-	 * valid index has been found.
-	 */
-	list_free(indexlist);
-
-	/*
-	 * The toast relation should have one valid index, so something is going
-	 * wrong if there is nothing.
-	 */
-	if (!found)
-		elog(ERROR, "no valid index found for toast relation with Oid %u",
-			 RelationGetRelid(toastrel));
-
-	return res;
-}
-
-/* ----------
- * toast_close_indexes
- *
- *	Close an array of indexes for a toast relation and free it. This should
- *	be called for a set of indexes opened previously with toast_open_indexes.
- */
-static void
-toast_close_indexes(Relation *toastidxs, int num_indexes, LOCKMODE lock)
-{
-	int			i;
-
-	/* Close relations and clean up things */
-	for (i = 0; i < num_indexes; i++)
-		index_close(toastidxs[i], lock);
-	pfree(toastidxs);
-}
-
-/* ----------
- * init_toast_snapshot
- *
- *	Initialize an appropriate TOAST snapshot.  We must use an MVCC snapshot
- *	to initialize the TOAST snapshot; since we don't know which one to use,
- *	just use the oldest one.  This is safe: at worst, we will get a "snapshot
- *	too old" error that might have been avoided otherwise.
- */
-static void
-init_toast_snapshot(Snapshot toast_snapshot)
-{
-	Snapshot	snapshot = GetOldestSnapshot();
-
-	if (snapshot == NULL)
-		elog(ERROR, "no known snapshots");
-
-	InitToastSnapshot(*toast_snapshot, snapshot->lsn, snapshot->whenTaken);
-}
diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c
index f553523857..26669ea36d 100644
--- a/src/backend/access/transam/xlog.c
+++ b/src/backend/access/transam/xlog.c
@@ -24,12 +24,12 @@
 
 #include "access/clog.h"
 #include "access/commit_ts.h"
+#include "access/heaptoast.h"
 #include "access/multixact.h"
 #include "access/rewriteheap.h"
 #include "access/subtrans.h"
 #include "access/timeline.h"
 #include "access/transam.h"
-#include "access/tuptoaster.h"
 #include "access/twophase.h"
 #include "access/xact.h"
 #include "access/xlog_internal.h"
diff --git a/src/backend/commands/analyze.c b/src/backend/commands/analyze.c
index 92285e848f..4924085f54 100644
--- a/src/backend/commands/analyze.c
+++ b/src/backend/commands/analyze.c
@@ -16,6 +16,7 @@
 
 #include <math.h>
 
+#include "access/detoast.h"
 #include "access/genam.h"
 #include "access/multixact.h"
 #include "access/relation.h"
@@ -24,7 +25,6 @@
 #include "access/tableam.h"
 #include "access/transam.h"
 #include "access/tupconvert.h"
-#include "access/tuptoaster.h"
 #include "access/visibilitymap.h"
 #include "access/xact.h"
 #include "catalog/catalog.h"
diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c
index cedb4ee844..a59e2553d1 100644
--- a/src/backend/commands/cluster.c
+++ b/src/backend/commands/cluster.c
@@ -23,7 +23,7 @@
 #include "access/relscan.h"
 #include "access/tableam.h"
 #include "access/transam.h"
-#include "access/tuptoaster.h"
+#include "access/toast_internals.h"
 #include "access/xact.h"
 #include "access/xlog.h"
 #include "catalog/pg_am.h"
diff --git a/src/backend/executor/execExprInterp.c b/src/backend/executor/execExprInterp.c
index 66a67c72b2..cfd3aa1fb8 100644
--- a/src/backend/executor/execExprInterp.c
+++ b/src/backend/executor/execExprInterp.c
@@ -56,7 +56,7 @@
  */
 #include "postgres.h"
 
-#include "access/tuptoaster.h"
+#include "access/heaptoast.h"
 #include "catalog/pg_type.h"
 #include "commands/sequence.h"
 #include "executor/execExpr.h"
diff --git a/src/backend/executor/execTuples.c b/src/backend/executor/execTuples.c
index 5ee2a464bb..82b69456ad 100644
--- a/src/backend/executor/execTuples.c
+++ b/src/backend/executor/execTuples.c
@@ -57,9 +57,9 @@
  */
 #include "postgres.h"
 
+#include "access/heaptoast.h"
 #include "access/htup_details.h"
 #include "access/tupdesc_details.h"
-#include "access/tuptoaster.h"
 #include "funcapi.h"
 #include "catalog/pg_type.h"
 #include "nodes/nodeFuncs.h"
diff --git a/src/backend/executor/tstoreReceiver.c b/src/backend/executor/tstoreReceiver.c
index cf79feb6bd..c0c81c82da 100644
--- a/src/backend/executor/tstoreReceiver.c
+++ b/src/backend/executor/tstoreReceiver.c
@@ -20,7 +20,7 @@
 
 #include "postgres.h"
 
-#include "access/tuptoaster.h"
+#include "access/detoast.h"
 #include "executor/tstoreReceiver.h"
 
 
diff --git a/src/backend/replication/logical/reorderbuffer.c b/src/backend/replication/logical/reorderbuffer.c
index e8ffa0492f..0bb008414f 100644
--- a/src/backend/replication/logical/reorderbuffer.c
+++ b/src/backend/replication/logical/reorderbuffer.c
@@ -56,10 +56,10 @@
 #include <unistd.h>
 #include <sys/stat.h>
 
+#include "access/detoast.h"
 #include "access/heapam.h"
 #include "access/rewriteheap.h"
 #include "access/transam.h"
-#include "access/tuptoaster.h"
 #include "access/xact.h"
 #include "access/xlog_internal.h"
 #include "catalog/catalog.h"
diff --git a/src/backend/statistics/extended_stats.c b/src/backend/statistics/extended_stats.c
index 23c74f7d90..d0ee5ff405 100644
--- a/src/backend/statistics/extended_stats.c
+++ b/src/backend/statistics/extended_stats.c
@@ -16,10 +16,10 @@
  */
 #include "postgres.h"
 
+#include "access/detoast.h"
 #include "access/genam.h"
 #include "access/htup_details.h"
 #include "access/table.h"
-#include "access/tuptoaster.h"
 #include "catalog/indexing.h"
 #include "catalog/pg_collation.h"
 #include "catalog/pg_statistic_ext.h"
diff --git a/src/backend/storage/large_object/inv_api.c b/src/backend/storage/large_object/inv_api.c
index a477cb9200..e591236343 100644
--- a/src/backend/storage/large_object/inv_api.c
+++ b/src/backend/storage/large_object/inv_api.c
@@ -32,10 +32,11 @@
 
 #include <limits.h>
 
+#include "access/detoast.h"
 #include "access/genam.h"
+#include "access/htup_details.h"
 #include "access/sysattr.h"
 #include "access/table.h"
-#include "access/tuptoaster.h"
 #include "access/xact.h"
 #include "catalog/dependency.h"
 #include "catalog/indexing.h"
diff --git a/src/backend/utils/adt/array_typanalyze.c b/src/backend/utils/adt/array_typanalyze.c
index eafb94b697..54f5849629 100644
--- a/src/backend/utils/adt/array_typanalyze.c
+++ b/src/backend/utils/adt/array_typanalyze.c
@@ -14,7 +14,7 @@
  */
 #include "postgres.h"
 
-#include "access/tuptoaster.h"
+#include "access/detoast.h"
 #include "commands/vacuum.h"
 #include "utils/array.h"
 #include "utils/builtins.h"
diff --git a/src/backend/utils/adt/datum.c b/src/backend/utils/adt/datum.c
index 81ea5a48e5..1568658bc9 100644
--- a/src/backend/utils/adt/datum.c
+++ b/src/backend/utils/adt/datum.c
@@ -42,7 +42,7 @@
 
 #include "postgres.h"
 
-#include "access/tuptoaster.h"
+#include "access/detoast.h"
 #include "fmgr.h"
 #include "utils/datum.h"
 #include "utils/expandeddatum.h"
diff --git a/src/backend/utils/adt/expandedrecord.c b/src/backend/utils/adt/expandedrecord.c
index 166c863026..369432d53c 100644
--- a/src/backend/utils/adt/expandedrecord.c
+++ b/src/backend/utils/adt/expandedrecord.c
@@ -18,8 +18,9 @@
  */
 #include "postgres.h"
 
+#include "access/detoast.h"
+#include "access/heaptoast.h"
 #include "access/htup_details.h"
-#include "access/tuptoaster.h"
 #include "catalog/heap.h"
 #include "catalog/pg_type.h"
 #include "utils/builtins.h"
diff --git a/src/backend/utils/adt/rowtypes.c b/src/backend/utils/adt/rowtypes.c
index aa7ec8735c..ea3e40a369 100644
--- a/src/backend/utils/adt/rowtypes.c
+++ b/src/backend/utils/adt/rowtypes.c
@@ -16,8 +16,8 @@
 
 #include <ctype.h>
 
+#include "access/detoast.h"
 #include "access/htup_details.h"
-#include "access/tuptoaster.h"
 #include "catalog/pg_type.h"
 #include "funcapi.h"
 #include "libpq/pqformat.h"
diff --git a/src/backend/utils/adt/tsgistidx.c b/src/backend/utils/adt/tsgistidx.c
index 4f256260fd..6ff71a49b8 100644
--- a/src/backend/utils/adt/tsgistidx.c
+++ b/src/backend/utils/adt/tsgistidx.c
@@ -15,7 +15,7 @@
 #include "postgres.h"
 
 #include "access/gist.h"
-#include "access/tuptoaster.h"
+#include "access/heaptoast.h"
 #include "port/pg_bitutils.h"
 #include "tsearch/ts_utils.h"
 #include "utils/builtins.h"
diff --git a/src/backend/utils/adt/varchar.c b/src/backend/utils/adt/varchar.c
index 332dc860c4..9d94399323 100644
--- a/src/backend/utils/adt/varchar.c
+++ b/src/backend/utils/adt/varchar.c
@@ -14,7 +14,7 @@
  */
 #include "postgres.h"
 
-#include "access/tuptoaster.h"
+#include "access/detoast.h"
 #include "catalog/pg_collation.h"
 #include "catalog/pg_type.h"
 #include "libpq/pqformat.h"
diff --git a/src/backend/utils/adt/varlena.c b/src/backend/utils/adt/varlena.c
index 0864838867..3685223922 100644
--- a/src/backend/utils/adt/varlena.c
+++ b/src/backend/utils/adt/varlena.c
@@ -17,7 +17,7 @@
 #include <ctype.h>
 #include <limits.h>
 
-#include "access/tuptoaster.h"
+#include "access/detoast.h"
 #include "catalog/pg_collation.h"
 #include "catalog/pg_type.h"
 #include "common/int.h"
diff --git a/src/backend/utils/cache/catcache.c b/src/backend/utils/cache/catcache.c
index 00def27881..c3e7d94aa5 100644
--- a/src/backend/utils/cache/catcache.c
+++ b/src/backend/utils/cache/catcache.c
@@ -15,10 +15,10 @@
 #include "postgres.h"
 
 #include "access/genam.h"
+#include "access/heaptoast.h"
 #include "access/relscan.h"
 #include "access/sysattr.h"
 #include "access/table.h"
-#include "access/tuptoaster.h"
 #include "access/valid.h"
 #include "access/xact.h"
 #include "catalog/pg_collation.h"
diff --git a/src/backend/utils/fmgr/fmgr.c b/src/backend/utils/fmgr/fmgr.c
index 99c34516bd..0484adb984 100644
--- a/src/backend/utils/fmgr/fmgr.c
+++ b/src/backend/utils/fmgr/fmgr.c
@@ -15,7 +15,7 @@
 
 #include "postgres.h"
 
-#include "access/tuptoaster.h"
+#include "access/detoast.h"
 #include "catalog/pg_language.h"
 #include "catalog/pg_proc.h"
 #include "executor/functions.h"
diff --git a/src/bin/pg_resetwal/pg_resetwal.c b/src/bin/pg_resetwal/pg_resetwal.c
index 9d9c33d78c..ba192d0f53 100644
--- a/src/bin/pg_resetwal/pg_resetwal.c
+++ b/src/bin/pg_resetwal/pg_resetwal.c
@@ -45,7 +45,7 @@
 #include <unistd.h>
 
 #include "access/transam.h"
-#include "access/tuptoaster.h"
+#include "access/heaptoast.h"
 #include "access/multixact.h"
 #include "access/xlog.h"
 #include "access/xlog_internal.h"
diff --git a/src/include/access/detoast.h b/src/include/access/detoast.h
new file mode 100644
index 0000000000..582af147ea
--- /dev/null
+++ b/src/include/access/detoast.h
@@ -0,0 +1,92 @@
+/*-------------------------------------------------------------------------
+ *
+ * detoast.h
+ *	  Access to compressed and external varlena values.
+ *
+ * Copyright (c) 2000-2019, PostgreSQL Global Development Group
+ *
+ * src/include/access/detoast.h
+ *
+ *-------------------------------------------------------------------------
+ */
+#ifndef DETOAST_H 
+#define DETOAST_H
+
+/*
+ * Testing whether an externally-stored value is compressed now requires
+ * comparing extsize (the actual length of the external data) to rawsize
+ * (the original uncompressed datum's size).  The latter includes VARHDRSZ
+ * overhead, the former doesn't.  We never use compression unless it actually
+ * saves space, so we expect either equality or less-than.
+ */
+#define VARATT_EXTERNAL_IS_COMPRESSED(toast_pointer) \
+	((toast_pointer).va_extsize < (toast_pointer).va_rawsize - VARHDRSZ)
+
+/*
+ * Macro to fetch the possibly-unaligned contents of an EXTERNAL datum
+ * into a local "struct varatt_external" toast pointer.  This should be
+ * just a memcpy, but some versions of gcc seem to produce broken code
+ * that assumes the datum contents are aligned.  Introducing an explicit
+ * intermediate "varattrib_1b_e *" variable seems to fix it.
+ */
+#define VARATT_EXTERNAL_GET_POINTER(toast_pointer, attr) \
+do { \
+	varattrib_1b_e *attre = (varattrib_1b_e *) (attr); \
+	Assert(VARATT_IS_EXTERNAL(attre)); \
+	Assert(VARSIZE_EXTERNAL(attre) == sizeof(toast_pointer) + VARHDRSZ_EXTERNAL); \
+	memcpy(&(toast_pointer), VARDATA_EXTERNAL(attre), sizeof(toast_pointer)); \
+} while (0)
+
+/* Size of an EXTERNAL datum that contains a standard TOAST pointer */
+#define TOAST_POINTER_SIZE (VARHDRSZ_EXTERNAL + sizeof(varatt_external))
+
+/* Size of an EXTERNAL datum that contains an indirection pointer */
+#define INDIRECT_POINTER_SIZE (VARHDRSZ_EXTERNAL + sizeof(varatt_indirect))
+
+/* ----------
+ * heap_tuple_fetch_attr() -
+ *
+ *		Fetches an external stored attribute from the toast
+ *		relation. Does NOT decompress it, if stored external
+ *		in compressed format.
+ * ----------
+ */
+extern struct varlena *heap_tuple_fetch_attr(struct varlena *attr);
+
+/* ----------
+ * heap_tuple_untoast_attr() -
+ *
+ *		Fully detoasts one attribute, fetching and/or decompressing
+ *		it as needed.
+ * ----------
+ */
+extern struct varlena *heap_tuple_untoast_attr(struct varlena *attr);
+
+/* ----------
+ * heap_tuple_untoast_attr_slice() -
+ *
+ *		Fetches only the specified portion of an attribute.
+ *		(Handles all cases for attribute storage)
+ * ----------
+ */
+extern struct varlena *heap_tuple_untoast_attr_slice(struct varlena *attr,
+							  int32 sliceoffset,
+							  int32 slicelength);
+
+/* ----------
+ * toast_raw_datum_size -
+ *
+ *	Return the raw (detoasted) size of a varlena datum
+ * ----------
+ */
+extern Size toast_raw_datum_size(Datum value);
+
+/* ----------
+ * toast_datum_size -
+ *
+ *	Return the storage size of a varlena datum
+ * ----------
+ */
+extern Size toast_datum_size(Datum value);
+
+#endif							/* DETOAST_H */
diff --git a/src/include/access/tuptoaster.h b/src/include/access/heaptoast.h
similarity index 57%
rename from src/include/access/tuptoaster.h
rename to src/include/access/heaptoast.h
index f0aea2496b..bf02d2c600 100644
--- a/src/include/access/tuptoaster.h
+++ b/src/include/access/heaptoast.h
@@ -1,29 +1,22 @@
 /*-------------------------------------------------------------------------
  *
- * tuptoaster.h
- *	  POSTGRES definitions for external and compressed storage
+ * heaptoast.h
+ *	  Heap-specific definitions for external and compressed storage
  *	  of variable size attributes.
  *
  * Copyright (c) 2000-2019, PostgreSQL Global Development Group
  *
- * src/include/access/tuptoaster.h
+ * src/include/access/heaptoast.h
  *
  *-------------------------------------------------------------------------
  */
-#ifndef TUPTOASTER_H
-#define TUPTOASTER_H
+#ifndef HEAPTOAST_H
+#define HEAPTOAST_H
 
 #include "access/htup_details.h"
 #include "storage/lockdefs.h"
 #include "utils/relcache.h"
 
-/*
- * This enables de-toasting of index entries.  Needed until VACUUM is
- * smart enough to rebuild indexes from scratch.
- */
-#define TOAST_INDEX_HACK
-
-
 /*
  * Find the maximum size of a tuple if there are to be N tuples per page.
  */
@@ -95,37 +88,6 @@
 	 sizeof(int32) -									\
 	 VARHDRSZ)
 
-/* Size of an EXTERNAL datum that contains a standard TOAST pointer */
-#define TOAST_POINTER_SIZE (VARHDRSZ_EXTERNAL + sizeof(varatt_external))
-
-/* Size of an EXTERNAL datum that contains an indirection pointer */
-#define INDIRECT_POINTER_SIZE (VARHDRSZ_EXTERNAL + sizeof(varatt_indirect))
-
-/*
- * Testing whether an externally-stored value is compressed now requires
- * comparing extsize (the actual length of the external data) to rawsize
- * (the original uncompressed datum's size).  The latter includes VARHDRSZ
- * overhead, the former doesn't.  We never use compression unless it actually
- * saves space, so we expect either equality or less-than.
- */
-#define VARATT_EXTERNAL_IS_COMPRESSED(toast_pointer) \
-	((toast_pointer).va_extsize < (toast_pointer).va_rawsize - VARHDRSZ)
-
-/*
- * Macro to fetch the possibly-unaligned contents of an EXTERNAL datum
- * into a local "struct varatt_external" toast pointer.  This should be
- * just a memcpy, but some versions of gcc seem to produce broken code
- * that assumes the datum contents are aligned.  Introducing an explicit
- * intermediate "varattrib_1b_e *" variable seems to fix it.
- */
-#define VARATT_EXTERNAL_GET_POINTER(toast_pointer, attr) \
-do { \
-	varattrib_1b_e *attre = (varattrib_1b_e *) (attr); \
-	Assert(VARATT_IS_EXTERNAL(attre)); \
-	Assert(VARSIZE_EXTERNAL(attre) == sizeof(toast_pointer) + VARHDRSZ_EXTERNAL); \
-	memcpy(&(toast_pointer), VARDATA_EXTERNAL(attre), sizeof(toast_pointer)); \
-} while (0)
-
 /* ----------
  * toast_insert_or_update -
  *
@@ -144,36 +106,6 @@ extern HeapTuple toast_insert_or_update(Relation rel,
  */
 extern void toast_delete(Relation rel, HeapTuple oldtup, bool is_speculative);
 
-/* ----------
- * heap_tuple_fetch_attr() -
- *
- *		Fetches an external stored attribute from the toast
- *		relation. Does NOT decompress it, if stored external
- *		in compressed format.
- * ----------
- */
-extern struct varlena *heap_tuple_fetch_attr(struct varlena *attr);
-
-/* ----------
- * heap_tuple_untoast_attr() -
- *
- *		Fully detoasts one attribute, fetching and/or decompressing
- *		it as needed.
- * ----------
- */
-extern struct varlena *heap_tuple_untoast_attr(struct varlena *attr);
-
-/* ----------
- * heap_tuple_untoast_attr_slice() -
- *
- *		Fetches only the specified portion of an attribute.
- *		(Handles all cases for attribute storage)
- * ----------
- */
-extern struct varlena *heap_tuple_untoast_attr_slice(struct varlena *attr,
-													 int32 sliceoffset,
-													 int32 slicelength);
-
 /* ----------
  * toast_flatten_tuple -
  *
@@ -204,36 +136,4 @@ extern HeapTuple toast_build_flattened_tuple(TupleDesc tupleDesc,
 											 Datum *values,
 											 bool *isnull);
 
-/* ----------
- * toast_compress_datum -
- *
- *	Create a compressed version of a varlena datum, if possible
- * ----------
- */
-extern Datum toast_compress_datum(Datum value);
-
-/* ----------
- * toast_raw_datum_size -
- *
- *	Return the raw (detoasted) size of a varlena datum
- * ----------
- */
-extern Size toast_raw_datum_size(Datum value);
-
-/* ----------
- * toast_datum_size -
- *
- *	Return the storage size of a varlena datum
- * ----------
- */
-extern Size toast_datum_size(Datum value);
-
-/* ----------
- * toast_get_valid_index -
- *
- *	Return OID of valid index associated to a toast relation
- * ----------
- */
-extern Oid	toast_get_valid_index(Oid toastoid, LOCKMODE lock);
-
-#endif							/* TUPTOASTER_H */
+#endif							/* HEAPTOAST_H */
diff --git a/src/include/access/toast_internals.h b/src/include/access/toast_internals.h
new file mode 100644
index 0000000000..494b07a4b1
--- /dev/null
+++ b/src/include/access/toast_internals.h
@@ -0,0 +1,54 @@
+/*-------------------------------------------------------------------------
+ *
+ * toast_internals.h
+ *	  Internal definitions for the TOAST system.
+ *
+ * Copyright (c) 2000-2019, PostgreSQL Global Development Group
+ *
+ * src/include/access/toast_internals.h
+ *
+ *-------------------------------------------------------------------------
+ */
+#ifndef TOAST_INTERNALS_H
+#define TOAST_INTERNALS_H
+
+#include "storage/lockdefs.h"
+#include "utils/relcache.h"
+#include "utils/snapshot.h"
+
+/*
+ *	The information at the start of the compressed toast data.
+ */
+typedef struct toast_compress_header
+{
+	int32		vl_len_;		/* varlena header (do not touch directly!) */
+	int32		rawsize;
+} toast_compress_header;
+
+/*
+ * Utilities for manipulation of header information for compressed
+ * toast entries.
+ */
+#define TOAST_COMPRESS_HDRSZ		((int32) sizeof(toast_compress_header))
+#define TOAST_COMPRESS_RAWSIZE(ptr) (((toast_compress_header *) (ptr))->rawsize)
+#define TOAST_COMPRESS_RAWDATA(ptr) \
+	(((char *) (ptr)) + TOAST_COMPRESS_HDRSZ)
+#define TOAST_COMPRESS_SET_RAWSIZE(ptr, len) \
+	(((toast_compress_header *) (ptr))->rawsize = (len))
+
+extern Datum toast_compress_datum(Datum value);
+extern Oid	toast_get_valid_index(Oid toastoid, LOCKMODE lock);
+
+extern void toast_delete_datum(Relation rel, Datum value, bool is_speculative);
+extern Datum toast_save_datum(Relation rel, Datum value,
+							  struct varlena *oldexternal, int options);
+
+extern int	toast_open_indexes(Relation toastrel,
+							   LOCKMODE lock,
+							   Relation **toastidxs,
+							   int *num_indexes);
+extern void toast_close_indexes(Relation *toastidxs, int num_indexes,
+								LOCKMODE lock);
+extern void init_toast_snapshot(Snapshot toast_snapshot);
+
+#endif							/* TOAST_INTERNALS_H */
diff --git a/src/pl/plpgsql/src/pl_exec.c b/src/pl/plpgsql/src/pl_exec.c
index f5fdf93d0a..db2eff1bbb 100644
--- a/src/pl/plpgsql/src/pl_exec.c
+++ b/src/pl/plpgsql/src/pl_exec.c
@@ -17,10 +17,10 @@
 
 #include <ctype.h>
 
+#include "access/detoast.h"
 #include "access/htup_details.h"
 #include "access/transam.h"
 #include "access/tupconvert.h"
-#include "access/tuptoaster.h"
 #include "catalog/pg_proc.h"
 #include "catalog/pg_type.h"
 #include "commands/defrem.h"
diff --git a/src/test/regress/regress.c b/src/test/regress/regress.c
index 7f03b7e857..826556eb29 100644
--- a/src/test/regress/regress.c
+++ b/src/test/regress/regress.c
@@ -19,9 +19,9 @@
 #include <math.h>
 #include <signal.h>
 
+#include "access/detoast.h"
 #include "access/htup_details.h"
 #include "access/transam.h"
-#include "access/tuptoaster.h"
 #include "access/xact.h"
 #include "catalog/pg_operator.h"
 #include "catalog/pg_type.h"
-- 
2.17.2 (Apple Git-113)

From 7b08fbe2759c4882be3293ac374e9343a41b776b Mon Sep 17 00:00:00 2001
From: Robert Haas <rhaas@postgresql.org>
Date: Thu, 5 Sep 2019 10:30:34 -0400
Subject: [PATCH] Split tuptoaster.c into three separate files.

detoast.c/h contain functions required to detoast a datum, partially
or completely, plus a few other utility functions for examining the
size of toasted datums.

toast_internals.c/h contain functions that are used internally to the
TOAST subsystem but which (mostly) do not need to be accessed from
outside.

heaptoast.c/h contains code that is intrinsically specific to the
heap AM, either because it operates on HeapTuples or is based on the
layout of a heap page.

detoast.c and toast_internals.c are placed in
src/backend/access/common rather than src/backend/access/heap.  At
present, both files still have dependencies on the heap, but that will
be improved in a future commit.

Discussion: http://postgr.es/m/CA+TgmoZv-=2iWM4jcw5ZhJeL18HF96+W1yJeYrnGMYdkFFnEpQ@mail.gmail.com
---
 doc/src/sgml/storage.sgml                     |    2 +-
 src/backend/access/common/Makefile            |    5 +-
 src/backend/access/common/detoast.c           |  869 ++++++
 src/backend/access/common/heaptuple.c         |    4 +-
 src/backend/access/common/indextuple.c        |    9 +-
 src/backend/access/common/reloptions.c        |    2 +-
 src/backend/access/common/toast_internals.c   |  632 +++++
 src/backend/access/heap/Makefile              |    2 +-
 src/backend/access/heap/heapam.c              |    2 +-
 src/backend/access/heap/heapam_handler.c      |    2 +-
 src/backend/access/heap/heaptoast.c           |  917 +++++++
 src/backend/access/heap/rewriteheap.c         |    2 +-
 src/backend/access/heap/tuptoaster.c          | 2419 -----------------
 src/backend/access/transam/xlog.c             |    2 +-
 src/backend/commands/analyze.c                |    2 +-
 src/backend/commands/cluster.c                |    2 +-
 src/backend/executor/execExprInterp.c         |    2 +-
 src/backend/executor/execTuples.c             |    2 +-
 src/backend/executor/tstoreReceiver.c         |    2 +-
 .../replication/logical/reorderbuffer.c       |    2 +-
 src/backend/statistics/extended_stats.c       |    2 +-
 src/backend/storage/large_object/inv_api.c    |    3 +-
 src/backend/utils/adt/array_typanalyze.c      |    2 +-
 src/backend/utils/adt/datum.c                 |    2 +-
 src/backend/utils/adt/expandedrecord.c        |    3 +-
 src/backend/utils/adt/rowtypes.c              |    2 +-
 src/backend/utils/adt/tsgistidx.c             |    2 +-
 src/backend/utils/adt/varchar.c               |    2 +-
 src/backend/utils/adt/varlena.c               |    2 +-
 src/backend/utils/cache/catcache.c            |    2 +-
 src/backend/utils/fmgr/fmgr.c                 |    2 +-
 src/bin/pg_resetwal/pg_resetwal.c             |    2 +-
 src/include/access/detoast.h                  |   92 +
 .../access/{tuptoaster.h => heaptoast.h}      |  112 +-
 src/include/access/toast_internals.h          |   54 +
 src/pl/plpgsql/src/pl_exec.c                  |    2 +-
 src/test/regress/regress.c                    |    2 +-
 37 files changed, 2612 insertions(+), 2557 deletions(-)
 create mode 100644 src/backend/access/common/detoast.c
 create mode 100644 src/backend/access/common/toast_internals.c
 create mode 100644 src/backend/access/heap/heaptoast.c
 create mode 100644 src/include/access/detoast.h
 rename src/include/access/{tuptoaster.h => heaptoast.h} (57%)
 create mode 100644 src/include/access/toast_internals.h

diff --git a/doc/src/sgml/storage.sgml b/doc/src/sgml/storage.sgml
index 342a0ff7b7..7802eb82d4 100644
--- a/doc/src/sgml/storage.sgml
+++ b/doc/src/sgml/storage.sgml
@@ -382,7 +382,7 @@ The oldest and most common type is a pointer to out-of-line data stored in
 a <firstterm><acronym>TOAST</acronym> table</firstterm> that is separate from, but
 associated with, the table containing the <acronym>TOAST</acronym> pointer datum
 itself.  These <firstterm>on-disk</firstterm> pointer datums are created by the
-<acronym>TOAST</acronym> management code (in <filename>access/heap/tuptoaster.c</filename>)
+<acronym>TOAST</acronym> management code (in <filename>access/common/toast_internals.c</filename>)
 when a tuple to be stored on disk is too large to be stored as-is.
 Further details appear in <xref linkend="storage-toast-ondisk"/>.
 Alternatively, a <acronym>TOAST</acronym> pointer datum can contain a pointer to
diff --git a/src/backend/access/common/Makefile b/src/backend/access/common/Makefile
index d469504337..9ac19d9f9e 100644
--- a/src/backend/access/common/Makefile
+++ b/src/backend/access/common/Makefile
@@ -12,7 +12,8 @@ subdir = src/backend/access/common
 top_builddir = ../../../..
 include $(top_builddir)/src/Makefile.global
 
-OBJS = bufmask.o heaptuple.o indextuple.o printsimple.o printtup.o \
-	relation.o reloptions.o scankey.o session.o tupconvert.o tupdesc.o
+OBJS = bufmask.o detoast.o heaptuple.o indextuple.o printsimple.o \
+	printtup.o relation.o reloptions.o scankey.o session.o toast_internals.o \
+	tupconvert.o tupdesc.o
 
 include $(top_srcdir)/src/backend/common.mk
diff --git a/src/backend/access/common/detoast.c b/src/backend/access/common/detoast.c
new file mode 100644
index 0000000000..c8b49d6a12
--- /dev/null
+++ b/src/backend/access/common/detoast.c
@@ -0,0 +1,869 @@
+/*-------------------------------------------------------------------------
+ *
+ * detoast.c
+ *	  Retrieve compressed or external variable size attributes.
+ *
+ * Copyright (c) 2000-2019, PostgreSQL Global Development Group
+ *
+ * IDENTIFICATION
+ *	  src/backend/access/common/detoast.c
+ *
+ *-------------------------------------------------------------------------
+ */
+
+#include "postgres.h"
+
+#include "access/detoast.h"
+#include "access/genam.h"
+#include "access/heaptoast.h"
+#include "access/table.h"
+#include "access/toast_internals.h"
+#include "common/pg_lzcompress.h"
+#include "utils/expandeddatum.h"
+#include "utils/fmgroids.h"
+#include "utils/rel.h"
+
+static struct varlena *toast_fetch_datum(struct varlena *attr);
+static struct varlena *toast_fetch_datum_slice(struct varlena *attr,
+											   int32 sliceoffset, int32 length);
+static struct varlena *toast_decompress_datum(struct varlena *attr);
+static struct varlena *toast_decompress_datum_slice(struct varlena *attr, int32 slicelength);
+
+/* ----------
+ * heap_tuple_fetch_attr -
+ *
+ *	Public entry point to get back a toasted value from
+ *	external source (possibly still in compressed format).
+ *
+ * This will return a datum that contains all the data internally, ie, not
+ * relying on external storage or memory, but it can still be compressed or
+ * have a short header.  Note some callers assume that if the input is an
+ * EXTERNAL datum, the result will be a pfree'able chunk.
+ * ----------
+ */
+struct varlena *
+heap_tuple_fetch_attr(struct varlena *attr)
+{
+	struct varlena *result;
+
+	if (VARATT_IS_EXTERNAL_ONDISK(attr))
+	{
+		/*
+		 * This is an external stored plain value
+		 */
+		result = toast_fetch_datum(attr);
+	}
+	else if (VARATT_IS_EXTERNAL_INDIRECT(attr))
+	{
+		/*
+		 * This is an indirect pointer --- dereference it
+		 */
+		struct varatt_indirect redirect;
+
+		VARATT_EXTERNAL_GET_POINTER(redirect, attr);
+		attr = (struct varlena *) redirect.pointer;
+
+		/* nested indirect Datums aren't allowed */
+		Assert(!VARATT_IS_EXTERNAL_INDIRECT(attr));
+
+		/* recurse if value is still external in some other way */
+		if (VARATT_IS_EXTERNAL(attr))
+			return heap_tuple_fetch_attr(attr);
+
+		/*
+		 * Copy into the caller's memory context, in case caller tries to
+		 * pfree the result.
+		 */
+		result = (struct varlena *) palloc(VARSIZE_ANY(attr));
+		memcpy(result, attr, VARSIZE_ANY(attr));
+	}
+	else if (VARATT_IS_EXTERNAL_EXPANDED(attr))
+	{
+		/*
+		 * This is an expanded-object pointer --- get flat format
+		 */
+		ExpandedObjectHeader *eoh;
+		Size		resultsize;
+
+		eoh = DatumGetEOHP(PointerGetDatum(attr));
+		resultsize = EOH_get_flat_size(eoh);
+		result = (struct varlena *) palloc(resultsize);
+		EOH_flatten_into(eoh, (void *) result, resultsize);
+	}
+	else
+	{
+		/*
+		 * This is a plain value inside of the main tuple - why am I called?
+		 */
+		result = attr;
+	}
+
+	return result;
+}
+
+
+/* ----------
+ * heap_tuple_untoast_attr -
+ *
+ *	Public entry point to get back a toasted value from compression
+ *	or external storage.  The result is always non-extended varlena form.
+ *
+ * Note some callers assume that if the input is an EXTERNAL or COMPRESSED
+ * datum, the result will be a pfree'able chunk.
+ * ----------
+ */
+struct varlena *
+heap_tuple_untoast_attr(struct varlena *attr)
+{
+	if (VARATT_IS_EXTERNAL_ONDISK(attr))
+	{
+		/*
+		 * This is an externally stored datum --- fetch it back from there
+		 */
+		attr = toast_fetch_datum(attr);
+		/* If it's compressed, decompress it */
+		if (VARATT_IS_COMPRESSED(attr))
+		{
+			struct varlena *tmp = attr;
+
+			attr = toast_decompress_datum(tmp);
+			pfree(tmp);
+		}
+	}
+	else if (VARATT_IS_EXTERNAL_INDIRECT(attr))
+	{
+		/*
+		 * This is an indirect pointer --- dereference it
+		 */
+		struct varatt_indirect redirect;
+
+		VARATT_EXTERNAL_GET_POINTER(redirect, attr);
+		attr = (struct varlena *) redirect.pointer;
+
+		/* nested indirect Datums aren't allowed */
+		Assert(!VARATT_IS_EXTERNAL_INDIRECT(attr));
+
+		/* recurse in case value is still extended in some other way */
+		attr = heap_tuple_untoast_attr(attr);
+
+		/* if it isn't, we'd better copy it */
+		if (attr == (struct varlena *) redirect.pointer)
+		{
+			struct varlena *result;
+
+			result = (struct varlena *) palloc(VARSIZE_ANY(attr));
+			memcpy(result, attr, VARSIZE_ANY(attr));
+			attr = result;
+		}
+	}
+	else if (VARATT_IS_EXTERNAL_EXPANDED(attr))
+	{
+		/*
+		 * This is an expanded-object pointer --- get flat format
+		 */
+		attr = heap_tuple_fetch_attr(attr);
+		/* flatteners are not allowed to produce compressed/short output */
+		Assert(!VARATT_IS_EXTENDED(attr));
+	}
+	else if (VARATT_IS_COMPRESSED(attr))
+	{
+		/*
+		 * This is a compressed value inside of the main tuple
+		 */
+		attr = toast_decompress_datum(attr);
+	}
+	else if (VARATT_IS_SHORT(attr))
+	{
+		/*
+		 * This is a short-header varlena --- convert to 4-byte header format
+		 */
+		Size		data_size = VARSIZE_SHORT(attr) - VARHDRSZ_SHORT;
+		Size		new_size = data_size + VARHDRSZ;
+		struct varlena *new_attr;
+
+		new_attr = (struct varlena *) palloc(new_size);
+		SET_VARSIZE(new_attr, new_size);
+		memcpy(VARDATA(new_attr), VARDATA_SHORT(attr), data_size);
+		attr = new_attr;
+	}
+
+	return attr;
+}
+
+
+/* ----------
+ * heap_tuple_untoast_attr_slice -
+ *
+ *		Public entry point to get back part of a toasted value
+ *		from compression or external storage.
+ * ----------
+ */
+struct varlena *
+heap_tuple_untoast_attr_slice(struct varlena *attr,
+							  int32 sliceoffset, int32 slicelength)
+{
+	struct varlena *preslice;
+	struct varlena *result;
+	char	   *attrdata;
+	int32		attrsize;
+
+	if (VARATT_IS_EXTERNAL_ONDISK(attr))
+	{
+		struct varatt_external toast_pointer;
+
+		VARATT_EXTERNAL_GET_POINTER(toast_pointer, attr);
+
+		/* fast path for non-compressed external datums */
+		if (!VARATT_EXTERNAL_IS_COMPRESSED(toast_pointer))
+			return toast_fetch_datum_slice(attr, sliceoffset, slicelength);
+
+		/* fetch it back (compressed marker will get set automatically) */
+		preslice = toast_fetch_datum(attr);
+	}
+	else if (VARATT_IS_EXTERNAL_INDIRECT(attr))
+	{
+		struct varatt_indirect redirect;
+
+		VARATT_EXTERNAL_GET_POINTER(redirect, attr);
+
+		/* nested indirect Datums aren't allowed */
+		Assert(!VARATT_IS_EXTERNAL_INDIRECT(redirect.pointer));
+
+		return heap_tuple_untoast_attr_slice(redirect.pointer,
+											 sliceoffset, slicelength);
+	}
+	else if (VARATT_IS_EXTERNAL_EXPANDED(attr))
+	{
+		/* pass it off to heap_tuple_fetch_attr to flatten */
+		preslice = heap_tuple_fetch_attr(attr);
+	}
+	else
+		preslice = attr;
+
+	Assert(!VARATT_IS_EXTERNAL(preslice));
+
+	if (VARATT_IS_COMPRESSED(preslice))
+	{
+		struct varlena *tmp = preslice;
+
+		/* Decompress enough to encompass the slice and the offset */
+		if (slicelength > 0 && sliceoffset >= 0)
+			preslice = toast_decompress_datum_slice(tmp, slicelength + sliceoffset);
+		else
+			preslice = toast_decompress_datum(tmp);
+
+		if (tmp != attr)
+			pfree(tmp);
+	}
+
+	if (VARATT_IS_SHORT(preslice))
+	{
+		attrdata = VARDATA_SHORT(preslice);
+		attrsize = VARSIZE_SHORT(preslice) - VARHDRSZ_SHORT;
+	}
+	else
+	{
+		attrdata = VARDATA(preslice);
+		attrsize = VARSIZE(preslice) - VARHDRSZ;
+	}
+
+	/* slicing of datum for compressed cases and plain value */
+
+	if (sliceoffset >= attrsize)
+	{
+		sliceoffset = 0;
+		slicelength = 0;
+	}
+
+	if (((sliceoffset + slicelength) > attrsize) || slicelength < 0)
+		slicelength = attrsize - sliceoffset;
+
+	result = (struct varlena *) palloc(slicelength + VARHDRSZ);
+	SET_VARSIZE(result, slicelength + VARHDRSZ);
+
+	memcpy(VARDATA(result), attrdata + sliceoffset, slicelength);
+
+	if (preslice != attr)
+		pfree(preslice);
+
+	return result;
+}
+
+/* ----------
+ * toast_fetch_datum -
+ *
+ *	Reconstruct an in memory Datum from the chunks saved
+ *	in the toast relation
+ * ----------
+ */
+static struct varlena *
+toast_fetch_datum(struct varlena *attr)
+{
+	Relation	toastrel;
+	Relation   *toastidxs;
+	ScanKeyData toastkey;
+	SysScanDesc toastscan;
+	HeapTuple	ttup;
+	TupleDesc	toasttupDesc;
+	struct varlena *result;
+	struct varatt_external toast_pointer;
+	int32		ressize;
+	int32		residx,
+				nextidx;
+	int32		numchunks;
+	Pointer		chunk;
+	bool		isnull;
+	char	   *chunkdata;
+	int32		chunksize;
+	int			num_indexes;
+	int			validIndex;
+	SnapshotData SnapshotToast;
+
+	if (!VARATT_IS_EXTERNAL_ONDISK(attr))
+		elog(ERROR, "toast_fetch_datum shouldn't be called for non-ondisk datums");
+
+	/* Must copy to access aligned fields */
+	VARATT_EXTERNAL_GET_POINTER(toast_pointer, attr);
+
+	ressize = toast_pointer.va_extsize;
+	numchunks = ((ressize - 1) / TOAST_MAX_CHUNK_SIZE) + 1;
+
+	result = (struct varlena *) palloc(ressize + VARHDRSZ);
+
+	if (VARATT_EXTERNAL_IS_COMPRESSED(toast_pointer))
+		SET_VARSIZE_COMPRESSED(result, ressize + VARHDRSZ);
+	else
+		SET_VARSIZE(result, ressize + VARHDRSZ);
+
+	/*
+	 * Open the toast relation and its indexes
+	 */
+	toastrel = table_open(toast_pointer.va_toastrelid, AccessShareLock);
+	toasttupDesc = toastrel->rd_att;
+
+	/* Look for the valid index of the toast relation */
+	validIndex = toast_open_indexes(toastrel,
+									AccessShareLock,
+									&toastidxs,
+									&num_indexes);
+
+	/*
+	 * Setup a scan key to fetch from the index by va_valueid
+	 */
+	ScanKeyInit(&toastkey,
+				(AttrNumber) 1,
+				BTEqualStrategyNumber, F_OIDEQ,
+				ObjectIdGetDatum(toast_pointer.va_valueid));
+
+	/*
+	 * Read the chunks by index
+	 *
+	 * Note that because the index is actually on (valueid, chunkidx) we will
+	 * see the chunks in chunkidx order, even though we didn't explicitly ask
+	 * for it.
+	 */
+	nextidx = 0;
+
+	init_toast_snapshot(&SnapshotToast);
+	toastscan = systable_beginscan_ordered(toastrel, toastidxs[validIndex],
+										   &SnapshotToast, 1, &toastkey);
+	while ((ttup = systable_getnext_ordered(toastscan, ForwardScanDirection)) != NULL)
+	{
+		/*
+		 * Have a chunk, extract the sequence number and the data
+		 */
+		residx = DatumGetInt32(fastgetattr(ttup, 2, toasttupDesc, &isnull));
+		Assert(!isnull);
+		chunk = DatumGetPointer(fastgetattr(ttup, 3, toasttupDesc, &isnull));
+		Assert(!isnull);
+		if (!VARATT_IS_EXTENDED(chunk))
+		{
+			chunksize = VARSIZE(chunk) - VARHDRSZ;
+			chunkdata = VARDATA(chunk);
+		}
+		else if (VARATT_IS_SHORT(chunk))
+		{
+			/* could happen due to heap_form_tuple doing its thing */
+			chunksize = VARSIZE_SHORT(chunk) - VARHDRSZ_SHORT;
+			chunkdata = VARDATA_SHORT(chunk);
+		}
+		else
+		{
+			/* should never happen */
+			elog(ERROR, "found toasted toast chunk for toast value %u in %s",
+				 toast_pointer.va_valueid,
+				 RelationGetRelationName(toastrel));
+			chunksize = 0;		/* keep compiler quiet */
+			chunkdata = NULL;
+		}
+
+		/*
+		 * Some checks on the data we've found
+		 */
+		if (residx != nextidx)
+			ereport(ERROR,
+					(errcode(ERRCODE_DATA_CORRUPTED),
+					 errmsg_internal("unexpected chunk number %d (expected %d) for toast value %u in %s",
+									 residx, nextidx,
+									 toast_pointer.va_valueid,
+									 RelationGetRelationName(toastrel))));
+		if (residx < numchunks - 1)
+		{
+			if (chunksize != TOAST_MAX_CHUNK_SIZE)
+				ereport(ERROR,
+						(errcode(ERRCODE_DATA_CORRUPTED),
+						 errmsg_internal("unexpected chunk size %d (expected %d) in chunk %d of %d for toast value %u in %s",
+										 chunksize, (int) TOAST_MAX_CHUNK_SIZE,
+										 residx, numchunks,
+										 toast_pointer.va_valueid,
+										 RelationGetRelationName(toastrel))));
+		}
+		else if (residx == numchunks - 1)
+		{
+			if ((residx * TOAST_MAX_CHUNK_SIZE + chunksize) != ressize)
+				ereport(ERROR,
+						(errcode(ERRCODE_DATA_CORRUPTED),
+						 errmsg_internal("unexpected chunk size %d (expected %d) in final chunk %d for toast value %u in %s",
+										 chunksize,
+										 (int) (ressize - residx * TOAST_MAX_CHUNK_SIZE),
+										 residx,
+										 toast_pointer.va_valueid,
+										 RelationGetRelationName(toastrel))));
+		}
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_DATA_CORRUPTED),
+					 errmsg_internal("unexpected chunk number %d (out of range %d..%d) for toast value %u in %s",
+									 residx,
+									 0, numchunks - 1,
+									 toast_pointer.va_valueid,
+									 RelationGetRelationName(toastrel))));
+
+		/*
+		 * Copy the data into proper place in our result
+		 */
+		memcpy(VARDATA(result) + residx * TOAST_MAX_CHUNK_SIZE,
+			   chunkdata,
+			   chunksize);
+
+		nextidx++;
+	}
+
+	/*
+	 * Final checks that we successfully fetched the datum
+	 */
+	if (nextidx != numchunks)
+		ereport(ERROR,
+				(errcode(ERRCODE_DATA_CORRUPTED),
+				 errmsg_internal("missing chunk number %d for toast value %u in %s",
+								 nextidx,
+								 toast_pointer.va_valueid,
+								 RelationGetRelationName(toastrel))));
+
+	/*
+	 * End scan and close relations
+	 */
+	systable_endscan_ordered(toastscan);
+	toast_close_indexes(toastidxs, num_indexes, AccessShareLock);
+	table_close(toastrel, AccessShareLock);
+
+	return result;
+}
+
+/* ----------
+ * toast_fetch_datum_slice -
+ *
+ *	Reconstruct a segment of a Datum from the chunks saved
+ *	in the toast relation
+ *
+ *	Note that this function only supports non-compressed external datums.
+ * ----------
+ */
+static struct varlena *
+toast_fetch_datum_slice(struct varlena *attr, int32 sliceoffset, int32 length)
+{
+	Relation	toastrel;
+	Relation   *toastidxs;
+	ScanKeyData toastkey[3];
+	int			nscankeys;
+	SysScanDesc toastscan;
+	HeapTuple	ttup;
+	TupleDesc	toasttupDesc;
+	struct varlena *result;
+	struct varatt_external toast_pointer;
+	int32		attrsize;
+	int32		residx;
+	int32		nextidx;
+	int			numchunks;
+	int			startchunk;
+	int			endchunk;
+	int32		startoffset;
+	int32		endoffset;
+	int			totalchunks;
+	Pointer		chunk;
+	bool		isnull;
+	char	   *chunkdata;
+	int32		chunksize;
+	int32		chcpystrt;
+	int32		chcpyend;
+	int			num_indexes;
+	int			validIndex;
+	SnapshotData SnapshotToast;
+
+	if (!VARATT_IS_EXTERNAL_ONDISK(attr))
+		elog(ERROR, "toast_fetch_datum_slice shouldn't be called for non-ondisk datums");
+
+	/* Must copy to access aligned fields */
+	VARATT_EXTERNAL_GET_POINTER(toast_pointer, attr);
+
+	/*
+	 * It's nonsense to fetch slices of a compressed datum -- this isn't lo_*
+	 * we can't return a compressed datum which is meaningful to toast later
+	 */
+	Assert(!VARATT_EXTERNAL_IS_COMPRESSED(toast_pointer));
+
+	attrsize = toast_pointer.va_extsize;
+	totalchunks = ((attrsize - 1) / TOAST_MAX_CHUNK_SIZE) + 1;
+
+	if (sliceoffset >= attrsize)
+	{
+		sliceoffset = 0;
+		length = 0;
+	}
+
+	if (((sliceoffset + length) > attrsize) || length < 0)
+		length = attrsize - sliceoffset;
+
+	result = (struct varlena *) palloc(length + VARHDRSZ);
+
+	SET_VARSIZE(result, length + VARHDRSZ);
+
+	if (length == 0)
+		return result;			/* Can save a lot of work at this point! */
+
+	startchunk = sliceoffset / TOAST_MAX_CHUNK_SIZE;
+	endchunk = (sliceoffset + length - 1) / TOAST_MAX_CHUNK_SIZE;
+	numchunks = (endchunk - startchunk) + 1;
+
+	startoffset = sliceoffset % TOAST_MAX_CHUNK_SIZE;
+	endoffset = (sliceoffset + length - 1) % TOAST_MAX_CHUNK_SIZE;
+
+	/*
+	 * Open the toast relation and its indexes
+	 */
+	toastrel = table_open(toast_pointer.va_toastrelid, AccessShareLock);
+	toasttupDesc = toastrel->rd_att;
+
+	/* Look for the valid index of toast relation */
+	validIndex = toast_open_indexes(toastrel,
+									AccessShareLock,
+									&toastidxs,
+									&num_indexes);
+
+	/*
+	 * Setup a scan key to fetch from the index. This is either two keys or
+	 * three depending on the number of chunks.
+	 */
+	ScanKeyInit(&toastkey[0],
+				(AttrNumber) 1,
+				BTEqualStrategyNumber, F_OIDEQ,
+				ObjectIdGetDatum(toast_pointer.va_valueid));
+
+	/*
+	 * Use equality condition for one chunk, a range condition otherwise:
+	 */
+	if (numchunks == 1)
+	{
+		ScanKeyInit(&toastkey[1],
+					(AttrNumber) 2,
+					BTEqualStrategyNumber, F_INT4EQ,
+					Int32GetDatum(startchunk));
+		nscankeys = 2;
+	}
+	else
+	{
+		ScanKeyInit(&toastkey[1],
+					(AttrNumber) 2,
+					BTGreaterEqualStrategyNumber, F_INT4GE,
+					Int32GetDatum(startchunk));
+		ScanKeyInit(&toastkey[2],
+					(AttrNumber) 2,
+					BTLessEqualStrategyNumber, F_INT4LE,
+					Int32GetDatum(endchunk));
+		nscankeys = 3;
+	}
+
+	/*
+	 * Read the chunks by index
+	 *
+	 * The index is on (valueid, chunkidx) so they will come in order
+	 */
+	init_toast_snapshot(&SnapshotToast);
+	nextidx = startchunk;
+	toastscan = systable_beginscan_ordered(toastrel, toastidxs[validIndex],
+										   &SnapshotToast, nscankeys, toastkey);
+	while ((ttup = systable_getnext_ordered(toastscan, ForwardScanDirection)) != NULL)
+	{
+		/*
+		 * Have a chunk, extract the sequence number and the data
+		 */
+		residx = DatumGetInt32(fastgetattr(ttup, 2, toasttupDesc, &isnull));
+		Assert(!isnull);
+		chunk = DatumGetPointer(fastgetattr(ttup, 3, toasttupDesc, &isnull));
+		Assert(!isnull);
+		if (!VARATT_IS_EXTENDED(chunk))
+		{
+			chunksize = VARSIZE(chunk) - VARHDRSZ;
+			chunkdata = VARDATA(chunk);
+		}
+		else if (VARATT_IS_SHORT(chunk))
+		{
+			/* could happen due to heap_form_tuple doing its thing */
+			chunksize = VARSIZE_SHORT(chunk) - VARHDRSZ_SHORT;
+			chunkdata = VARDATA_SHORT(chunk);
+		}
+		else
+		{
+			/* should never happen */
+			elog(ERROR, "found toasted toast chunk for toast value %u in %s",
+				 toast_pointer.va_valueid,
+				 RelationGetRelationName(toastrel));
+			chunksize = 0;		/* keep compiler quiet */
+			chunkdata = NULL;
+		}
+
+		/*
+		 * Some checks on the data we've found
+		 */
+		if ((residx != nextidx) || (residx > endchunk) || (residx < startchunk))
+			elog(ERROR, "unexpected chunk number %d (expected %d) for toast value %u in %s",
+				 residx, nextidx,
+				 toast_pointer.va_valueid,
+				 RelationGetRelationName(toastrel));
+		if (residx < totalchunks - 1)
+		{
+			if (chunksize != TOAST_MAX_CHUNK_SIZE)
+				elog(ERROR, "unexpected chunk size %d (expected %d) in chunk %d of %d for toast value %u in %s when fetching slice",
+					 chunksize, (int) TOAST_MAX_CHUNK_SIZE,
+					 residx, totalchunks,
+					 toast_pointer.va_valueid,
+					 RelationGetRelationName(toastrel));
+		}
+		else if (residx == totalchunks - 1)
+		{
+			if ((residx * TOAST_MAX_CHUNK_SIZE + chunksize) != attrsize)
+				elog(ERROR, "unexpected chunk size %d (expected %d) in final chunk %d for toast value %u in %s when fetching slice",
+					 chunksize,
+					 (int) (attrsize - residx * TOAST_MAX_CHUNK_SIZE),
+					 residx,
+					 toast_pointer.va_valueid,
+					 RelationGetRelationName(toastrel));
+		}
+		else
+			elog(ERROR, "unexpected chunk number %d (out of range %d..%d) for toast value %u in %s",
+				 residx,
+				 0, totalchunks - 1,
+				 toast_pointer.va_valueid,
+				 RelationGetRelationName(toastrel));
+
+		/*
+		 * Copy the data into proper place in our result
+		 */
+		chcpystrt = 0;
+		chcpyend = chunksize - 1;
+		if (residx == startchunk)
+			chcpystrt = startoffset;
+		if (residx == endchunk)
+			chcpyend = endoffset;
+
+		memcpy(VARDATA(result) +
+			   (residx * TOAST_MAX_CHUNK_SIZE - sliceoffset) + chcpystrt,
+			   chunkdata + chcpystrt,
+			   (chcpyend - chcpystrt) + 1);
+
+		nextidx++;
+	}
+
+	/*
+	 * Final checks that we successfully fetched the datum
+	 */
+	if (nextidx != (endchunk + 1))
+		elog(ERROR, "missing chunk number %d for toast value %u in %s",
+			 nextidx,
+			 toast_pointer.va_valueid,
+			 RelationGetRelationName(toastrel));
+
+	/*
+	 * End scan and close relations
+	 */
+	systable_endscan_ordered(toastscan);
+	toast_close_indexes(toastidxs, num_indexes, AccessShareLock);
+	table_close(toastrel, AccessShareLock);
+
+	return result;
+}
+
+/* ----------
+ * toast_decompress_datum -
+ *
+ * Decompress a compressed version of a varlena datum
+ */
+static struct varlena *
+toast_decompress_datum(struct varlena *attr)
+{
+	struct varlena *result;
+
+	Assert(VARATT_IS_COMPRESSED(attr));
+
+	result = (struct varlena *)
+		palloc(TOAST_COMPRESS_RAWSIZE(attr) + VARHDRSZ);
+	SET_VARSIZE(result, TOAST_COMPRESS_RAWSIZE(attr) + VARHDRSZ);
+
+	if (pglz_decompress(TOAST_COMPRESS_RAWDATA(attr),
+						VARSIZE(attr) - TOAST_COMPRESS_HDRSZ,
+						VARDATA(result),
+						TOAST_COMPRESS_RAWSIZE(attr), true) < 0)
+		elog(ERROR, "compressed data is corrupted");
+
+	return result;
+}
+
+
+/* ----------
+ * toast_decompress_datum_slice -
+ *
+ * Decompress the front of a compressed version of a varlena datum.
+ * offset handling happens in heap_tuple_untoast_attr_slice.
+ * Here we just decompress a slice from the front.
+ */
+static struct varlena *
+toast_decompress_datum_slice(struct varlena *attr, int32 slicelength)
+{
+	struct varlena *result;
+	int32		rawsize;
+
+	Assert(VARATT_IS_COMPRESSED(attr));
+
+	result = (struct varlena *) palloc(slicelength + VARHDRSZ);
+
+	rawsize = pglz_decompress(TOAST_COMPRESS_RAWDATA(attr),
+							  VARSIZE(attr) - TOAST_COMPRESS_HDRSZ,
+							  VARDATA(result),
+							  slicelength, false);
+	if (rawsize < 0)
+		elog(ERROR, "compressed data is corrupted");
+
+	SET_VARSIZE(result, rawsize + VARHDRSZ);
+	return result;
+}
+
+/* ----------
+ * toast_raw_datum_size -
+ *
+ *	Return the raw (detoasted) size of a varlena datum
+ *	(including the VARHDRSZ header)
+ * ----------
+ */
+Size
+toast_raw_datum_size(Datum value)
+{
+	struct varlena *attr = (struct varlena *) DatumGetPointer(value);
+	Size		result;
+
+	if (VARATT_IS_EXTERNAL_ONDISK(attr))
+	{
+		/* va_rawsize is the size of the original datum -- including header */
+		struct varatt_external toast_pointer;
+
+		VARATT_EXTERNAL_GET_POINTER(toast_pointer, attr);
+		result = toast_pointer.va_rawsize;
+	}
+	else if (VARATT_IS_EXTERNAL_INDIRECT(attr))
+	{
+		struct varatt_indirect toast_pointer;
+
+		VARATT_EXTERNAL_GET_POINTER(toast_pointer, attr);
+
+		/* nested indirect Datums aren't allowed */
+		Assert(!VARATT_IS_EXTERNAL_INDIRECT(toast_pointer.pointer));
+
+		return toast_raw_datum_size(PointerGetDatum(toast_pointer.pointer));
+	}
+	else if (VARATT_IS_EXTERNAL_EXPANDED(attr))
+	{
+		result = EOH_get_flat_size(DatumGetEOHP(value));
+	}
+	else if (VARATT_IS_COMPRESSED(attr))
+	{
+		/* here, va_rawsize is just the payload size */
+		result = VARRAWSIZE_4B_C(attr) + VARHDRSZ;
+	}
+	else if (VARATT_IS_SHORT(attr))
+	{
+		/*
+		 * we have to normalize the header length to VARHDRSZ or else the
+		 * callers of this function will be confused.
+		 */
+		result = VARSIZE_SHORT(attr) - VARHDRSZ_SHORT + VARHDRSZ;
+	}
+	else
+	{
+		/* plain untoasted datum */
+		result = VARSIZE(attr);
+	}
+	return result;
+}
+
+/* ----------
+ * toast_datum_size
+ *
+ *	Return the physical storage size (possibly compressed) of a varlena datum
+ * ----------
+ */
+Size
+toast_datum_size(Datum value)
+{
+	struct varlena *attr = (struct varlena *) DatumGetPointer(value);
+	Size		result;
+
+	if (VARATT_IS_EXTERNAL_ONDISK(attr))
+	{
+		/*
+		 * Attribute is stored externally - return the extsize whether
+		 * compressed or not.  We do not count the size of the toast pointer
+		 * ... should we?
+		 */
+		struct varatt_external toast_pointer;
+
+		VARATT_EXTERNAL_GET_POINTER(toast_pointer, attr);
+		result = toast_pointer.va_extsize;
+	}
+	else if (VARATT_IS_EXTERNAL_INDIRECT(attr))
+	{
+		struct varatt_indirect toast_pointer;
+
+		VARATT_EXTERNAL_GET_POINTER(toast_pointer, attr);
+
+		/* nested indirect Datums aren't allowed */
+		Assert(!VARATT_IS_EXTERNAL_INDIRECT(attr));
+
+		return toast_datum_size(PointerGetDatum(toast_pointer.pointer));
+	}
+	else if (VARATT_IS_EXTERNAL_EXPANDED(attr))
+	{
+		result = EOH_get_flat_size(DatumGetEOHP(value));
+	}
+	else if (VARATT_IS_SHORT(attr))
+	{
+		result = VARSIZE_SHORT(attr);
+	}
+	else
+	{
+		/*
+		 * Attribute is stored inline either compressed or not, just calculate
+		 * the size of the datum in either case.
+		 */
+		result = VARSIZE(attr);
+	}
+	return result;
+}
diff --git a/src/backend/access/common/heaptuple.c b/src/backend/access/common/heaptuple.c
index a48a6cd757..cc948958d7 100644
--- a/src/backend/access/common/heaptuple.c
+++ b/src/backend/access/common/heaptuple.c
@@ -18,7 +18,7 @@
  * (In performance-critical code paths we can use pg_detoast_datum_packed
  * and the appropriate access macros to avoid that overhead.)  Note that this
  * conversion is performed directly in heap_form_tuple, without invoking
- * tuptoaster.c.
+ * heaptoast.c.
  *
  * This change will break any code that assumes it needn't detoast values
  * that have been put into a tuple but never sent to disk.  Hopefully there
@@ -57,9 +57,9 @@
 
 #include "postgres.h"
 
+#include "access/heaptoast.h"
 #include "access/sysattr.h"
 #include "access/tupdesc_details.h"
-#include "access/tuptoaster.h"
 #include "executor/tuptable.h"
 #include "utils/expandeddatum.h"
 
diff --git a/src/backend/access/common/indextuple.c b/src/backend/access/common/indextuple.c
index cb23be859d..07586201b9 100644
--- a/src/backend/access/common/indextuple.c
+++ b/src/backend/access/common/indextuple.c
@@ -16,10 +16,17 @@
 
 #include "postgres.h"
 
+#include "access/detoast.h"
+#include "access/heaptoast.h"
 #include "access/htup_details.h"
 #include "access/itup.h"
-#include "access/tuptoaster.h"
+#include "access/toast_internals.h"
 
+/*
+ * This enables de-toasting of index entries.  Needed until VACUUM is
+ * smart enough to rebuild indexes from scratch.
+ */
+#define TOAST_INDEX_HACK
 
 /* ----------------------------------------------------------------
  *				  index_ tuple interface routines
diff --git a/src/backend/access/common/reloptions.c b/src/backend/access/common/reloptions.c
index 42647b0526..20f4ed3c38 100644
--- a/src/backend/access/common/reloptions.c
+++ b/src/backend/access/common/reloptions.c
@@ -19,11 +19,11 @@
 
 #include "access/gist_private.h"
 #include "access/hash.h"
+#include "access/heaptoast.h"
 #include "access/htup_details.h"
 #include "access/nbtree.h"
 #include "access/reloptions.h"
 #include "access/spgist.h"
-#include "access/tuptoaster.h"
 #include "catalog/pg_type.h"
 #include "commands/defrem.h"
 #include "commands/tablespace.h"
diff --git a/src/backend/access/common/toast_internals.c b/src/backend/access/common/toast_internals.c
new file mode 100644
index 0000000000..a971242490
--- /dev/null
+++ b/src/backend/access/common/toast_internals.c
@@ -0,0 +1,632 @@
+/*-------------------------------------------------------------------------
+ *
+ * toast_internals.c
+ *	  Functions for internal use by the TOAST system.
+ *
+ * Copyright (c) 2000-2019, PostgreSQL Global Development Group
+ *
+ * IDENTIFICATION
+ *	  src/backend/access/common/toast_internals.c
+ *
+ *-------------------------------------------------------------------------
+ */
+
+#include "postgres.h"
+
+#include "access/detoast.h"
+#include "access/genam.h"
+#include "access/heapam.h"
+#include "access/heaptoast.h"
+#include "access/table.h"
+#include "access/toast_internals.h"
+#include "access/xact.h"
+#include "catalog/catalog.h"
+#include "common/pg_lzcompress.h"
+#include "miscadmin.h"
+#include "utils/fmgroids.h"
+#include "utils/rel.h"
+#include "utils/snapmgr.h"
+
+static bool toastrel_valueid_exists(Relation toastrel, Oid valueid);
+static bool toastid_valueid_exists(Oid toastrelid, Oid valueid);
+
+/* ----------
+ * toast_compress_datum -
+ *
+ *	Create a compressed version of a varlena datum
+ *
+ *	If we fail (ie, compressed result is actually bigger than original)
+ *	then return NULL.  We must not use compressed data if it'd expand
+ *	the tuple!
+ *
+ *	We use VAR{SIZE,DATA}_ANY so we can handle short varlenas here without
+ *	copying them.  But we can't handle external or compressed datums.
+ * ----------
+ */
+Datum
+toast_compress_datum(Datum value)
+{
+	struct varlena *tmp;
+	int32		valsize = VARSIZE_ANY_EXHDR(DatumGetPointer(value));
+	int32		len;
+
+	Assert(!VARATT_IS_EXTERNAL(DatumGetPointer(value)));
+	Assert(!VARATT_IS_COMPRESSED(DatumGetPointer(value)));
+
+	/*
+	 * No point in wasting a palloc cycle if value size is out of the allowed
+	 * range for compression
+	 */
+	if (valsize < PGLZ_strategy_default->min_input_size ||
+		valsize > PGLZ_strategy_default->max_input_size)
+		return PointerGetDatum(NULL);
+
+	tmp = (struct varlena *) palloc(PGLZ_MAX_OUTPUT(valsize) +
+									TOAST_COMPRESS_HDRSZ);
+
+	/*
+	 * We recheck the actual size even if pglz_compress() reports success,
+	 * because it might be satisfied with having saved as little as one byte
+	 * in the compressed data --- which could turn into a net loss once you
+	 * consider header and alignment padding.  Worst case, the compressed
+	 * format might require three padding bytes (plus header, which is
+	 * included in VARSIZE(tmp)), whereas the uncompressed format would take
+	 * only one header byte and no padding if the value is short enough.  So
+	 * we insist on a savings of more than 2 bytes to ensure we have a gain.
+	 */
+	len = pglz_compress(VARDATA_ANY(DatumGetPointer(value)),
+						valsize,
+						TOAST_COMPRESS_RAWDATA(tmp),
+						PGLZ_strategy_default);
+	if (len >= 0 &&
+		len + TOAST_COMPRESS_HDRSZ < valsize - 2)
+	{
+		TOAST_COMPRESS_SET_RAWSIZE(tmp, valsize);
+		SET_VARSIZE_COMPRESSED(tmp, len + TOAST_COMPRESS_HDRSZ);
+		/* successful compression */
+		return PointerGetDatum(tmp);
+	}
+	else
+	{
+		/* incompressible data */
+		pfree(tmp);
+		return PointerGetDatum(NULL);
+	}
+}
+
+/* ----------
+ * toast_save_datum -
+ *
+ *	Save one single datum into the secondary relation and return
+ *	a Datum reference for it.
+ *
+ * rel: the main relation we're working with (not the toast rel!)
+ * value: datum to be pushed to toast storage
+ * oldexternal: if not NULL, toast pointer previously representing the datum
+ * options: options to be passed to heap_insert() for toast rows
+ * ----------
+ */
+Datum
+toast_save_datum(Relation rel, Datum value,
+				 struct varlena *oldexternal, int options)
+{
+	Relation	toastrel;
+	Relation   *toastidxs;
+	HeapTuple	toasttup;
+	TupleDesc	toasttupDesc;
+	Datum		t_values[3];
+	bool		t_isnull[3];
+	CommandId	mycid = GetCurrentCommandId(true);
+	struct varlena *result;
+	struct varatt_external toast_pointer;
+	union
+	{
+		struct varlena hdr;
+		/* this is to make the union big enough for a chunk: */
+		char		data[TOAST_MAX_CHUNK_SIZE + VARHDRSZ];
+		/* ensure union is aligned well enough: */
+		int32		align_it;
+	}			chunk_data;
+	int32		chunk_size;
+	int32		chunk_seq = 0;
+	char	   *data_p;
+	int32		data_todo;
+	Pointer		dval = DatumGetPointer(value);
+	int			num_indexes;
+	int			validIndex;
+
+	Assert(!VARATT_IS_EXTERNAL(value));
+
+	/*
+	 * Open the toast relation and its indexes.  We can use the index to check
+	 * uniqueness of the OID we assign to the toasted item, even though it has
+	 * additional columns besides OID.
+	 */
+	toastrel = table_open(rel->rd_rel->reltoastrelid, RowExclusiveLock);
+	toasttupDesc = toastrel->rd_att;
+
+	/* Open all the toast indexes and look for the valid one */
+	validIndex = toast_open_indexes(toastrel,
+									RowExclusiveLock,
+									&toastidxs,
+									&num_indexes);
+
+	/*
+	 * Get the data pointer and length, and compute va_rawsize and va_extsize.
+	 *
+	 * va_rawsize is the size of the equivalent fully uncompressed datum, so
+	 * we have to adjust for short headers.
+	 *
+	 * va_extsize is the actual size of the data payload in the toast records.
+	 */
+	if (VARATT_IS_SHORT(dval))
+	{
+		data_p = VARDATA_SHORT(dval);
+		data_todo = VARSIZE_SHORT(dval) - VARHDRSZ_SHORT;
+		toast_pointer.va_rawsize = data_todo + VARHDRSZ;	/* as if not short */
+		toast_pointer.va_extsize = data_todo;
+	}
+	else if (VARATT_IS_COMPRESSED(dval))
+	{
+		data_p = VARDATA(dval);
+		data_todo = VARSIZE(dval) - VARHDRSZ;
+		/* rawsize in a compressed datum is just the size of the payload */
+		toast_pointer.va_rawsize = VARRAWSIZE_4B_C(dval) + VARHDRSZ;
+		toast_pointer.va_extsize = data_todo;
+		/* Assert that the numbers look like it's compressed */
+		Assert(VARATT_EXTERNAL_IS_COMPRESSED(toast_pointer));
+	}
+	else
+	{
+		data_p = VARDATA(dval);
+		data_todo = VARSIZE(dval) - VARHDRSZ;
+		toast_pointer.va_rawsize = VARSIZE(dval);
+		toast_pointer.va_extsize = data_todo;
+	}
+
+	/*
+	 * Insert the correct table OID into the result TOAST pointer.
+	 *
+	 * Normally this is the actual OID of the target toast table, but during
+	 * table-rewriting operations such as CLUSTER, we have to insert the OID
+	 * of the table's real permanent toast table instead.  rd_toastoid is set
+	 * if we have to substitute such an OID.
+	 */
+	if (OidIsValid(rel->rd_toastoid))
+		toast_pointer.va_toastrelid = rel->rd_toastoid;
+	else
+		toast_pointer.va_toastrelid = RelationGetRelid(toastrel);
+
+	/*
+	 * Choose an OID to use as the value ID for this toast value.
+	 *
+	 * Normally we just choose an unused OID within the toast table.  But
+	 * during table-rewriting operations where we are preserving an existing
+	 * toast table OID, we want to preserve toast value OIDs too.  So, if
+	 * rd_toastoid is set and we had a prior external value from that same
+	 * toast table, re-use its value ID.  If we didn't have a prior external
+	 * value (which is a corner case, but possible if the table's attstorage
+	 * options have been changed), we have to pick a value ID that doesn't
+	 * conflict with either new or existing toast value OIDs.
+	 */
+	if (!OidIsValid(rel->rd_toastoid))
+	{
+		/* normal case: just choose an unused OID */
+		toast_pointer.va_valueid =
+			GetNewOidWithIndex(toastrel,
+							   RelationGetRelid(toastidxs[validIndex]),
+							   (AttrNumber) 1);
+	}
+	else
+	{
+		/* rewrite case: check to see if value was in old toast table */
+		toast_pointer.va_valueid = InvalidOid;
+		if (oldexternal != NULL)
+		{
+			struct varatt_external old_toast_pointer;
+
+			Assert(VARATT_IS_EXTERNAL_ONDISK(oldexternal));
+			/* Must copy to access aligned fields */
+			VARATT_EXTERNAL_GET_POINTER(old_toast_pointer, oldexternal);
+			if (old_toast_pointer.va_toastrelid == rel->rd_toastoid)
+			{
+				/* This value came from the old toast table; reuse its OID */
+				toast_pointer.va_valueid = old_toast_pointer.va_valueid;
+
+				/*
+				 * There is a corner case here: the table rewrite might have
+				 * to copy both live and recently-dead versions of a row, and
+				 * those versions could easily reference the same toast value.
+				 * When we copy the second or later version of such a row,
+				 * reusing the OID will mean we select an OID that's already
+				 * in the new toast table.  Check for that, and if so, just
+				 * fall through without writing the data again.
+				 *
+				 * While annoying and ugly-looking, this is a good thing
+				 * because it ensures that we wind up with only one copy of
+				 * the toast value when there is only one copy in the old
+				 * toast table.  Before we detected this case, we'd have made
+				 * multiple copies, wasting space; and what's worse, the
+				 * copies belonging to already-deleted heap tuples would not
+				 * be reclaimed by VACUUM.
+				 */
+				if (toastrel_valueid_exists(toastrel,
+											toast_pointer.va_valueid))
+				{
+					/* Match, so short-circuit the data storage loop below */
+					data_todo = 0;
+				}
+			}
+		}
+		if (toast_pointer.va_valueid == InvalidOid)
+		{
+			/*
+			 * new value; must choose an OID that doesn't conflict in either
+			 * old or new toast table
+			 */
+			do
+			{
+				toast_pointer.va_valueid =
+					GetNewOidWithIndex(toastrel,
+									   RelationGetRelid(toastidxs[validIndex]),
+									   (AttrNumber) 1);
+			} while (toastid_valueid_exists(rel->rd_toastoid,
+											toast_pointer.va_valueid));
+		}
+	}
+
+	/*
+	 * Initialize constant parts of the tuple data
+	 */
+	t_values[0] = ObjectIdGetDatum(toast_pointer.va_valueid);
+	t_values[2] = PointerGetDatum(&chunk_data);
+	t_isnull[0] = false;
+	t_isnull[1] = false;
+	t_isnull[2] = false;
+
+	/*
+	 * Split up the item into chunks
+	 */
+	while (data_todo > 0)
+	{
+		int			i;
+
+		CHECK_FOR_INTERRUPTS();
+
+		/*
+		 * Calculate the size of this chunk
+		 */
+		chunk_size = Min(TOAST_MAX_CHUNK_SIZE, data_todo);
+
+		/*
+		 * Build a tuple and store it
+		 */
+		t_values[1] = Int32GetDatum(chunk_seq++);
+		SET_VARSIZE(&chunk_data, chunk_size + VARHDRSZ);
+		memcpy(VARDATA(&chunk_data), data_p, chunk_size);
+		toasttup = heap_form_tuple(toasttupDesc, t_values, t_isnull);
+
+		heap_insert(toastrel, toasttup, mycid, options, NULL);
+
+		/*
+		 * Create the index entry.  We cheat a little here by not using
+		 * FormIndexDatum: this relies on the knowledge that the index columns
+		 * are the same as the initial columns of the table for all the
+		 * indexes.  We also cheat by not providing an IndexInfo: this is okay
+		 * for now because btree doesn't need one, but we might have to be
+		 * more honest someday.
+		 *
+		 * Note also that there had better not be any user-created index on
+		 * the TOAST table, since we don't bother to update anything else.
+		 */
+		for (i = 0; i < num_indexes; i++)
+		{
+			/* Only index relations marked as ready can be updated */
+			if (toastidxs[i]->rd_index->indisready)
+				index_insert(toastidxs[i], t_values, t_isnull,
+							 &(toasttup->t_self),
+							 toastrel,
+							 toastidxs[i]->rd_index->indisunique ?
+							 UNIQUE_CHECK_YES : UNIQUE_CHECK_NO,
+							 NULL);
+		}
+
+		/*
+		 * Free memory
+		 */
+		heap_freetuple(toasttup);
+
+		/*
+		 * Move on to next chunk
+		 */
+		data_todo -= chunk_size;
+		data_p += chunk_size;
+	}
+
+	/*
+	 * Done - close toast relation and its indexes
+	 */
+	toast_close_indexes(toastidxs, num_indexes, RowExclusiveLock);
+	table_close(toastrel, RowExclusiveLock);
+
+	/*
+	 * Create the TOAST pointer value that we'll return
+	 */
+	result = (struct varlena *) palloc(TOAST_POINTER_SIZE);
+	SET_VARTAG_EXTERNAL(result, VARTAG_ONDISK);
+	memcpy(VARDATA_EXTERNAL(result), &toast_pointer, sizeof(toast_pointer));
+
+	return PointerGetDatum(result);
+}
+
+/* ----------
+ * toast_delete_datum -
+ *
+ *	Delete a single external stored value.
+ * ----------
+ */
+void
+toast_delete_datum(Relation rel, Datum value, bool is_speculative)
+{
+	struct varlena *attr = (struct varlena *) DatumGetPointer(value);
+	struct varatt_external toast_pointer;
+	Relation	toastrel;
+	Relation   *toastidxs;
+	ScanKeyData toastkey;
+	SysScanDesc toastscan;
+	HeapTuple	toasttup;
+	int			num_indexes;
+	int			validIndex;
+	SnapshotData SnapshotToast;
+
+	if (!VARATT_IS_EXTERNAL_ONDISK(attr))
+		return;
+
+	/* Must copy to access aligned fields */
+	VARATT_EXTERNAL_GET_POINTER(toast_pointer, attr);
+
+	/*
+	 * Open the toast relation and its indexes
+	 */
+	toastrel = table_open(toast_pointer.va_toastrelid, RowExclusiveLock);
+
+	/* Fetch valid relation used for process */
+	validIndex = toast_open_indexes(toastrel,
+									RowExclusiveLock,
+									&toastidxs,
+									&num_indexes);
+
+	/*
+	 * Setup a scan key to find chunks with matching va_valueid
+	 */
+	ScanKeyInit(&toastkey,
+				(AttrNumber) 1,
+				BTEqualStrategyNumber, F_OIDEQ,
+				ObjectIdGetDatum(toast_pointer.va_valueid));
+
+	/*
+	 * Find all the chunks.  (We don't actually care whether we see them in
+	 * sequence or not, but since we've already locked the index we might as
+	 * well use systable_beginscan_ordered.)
+	 */
+	init_toast_snapshot(&SnapshotToast);
+	toastscan = systable_beginscan_ordered(toastrel, toastidxs[validIndex],
+										   &SnapshotToast, 1, &toastkey);
+	while ((toasttup = systable_getnext_ordered(toastscan, ForwardScanDirection)) != NULL)
+	{
+		/*
+		 * Have a chunk, delete it
+		 */
+		if (is_speculative)
+			heap_abort_speculative(toastrel, &toasttup->t_self);
+		else
+			simple_heap_delete(toastrel, &toasttup->t_self);
+	}
+
+	/*
+	 * End scan and close relations
+	 */
+	systable_endscan_ordered(toastscan);
+	toast_close_indexes(toastidxs, num_indexes, RowExclusiveLock);
+	table_close(toastrel, RowExclusiveLock);
+}
+
+/* ----------
+ * toastrel_valueid_exists -
+ *
+ *	Test whether a toast value with the given ID exists in the toast relation.
+ *	For safety, we consider a value to exist if there are either live or dead
+ *	toast rows with that ID; see notes for GetNewOidWithIndex().
+ * ----------
+ */
+static bool
+toastrel_valueid_exists(Relation toastrel, Oid valueid)
+{
+	bool		result = false;
+	ScanKeyData toastkey;
+	SysScanDesc toastscan;
+	int			num_indexes;
+	int			validIndex;
+	Relation   *toastidxs;
+
+	/* Fetch a valid index relation */
+	validIndex = toast_open_indexes(toastrel,
+									RowExclusiveLock,
+									&toastidxs,
+									&num_indexes);
+
+	/*
+	 * Setup a scan key to find chunks with matching va_valueid
+	 */
+	ScanKeyInit(&toastkey,
+				(AttrNumber) 1,
+				BTEqualStrategyNumber, F_OIDEQ,
+				ObjectIdGetDatum(valueid));
+
+	/*
+	 * Is there any such chunk?
+	 */
+	toastscan = systable_beginscan(toastrel,
+								   RelationGetRelid(toastidxs[validIndex]),
+								   true, SnapshotAny, 1, &toastkey);
+
+	if (systable_getnext(toastscan) != NULL)
+		result = true;
+
+	systable_endscan(toastscan);
+
+	/* Clean up */
+	toast_close_indexes(toastidxs, num_indexes, RowExclusiveLock);
+
+	return result;
+}
+
+/* ----------
+ * toastid_valueid_exists -
+ *
+ *	As above, but work from toast rel's OID not an open relation
+ * ----------
+ */
+static bool
+toastid_valueid_exists(Oid toastrelid, Oid valueid)
+{
+	bool		result;
+	Relation	toastrel;
+
+	toastrel = table_open(toastrelid, AccessShareLock);
+
+	result = toastrel_valueid_exists(toastrel, valueid);
+
+	table_close(toastrel, AccessShareLock);
+
+	return result;
+}
+
+/* ----------
+ * toast_get_valid_index
+ *
+ *	Get OID of valid index associated to given toast relation. A toast
+ *	relation can have only one valid index at the same time.
+ */
+Oid
+toast_get_valid_index(Oid toastoid, LOCKMODE lock)
+{
+	int			num_indexes;
+	int			validIndex;
+	Oid			validIndexOid;
+	Relation   *toastidxs;
+	Relation	toastrel;
+
+	/* Open the toast relation */
+	toastrel = table_open(toastoid, lock);
+
+	/* Look for the valid index of the toast relation */
+	validIndex = toast_open_indexes(toastrel,
+									lock,
+									&toastidxs,
+									&num_indexes);
+	validIndexOid = RelationGetRelid(toastidxs[validIndex]);
+
+	/* Close the toast relation and all its indexes */
+	toast_close_indexes(toastidxs, num_indexes, lock);
+	table_close(toastrel, lock);
+
+	return validIndexOid;
+}
+
+/* ----------
+ * toast_open_indexes
+ *
+ *	Get an array of the indexes associated to the given toast relation
+ *	and return as well the position of the valid index used by the toast
+ *	relation in this array. It is the responsibility of the caller of this
+ *	function to close the indexes as well as free them.
+ */
+int
+toast_open_indexes(Relation toastrel,
+				   LOCKMODE lock,
+				   Relation **toastidxs,
+				   int *num_indexes)
+{
+	int			i = 0;
+	int			res = 0;
+	bool		found = false;
+	List	   *indexlist;
+	ListCell   *lc;
+
+	/* Get index list of the toast relation */
+	indexlist = RelationGetIndexList(toastrel);
+	Assert(indexlist != NIL);
+
+	*num_indexes = list_length(indexlist);
+
+	/* Open all the index relations */
+	*toastidxs = (Relation *) palloc(*num_indexes * sizeof(Relation));
+	foreach(lc, indexlist)
+		(*toastidxs)[i++] = index_open(lfirst_oid(lc), lock);
+
+	/* Fetch the first valid index in list */
+	for (i = 0; i < *num_indexes; i++)
+	{
+		Relation	toastidx = (*toastidxs)[i];
+
+		if (toastidx->rd_index->indisvalid)
+		{
+			res = i;
+			found = true;
+			break;
+		}
+	}
+
+	/*
+	 * Free index list, not necessary anymore as relations are opened and a
+	 * valid index has been found.
+	 */
+	list_free(indexlist);
+
+	/*
+	 * The toast relation should have one valid index, so something is going
+	 * wrong if there is nothing.
+	 */
+	if (!found)
+		elog(ERROR, "no valid index found for toast relation with Oid %u",
+			 RelationGetRelid(toastrel));
+
+	return res;
+}
+
+/* ----------
+ * toast_close_indexes
+ *
+ *	Close an array of indexes for a toast relation and free it. This should
+ *	be called for a set of indexes opened previously with toast_open_indexes.
+ */
+void
+toast_close_indexes(Relation *toastidxs, int num_indexes, LOCKMODE lock)
+{
+	int			i;
+
+	/* Close relations and clean up things */
+	for (i = 0; i < num_indexes; i++)
+		index_close(toastidxs[i], lock);
+	pfree(toastidxs);
+}
+
+/* ----------
+ * init_toast_snapshot
+ *
+ *	Initialize an appropriate TOAST snapshot.  We must use an MVCC snapshot
+ *	to initialize the TOAST snapshot; since we don't know which one to use,
+ *	just use the oldest one.  This is safe: at worst, we will get a "snapshot
+ *	too old" error that might have been avoided otherwise.
+ */
+void
+init_toast_snapshot(Snapshot toast_snapshot)
+{
+	Snapshot	snapshot = GetOldestSnapshot();
+
+	if (snapshot == NULL)
+		elog(ERROR, "no known snapshots");
+
+	InitToastSnapshot(*toast_snapshot, snapshot->lsn, snapshot->whenTaken);
+}
diff --git a/src/backend/access/heap/Makefile b/src/backend/access/heap/Makefile
index b2a017249b..38497b09c0 100644
--- a/src/backend/access/heap/Makefile
+++ b/src/backend/access/heap/Makefile
@@ -13,6 +13,6 @@ top_builddir = ../../../..
 include $(top_builddir)/src/Makefile.global
 
 OBJS = heapam.o heapam_handler.o heapam_visibility.o hio.o pruneheap.o rewriteheap.o \
-	syncscan.o tuptoaster.o vacuumlazy.o visibilitymap.o
+	syncscan.o heaptoast.o vacuumlazy.o visibilitymap.o
 
 include $(top_srcdir)/src/backend/common.mk
diff --git a/src/backend/access/heap/heapam.c b/src/backend/access/heap/heapam.c
index 34143a6853..e9544822bf 100644
--- a/src/backend/access/heap/heapam.c
+++ b/src/backend/access/heap/heapam.c
@@ -36,6 +36,7 @@
 #include "access/genam.h"
 #include "access/heapam.h"
 #include "access/heapam_xlog.h"
+#include "access/heaptoast.h"
 #include "access/hio.h"
 #include "access/multixact.h"
 #include "access/parallel.h"
@@ -43,7 +44,6 @@
 #include "access/sysattr.h"
 #include "access/tableam.h"
 #include "access/transam.h"
-#include "access/tuptoaster.h"
 #include "access/valid.h"
 #include "access/visibilitymap.h"
 #include "access/xact.h"
diff --git a/src/backend/access/heap/heapam_handler.c b/src/backend/access/heap/heapam_handler.c
index f1ff01e8cb..2dd8821fac 100644
--- a/src/backend/access/heap/heapam_handler.c
+++ b/src/backend/access/heap/heapam_handler.c
@@ -23,11 +23,11 @@
 
 #include "access/genam.h"
 #include "access/heapam.h"
+#include "access/heaptoast.h"
 #include "access/multixact.h"
 #include "access/rewriteheap.h"
 #include "access/tableam.h"
 #include "access/tsmapi.h"
-#include "access/tuptoaster.h"
 #include "access/xact.h"
 #include "catalog/catalog.h"
 #include "catalog/index.h"
diff --git a/src/backend/access/heap/heaptoast.c b/src/backend/access/heap/heaptoast.c
new file mode 100644
index 0000000000..5d105e3517
--- /dev/null
+++ b/src/backend/access/heap/heaptoast.c
@@ -0,0 +1,917 @@
+/*-------------------------------------------------------------------------
+ *
+ * heaptoast.c
+ *	  Heap-specific definitions for external and compressed storage
+ *	  of variable size attributes.
+ *
+ * Copyright (c) 2000-2019, PostgreSQL Global Development Group
+ *
+ *
+ * IDENTIFICATION
+ *	  src/backend/access/heap/heaptoast.c
+ *
+ *
+ * INTERFACE ROUTINES
+ *		toast_insert_or_update -
+ *			Try to make a given tuple fit into one page by compressing
+ *			or moving off attributes
+ *
+ *		toast_delete -
+ *			Reclaim toast storage when a tuple is deleted
+ *
+ *-------------------------------------------------------------------------
+ */
+
+#include "postgres.h"
+
+#include "access/detoast.h"
+#include "access/heapam.h"
+#include "access/heaptoast.h"
+#include "access/toast_internals.h"
+
+
+/* ----------
+ * toast_delete -
+ *
+ *	Cascaded delete toast-entries on DELETE
+ * ----------
+ */
+void
+toast_delete(Relation rel, HeapTuple oldtup, bool is_speculative)
+{
+	TupleDesc	tupleDesc;
+	int			numAttrs;
+	int			i;
+	Datum		toast_values[MaxHeapAttributeNumber];
+	bool		toast_isnull[MaxHeapAttributeNumber];
+
+	/*
+	 * We should only ever be called for tuples of plain relations or
+	 * materialized views --- recursing on a toast rel is bad news.
+	 */
+	Assert(rel->rd_rel->relkind == RELKIND_RELATION ||
+		   rel->rd_rel->relkind == RELKIND_MATVIEW);
+
+	/*
+	 * Get the tuple descriptor and break down the tuple into fields.
+	 *
+	 * NOTE: it's debatable whether to use heap_deform_tuple() here or just
+	 * heap_getattr() only the varlena columns.  The latter could win if there
+	 * are few varlena columns and many non-varlena ones. However,
+	 * heap_deform_tuple costs only O(N) while the heap_getattr way would cost
+	 * O(N^2) if there are many varlena columns, so it seems better to err on
+	 * the side of linear cost.  (We won't even be here unless there's at
+	 * least one varlena column, by the way.)
+	 */
+	tupleDesc = rel->rd_att;
+	numAttrs = tupleDesc->natts;
+
+	Assert(numAttrs <= MaxHeapAttributeNumber);
+	heap_deform_tuple(oldtup, tupleDesc, toast_values, toast_isnull);
+
+	/*
+	 * Check for external stored attributes and delete them from the secondary
+	 * relation.
+	 */
+	for (i = 0; i < numAttrs; i++)
+	{
+		if (TupleDescAttr(tupleDesc, i)->attlen == -1)
+		{
+			Datum		value = toast_values[i];
+
+			if (toast_isnull[i])
+				continue;
+			else if (VARATT_IS_EXTERNAL_ONDISK(PointerGetDatum(value)))
+				toast_delete_datum(rel, value, is_speculative);
+		}
+	}
+}
+
+
+/* ----------
+ * toast_insert_or_update -
+ *
+ *	Delete no-longer-used toast-entries and create new ones to
+ *	make the new tuple fit on INSERT or UPDATE
+ *
+ * Inputs:
+ *	newtup: the candidate new tuple to be inserted
+ *	oldtup: the old row version for UPDATE, or NULL for INSERT
+ *	options: options to be passed to heap_insert() for toast rows
+ * Result:
+ *	either newtup if no toasting is needed, or a palloc'd modified tuple
+ *	that is what should actually get stored
+ *
+ * NOTE: neither newtup nor oldtup will be modified.  This is a change
+ * from the pre-8.1 API of this routine.
+ * ----------
+ */
+HeapTuple
+toast_insert_or_update(Relation rel, HeapTuple newtup, HeapTuple oldtup,
+					   int options)
+{
+	HeapTuple	result_tuple;
+	TupleDesc	tupleDesc;
+	int			numAttrs;
+	int			i;
+
+	bool		need_change = false;
+	bool		need_free = false;
+	bool		need_delold = false;
+	bool		has_nulls = false;
+
+	Size		maxDataLen;
+	Size		hoff;
+
+	char		toast_action[MaxHeapAttributeNumber];
+	bool		toast_isnull[MaxHeapAttributeNumber];
+	bool		toast_oldisnull[MaxHeapAttributeNumber];
+	Datum		toast_values[MaxHeapAttributeNumber];
+	Datum		toast_oldvalues[MaxHeapAttributeNumber];
+	struct varlena *toast_oldexternal[MaxHeapAttributeNumber];
+	int32		toast_sizes[MaxHeapAttributeNumber];
+	bool		toast_free[MaxHeapAttributeNumber];
+	bool		toast_delold[MaxHeapAttributeNumber];
+
+	/*
+	 * Ignore the INSERT_SPECULATIVE option. Speculative insertions/super
+	 * deletions just normally insert/delete the toast values. It seems
+	 * easiest to deal with that here, instead on, potentially, multiple
+	 * callers.
+	 */
+	options &= ~HEAP_INSERT_SPECULATIVE;
+
+	/*
+	 * We should only ever be called for tuples of plain relations or
+	 * materialized views --- recursing on a toast rel is bad news.
+	 */
+	Assert(rel->rd_rel->relkind == RELKIND_RELATION ||
+		   rel->rd_rel->relkind == RELKIND_MATVIEW);
+
+	/*
+	 * Get the tuple descriptor and break down the tuple(s) into fields.
+	 */
+	tupleDesc = rel->rd_att;
+	numAttrs = tupleDesc->natts;
+
+	Assert(numAttrs <= MaxHeapAttributeNumber);
+	heap_deform_tuple(newtup, tupleDesc, toast_values, toast_isnull);
+	if (oldtup != NULL)
+		heap_deform_tuple(oldtup, tupleDesc, toast_oldvalues, toast_oldisnull);
+
+	/* ----------
+	 * Then collect information about the values given
+	 *
+	 * NOTE: toast_action[i] can have these values:
+	 *		' '		default handling
+	 *		'p'		already processed --- don't touch it
+	 *		'x'		incompressible, but OK to move off
+	 *
+	 * NOTE: toast_sizes[i] is only made valid for varlena attributes with
+	 *		toast_action[i] different from 'p'.
+	 * ----------
+	 */
+	memset(toast_action, ' ', numAttrs * sizeof(char));
+	memset(toast_oldexternal, 0, numAttrs * sizeof(struct varlena *));
+	memset(toast_free, 0, numAttrs * sizeof(bool));
+	memset(toast_delold, 0, numAttrs * sizeof(bool));
+
+	for (i = 0; i < numAttrs; i++)
+	{
+		Form_pg_attribute att = TupleDescAttr(tupleDesc, i);
+		struct varlena *old_value;
+		struct varlena *new_value;
+
+		if (oldtup != NULL)
+		{
+			/*
+			 * For UPDATE get the old and new values of this attribute
+			 */
+			old_value = (struct varlena *) DatumGetPointer(toast_oldvalues[i]);
+			new_value = (struct varlena *) DatumGetPointer(toast_values[i]);
+
+			/*
+			 * If the old value is stored on disk, check if it has changed so
+			 * we have to delete it later.
+			 */
+			if (att->attlen == -1 && !toast_oldisnull[i] &&
+				VARATT_IS_EXTERNAL_ONDISK(old_value))
+			{
+				if (toast_isnull[i] || !VARATT_IS_EXTERNAL_ONDISK(new_value) ||
+					memcmp((char *) old_value, (char *) new_value,
+						   VARSIZE_EXTERNAL(old_value)) != 0)
+				{
+					/*
+					 * The old external stored value isn't needed any more
+					 * after the update
+					 */
+					toast_delold[i] = true;
+					need_delold = true;
+				}
+				else
+				{
+					/*
+					 * This attribute isn't changed by this update so we reuse
+					 * the original reference to the old value in the new
+					 * tuple.
+					 */
+					toast_action[i] = 'p';
+					continue;
+				}
+			}
+		}
+		else
+		{
+			/*
+			 * For INSERT simply get the new value
+			 */
+			new_value = (struct varlena *) DatumGetPointer(toast_values[i]);
+		}
+
+		/*
+		 * Handle NULL attributes
+		 */
+		if (toast_isnull[i])
+		{
+			toast_action[i] = 'p';
+			has_nulls = true;
+			continue;
+		}
+
+		/*
+		 * Now look at varlena attributes
+		 */
+		if (att->attlen == -1)
+		{
+			/*
+			 * If the table's attribute says PLAIN always, force it so.
+			 */
+			if (att->attstorage == 'p')
+				toast_action[i] = 'p';
+
+			/*
+			 * We took care of UPDATE above, so any external value we find
+			 * still in the tuple must be someone else's that we cannot reuse
+			 * (this includes the case of an out-of-line in-memory datum).
+			 * Fetch it back (without decompression, unless we are forcing
+			 * PLAIN storage).  If necessary, we'll push it out as a new
+			 * external value below.
+			 */
+			if (VARATT_IS_EXTERNAL(new_value))
+			{
+				toast_oldexternal[i] = new_value;
+				if (att->attstorage == 'p')
+					new_value = heap_tuple_untoast_attr(new_value);
+				else
+					new_value = heap_tuple_fetch_attr(new_value);
+				toast_values[i] = PointerGetDatum(new_value);
+				toast_free[i] = true;
+				need_change = true;
+				need_free = true;
+			}
+
+			/*
+			 * Remember the size of this attribute
+			 */
+			toast_sizes[i] = VARSIZE_ANY(new_value);
+		}
+		else
+		{
+			/*
+			 * Not a varlena attribute, plain storage always
+			 */
+			toast_action[i] = 'p';
+		}
+	}
+
+	/* ----------
+	 * Compress and/or save external until data fits into target length
+	 *
+	 *	1: Inline compress attributes with attstorage 'x', and store very
+	 *	   large attributes with attstorage 'x' or 'e' external immediately
+	 *	2: Store attributes with attstorage 'x' or 'e' external
+	 *	3: Inline compress attributes with attstorage 'm'
+	 *	4: Store attributes with attstorage 'm' external
+	 * ----------
+	 */
+
+	/* compute header overhead --- this should match heap_form_tuple() */
+	hoff = SizeofHeapTupleHeader;
+	if (has_nulls)
+		hoff += BITMAPLEN(numAttrs);
+	hoff = MAXALIGN(hoff);
+	/* now convert to a limit on the tuple data size */
+	maxDataLen = RelationGetToastTupleTarget(rel, TOAST_TUPLE_TARGET) - hoff;
+
+	/*
+	 * Look for attributes with attstorage 'x' to compress.  Also find large
+	 * attributes with attstorage 'x' or 'e', and store them external.
+	 */
+	while (heap_compute_data_size(tupleDesc,
+								  toast_values, toast_isnull) > maxDataLen)
+	{
+		int			biggest_attno = -1;
+		int32		biggest_size = MAXALIGN(TOAST_POINTER_SIZE);
+		Datum		old_value;
+		Datum		new_value;
+
+		/*
+		 * Search for the biggest yet unprocessed internal attribute
+		 */
+		for (i = 0; i < numAttrs; i++)
+		{
+			Form_pg_attribute att = TupleDescAttr(tupleDesc, i);
+
+			if (toast_action[i] != ' ')
+				continue;
+			if (VARATT_IS_EXTERNAL(DatumGetPointer(toast_values[i])))
+				continue;		/* can't happen, toast_action would be 'p' */
+			if (VARATT_IS_COMPRESSED(DatumGetPointer(toast_values[i])))
+				continue;
+			if (att->attstorage != 'x' && att->attstorage != 'e')
+				continue;
+			if (toast_sizes[i] > biggest_size)
+			{
+				biggest_attno = i;
+				biggest_size = toast_sizes[i];
+			}
+		}
+
+		if (biggest_attno < 0)
+			break;
+
+		/*
+		 * Attempt to compress it inline, if it has attstorage 'x'
+		 */
+		i = biggest_attno;
+		if (TupleDescAttr(tupleDesc, i)->attstorage == 'x')
+		{
+			old_value = toast_values[i];
+			new_value = toast_compress_datum(old_value);
+
+			if (DatumGetPointer(new_value) != NULL)
+			{
+				/* successful compression */
+				if (toast_free[i])
+					pfree(DatumGetPointer(old_value));
+				toast_values[i] = new_value;
+				toast_free[i] = true;
+				toast_sizes[i] = VARSIZE(DatumGetPointer(toast_values[i]));
+				need_change = true;
+				need_free = true;
+			}
+			else
+			{
+				/* incompressible, ignore on subsequent compression passes */
+				toast_action[i] = 'x';
+			}
+		}
+		else
+		{
+			/* has attstorage 'e', ignore on subsequent compression passes */
+			toast_action[i] = 'x';
+		}
+
+		/*
+		 * If this value is by itself more than maxDataLen (after compression
+		 * if any), push it out to the toast table immediately, if possible.
+		 * This avoids uselessly compressing other fields in the common case
+		 * where we have one long field and several short ones.
+		 *
+		 * XXX maybe the threshold should be less than maxDataLen?
+		 */
+		if (toast_sizes[i] > maxDataLen &&
+			rel->rd_rel->reltoastrelid != InvalidOid)
+		{
+			old_value = toast_values[i];
+			toast_action[i] = 'p';
+			toast_values[i] = toast_save_datum(rel, toast_values[i],
+											   toast_oldexternal[i], options);
+			if (toast_free[i])
+				pfree(DatumGetPointer(old_value));
+			toast_free[i] = true;
+			need_change = true;
+			need_free = true;
+		}
+	}
+
+	/*
+	 * Second we look for attributes of attstorage 'x' or 'e' that are still
+	 * inline.  But skip this if there's no toast table to push them to.
+	 */
+	while (heap_compute_data_size(tupleDesc,
+								  toast_values, toast_isnull) > maxDataLen &&
+		   rel->rd_rel->reltoastrelid != InvalidOid)
+	{
+		int			biggest_attno = -1;
+		int32		biggest_size = MAXALIGN(TOAST_POINTER_SIZE);
+		Datum		old_value;
+
+		/*------
+		 * Search for the biggest yet inlined attribute with
+		 * attstorage equals 'x' or 'e'
+		 *------
+		 */
+		for (i = 0; i < numAttrs; i++)
+		{
+			Form_pg_attribute att = TupleDescAttr(tupleDesc, i);
+
+			if (toast_action[i] == 'p')
+				continue;
+			if (VARATT_IS_EXTERNAL(DatumGetPointer(toast_values[i])))
+				continue;		/* can't happen, toast_action would be 'p' */
+			if (att->attstorage != 'x' && att->attstorage != 'e')
+				continue;
+			if (toast_sizes[i] > biggest_size)
+			{
+				biggest_attno = i;
+				biggest_size = toast_sizes[i];
+			}
+		}
+
+		if (biggest_attno < 0)
+			break;
+
+		/*
+		 * Store this external
+		 */
+		i = biggest_attno;
+		old_value = toast_values[i];
+		toast_action[i] = 'p';
+		toast_values[i] = toast_save_datum(rel, toast_values[i],
+										   toast_oldexternal[i], options);
+		if (toast_free[i])
+			pfree(DatumGetPointer(old_value));
+		toast_free[i] = true;
+
+		need_change = true;
+		need_free = true;
+	}
+
+	/*
+	 * Round 3 - this time we take attributes with storage 'm' into
+	 * compression
+	 */
+	while (heap_compute_data_size(tupleDesc,
+								  toast_values, toast_isnull) > maxDataLen)
+	{
+		int			biggest_attno = -1;
+		int32		biggest_size = MAXALIGN(TOAST_POINTER_SIZE);
+		Datum		old_value;
+		Datum		new_value;
+
+		/*
+		 * Search for the biggest yet uncompressed internal attribute
+		 */
+		for (i = 0; i < numAttrs; i++)
+		{
+			if (toast_action[i] != ' ')
+				continue;
+			if (VARATT_IS_EXTERNAL(DatumGetPointer(toast_values[i])))
+				continue;		/* can't happen, toast_action would be 'p' */
+			if (VARATT_IS_COMPRESSED(DatumGetPointer(toast_values[i])))
+				continue;
+			if (TupleDescAttr(tupleDesc, i)->attstorage != 'm')
+				continue;
+			if (toast_sizes[i] > biggest_size)
+			{
+				biggest_attno = i;
+				biggest_size = toast_sizes[i];
+			}
+		}
+
+		if (biggest_attno < 0)
+			break;
+
+		/*
+		 * Attempt to compress it inline
+		 */
+		i = biggest_attno;
+		old_value = toast_values[i];
+		new_value = toast_compress_datum(old_value);
+
+		if (DatumGetPointer(new_value) != NULL)
+		{
+			/* successful compression */
+			if (toast_free[i])
+				pfree(DatumGetPointer(old_value));
+			toast_values[i] = new_value;
+			toast_free[i] = true;
+			toast_sizes[i] = VARSIZE(DatumGetPointer(toast_values[i]));
+			need_change = true;
+			need_free = true;
+		}
+		else
+		{
+			/* incompressible, ignore on subsequent compression passes */
+			toast_action[i] = 'x';
+		}
+	}
+
+	/*
+	 * Finally we store attributes of type 'm' externally.  At this point we
+	 * increase the target tuple size, so that 'm' attributes aren't stored
+	 * externally unless really necessary.
+	 */
+	maxDataLen = TOAST_TUPLE_TARGET_MAIN - hoff;
+
+	while (heap_compute_data_size(tupleDesc,
+								  toast_values, toast_isnull) > maxDataLen &&
+		   rel->rd_rel->reltoastrelid != InvalidOid)
+	{
+		int			biggest_attno = -1;
+		int32		biggest_size = MAXALIGN(TOAST_POINTER_SIZE);
+		Datum		old_value;
+
+		/*--------
+		 * Search for the biggest yet inlined attribute with
+		 * attstorage = 'm'
+		 *--------
+		 */
+		for (i = 0; i < numAttrs; i++)
+		{
+			if (toast_action[i] == 'p')
+				continue;
+			if (VARATT_IS_EXTERNAL(DatumGetPointer(toast_values[i])))
+				continue;		/* can't happen, toast_action would be 'p' */
+			if (TupleDescAttr(tupleDesc, i)->attstorage != 'm')
+				continue;
+			if (toast_sizes[i] > biggest_size)
+			{
+				biggest_attno = i;
+				biggest_size = toast_sizes[i];
+			}
+		}
+
+		if (biggest_attno < 0)
+			break;
+
+		/*
+		 * Store this external
+		 */
+		i = biggest_attno;
+		old_value = toast_values[i];
+		toast_action[i] = 'p';
+		toast_values[i] = toast_save_datum(rel, toast_values[i],
+										   toast_oldexternal[i], options);
+		if (toast_free[i])
+			pfree(DatumGetPointer(old_value));
+		toast_free[i] = true;
+
+		need_change = true;
+		need_free = true;
+	}
+
+	/*
+	 * In the case we toasted any values, we need to build a new heap tuple
+	 * with the changed values.
+	 */
+	if (need_change)
+	{
+		HeapTupleHeader olddata = newtup->t_data;
+		HeapTupleHeader new_data;
+		int32		new_header_len;
+		int32		new_data_len;
+		int32		new_tuple_len;
+
+		/*
+		 * Calculate the new size of the tuple.
+		 *
+		 * Note: we used to assume here that the old tuple's t_hoff must equal
+		 * the new_header_len value, but that was incorrect.  The old tuple
+		 * might have a smaller-than-current natts, if there's been an ALTER
+		 * TABLE ADD COLUMN since it was stored; and that would lead to a
+		 * different conclusion about the size of the null bitmap, or even
+		 * whether there needs to be one at all.
+		 */
+		new_header_len = SizeofHeapTupleHeader;
+		if (has_nulls)
+			new_header_len += BITMAPLEN(numAttrs);
+		new_header_len = MAXALIGN(new_header_len);
+		new_data_len = heap_compute_data_size(tupleDesc,
+											  toast_values, toast_isnull);
+		new_tuple_len = new_header_len + new_data_len;
+
+		/*
+		 * Allocate and zero the space needed, and fill HeapTupleData fields.
+		 */
+		result_tuple = (HeapTuple) palloc0(HEAPTUPLESIZE + new_tuple_len);
+		result_tuple->t_len = new_tuple_len;
+		result_tuple->t_self = newtup->t_self;
+		result_tuple->t_tableOid = newtup->t_tableOid;
+		new_data = (HeapTupleHeader) ((char *) result_tuple + HEAPTUPLESIZE);
+		result_tuple->t_data = new_data;
+
+		/*
+		 * Copy the existing tuple header, but adjust natts and t_hoff.
+		 */
+		memcpy(new_data, olddata, SizeofHeapTupleHeader);
+		HeapTupleHeaderSetNatts(new_data, numAttrs);
+		new_data->t_hoff = new_header_len;
+
+		/* Copy over the data, and fill the null bitmap if needed */
+		heap_fill_tuple(tupleDesc,
+						toast_values,
+						toast_isnull,
+						(char *) new_data + new_header_len,
+						new_data_len,
+						&(new_data->t_infomask),
+						has_nulls ? new_data->t_bits : NULL);
+	}
+	else
+		result_tuple = newtup;
+
+	/*
+	 * Free allocated temp values
+	 */
+	if (need_free)
+		for (i = 0; i < numAttrs; i++)
+			if (toast_free[i])
+				pfree(DatumGetPointer(toast_values[i]));
+
+	/*
+	 * Delete external values from the old tuple
+	 */
+	if (need_delold)
+		for (i = 0; i < numAttrs; i++)
+			if (toast_delold[i])
+				toast_delete_datum(rel, toast_oldvalues[i], false);
+
+	return result_tuple;
+}
+
+
+/* ----------
+ * toast_flatten_tuple -
+ *
+ *	"Flatten" a tuple to contain no out-of-line toasted fields.
+ *	(This does not eliminate compressed or short-header datums.)
+ *
+ *	Note: we expect the caller already checked HeapTupleHasExternal(tup),
+ *	so there is no need for a short-circuit path.
+ * ----------
+ */
+HeapTuple
+toast_flatten_tuple(HeapTuple tup, TupleDesc tupleDesc)
+{
+	HeapTuple	new_tuple;
+	int			numAttrs = tupleDesc->natts;
+	int			i;
+	Datum		toast_values[MaxTupleAttributeNumber];
+	bool		toast_isnull[MaxTupleAttributeNumber];
+	bool		toast_free[MaxTupleAttributeNumber];
+
+	/*
+	 * Break down the tuple into fields.
+	 */
+	Assert(numAttrs <= MaxTupleAttributeNumber);
+	heap_deform_tuple(tup, tupleDesc, toast_values, toast_isnull);
+
+	memset(toast_free, 0, numAttrs * sizeof(bool));
+
+	for (i = 0; i < numAttrs; i++)
+	{
+		/*
+		 * Look at non-null varlena attributes
+		 */
+		if (!toast_isnull[i] && TupleDescAttr(tupleDesc, i)->attlen == -1)
+		{
+			struct varlena *new_value;
+
+			new_value = (struct varlena *) DatumGetPointer(toast_values[i]);
+			if (VARATT_IS_EXTERNAL(new_value))
+			{
+				new_value = heap_tuple_fetch_attr(new_value);
+				toast_values[i] = PointerGetDatum(new_value);
+				toast_free[i] = true;
+			}
+		}
+	}
+
+	/*
+	 * Form the reconfigured tuple.
+	 */
+	new_tuple = heap_form_tuple(tupleDesc, toast_values, toast_isnull);
+
+	/*
+	 * Be sure to copy the tuple's identity fields.  We also make a point of
+	 * copying visibility info, just in case anybody looks at those fields in
+	 * a syscache entry.
+	 */
+	new_tuple->t_self = tup->t_self;
+	new_tuple->t_tableOid = tup->t_tableOid;
+
+	new_tuple->t_data->t_choice = tup->t_data->t_choice;
+	new_tuple->t_data->t_ctid = tup->t_data->t_ctid;
+	new_tuple->t_data->t_infomask &= ~HEAP_XACT_MASK;
+	new_tuple->t_data->t_infomask |=
+		tup->t_data->t_infomask & HEAP_XACT_MASK;
+	new_tuple->t_data->t_infomask2 &= ~HEAP2_XACT_MASK;
+	new_tuple->t_data->t_infomask2 |=
+		tup->t_data->t_infomask2 & HEAP2_XACT_MASK;
+
+	/*
+	 * Free allocated temp values
+	 */
+	for (i = 0; i < numAttrs; i++)
+		if (toast_free[i])
+			pfree(DatumGetPointer(toast_values[i]));
+
+	return new_tuple;
+}
+
+
+/* ----------
+ * toast_flatten_tuple_to_datum -
+ *
+ *	"Flatten" a tuple containing out-of-line toasted fields into a Datum.
+ *	The result is always palloc'd in the current memory context.
+ *
+ *	We have a general rule that Datums of container types (rows, arrays,
+ *	ranges, etc) must not contain any external TOAST pointers.  Without
+ *	this rule, we'd have to look inside each Datum when preparing a tuple
+ *	for storage, which would be expensive and would fail to extend cleanly
+ *	to new sorts of container types.
+ *
+ *	However, we don't want to say that tuples represented as HeapTuples
+ *	can't contain toasted fields, so instead this routine should be called
+ *	when such a HeapTuple is being converted into a Datum.
+ *
+ *	While we're at it, we decompress any compressed fields too.  This is not
+ *	necessary for correctness, but reflects an expectation that compression
+ *	will be more effective if applied to the whole tuple not individual
+ *	fields.  We are not so concerned about that that we want to deconstruct
+ *	and reconstruct tuples just to get rid of compressed fields, however.
+ *	So callers typically won't call this unless they see that the tuple has
+ *	at least one external field.
+ *
+ *	On the other hand, in-line short-header varlena fields are left alone.
+ *	If we "untoasted" them here, they'd just get changed back to short-header
+ *	format anyway within heap_fill_tuple.
+ * ----------
+ */
+Datum
+toast_flatten_tuple_to_datum(HeapTupleHeader tup,
+							 uint32 tup_len,
+							 TupleDesc tupleDesc)
+{
+	HeapTupleHeader new_data;
+	int32		new_header_len;
+	int32		new_data_len;
+	int32		new_tuple_len;
+	HeapTupleData tmptup;
+	int			numAttrs = tupleDesc->natts;
+	int			i;
+	bool		has_nulls = false;
+	Datum		toast_values[MaxTupleAttributeNumber];
+	bool		toast_isnull[MaxTupleAttributeNumber];
+	bool		toast_free[MaxTupleAttributeNumber];
+
+	/* Build a temporary HeapTuple control structure */
+	tmptup.t_len = tup_len;
+	ItemPointerSetInvalid(&(tmptup.t_self));
+	tmptup.t_tableOid = InvalidOid;
+	tmptup.t_data = tup;
+
+	/*
+	 * Break down the tuple into fields.
+	 */
+	Assert(numAttrs <= MaxTupleAttributeNumber);
+	heap_deform_tuple(&tmptup, tupleDesc, toast_values, toast_isnull);
+
+	memset(toast_free, 0, numAttrs * sizeof(bool));
+
+	for (i = 0; i < numAttrs; i++)
+	{
+		/*
+		 * Look at non-null varlena attributes
+		 */
+		if (toast_isnull[i])
+			has_nulls = true;
+		else if (TupleDescAttr(tupleDesc, i)->attlen == -1)
+		{
+			struct varlena *new_value;
+
+			new_value = (struct varlena *) DatumGetPointer(toast_values[i]);
+			if (VARATT_IS_EXTERNAL(new_value) ||
+				VARATT_IS_COMPRESSED(new_value))
+			{
+				new_value = heap_tuple_untoast_attr(new_value);
+				toast_values[i] = PointerGetDatum(new_value);
+				toast_free[i] = true;
+			}
+		}
+	}
+
+	/*
+	 * Calculate the new size of the tuple.
+	 *
+	 * This should match the reconstruction code in toast_insert_or_update.
+	 */
+	new_header_len = SizeofHeapTupleHeader;
+	if (has_nulls)
+		new_header_len += BITMAPLEN(numAttrs);
+	new_header_len = MAXALIGN(new_header_len);
+	new_data_len = heap_compute_data_size(tupleDesc,
+										  toast_values, toast_isnull);
+	new_tuple_len = new_header_len + new_data_len;
+
+	new_data = (HeapTupleHeader) palloc0(new_tuple_len);
+
+	/*
+	 * Copy the existing tuple header, but adjust natts and t_hoff.
+	 */
+	memcpy(new_data, tup, SizeofHeapTupleHeader);
+	HeapTupleHeaderSetNatts(new_data, numAttrs);
+	new_data->t_hoff = new_header_len;
+
+	/* Set the composite-Datum header fields correctly */
+	HeapTupleHeaderSetDatumLength(new_data, new_tuple_len);
+	HeapTupleHeaderSetTypeId(new_data, tupleDesc->tdtypeid);
+	HeapTupleHeaderSetTypMod(new_data, tupleDesc->tdtypmod);
+
+	/* Copy over the data, and fill the null bitmap if needed */
+	heap_fill_tuple(tupleDesc,
+					toast_values,
+					toast_isnull,
+					(char *) new_data + new_header_len,
+					new_data_len,
+					&(new_data->t_infomask),
+					has_nulls ? new_data->t_bits : NULL);
+
+	/*
+	 * Free allocated temp values
+	 */
+	for (i = 0; i < numAttrs; i++)
+		if (toast_free[i])
+			pfree(DatumGetPointer(toast_values[i]));
+
+	return PointerGetDatum(new_data);
+}
+
+
+/* ----------
+ * toast_build_flattened_tuple -
+ *
+ *	Build a tuple containing no out-of-line toasted fields.
+ *	(This does not eliminate compressed or short-header datums.)
+ *
+ *	This is essentially just like heap_form_tuple, except that it will
+ *	expand any external-data pointers beforehand.
+ *
+ *	It's not very clear whether it would be preferable to decompress
+ *	in-line compressed datums while at it.  For now, we don't.
+ * ----------
+ */
+HeapTuple
+toast_build_flattened_tuple(TupleDesc tupleDesc,
+							Datum *values,
+							bool *isnull)
+{
+	HeapTuple	new_tuple;
+	int			numAttrs = tupleDesc->natts;
+	int			num_to_free;
+	int			i;
+	Datum		new_values[MaxTupleAttributeNumber];
+	Pointer		freeable_values[MaxTupleAttributeNumber];
+
+	/*
+	 * We can pass the caller's isnull array directly to heap_form_tuple, but
+	 * we potentially need to modify the values array.
+	 */
+	Assert(numAttrs <= MaxTupleAttributeNumber);
+	memcpy(new_values, values, numAttrs * sizeof(Datum));
+
+	num_to_free = 0;
+	for (i = 0; i < numAttrs; i++)
+	{
+		/*
+		 * Look at non-null varlena attributes
+		 */
+		if (!isnull[i] && TupleDescAttr(tupleDesc, i)->attlen == -1)
+		{
+			struct varlena *new_value;
+
+			new_value = (struct varlena *) DatumGetPointer(new_values[i]);
+			if (VARATT_IS_EXTERNAL(new_value))
+			{
+				new_value = heap_tuple_fetch_attr(new_value);
+				new_values[i] = PointerGetDatum(new_value);
+				freeable_values[num_to_free++] = (Pointer) new_value;
+			}
+		}
+	}
+
+	/*
+	 * Form the reconfigured tuple.
+	 */
+	new_tuple = heap_form_tuple(tupleDesc, new_values, isnull);
+
+	/*
+	 * Free allocated temp values
+	 */
+	for (i = 0; i < num_to_free; i++)
+		pfree(freeable_values[i]);
+
+	return new_tuple;
+}
diff --git a/src/backend/access/heap/rewriteheap.c b/src/backend/access/heap/rewriteheap.c
index a17508a82f..0172a13957 100644
--- a/src/backend/access/heap/rewriteheap.c
+++ b/src/backend/access/heap/rewriteheap.c
@@ -109,9 +109,9 @@
 
 #include "access/heapam.h"
 #include "access/heapam_xlog.h"
+#include "access/heaptoast.h"
 #include "access/rewriteheap.h"
 #include "access/transam.h"
-#include "access/tuptoaster.h"
 #include "access/xact.h"
 #include "access/xloginsert.h"
 
diff --git a/src/backend/access/heap/tuptoaster.c b/src/backend/access/heap/tuptoaster.c
index 970e78d849..e69de29bb2 100644
--- a/src/backend/access/heap/tuptoaster.c
+++ b/src/backend/access/heap/tuptoaster.c
@@ -1,2419 +0,0 @@
-/*-------------------------------------------------------------------------
- *
- * tuptoaster.c
- *	  Support routines for external and compressed storage of
- *	  variable size attributes.
- *
- * Copyright (c) 2000-2019, PostgreSQL Global Development Group
- *
- *
- * IDENTIFICATION
- *	  src/backend/access/heap/tuptoaster.c
- *
- *
- * INTERFACE ROUTINES
- *		toast_insert_or_update -
- *			Try to make a given tuple fit into one page by compressing
- *			or moving off attributes
- *
- *		toast_delete -
- *			Reclaim toast storage when a tuple is deleted
- *
- *		heap_tuple_untoast_attr -
- *			Fetch back a given value from the "secondary" relation
- *
- *-------------------------------------------------------------------------
- */
-
-#include "postgres.h"
-
-#include <unistd.h>
-#include <fcntl.h>
-
-#include "access/genam.h"
-#include "access/heapam.h"
-#include "access/tuptoaster.h"
-#include "access/xact.h"
-#include "catalog/catalog.h"
-#include "common/pg_lzcompress.h"
-#include "miscadmin.h"
-#include "utils/expandeddatum.h"
-#include "utils/fmgroids.h"
-#include "utils/rel.h"
-#include "utils/snapmgr.h"
-#include "utils/typcache.h"
-
-
-/*
- *	The information at the start of the compressed toast data.
- */
-typedef struct toast_compress_header
-{
-	int32		vl_len_;		/* varlena header (do not touch directly!) */
-	int32		rawsize;
-} toast_compress_header;
-
-/*
- * Utilities for manipulation of header information for compressed
- * toast entries.
- */
-#define TOAST_COMPRESS_HDRSZ		((int32) sizeof(toast_compress_header))
-#define TOAST_COMPRESS_RAWSIZE(ptr) (((toast_compress_header *) (ptr))->rawsize)
-#define TOAST_COMPRESS_RAWDATA(ptr) \
-	(((char *) (ptr)) + TOAST_COMPRESS_HDRSZ)
-#define TOAST_COMPRESS_SET_RAWSIZE(ptr, len) \
-	(((toast_compress_header *) (ptr))->rawsize = (len))
-
-static void toast_delete_datum(Relation rel, Datum value, bool is_speculative);
-static Datum toast_save_datum(Relation rel, Datum value,
-							  struct varlena *oldexternal, int options);
-static bool toastrel_valueid_exists(Relation toastrel, Oid valueid);
-static bool toastid_valueid_exists(Oid toastrelid, Oid valueid);
-static struct varlena *toast_fetch_datum(struct varlena *attr);
-static struct varlena *toast_fetch_datum_slice(struct varlena *attr,
-											   int32 sliceoffset, int32 length);
-static struct varlena *toast_decompress_datum(struct varlena *attr);
-static struct varlena *toast_decompress_datum_slice(struct varlena *attr, int32 slicelength);
-static int	toast_open_indexes(Relation toastrel,
-							   LOCKMODE lock,
-							   Relation **toastidxs,
-							   int *num_indexes);
-static void toast_close_indexes(Relation *toastidxs, int num_indexes,
-								LOCKMODE lock);
-static void init_toast_snapshot(Snapshot toast_snapshot);
-
-
-/* ----------
- * heap_tuple_fetch_attr -
- *
- *	Public entry point to get back a toasted value from
- *	external source (possibly still in compressed format).
- *
- * This will return a datum that contains all the data internally, ie, not
- * relying on external storage or memory, but it can still be compressed or
- * have a short header.  Note some callers assume that if the input is an
- * EXTERNAL datum, the result will be a pfree'able chunk.
- * ----------
- */
-struct varlena *
-heap_tuple_fetch_attr(struct varlena *attr)
-{
-	struct varlena *result;
-
-	if (VARATT_IS_EXTERNAL_ONDISK(attr))
-	{
-		/*
-		 * This is an external stored plain value
-		 */
-		result = toast_fetch_datum(attr);
-	}
-	else if (VARATT_IS_EXTERNAL_INDIRECT(attr))
-	{
-		/*
-		 * This is an indirect pointer --- dereference it
-		 */
-		struct varatt_indirect redirect;
-
-		VARATT_EXTERNAL_GET_POINTER(redirect, attr);
-		attr = (struct varlena *) redirect.pointer;
-
-		/* nested indirect Datums aren't allowed */
-		Assert(!VARATT_IS_EXTERNAL_INDIRECT(attr));
-
-		/* recurse if value is still external in some other way */
-		if (VARATT_IS_EXTERNAL(attr))
-			return heap_tuple_fetch_attr(attr);
-
-		/*
-		 * Copy into the caller's memory context, in case caller tries to
-		 * pfree the result.
-		 */
-		result = (struct varlena *) palloc(VARSIZE_ANY(attr));
-		memcpy(result, attr, VARSIZE_ANY(attr));
-	}
-	else if (VARATT_IS_EXTERNAL_EXPANDED(attr))
-	{
-		/*
-		 * This is an expanded-object pointer --- get flat format
-		 */
-		ExpandedObjectHeader *eoh;
-		Size		resultsize;
-
-		eoh = DatumGetEOHP(PointerGetDatum(attr));
-		resultsize = EOH_get_flat_size(eoh);
-		result = (struct varlena *) palloc(resultsize);
-		EOH_flatten_into(eoh, (void *) result, resultsize);
-	}
-	else
-	{
-		/*
-		 * This is a plain value inside of the main tuple - why am I called?
-		 */
-		result = attr;
-	}
-
-	return result;
-}
-
-
-/* ----------
- * heap_tuple_untoast_attr -
- *
- *	Public entry point to get back a toasted value from compression
- *	or external storage.  The result is always non-extended varlena form.
- *
- * Note some callers assume that if the input is an EXTERNAL or COMPRESSED
- * datum, the result will be a pfree'able chunk.
- * ----------
- */
-struct varlena *
-heap_tuple_untoast_attr(struct varlena *attr)
-{
-	if (VARATT_IS_EXTERNAL_ONDISK(attr))
-	{
-		/*
-		 * This is an externally stored datum --- fetch it back from there
-		 */
-		attr = toast_fetch_datum(attr);
-		/* If it's compressed, decompress it */
-		if (VARATT_IS_COMPRESSED(attr))
-		{
-			struct varlena *tmp = attr;
-
-			attr = toast_decompress_datum(tmp);
-			pfree(tmp);
-		}
-	}
-	else if (VARATT_IS_EXTERNAL_INDIRECT(attr))
-	{
-		/*
-		 * This is an indirect pointer --- dereference it
-		 */
-		struct varatt_indirect redirect;
-
-		VARATT_EXTERNAL_GET_POINTER(redirect, attr);
-		attr = (struct varlena *) redirect.pointer;
-
-		/* nested indirect Datums aren't allowed */
-		Assert(!VARATT_IS_EXTERNAL_INDIRECT(attr));
-
-		/* recurse in case value is still extended in some other way */
-		attr = heap_tuple_untoast_attr(attr);
-
-		/* if it isn't, we'd better copy it */
-		if (attr == (struct varlena *) redirect.pointer)
-		{
-			struct varlena *result;
-
-			result = (struct varlena *) palloc(VARSIZE_ANY(attr));
-			memcpy(result, attr, VARSIZE_ANY(attr));
-			attr = result;
-		}
-	}
-	else if (VARATT_IS_EXTERNAL_EXPANDED(attr))
-	{
-		/*
-		 * This is an expanded-object pointer --- get flat format
-		 */
-		attr = heap_tuple_fetch_attr(attr);
-		/* flatteners are not allowed to produce compressed/short output */
-		Assert(!VARATT_IS_EXTENDED(attr));
-	}
-	else if (VARATT_IS_COMPRESSED(attr))
-	{
-		/*
-		 * This is a compressed value inside of the main tuple
-		 */
-		attr = toast_decompress_datum(attr);
-	}
-	else if (VARATT_IS_SHORT(attr))
-	{
-		/*
-		 * This is a short-header varlena --- convert to 4-byte header format
-		 */
-		Size		data_size = VARSIZE_SHORT(attr) - VARHDRSZ_SHORT;
-		Size		new_size = data_size + VARHDRSZ;
-		struct varlena *new_attr;
-
-		new_attr = (struct varlena *) palloc(new_size);
-		SET_VARSIZE(new_attr, new_size);
-		memcpy(VARDATA(new_attr), VARDATA_SHORT(attr), data_size);
-		attr = new_attr;
-	}
-
-	return attr;
-}
-
-
-/* ----------
- * heap_tuple_untoast_attr_slice -
- *
- *		Public entry point to get back part of a toasted value
- *		from compression or external storage.
- * ----------
- */
-struct varlena *
-heap_tuple_untoast_attr_slice(struct varlena *attr,
-							  int32 sliceoffset, int32 slicelength)
-{
-	struct varlena *preslice;
-	struct varlena *result;
-	char	   *attrdata;
-	int32		attrsize;
-
-	if (VARATT_IS_EXTERNAL_ONDISK(attr))
-	{
-		struct varatt_external toast_pointer;
-
-		VARATT_EXTERNAL_GET_POINTER(toast_pointer, attr);
-
-		/* fast path for non-compressed external datums */
-		if (!VARATT_EXTERNAL_IS_COMPRESSED(toast_pointer))
-			return toast_fetch_datum_slice(attr, sliceoffset, slicelength);
-
-		/* fetch it back (compressed marker will get set automatically) */
-		preslice = toast_fetch_datum(attr);
-	}
-	else if (VARATT_IS_EXTERNAL_INDIRECT(attr))
-	{
-		struct varatt_indirect redirect;
-
-		VARATT_EXTERNAL_GET_POINTER(redirect, attr);
-
-		/* nested indirect Datums aren't allowed */
-		Assert(!VARATT_IS_EXTERNAL_INDIRECT(redirect.pointer));
-
-		return heap_tuple_untoast_attr_slice(redirect.pointer,
-											 sliceoffset, slicelength);
-	}
-	else if (VARATT_IS_EXTERNAL_EXPANDED(attr))
-	{
-		/* pass it off to heap_tuple_fetch_attr to flatten */
-		preslice = heap_tuple_fetch_attr(attr);
-	}
-	else
-		preslice = attr;
-
-	Assert(!VARATT_IS_EXTERNAL(preslice));
-
-	if (VARATT_IS_COMPRESSED(preslice))
-	{
-		struct varlena *tmp = preslice;
-
-		/* Decompress enough to encompass the slice and the offset */
-		if (slicelength > 0 && sliceoffset >= 0)
-			preslice = toast_decompress_datum_slice(tmp, slicelength + sliceoffset);
-		else
-			preslice = toast_decompress_datum(tmp);
-
-		if (tmp != attr)
-			pfree(tmp);
-	}
-
-	if (VARATT_IS_SHORT(preslice))
-	{
-		attrdata = VARDATA_SHORT(preslice);
-		attrsize = VARSIZE_SHORT(preslice) - VARHDRSZ_SHORT;
-	}
-	else
-	{
-		attrdata = VARDATA(preslice);
-		attrsize = VARSIZE(preslice) - VARHDRSZ;
-	}
-
-	/* slicing of datum for compressed cases and plain value */
-
-	if (sliceoffset >= attrsize)
-	{
-		sliceoffset = 0;
-		slicelength = 0;
-	}
-
-	if (((sliceoffset + slicelength) > attrsize) || slicelength < 0)
-		slicelength = attrsize - sliceoffset;
-
-	result = (struct varlena *) palloc(slicelength + VARHDRSZ);
-	SET_VARSIZE(result, slicelength + VARHDRSZ);
-
-	memcpy(VARDATA(result), attrdata + sliceoffset, slicelength);
-
-	if (preslice != attr)
-		pfree(preslice);
-
-	return result;
-}
-
-
-/* ----------
- * toast_raw_datum_size -
- *
- *	Return the raw (detoasted) size of a varlena datum
- *	(including the VARHDRSZ header)
- * ----------
- */
-Size
-toast_raw_datum_size(Datum value)
-{
-	struct varlena *attr = (struct varlena *) DatumGetPointer(value);
-	Size		result;
-
-	if (VARATT_IS_EXTERNAL_ONDISK(attr))
-	{
-		/* va_rawsize is the size of the original datum -- including header */
-		struct varatt_external toast_pointer;
-
-		VARATT_EXTERNAL_GET_POINTER(toast_pointer, attr);
-		result = toast_pointer.va_rawsize;
-	}
-	else if (VARATT_IS_EXTERNAL_INDIRECT(attr))
-	{
-		struct varatt_indirect toast_pointer;
-
-		VARATT_EXTERNAL_GET_POINTER(toast_pointer, attr);
-
-		/* nested indirect Datums aren't allowed */
-		Assert(!VARATT_IS_EXTERNAL_INDIRECT(toast_pointer.pointer));
-
-		return toast_raw_datum_size(PointerGetDatum(toast_pointer.pointer));
-	}
-	else if (VARATT_IS_EXTERNAL_EXPANDED(attr))
-	{
-		result = EOH_get_flat_size(DatumGetEOHP(value));
-	}
-	else if (VARATT_IS_COMPRESSED(attr))
-	{
-		/* here, va_rawsize is just the payload size */
-		result = VARRAWSIZE_4B_C(attr) + VARHDRSZ;
-	}
-	else if (VARATT_IS_SHORT(attr))
-	{
-		/*
-		 * we have to normalize the header length to VARHDRSZ or else the
-		 * callers of this function will be confused.
-		 */
-		result = VARSIZE_SHORT(attr) - VARHDRSZ_SHORT + VARHDRSZ;
-	}
-	else
-	{
-		/* plain untoasted datum */
-		result = VARSIZE(attr);
-	}
-	return result;
-}
-
-/* ----------
- * toast_datum_size
- *
- *	Return the physical storage size (possibly compressed) of a varlena datum
- * ----------
- */
-Size
-toast_datum_size(Datum value)
-{
-	struct varlena *attr = (struct varlena *) DatumGetPointer(value);
-	Size		result;
-
-	if (VARATT_IS_EXTERNAL_ONDISK(attr))
-	{
-		/*
-		 * Attribute is stored externally - return the extsize whether
-		 * compressed or not.  We do not count the size of the toast pointer
-		 * ... should we?
-		 */
-		struct varatt_external toast_pointer;
-
-		VARATT_EXTERNAL_GET_POINTER(toast_pointer, attr);
-		result = toast_pointer.va_extsize;
-	}
-	else if (VARATT_IS_EXTERNAL_INDIRECT(attr))
-	{
-		struct varatt_indirect toast_pointer;
-
-		VARATT_EXTERNAL_GET_POINTER(toast_pointer, attr);
-
-		/* nested indirect Datums aren't allowed */
-		Assert(!VARATT_IS_EXTERNAL_INDIRECT(attr));
-
-		return toast_datum_size(PointerGetDatum(toast_pointer.pointer));
-	}
-	else if (VARATT_IS_EXTERNAL_EXPANDED(attr))
-	{
-		result = EOH_get_flat_size(DatumGetEOHP(value));
-	}
-	else if (VARATT_IS_SHORT(attr))
-	{
-		result = VARSIZE_SHORT(attr);
-	}
-	else
-	{
-		/*
-		 * Attribute is stored inline either compressed or not, just calculate
-		 * the size of the datum in either case.
-		 */
-		result = VARSIZE(attr);
-	}
-	return result;
-}
-
-
-/* ----------
- * toast_delete -
- *
- *	Cascaded delete toast-entries on DELETE
- * ----------
- */
-void
-toast_delete(Relation rel, HeapTuple oldtup, bool is_speculative)
-{
-	TupleDesc	tupleDesc;
-	int			numAttrs;
-	int			i;
-	Datum		toast_values[MaxHeapAttributeNumber];
-	bool		toast_isnull[MaxHeapAttributeNumber];
-
-	/*
-	 * We should only ever be called for tuples of plain relations or
-	 * materialized views --- recursing on a toast rel is bad news.
-	 */
-	Assert(rel->rd_rel->relkind == RELKIND_RELATION ||
-		   rel->rd_rel->relkind == RELKIND_MATVIEW);
-
-	/*
-	 * Get the tuple descriptor and break down the tuple into fields.
-	 *
-	 * NOTE: it's debatable whether to use heap_deform_tuple() here or just
-	 * heap_getattr() only the varlena columns.  The latter could win if there
-	 * are few varlena columns and many non-varlena ones. However,
-	 * heap_deform_tuple costs only O(N) while the heap_getattr way would cost
-	 * O(N^2) if there are many varlena columns, so it seems better to err on
-	 * the side of linear cost.  (We won't even be here unless there's at
-	 * least one varlena column, by the way.)
-	 */
-	tupleDesc = rel->rd_att;
-	numAttrs = tupleDesc->natts;
-
-	Assert(numAttrs <= MaxHeapAttributeNumber);
-	heap_deform_tuple(oldtup, tupleDesc, toast_values, toast_isnull);
-
-	/*
-	 * Check for external stored attributes and delete them from the secondary
-	 * relation.
-	 */
-	for (i = 0; i < numAttrs; i++)
-	{
-		if (TupleDescAttr(tupleDesc, i)->attlen == -1)
-		{
-			Datum		value = toast_values[i];
-
-			if (toast_isnull[i])
-				continue;
-			else if (VARATT_IS_EXTERNAL_ONDISK(PointerGetDatum(value)))
-				toast_delete_datum(rel, value, is_speculative);
-		}
-	}
-}
-
-
-/* ----------
- * toast_insert_or_update -
- *
- *	Delete no-longer-used toast-entries and create new ones to
- *	make the new tuple fit on INSERT or UPDATE
- *
- * Inputs:
- *	newtup: the candidate new tuple to be inserted
- *	oldtup: the old row version for UPDATE, or NULL for INSERT
- *	options: options to be passed to heap_insert() for toast rows
- * Result:
- *	either newtup if no toasting is needed, or a palloc'd modified tuple
- *	that is what should actually get stored
- *
- * NOTE: neither newtup nor oldtup will be modified.  This is a change
- * from the pre-8.1 API of this routine.
- * ----------
- */
-HeapTuple
-toast_insert_or_update(Relation rel, HeapTuple newtup, HeapTuple oldtup,
-					   int options)
-{
-	HeapTuple	result_tuple;
-	TupleDesc	tupleDesc;
-	int			numAttrs;
-	int			i;
-
-	bool		need_change = false;
-	bool		need_free = false;
-	bool		need_delold = false;
-	bool		has_nulls = false;
-
-	Size		maxDataLen;
-	Size		hoff;
-
-	char		toast_action[MaxHeapAttributeNumber];
-	bool		toast_isnull[MaxHeapAttributeNumber];
-	bool		toast_oldisnull[MaxHeapAttributeNumber];
-	Datum		toast_values[MaxHeapAttributeNumber];
-	Datum		toast_oldvalues[MaxHeapAttributeNumber];
-	struct varlena *toast_oldexternal[MaxHeapAttributeNumber];
-	int32		toast_sizes[MaxHeapAttributeNumber];
-	bool		toast_free[MaxHeapAttributeNumber];
-	bool		toast_delold[MaxHeapAttributeNumber];
-
-	/*
-	 * Ignore the INSERT_SPECULATIVE option. Speculative insertions/super
-	 * deletions just normally insert/delete the toast values. It seems
-	 * easiest to deal with that here, instead on, potentially, multiple
-	 * callers.
-	 */
-	options &= ~HEAP_INSERT_SPECULATIVE;
-
-	/*
-	 * We should only ever be called for tuples of plain relations or
-	 * materialized views --- recursing on a toast rel is bad news.
-	 */
-	Assert(rel->rd_rel->relkind == RELKIND_RELATION ||
-		   rel->rd_rel->relkind == RELKIND_MATVIEW);
-
-	/*
-	 * Get the tuple descriptor and break down the tuple(s) into fields.
-	 */
-	tupleDesc = rel->rd_att;
-	numAttrs = tupleDesc->natts;
-
-	Assert(numAttrs <= MaxHeapAttributeNumber);
-	heap_deform_tuple(newtup, tupleDesc, toast_values, toast_isnull);
-	if (oldtup != NULL)
-		heap_deform_tuple(oldtup, tupleDesc, toast_oldvalues, toast_oldisnull);
-
-	/* ----------
-	 * Then collect information about the values given
-	 *
-	 * NOTE: toast_action[i] can have these values:
-	 *		' '		default handling
-	 *		'p'		already processed --- don't touch it
-	 *		'x'		incompressible, but OK to move off
-	 *
-	 * NOTE: toast_sizes[i] is only made valid for varlena attributes with
-	 *		toast_action[i] different from 'p'.
-	 * ----------
-	 */
-	memset(toast_action, ' ', numAttrs * sizeof(char));
-	memset(toast_oldexternal, 0, numAttrs * sizeof(struct varlena *));
-	memset(toast_free, 0, numAttrs * sizeof(bool));
-	memset(toast_delold, 0, numAttrs * sizeof(bool));
-
-	for (i = 0; i < numAttrs; i++)
-	{
-		Form_pg_attribute att = TupleDescAttr(tupleDesc, i);
-		struct varlena *old_value;
-		struct varlena *new_value;
-
-		if (oldtup != NULL)
-		{
-			/*
-			 * For UPDATE get the old and new values of this attribute
-			 */
-			old_value = (struct varlena *) DatumGetPointer(toast_oldvalues[i]);
-			new_value = (struct varlena *) DatumGetPointer(toast_values[i]);
-
-			/*
-			 * If the old value is stored on disk, check if it has changed so
-			 * we have to delete it later.
-			 */
-			if (att->attlen == -1 && !toast_oldisnull[i] &&
-				VARATT_IS_EXTERNAL_ONDISK(old_value))
-			{
-				if (toast_isnull[i] || !VARATT_IS_EXTERNAL_ONDISK(new_value) ||
-					memcmp((char *) old_value, (char *) new_value,
-						   VARSIZE_EXTERNAL(old_value)) != 0)
-				{
-					/*
-					 * The old external stored value isn't needed any more
-					 * after the update
-					 */
-					toast_delold[i] = true;
-					need_delold = true;
-				}
-				else
-				{
-					/*
-					 * This attribute isn't changed by this update so we reuse
-					 * the original reference to the old value in the new
-					 * tuple.
-					 */
-					toast_action[i] = 'p';
-					continue;
-				}
-			}
-		}
-		else
-		{
-			/*
-			 * For INSERT simply get the new value
-			 */
-			new_value = (struct varlena *) DatumGetPointer(toast_values[i]);
-		}
-
-		/*
-		 * Handle NULL attributes
-		 */
-		if (toast_isnull[i])
-		{
-			toast_action[i] = 'p';
-			has_nulls = true;
-			continue;
-		}
-
-		/*
-		 * Now look at varlena attributes
-		 */
-		if (att->attlen == -1)
-		{
-			/*
-			 * If the table's attribute says PLAIN always, force it so.
-			 */
-			if (att->attstorage == 'p')
-				toast_action[i] = 'p';
-
-			/*
-			 * We took care of UPDATE above, so any external value we find
-			 * still in the tuple must be someone else's that we cannot reuse
-			 * (this includes the case of an out-of-line in-memory datum).
-			 * Fetch it back (without decompression, unless we are forcing
-			 * PLAIN storage).  If necessary, we'll push it out as a new
-			 * external value below.
-			 */
-			if (VARATT_IS_EXTERNAL(new_value))
-			{
-				toast_oldexternal[i] = new_value;
-				if (att->attstorage == 'p')
-					new_value = heap_tuple_untoast_attr(new_value);
-				else
-					new_value = heap_tuple_fetch_attr(new_value);
-				toast_values[i] = PointerGetDatum(new_value);
-				toast_free[i] = true;
-				need_change = true;
-				need_free = true;
-			}
-
-			/*
-			 * Remember the size of this attribute
-			 */
-			toast_sizes[i] = VARSIZE_ANY(new_value);
-		}
-		else
-		{
-			/*
-			 * Not a varlena attribute, plain storage always
-			 */
-			toast_action[i] = 'p';
-		}
-	}
-
-	/* ----------
-	 * Compress and/or save external until data fits into target length
-	 *
-	 *	1: Inline compress attributes with attstorage 'x', and store very
-	 *	   large attributes with attstorage 'x' or 'e' external immediately
-	 *	2: Store attributes with attstorage 'x' or 'e' external
-	 *	3: Inline compress attributes with attstorage 'm'
-	 *	4: Store attributes with attstorage 'm' external
-	 * ----------
-	 */
-
-	/* compute header overhead --- this should match heap_form_tuple() */
-	hoff = SizeofHeapTupleHeader;
-	if (has_nulls)
-		hoff += BITMAPLEN(numAttrs);
-	hoff = MAXALIGN(hoff);
-	/* now convert to a limit on the tuple data size */
-	maxDataLen = RelationGetToastTupleTarget(rel, TOAST_TUPLE_TARGET) - hoff;
-
-	/*
-	 * Look for attributes with attstorage 'x' to compress.  Also find large
-	 * attributes with attstorage 'x' or 'e', and store them external.
-	 */
-	while (heap_compute_data_size(tupleDesc,
-								  toast_values, toast_isnull) > maxDataLen)
-	{
-		int			biggest_attno = -1;
-		int32		biggest_size = MAXALIGN(TOAST_POINTER_SIZE);
-		Datum		old_value;
-		Datum		new_value;
-
-		/*
-		 * Search for the biggest yet unprocessed internal attribute
-		 */
-		for (i = 0; i < numAttrs; i++)
-		{
-			Form_pg_attribute att = TupleDescAttr(tupleDesc, i);
-
-			if (toast_action[i] != ' ')
-				continue;
-			if (VARATT_IS_EXTERNAL(DatumGetPointer(toast_values[i])))
-				continue;		/* can't happen, toast_action would be 'p' */
-			if (VARATT_IS_COMPRESSED(DatumGetPointer(toast_values[i])))
-				continue;
-			if (att->attstorage != 'x' && att->attstorage != 'e')
-				continue;
-			if (toast_sizes[i] > biggest_size)
-			{
-				biggest_attno = i;
-				biggest_size = toast_sizes[i];
-			}
-		}
-
-		if (biggest_attno < 0)
-			break;
-
-		/*
-		 * Attempt to compress it inline, if it has attstorage 'x'
-		 */
-		i = biggest_attno;
-		if (TupleDescAttr(tupleDesc, i)->attstorage == 'x')
-		{
-			old_value = toast_values[i];
-			new_value = toast_compress_datum(old_value);
-
-			if (DatumGetPointer(new_value) != NULL)
-			{
-				/* successful compression */
-				if (toast_free[i])
-					pfree(DatumGetPointer(old_value));
-				toast_values[i] = new_value;
-				toast_free[i] = true;
-				toast_sizes[i] = VARSIZE(DatumGetPointer(toast_values[i]));
-				need_change = true;
-				need_free = true;
-			}
-			else
-			{
-				/* incompressible, ignore on subsequent compression passes */
-				toast_action[i] = 'x';
-			}
-		}
-		else
-		{
-			/* has attstorage 'e', ignore on subsequent compression passes */
-			toast_action[i] = 'x';
-		}
-
-		/*
-		 * If this value is by itself more than maxDataLen (after compression
-		 * if any), push it out to the toast table immediately, if possible.
-		 * This avoids uselessly compressing other fields in the common case
-		 * where we have one long field and several short ones.
-		 *
-		 * XXX maybe the threshold should be less than maxDataLen?
-		 */
-		if (toast_sizes[i] > maxDataLen &&
-			rel->rd_rel->reltoastrelid != InvalidOid)
-		{
-			old_value = toast_values[i];
-			toast_action[i] = 'p';
-			toast_values[i] = toast_save_datum(rel, toast_values[i],
-											   toast_oldexternal[i], options);
-			if (toast_free[i])
-				pfree(DatumGetPointer(old_value));
-			toast_free[i] = true;
-			need_change = true;
-			need_free = true;
-		}
-	}
-
-	/*
-	 * Second we look for attributes of attstorage 'x' or 'e' that are still
-	 * inline.  But skip this if there's no toast table to push them to.
-	 */
-	while (heap_compute_data_size(tupleDesc,
-								  toast_values, toast_isnull) > maxDataLen &&
-		   rel->rd_rel->reltoastrelid != InvalidOid)
-	{
-		int			biggest_attno = -1;
-		int32		biggest_size = MAXALIGN(TOAST_POINTER_SIZE);
-		Datum		old_value;
-
-		/*------
-		 * Search for the biggest yet inlined attribute with
-		 * attstorage equals 'x' or 'e'
-		 *------
-		 */
-		for (i = 0; i < numAttrs; i++)
-		{
-			Form_pg_attribute att = TupleDescAttr(tupleDesc, i);
-
-			if (toast_action[i] == 'p')
-				continue;
-			if (VARATT_IS_EXTERNAL(DatumGetPointer(toast_values[i])))
-				continue;		/* can't happen, toast_action would be 'p' */
-			if (att->attstorage != 'x' && att->attstorage != 'e')
-				continue;
-			if (toast_sizes[i] > biggest_size)
-			{
-				biggest_attno = i;
-				biggest_size = toast_sizes[i];
-			}
-		}
-
-		if (biggest_attno < 0)
-			break;
-
-		/*
-		 * Store this external
-		 */
-		i = biggest_attno;
-		old_value = toast_values[i];
-		toast_action[i] = 'p';
-		toast_values[i] = toast_save_datum(rel, toast_values[i],
-										   toast_oldexternal[i], options);
-		if (toast_free[i])
-			pfree(DatumGetPointer(old_value));
-		toast_free[i] = true;
-
-		need_change = true;
-		need_free = true;
-	}
-
-	/*
-	 * Round 3 - this time we take attributes with storage 'm' into
-	 * compression
-	 */
-	while (heap_compute_data_size(tupleDesc,
-								  toast_values, toast_isnull) > maxDataLen)
-	{
-		int			biggest_attno = -1;
-		int32		biggest_size = MAXALIGN(TOAST_POINTER_SIZE);
-		Datum		old_value;
-		Datum		new_value;
-
-		/*
-		 * Search for the biggest yet uncompressed internal attribute
-		 */
-		for (i = 0; i < numAttrs; i++)
-		{
-			if (toast_action[i] != ' ')
-				continue;
-			if (VARATT_IS_EXTERNAL(DatumGetPointer(toast_values[i])))
-				continue;		/* can't happen, toast_action would be 'p' */
-			if (VARATT_IS_COMPRESSED(DatumGetPointer(toast_values[i])))
-				continue;
-			if (TupleDescAttr(tupleDesc, i)->attstorage != 'm')
-				continue;
-			if (toast_sizes[i] > biggest_size)
-			{
-				biggest_attno = i;
-				biggest_size = toast_sizes[i];
-			}
-		}
-
-		if (biggest_attno < 0)
-			break;
-
-		/*
-		 * Attempt to compress it inline
-		 */
-		i = biggest_attno;
-		old_value = toast_values[i];
-		new_value = toast_compress_datum(old_value);
-
-		if (DatumGetPointer(new_value) != NULL)
-		{
-			/* successful compression */
-			if (toast_free[i])
-				pfree(DatumGetPointer(old_value));
-			toast_values[i] = new_value;
-			toast_free[i] = true;
-			toast_sizes[i] = VARSIZE(DatumGetPointer(toast_values[i]));
-			need_change = true;
-			need_free = true;
-		}
-		else
-		{
-			/* incompressible, ignore on subsequent compression passes */
-			toast_action[i] = 'x';
-		}
-	}
-
-	/*
-	 * Finally we store attributes of type 'm' externally.  At this point we
-	 * increase the target tuple size, so that 'm' attributes aren't stored
-	 * externally unless really necessary.
-	 */
-	maxDataLen = TOAST_TUPLE_TARGET_MAIN - hoff;
-
-	while (heap_compute_data_size(tupleDesc,
-								  toast_values, toast_isnull) > maxDataLen &&
-		   rel->rd_rel->reltoastrelid != InvalidOid)
-	{
-		int			biggest_attno = -1;
-		int32		biggest_size = MAXALIGN(TOAST_POINTER_SIZE);
-		Datum		old_value;
-
-		/*--------
-		 * Search for the biggest yet inlined attribute with
-		 * attstorage = 'm'
-		 *--------
-		 */
-		for (i = 0; i < numAttrs; i++)
-		{
-			if (toast_action[i] == 'p')
-				continue;
-			if (VARATT_IS_EXTERNAL(DatumGetPointer(toast_values[i])))
-				continue;		/* can't happen, toast_action would be 'p' */
-			if (TupleDescAttr(tupleDesc, i)->attstorage != 'm')
-				continue;
-			if (toast_sizes[i] > biggest_size)
-			{
-				biggest_attno = i;
-				biggest_size = toast_sizes[i];
-			}
-		}
-
-		if (biggest_attno < 0)
-			break;
-
-		/*
-		 * Store this external
-		 */
-		i = biggest_attno;
-		old_value = toast_values[i];
-		toast_action[i] = 'p';
-		toast_values[i] = toast_save_datum(rel, toast_values[i],
-										   toast_oldexternal[i], options);
-		if (toast_free[i])
-			pfree(DatumGetPointer(old_value));
-		toast_free[i] = true;
-
-		need_change = true;
-		need_free = true;
-	}
-
-	/*
-	 * In the case we toasted any values, we need to build a new heap tuple
-	 * with the changed values.
-	 */
-	if (need_change)
-	{
-		HeapTupleHeader olddata = newtup->t_data;
-		HeapTupleHeader new_data;
-		int32		new_header_len;
-		int32		new_data_len;
-		int32		new_tuple_len;
-
-		/*
-		 * Calculate the new size of the tuple.
-		 *
-		 * Note: we used to assume here that the old tuple's t_hoff must equal
-		 * the new_header_len value, but that was incorrect.  The old tuple
-		 * might have a smaller-than-current natts, if there's been an ALTER
-		 * TABLE ADD COLUMN since it was stored; and that would lead to a
-		 * different conclusion about the size of the null bitmap, or even
-		 * whether there needs to be one at all.
-		 */
-		new_header_len = SizeofHeapTupleHeader;
-		if (has_nulls)
-			new_header_len += BITMAPLEN(numAttrs);
-		new_header_len = MAXALIGN(new_header_len);
-		new_data_len = heap_compute_data_size(tupleDesc,
-											  toast_values, toast_isnull);
-		new_tuple_len = new_header_len + new_data_len;
-
-		/*
-		 * Allocate and zero the space needed, and fill HeapTupleData fields.
-		 */
-		result_tuple = (HeapTuple) palloc0(HEAPTUPLESIZE + new_tuple_len);
-		result_tuple->t_len = new_tuple_len;
-		result_tuple->t_self = newtup->t_self;
-		result_tuple->t_tableOid = newtup->t_tableOid;
-		new_data = (HeapTupleHeader) ((char *) result_tuple + HEAPTUPLESIZE);
-		result_tuple->t_data = new_data;
-
-		/*
-		 * Copy the existing tuple header, but adjust natts and t_hoff.
-		 */
-		memcpy(new_data, olddata, SizeofHeapTupleHeader);
-		HeapTupleHeaderSetNatts(new_data, numAttrs);
-		new_data->t_hoff = new_header_len;
-
-		/* Copy over the data, and fill the null bitmap if needed */
-		heap_fill_tuple(tupleDesc,
-						toast_values,
-						toast_isnull,
-						(char *) new_data + new_header_len,
-						new_data_len,
-						&(new_data->t_infomask),
-						has_nulls ? new_data->t_bits : NULL);
-	}
-	else
-		result_tuple = newtup;
-
-	/*
-	 * Free allocated temp values
-	 */
-	if (need_free)
-		for (i = 0; i < numAttrs; i++)
-			if (toast_free[i])
-				pfree(DatumGetPointer(toast_values[i]));
-
-	/*
-	 * Delete external values from the old tuple
-	 */
-	if (need_delold)
-		for (i = 0; i < numAttrs; i++)
-			if (toast_delold[i])
-				toast_delete_datum(rel, toast_oldvalues[i], false);
-
-	return result_tuple;
-}
-
-
-/* ----------
- * toast_flatten_tuple -
- *
- *	"Flatten" a tuple to contain no out-of-line toasted fields.
- *	(This does not eliminate compressed or short-header datums.)
- *
- *	Note: we expect the caller already checked HeapTupleHasExternal(tup),
- *	so there is no need for a short-circuit path.
- * ----------
- */
-HeapTuple
-toast_flatten_tuple(HeapTuple tup, TupleDesc tupleDesc)
-{
-	HeapTuple	new_tuple;
-	int			numAttrs = tupleDesc->natts;
-	int			i;
-	Datum		toast_values[MaxTupleAttributeNumber];
-	bool		toast_isnull[MaxTupleAttributeNumber];
-	bool		toast_free[MaxTupleAttributeNumber];
-
-	/*
-	 * Break down the tuple into fields.
-	 */
-	Assert(numAttrs <= MaxTupleAttributeNumber);
-	heap_deform_tuple(tup, tupleDesc, toast_values, toast_isnull);
-
-	memset(toast_free, 0, numAttrs * sizeof(bool));
-
-	for (i = 0; i < numAttrs; i++)
-	{
-		/*
-		 * Look at non-null varlena attributes
-		 */
-		if (!toast_isnull[i] && TupleDescAttr(tupleDesc, i)->attlen == -1)
-		{
-			struct varlena *new_value;
-
-			new_value = (struct varlena *) DatumGetPointer(toast_values[i]);
-			if (VARATT_IS_EXTERNAL(new_value))
-			{
-				new_value = heap_tuple_fetch_attr(new_value);
-				toast_values[i] = PointerGetDatum(new_value);
-				toast_free[i] = true;
-			}
-		}
-	}
-
-	/*
-	 * Form the reconfigured tuple.
-	 */
-	new_tuple = heap_form_tuple(tupleDesc, toast_values, toast_isnull);
-
-	/*
-	 * Be sure to copy the tuple's identity fields.  We also make a point of
-	 * copying visibility info, just in case anybody looks at those fields in
-	 * a syscache entry.
-	 */
-	new_tuple->t_self = tup->t_self;
-	new_tuple->t_tableOid = tup->t_tableOid;
-
-	new_tuple->t_data->t_choice = tup->t_data->t_choice;
-	new_tuple->t_data->t_ctid = tup->t_data->t_ctid;
-	new_tuple->t_data->t_infomask &= ~HEAP_XACT_MASK;
-	new_tuple->t_data->t_infomask |=
-		tup->t_data->t_infomask & HEAP_XACT_MASK;
-	new_tuple->t_data->t_infomask2 &= ~HEAP2_XACT_MASK;
-	new_tuple->t_data->t_infomask2 |=
-		tup->t_data->t_infomask2 & HEAP2_XACT_MASK;
-
-	/*
-	 * Free allocated temp values
-	 */
-	for (i = 0; i < numAttrs; i++)
-		if (toast_free[i])
-			pfree(DatumGetPointer(toast_values[i]));
-
-	return new_tuple;
-}
-
-
-/* ----------
- * toast_flatten_tuple_to_datum -
- *
- *	"Flatten" a tuple containing out-of-line toasted fields into a Datum.
- *	The result is always palloc'd in the current memory context.
- *
- *	We have a general rule that Datums of container types (rows, arrays,
- *	ranges, etc) must not contain any external TOAST pointers.  Without
- *	this rule, we'd have to look inside each Datum when preparing a tuple
- *	for storage, which would be expensive and would fail to extend cleanly
- *	to new sorts of container types.
- *
- *	However, we don't want to say that tuples represented as HeapTuples
- *	can't contain toasted fields, so instead this routine should be called
- *	when such a HeapTuple is being converted into a Datum.
- *
- *	While we're at it, we decompress any compressed fields too.  This is not
- *	necessary for correctness, but reflects an expectation that compression
- *	will be more effective if applied to the whole tuple not individual
- *	fields.  We are not so concerned about that that we want to deconstruct
- *	and reconstruct tuples just to get rid of compressed fields, however.
- *	So callers typically won't call this unless they see that the tuple has
- *	at least one external field.
- *
- *	On the other hand, in-line short-header varlena fields are left alone.
- *	If we "untoasted" them here, they'd just get changed back to short-header
- *	format anyway within heap_fill_tuple.
- * ----------
- */
-Datum
-toast_flatten_tuple_to_datum(HeapTupleHeader tup,
-							 uint32 tup_len,
-							 TupleDesc tupleDesc)
-{
-	HeapTupleHeader new_data;
-	int32		new_header_len;
-	int32		new_data_len;
-	int32		new_tuple_len;
-	HeapTupleData tmptup;
-	int			numAttrs = tupleDesc->natts;
-	int			i;
-	bool		has_nulls = false;
-	Datum		toast_values[MaxTupleAttributeNumber];
-	bool		toast_isnull[MaxTupleAttributeNumber];
-	bool		toast_free[MaxTupleAttributeNumber];
-
-	/* Build a temporary HeapTuple control structure */
-	tmptup.t_len = tup_len;
-	ItemPointerSetInvalid(&(tmptup.t_self));
-	tmptup.t_tableOid = InvalidOid;
-	tmptup.t_data = tup;
-
-	/*
-	 * Break down the tuple into fields.
-	 */
-	Assert(numAttrs <= MaxTupleAttributeNumber);
-	heap_deform_tuple(&tmptup, tupleDesc, toast_values, toast_isnull);
-
-	memset(toast_free, 0, numAttrs * sizeof(bool));
-
-	for (i = 0; i < numAttrs; i++)
-	{
-		/*
-		 * Look at non-null varlena attributes
-		 */
-		if (toast_isnull[i])
-			has_nulls = true;
-		else if (TupleDescAttr(tupleDesc, i)->attlen == -1)
-		{
-			struct varlena *new_value;
-
-			new_value = (struct varlena *) DatumGetPointer(toast_values[i]);
-			if (VARATT_IS_EXTERNAL(new_value) ||
-				VARATT_IS_COMPRESSED(new_value))
-			{
-				new_value = heap_tuple_untoast_attr(new_value);
-				toast_values[i] = PointerGetDatum(new_value);
-				toast_free[i] = true;
-			}
-		}
-	}
-
-	/*
-	 * Calculate the new size of the tuple.
-	 *
-	 * This should match the reconstruction code in toast_insert_or_update.
-	 */
-	new_header_len = SizeofHeapTupleHeader;
-	if (has_nulls)
-		new_header_len += BITMAPLEN(numAttrs);
-	new_header_len = MAXALIGN(new_header_len);
-	new_data_len = heap_compute_data_size(tupleDesc,
-										  toast_values, toast_isnull);
-	new_tuple_len = new_header_len + new_data_len;
-
-	new_data = (HeapTupleHeader) palloc0(new_tuple_len);
-
-	/*
-	 * Copy the existing tuple header, but adjust natts and t_hoff.
-	 */
-	memcpy(new_data, tup, SizeofHeapTupleHeader);
-	HeapTupleHeaderSetNatts(new_data, numAttrs);
-	new_data->t_hoff = new_header_len;
-
-	/* Set the composite-Datum header fields correctly */
-	HeapTupleHeaderSetDatumLength(new_data, new_tuple_len);
-	HeapTupleHeaderSetTypeId(new_data, tupleDesc->tdtypeid);
-	HeapTupleHeaderSetTypMod(new_data, tupleDesc->tdtypmod);
-
-	/* Copy over the data, and fill the null bitmap if needed */
-	heap_fill_tuple(tupleDesc,
-					toast_values,
-					toast_isnull,
-					(char *) new_data + new_header_len,
-					new_data_len,
-					&(new_data->t_infomask),
-					has_nulls ? new_data->t_bits : NULL);
-
-	/*
-	 * Free allocated temp values
-	 */
-	for (i = 0; i < numAttrs; i++)
-		if (toast_free[i])
-			pfree(DatumGetPointer(toast_values[i]));
-
-	return PointerGetDatum(new_data);
-}
-
-
-/* ----------
- * toast_build_flattened_tuple -
- *
- *	Build a tuple containing no out-of-line toasted fields.
- *	(This does not eliminate compressed or short-header datums.)
- *
- *	This is essentially just like heap_form_tuple, except that it will
- *	expand any external-data pointers beforehand.
- *
- *	It's not very clear whether it would be preferable to decompress
- *	in-line compressed datums while at it.  For now, we don't.
- * ----------
- */
-HeapTuple
-toast_build_flattened_tuple(TupleDesc tupleDesc,
-							Datum *values,
-							bool *isnull)
-{
-	HeapTuple	new_tuple;
-	int			numAttrs = tupleDesc->natts;
-	int			num_to_free;
-	int			i;
-	Datum		new_values[MaxTupleAttributeNumber];
-	Pointer		freeable_values[MaxTupleAttributeNumber];
-
-	/*
-	 * We can pass the caller's isnull array directly to heap_form_tuple, but
-	 * we potentially need to modify the values array.
-	 */
-	Assert(numAttrs <= MaxTupleAttributeNumber);
-	memcpy(new_values, values, numAttrs * sizeof(Datum));
-
-	num_to_free = 0;
-	for (i = 0; i < numAttrs; i++)
-	{
-		/*
-		 * Look at non-null varlena attributes
-		 */
-		if (!isnull[i] && TupleDescAttr(tupleDesc, i)->attlen == -1)
-		{
-			struct varlena *new_value;
-
-			new_value = (struct varlena *) DatumGetPointer(new_values[i]);
-			if (VARATT_IS_EXTERNAL(new_value))
-			{
-				new_value = heap_tuple_fetch_attr(new_value);
-				new_values[i] = PointerGetDatum(new_value);
-				freeable_values[num_to_free++] = (Pointer) new_value;
-			}
-		}
-	}
-
-	/*
-	 * Form the reconfigured tuple.
-	 */
-	new_tuple = heap_form_tuple(tupleDesc, new_values, isnull);
-
-	/*
-	 * Free allocated temp values
-	 */
-	for (i = 0; i < num_to_free; i++)
-		pfree(freeable_values[i]);
-
-	return new_tuple;
-}
-
-
-/* ----------
- * toast_compress_datum -
- *
- *	Create a compressed version of a varlena datum
- *
- *	If we fail (ie, compressed result is actually bigger than original)
- *	then return NULL.  We must not use compressed data if it'd expand
- *	the tuple!
- *
- *	We use VAR{SIZE,DATA}_ANY so we can handle short varlenas here without
- *	copying them.  But we can't handle external or compressed datums.
- * ----------
- */
-Datum
-toast_compress_datum(Datum value)
-{
-	struct varlena *tmp;
-	int32		valsize = VARSIZE_ANY_EXHDR(DatumGetPointer(value));
-	int32		len;
-
-	Assert(!VARATT_IS_EXTERNAL(DatumGetPointer(value)));
-	Assert(!VARATT_IS_COMPRESSED(DatumGetPointer(value)));
-
-	/*
-	 * No point in wasting a palloc cycle if value size is out of the allowed
-	 * range for compression
-	 */
-	if (valsize < PGLZ_strategy_default->min_input_size ||
-		valsize > PGLZ_strategy_default->max_input_size)
-		return PointerGetDatum(NULL);
-
-	tmp = (struct varlena *) palloc(PGLZ_MAX_OUTPUT(valsize) +
-									TOAST_COMPRESS_HDRSZ);
-
-	/*
-	 * We recheck the actual size even if pglz_compress() reports success,
-	 * because it might be satisfied with having saved as little as one byte
-	 * in the compressed data --- which could turn into a net loss once you
-	 * consider header and alignment padding.  Worst case, the compressed
-	 * format might require three padding bytes (plus header, which is
-	 * included in VARSIZE(tmp)), whereas the uncompressed format would take
-	 * only one header byte and no padding if the value is short enough.  So
-	 * we insist on a savings of more than 2 bytes to ensure we have a gain.
-	 */
-	len = pglz_compress(VARDATA_ANY(DatumGetPointer(value)),
-						valsize,
-						TOAST_COMPRESS_RAWDATA(tmp),
-						PGLZ_strategy_default);
-	if (len >= 0 &&
-		len + TOAST_COMPRESS_HDRSZ < valsize - 2)
-	{
-		TOAST_COMPRESS_SET_RAWSIZE(tmp, valsize);
-		SET_VARSIZE_COMPRESSED(tmp, len + TOAST_COMPRESS_HDRSZ);
-		/* successful compression */
-		return PointerGetDatum(tmp);
-	}
-	else
-	{
-		/* incompressible data */
-		pfree(tmp);
-		return PointerGetDatum(NULL);
-	}
-}
-
-
-/* ----------
- * toast_get_valid_index
- *
- *	Get OID of valid index associated to given toast relation. A toast
- *	relation can have only one valid index at the same time.
- */
-Oid
-toast_get_valid_index(Oid toastoid, LOCKMODE lock)
-{
-	int			num_indexes;
-	int			validIndex;
-	Oid			validIndexOid;
-	Relation   *toastidxs;
-	Relation	toastrel;
-
-	/* Open the toast relation */
-	toastrel = table_open(toastoid, lock);
-
-	/* Look for the valid index of the toast relation */
-	validIndex = toast_open_indexes(toastrel,
-									lock,
-									&toastidxs,
-									&num_indexes);
-	validIndexOid = RelationGetRelid(toastidxs[validIndex]);
-
-	/* Close the toast relation and all its indexes */
-	toast_close_indexes(toastidxs, num_indexes, lock);
-	table_close(toastrel, lock);
-
-	return validIndexOid;
-}
-
-
-/* ----------
- * toast_save_datum -
- *
- *	Save one single datum into the secondary relation and return
- *	a Datum reference for it.
- *
- * rel: the main relation we're working with (not the toast rel!)
- * value: datum to be pushed to toast storage
- * oldexternal: if not NULL, toast pointer previously representing the datum
- * options: options to be passed to heap_insert() for toast rows
- * ----------
- */
-static Datum
-toast_save_datum(Relation rel, Datum value,
-				 struct varlena *oldexternal, int options)
-{
-	Relation	toastrel;
-	Relation   *toastidxs;
-	HeapTuple	toasttup;
-	TupleDesc	toasttupDesc;
-	Datum		t_values[3];
-	bool		t_isnull[3];
-	CommandId	mycid = GetCurrentCommandId(true);
-	struct varlena *result;
-	struct varatt_external toast_pointer;
-	union
-	{
-		struct varlena hdr;
-		/* this is to make the union big enough for a chunk: */
-		char		data[TOAST_MAX_CHUNK_SIZE + VARHDRSZ];
-		/* ensure union is aligned well enough: */
-		int32		align_it;
-	}			chunk_data;
-	int32		chunk_size;
-	int32		chunk_seq = 0;
-	char	   *data_p;
-	int32		data_todo;
-	Pointer		dval = DatumGetPointer(value);
-	int			num_indexes;
-	int			validIndex;
-
-	Assert(!VARATT_IS_EXTERNAL(value));
-
-	/*
-	 * Open the toast relation and its indexes.  We can use the index to check
-	 * uniqueness of the OID we assign to the toasted item, even though it has
-	 * additional columns besides OID.
-	 */
-	toastrel = table_open(rel->rd_rel->reltoastrelid, RowExclusiveLock);
-	toasttupDesc = toastrel->rd_att;
-
-	/* Open all the toast indexes and look for the valid one */
-	validIndex = toast_open_indexes(toastrel,
-									RowExclusiveLock,
-									&toastidxs,
-									&num_indexes);
-
-	/*
-	 * Get the data pointer and length, and compute va_rawsize and va_extsize.
-	 *
-	 * va_rawsize is the size of the equivalent fully uncompressed datum, so
-	 * we have to adjust for short headers.
-	 *
-	 * va_extsize is the actual size of the data payload in the toast records.
-	 */
-	if (VARATT_IS_SHORT(dval))
-	{
-		data_p = VARDATA_SHORT(dval);
-		data_todo = VARSIZE_SHORT(dval) - VARHDRSZ_SHORT;
-		toast_pointer.va_rawsize = data_todo + VARHDRSZ;	/* as if not short */
-		toast_pointer.va_extsize = data_todo;
-	}
-	else if (VARATT_IS_COMPRESSED(dval))
-	{
-		data_p = VARDATA(dval);
-		data_todo = VARSIZE(dval) - VARHDRSZ;
-		/* rawsize in a compressed datum is just the size of the payload */
-		toast_pointer.va_rawsize = VARRAWSIZE_4B_C(dval) + VARHDRSZ;
-		toast_pointer.va_extsize = data_todo;
-		/* Assert that the numbers look like it's compressed */
-		Assert(VARATT_EXTERNAL_IS_COMPRESSED(toast_pointer));
-	}
-	else
-	{
-		data_p = VARDATA(dval);
-		data_todo = VARSIZE(dval) - VARHDRSZ;
-		toast_pointer.va_rawsize = VARSIZE(dval);
-		toast_pointer.va_extsize = data_todo;
-	}
-
-	/*
-	 * Insert the correct table OID into the result TOAST pointer.
-	 *
-	 * Normally this is the actual OID of the target toast table, but during
-	 * table-rewriting operations such as CLUSTER, we have to insert the OID
-	 * of the table's real permanent toast table instead.  rd_toastoid is set
-	 * if we have to substitute such an OID.
-	 */
-	if (OidIsValid(rel->rd_toastoid))
-		toast_pointer.va_toastrelid = rel->rd_toastoid;
-	else
-		toast_pointer.va_toastrelid = RelationGetRelid(toastrel);
-
-	/*
-	 * Choose an OID to use as the value ID for this toast value.
-	 *
-	 * Normally we just choose an unused OID within the toast table.  But
-	 * during table-rewriting operations where we are preserving an existing
-	 * toast table OID, we want to preserve toast value OIDs too.  So, if
-	 * rd_toastoid is set and we had a prior external value from that same
-	 * toast table, re-use its value ID.  If we didn't have a prior external
-	 * value (which is a corner case, but possible if the table's attstorage
-	 * options have been changed), we have to pick a value ID that doesn't
-	 * conflict with either new or existing toast value OIDs.
-	 */
-	if (!OidIsValid(rel->rd_toastoid))
-	{
-		/* normal case: just choose an unused OID */
-		toast_pointer.va_valueid =
-			GetNewOidWithIndex(toastrel,
-							   RelationGetRelid(toastidxs[validIndex]),
-							   (AttrNumber) 1);
-	}
-	else
-	{
-		/* rewrite case: check to see if value was in old toast table */
-		toast_pointer.va_valueid = InvalidOid;
-		if (oldexternal != NULL)
-		{
-			struct varatt_external old_toast_pointer;
-
-			Assert(VARATT_IS_EXTERNAL_ONDISK(oldexternal));
-			/* Must copy to access aligned fields */
-			VARATT_EXTERNAL_GET_POINTER(old_toast_pointer, oldexternal);
-			if (old_toast_pointer.va_toastrelid == rel->rd_toastoid)
-			{
-				/* This value came from the old toast table; reuse its OID */
-				toast_pointer.va_valueid = old_toast_pointer.va_valueid;
-
-				/*
-				 * There is a corner case here: the table rewrite might have
-				 * to copy both live and recently-dead versions of a row, and
-				 * those versions could easily reference the same toast value.
-				 * When we copy the second or later version of such a row,
-				 * reusing the OID will mean we select an OID that's already
-				 * in the new toast table.  Check for that, and if so, just
-				 * fall through without writing the data again.
-				 *
-				 * While annoying and ugly-looking, this is a good thing
-				 * because it ensures that we wind up with only one copy of
-				 * the toast value when there is only one copy in the old
-				 * toast table.  Before we detected this case, we'd have made
-				 * multiple copies, wasting space; and what's worse, the
-				 * copies belonging to already-deleted heap tuples would not
-				 * be reclaimed by VACUUM.
-				 */
-				if (toastrel_valueid_exists(toastrel,
-											toast_pointer.va_valueid))
-				{
-					/* Match, so short-circuit the data storage loop below */
-					data_todo = 0;
-				}
-			}
-		}
-		if (toast_pointer.va_valueid == InvalidOid)
-		{
-			/*
-			 * new value; must choose an OID that doesn't conflict in either
-			 * old or new toast table
-			 */
-			do
-			{
-				toast_pointer.va_valueid =
-					GetNewOidWithIndex(toastrel,
-									   RelationGetRelid(toastidxs[validIndex]),
-									   (AttrNumber) 1);
-			} while (toastid_valueid_exists(rel->rd_toastoid,
-											toast_pointer.va_valueid));
-		}
-	}
-
-	/*
-	 * Initialize constant parts of the tuple data
-	 */
-	t_values[0] = ObjectIdGetDatum(toast_pointer.va_valueid);
-	t_values[2] = PointerGetDatum(&chunk_data);
-	t_isnull[0] = false;
-	t_isnull[1] = false;
-	t_isnull[2] = false;
-
-	/*
-	 * Split up the item into chunks
-	 */
-	while (data_todo > 0)
-	{
-		int			i;
-
-		CHECK_FOR_INTERRUPTS();
-
-		/*
-		 * Calculate the size of this chunk
-		 */
-		chunk_size = Min(TOAST_MAX_CHUNK_SIZE, data_todo);
-
-		/*
-		 * Build a tuple and store it
-		 */
-		t_values[1] = Int32GetDatum(chunk_seq++);
-		SET_VARSIZE(&chunk_data, chunk_size + VARHDRSZ);
-		memcpy(VARDATA(&chunk_data), data_p, chunk_size);
-		toasttup = heap_form_tuple(toasttupDesc, t_values, t_isnull);
-
-		heap_insert(toastrel, toasttup, mycid, options, NULL);
-
-		/*
-		 * Create the index entry.  We cheat a little here by not using
-		 * FormIndexDatum: this relies on the knowledge that the index columns
-		 * are the same as the initial columns of the table for all the
-		 * indexes.  We also cheat by not providing an IndexInfo: this is okay
-		 * for now because btree doesn't need one, but we might have to be
-		 * more honest someday.
-		 *
-		 * Note also that there had better not be any user-created index on
-		 * the TOAST table, since we don't bother to update anything else.
-		 */
-		for (i = 0; i < num_indexes; i++)
-		{
-			/* Only index relations marked as ready can be updated */
-			if (toastidxs[i]->rd_index->indisready)
-				index_insert(toastidxs[i], t_values, t_isnull,
-							 &(toasttup->t_self),
-							 toastrel,
-							 toastidxs[i]->rd_index->indisunique ?
-							 UNIQUE_CHECK_YES : UNIQUE_CHECK_NO,
-							 NULL);
-		}
-
-		/*
-		 * Free memory
-		 */
-		heap_freetuple(toasttup);
-
-		/*
-		 * Move on to next chunk
-		 */
-		data_todo -= chunk_size;
-		data_p += chunk_size;
-	}
-
-	/*
-	 * Done - close toast relation and its indexes
-	 */
-	toast_close_indexes(toastidxs, num_indexes, RowExclusiveLock);
-	table_close(toastrel, RowExclusiveLock);
-
-	/*
-	 * Create the TOAST pointer value that we'll return
-	 */
-	result = (struct varlena *) palloc(TOAST_POINTER_SIZE);
-	SET_VARTAG_EXTERNAL(result, VARTAG_ONDISK);
-	memcpy(VARDATA_EXTERNAL(result), &toast_pointer, sizeof(toast_pointer));
-
-	return PointerGetDatum(result);
-}
-
-
-/* ----------
- * toast_delete_datum -
- *
- *	Delete a single external stored value.
- * ----------
- */
-static void
-toast_delete_datum(Relation rel, Datum value, bool is_speculative)
-{
-	struct varlena *attr = (struct varlena *) DatumGetPointer(value);
-	struct varatt_external toast_pointer;
-	Relation	toastrel;
-	Relation   *toastidxs;
-	ScanKeyData toastkey;
-	SysScanDesc toastscan;
-	HeapTuple	toasttup;
-	int			num_indexes;
-	int			validIndex;
-	SnapshotData SnapshotToast;
-
-	if (!VARATT_IS_EXTERNAL_ONDISK(attr))
-		return;
-
-	/* Must copy to access aligned fields */
-	VARATT_EXTERNAL_GET_POINTER(toast_pointer, attr);
-
-	/*
-	 * Open the toast relation and its indexes
-	 */
-	toastrel = table_open(toast_pointer.va_toastrelid, RowExclusiveLock);
-
-	/* Fetch valid relation used for process */
-	validIndex = toast_open_indexes(toastrel,
-									RowExclusiveLock,
-									&toastidxs,
-									&num_indexes);
-
-	/*
-	 * Setup a scan key to find chunks with matching va_valueid
-	 */
-	ScanKeyInit(&toastkey,
-				(AttrNumber) 1,
-				BTEqualStrategyNumber, F_OIDEQ,
-				ObjectIdGetDatum(toast_pointer.va_valueid));
-
-	/*
-	 * Find all the chunks.  (We don't actually care whether we see them in
-	 * sequence or not, but since we've already locked the index we might as
-	 * well use systable_beginscan_ordered.)
-	 */
-	init_toast_snapshot(&SnapshotToast);
-	toastscan = systable_beginscan_ordered(toastrel, toastidxs[validIndex],
-										   &SnapshotToast, 1, &toastkey);
-	while ((toasttup = systable_getnext_ordered(toastscan, ForwardScanDirection)) != NULL)
-	{
-		/*
-		 * Have a chunk, delete it
-		 */
-		if (is_speculative)
-			heap_abort_speculative(toastrel, &toasttup->t_self);
-		else
-			simple_heap_delete(toastrel, &toasttup->t_self);
-	}
-
-	/*
-	 * End scan and close relations
-	 */
-	systable_endscan_ordered(toastscan);
-	toast_close_indexes(toastidxs, num_indexes, RowExclusiveLock);
-	table_close(toastrel, RowExclusiveLock);
-}
-
-
-/* ----------
- * toastrel_valueid_exists -
- *
- *	Test whether a toast value with the given ID exists in the toast relation.
- *	For safety, we consider a value to exist if there are either live or dead
- *	toast rows with that ID; see notes for GetNewOidWithIndex().
- * ----------
- */
-static bool
-toastrel_valueid_exists(Relation toastrel, Oid valueid)
-{
-	bool		result = false;
-	ScanKeyData toastkey;
-	SysScanDesc toastscan;
-	int			num_indexes;
-	int			validIndex;
-	Relation   *toastidxs;
-
-	/* Fetch a valid index relation */
-	validIndex = toast_open_indexes(toastrel,
-									RowExclusiveLock,
-									&toastidxs,
-									&num_indexes);
-
-	/*
-	 * Setup a scan key to find chunks with matching va_valueid
-	 */
-	ScanKeyInit(&toastkey,
-				(AttrNumber) 1,
-				BTEqualStrategyNumber, F_OIDEQ,
-				ObjectIdGetDatum(valueid));
-
-	/*
-	 * Is there any such chunk?
-	 */
-	toastscan = systable_beginscan(toastrel,
-								   RelationGetRelid(toastidxs[validIndex]),
-								   true, SnapshotAny, 1, &toastkey);
-
-	if (systable_getnext(toastscan) != NULL)
-		result = true;
-
-	systable_endscan(toastscan);
-
-	/* Clean up */
-	toast_close_indexes(toastidxs, num_indexes, RowExclusiveLock);
-
-	return result;
-}
-
-/* ----------
- * toastid_valueid_exists -
- *
- *	As above, but work from toast rel's OID not an open relation
- * ----------
- */
-static bool
-toastid_valueid_exists(Oid toastrelid, Oid valueid)
-{
-	bool		result;
-	Relation	toastrel;
-
-	toastrel = table_open(toastrelid, AccessShareLock);
-
-	result = toastrel_valueid_exists(toastrel, valueid);
-
-	table_close(toastrel, AccessShareLock);
-
-	return result;
-}
-
-
-/* ----------
- * toast_fetch_datum -
- *
- *	Reconstruct an in memory Datum from the chunks saved
- *	in the toast relation
- * ----------
- */
-static struct varlena *
-toast_fetch_datum(struct varlena *attr)
-{
-	Relation	toastrel;
-	Relation   *toastidxs;
-	ScanKeyData toastkey;
-	SysScanDesc toastscan;
-	HeapTuple	ttup;
-	TupleDesc	toasttupDesc;
-	struct varlena *result;
-	struct varatt_external toast_pointer;
-	int32		ressize;
-	int32		residx,
-				nextidx;
-	int32		numchunks;
-	Pointer		chunk;
-	bool		isnull;
-	char	   *chunkdata;
-	int32		chunksize;
-	int			num_indexes;
-	int			validIndex;
-	SnapshotData SnapshotToast;
-
-	if (!VARATT_IS_EXTERNAL_ONDISK(attr))
-		elog(ERROR, "toast_fetch_datum shouldn't be called for non-ondisk datums");
-
-	/* Must copy to access aligned fields */
-	VARATT_EXTERNAL_GET_POINTER(toast_pointer, attr);
-
-	ressize = toast_pointer.va_extsize;
-	numchunks = ((ressize - 1) / TOAST_MAX_CHUNK_SIZE) + 1;
-
-	result = (struct varlena *) palloc(ressize + VARHDRSZ);
-
-	if (VARATT_EXTERNAL_IS_COMPRESSED(toast_pointer))
-		SET_VARSIZE_COMPRESSED(result, ressize + VARHDRSZ);
-	else
-		SET_VARSIZE(result, ressize + VARHDRSZ);
-
-	/*
-	 * Open the toast relation and its indexes
-	 */
-	toastrel = table_open(toast_pointer.va_toastrelid, AccessShareLock);
-	toasttupDesc = toastrel->rd_att;
-
-	/* Look for the valid index of the toast relation */
-	validIndex = toast_open_indexes(toastrel,
-									AccessShareLock,
-									&toastidxs,
-									&num_indexes);
-
-	/*
-	 * Setup a scan key to fetch from the index by va_valueid
-	 */
-	ScanKeyInit(&toastkey,
-				(AttrNumber) 1,
-				BTEqualStrategyNumber, F_OIDEQ,
-				ObjectIdGetDatum(toast_pointer.va_valueid));
-
-	/*
-	 * Read the chunks by index
-	 *
-	 * Note that because the index is actually on (valueid, chunkidx) we will
-	 * see the chunks in chunkidx order, even though we didn't explicitly ask
-	 * for it.
-	 */
-	nextidx = 0;
-
-	init_toast_snapshot(&SnapshotToast);
-	toastscan = systable_beginscan_ordered(toastrel, toastidxs[validIndex],
-										   &SnapshotToast, 1, &toastkey);
-	while ((ttup = systable_getnext_ordered(toastscan, ForwardScanDirection)) != NULL)
-	{
-		/*
-		 * Have a chunk, extract the sequence number and the data
-		 */
-		residx = DatumGetInt32(fastgetattr(ttup, 2, toasttupDesc, &isnull));
-		Assert(!isnull);
-		chunk = DatumGetPointer(fastgetattr(ttup, 3, toasttupDesc, &isnull));
-		Assert(!isnull);
-		if (!VARATT_IS_EXTENDED(chunk))
-		{
-			chunksize = VARSIZE(chunk) - VARHDRSZ;
-			chunkdata = VARDATA(chunk);
-		}
-		else if (VARATT_IS_SHORT(chunk))
-		{
-			/* could happen due to heap_form_tuple doing its thing */
-			chunksize = VARSIZE_SHORT(chunk) - VARHDRSZ_SHORT;
-			chunkdata = VARDATA_SHORT(chunk);
-		}
-		else
-		{
-			/* should never happen */
-			elog(ERROR, "found toasted toast chunk for toast value %u in %s",
-				 toast_pointer.va_valueid,
-				 RelationGetRelationName(toastrel));
-			chunksize = 0;		/* keep compiler quiet */
-			chunkdata = NULL;
-		}
-
-		/*
-		 * Some checks on the data we've found
-		 */
-		if (residx != nextidx)
-			ereport(ERROR,
-					(errcode(ERRCODE_DATA_CORRUPTED),
-					 errmsg_internal("unexpected chunk number %d (expected %d) for toast value %u in %s",
-									 residx, nextidx,
-									 toast_pointer.va_valueid,
-									 RelationGetRelationName(toastrel))));
-		if (residx < numchunks - 1)
-		{
-			if (chunksize != TOAST_MAX_CHUNK_SIZE)
-				ereport(ERROR,
-						(errcode(ERRCODE_DATA_CORRUPTED),
-						 errmsg_internal("unexpected chunk size %d (expected %d) in chunk %d of %d for toast value %u in %s",
-										 chunksize, (int) TOAST_MAX_CHUNK_SIZE,
-										 residx, numchunks,
-										 toast_pointer.va_valueid,
-										 RelationGetRelationName(toastrel))));
-		}
-		else if (residx == numchunks - 1)
-		{
-			if ((residx * TOAST_MAX_CHUNK_SIZE + chunksize) != ressize)
-				ereport(ERROR,
-						(errcode(ERRCODE_DATA_CORRUPTED),
-						 errmsg_internal("unexpected chunk size %d (expected %d) in final chunk %d for toast value %u in %s",
-										 chunksize,
-										 (int) (ressize - residx * TOAST_MAX_CHUNK_SIZE),
-										 residx,
-										 toast_pointer.va_valueid,
-										 RelationGetRelationName(toastrel))));
-		}
-		else
-			ereport(ERROR,
-					(errcode(ERRCODE_DATA_CORRUPTED),
-					 errmsg_internal("unexpected chunk number %d (out of range %d..%d) for toast value %u in %s",
-									 residx,
-									 0, numchunks - 1,
-									 toast_pointer.va_valueid,
-									 RelationGetRelationName(toastrel))));
-
-		/*
-		 * Copy the data into proper place in our result
-		 */
-		memcpy(VARDATA(result) + residx * TOAST_MAX_CHUNK_SIZE,
-			   chunkdata,
-			   chunksize);
-
-		nextidx++;
-	}
-
-	/*
-	 * Final checks that we successfully fetched the datum
-	 */
-	if (nextidx != numchunks)
-		ereport(ERROR,
-				(errcode(ERRCODE_DATA_CORRUPTED),
-				 errmsg_internal("missing chunk number %d for toast value %u in %s",
-								 nextidx,
-								 toast_pointer.va_valueid,
-								 RelationGetRelationName(toastrel))));
-
-	/*
-	 * End scan and close relations
-	 */
-	systable_endscan_ordered(toastscan);
-	toast_close_indexes(toastidxs, num_indexes, AccessShareLock);
-	table_close(toastrel, AccessShareLock);
-
-	return result;
-}
-
-/* ----------
- * toast_fetch_datum_slice -
- *
- *	Reconstruct a segment of a Datum from the chunks saved
- *	in the toast relation
- *
- *	Note that this function only supports non-compressed external datums.
- * ----------
- */
-static struct varlena *
-toast_fetch_datum_slice(struct varlena *attr, int32 sliceoffset, int32 length)
-{
-	Relation	toastrel;
-	Relation   *toastidxs;
-	ScanKeyData toastkey[3];
-	int			nscankeys;
-	SysScanDesc toastscan;
-	HeapTuple	ttup;
-	TupleDesc	toasttupDesc;
-	struct varlena *result;
-	struct varatt_external toast_pointer;
-	int32		attrsize;
-	int32		residx;
-	int32		nextidx;
-	int			numchunks;
-	int			startchunk;
-	int			endchunk;
-	int32		startoffset;
-	int32		endoffset;
-	int			totalchunks;
-	Pointer		chunk;
-	bool		isnull;
-	char	   *chunkdata;
-	int32		chunksize;
-	int32		chcpystrt;
-	int32		chcpyend;
-	int			num_indexes;
-	int			validIndex;
-	SnapshotData SnapshotToast;
-
-	if (!VARATT_IS_EXTERNAL_ONDISK(attr))
-		elog(ERROR, "toast_fetch_datum_slice shouldn't be called for non-ondisk datums");
-
-	/* Must copy to access aligned fields */
-	VARATT_EXTERNAL_GET_POINTER(toast_pointer, attr);
-
-	/*
-	 * It's nonsense to fetch slices of a compressed datum -- this isn't lo_*
-	 * we can't return a compressed datum which is meaningful to toast later
-	 */
-	Assert(!VARATT_EXTERNAL_IS_COMPRESSED(toast_pointer));
-
-	attrsize = toast_pointer.va_extsize;
-	totalchunks = ((attrsize - 1) / TOAST_MAX_CHUNK_SIZE) + 1;
-
-	if (sliceoffset >= attrsize)
-	{
-		sliceoffset = 0;
-		length = 0;
-	}
-
-	if (((sliceoffset + length) > attrsize) || length < 0)
-		length = attrsize - sliceoffset;
-
-	result = (struct varlena *) palloc(length + VARHDRSZ);
-
-	SET_VARSIZE(result, length + VARHDRSZ);
-
-	if (length == 0)
-		return result;			/* Can save a lot of work at this point! */
-
-	startchunk = sliceoffset / TOAST_MAX_CHUNK_SIZE;
-	endchunk = (sliceoffset + length - 1) / TOAST_MAX_CHUNK_SIZE;
-	numchunks = (endchunk - startchunk) + 1;
-
-	startoffset = sliceoffset % TOAST_MAX_CHUNK_SIZE;
-	endoffset = (sliceoffset + length - 1) % TOAST_MAX_CHUNK_SIZE;
-
-	/*
-	 * Open the toast relation and its indexes
-	 */
-	toastrel = table_open(toast_pointer.va_toastrelid, AccessShareLock);
-	toasttupDesc = toastrel->rd_att;
-
-	/* Look for the valid index of toast relation */
-	validIndex = toast_open_indexes(toastrel,
-									AccessShareLock,
-									&toastidxs,
-									&num_indexes);
-
-	/*
-	 * Setup a scan key to fetch from the index. This is either two keys or
-	 * three depending on the number of chunks.
-	 */
-	ScanKeyInit(&toastkey[0],
-				(AttrNumber) 1,
-				BTEqualStrategyNumber, F_OIDEQ,
-				ObjectIdGetDatum(toast_pointer.va_valueid));
-
-	/*
-	 * Use equality condition for one chunk, a range condition otherwise:
-	 */
-	if (numchunks == 1)
-	{
-		ScanKeyInit(&toastkey[1],
-					(AttrNumber) 2,
-					BTEqualStrategyNumber, F_INT4EQ,
-					Int32GetDatum(startchunk));
-		nscankeys = 2;
-	}
-	else
-	{
-		ScanKeyInit(&toastkey[1],
-					(AttrNumber) 2,
-					BTGreaterEqualStrategyNumber, F_INT4GE,
-					Int32GetDatum(startchunk));
-		ScanKeyInit(&toastkey[2],
-					(AttrNumber) 2,
-					BTLessEqualStrategyNumber, F_INT4LE,
-					Int32GetDatum(endchunk));
-		nscankeys = 3;
-	}
-
-	/*
-	 * Read the chunks by index
-	 *
-	 * The index is on (valueid, chunkidx) so they will come in order
-	 */
-	init_toast_snapshot(&SnapshotToast);
-	nextidx = startchunk;
-	toastscan = systable_beginscan_ordered(toastrel, toastidxs[validIndex],
-										   &SnapshotToast, nscankeys, toastkey);
-	while ((ttup = systable_getnext_ordered(toastscan, ForwardScanDirection)) != NULL)
-	{
-		/*
-		 * Have a chunk, extract the sequence number and the data
-		 */
-		residx = DatumGetInt32(fastgetattr(ttup, 2, toasttupDesc, &isnull));
-		Assert(!isnull);
-		chunk = DatumGetPointer(fastgetattr(ttup, 3, toasttupDesc, &isnull));
-		Assert(!isnull);
-		if (!VARATT_IS_EXTENDED(chunk))
-		{
-			chunksize = VARSIZE(chunk) - VARHDRSZ;
-			chunkdata = VARDATA(chunk);
-		}
-		else if (VARATT_IS_SHORT(chunk))
-		{
-			/* could happen due to heap_form_tuple doing its thing */
-			chunksize = VARSIZE_SHORT(chunk) - VARHDRSZ_SHORT;
-			chunkdata = VARDATA_SHORT(chunk);
-		}
-		else
-		{
-			/* should never happen */
-			elog(ERROR, "found toasted toast chunk for toast value %u in %s",
-				 toast_pointer.va_valueid,
-				 RelationGetRelationName(toastrel));
-			chunksize = 0;		/* keep compiler quiet */
-			chunkdata = NULL;
-		}
-
-		/*
-		 * Some checks on the data we've found
-		 */
-		if ((residx != nextidx) || (residx > endchunk) || (residx < startchunk))
-			elog(ERROR, "unexpected chunk number %d (expected %d) for toast value %u in %s",
-				 residx, nextidx,
-				 toast_pointer.va_valueid,
-				 RelationGetRelationName(toastrel));
-		if (residx < totalchunks - 1)
-		{
-			if (chunksize != TOAST_MAX_CHUNK_SIZE)
-				elog(ERROR, "unexpected chunk size %d (expected %d) in chunk %d of %d for toast value %u in %s when fetching slice",
-					 chunksize, (int) TOAST_MAX_CHUNK_SIZE,
-					 residx, totalchunks,
-					 toast_pointer.va_valueid,
-					 RelationGetRelationName(toastrel));
-		}
-		else if (residx == totalchunks - 1)
-		{
-			if ((residx * TOAST_MAX_CHUNK_SIZE + chunksize) != attrsize)
-				elog(ERROR, "unexpected chunk size %d (expected %d) in final chunk %d for toast value %u in %s when fetching slice",
-					 chunksize,
-					 (int) (attrsize - residx * TOAST_MAX_CHUNK_SIZE),
-					 residx,
-					 toast_pointer.va_valueid,
-					 RelationGetRelationName(toastrel));
-		}
-		else
-			elog(ERROR, "unexpected chunk number %d (out of range %d..%d) for toast value %u in %s",
-				 residx,
-				 0, totalchunks - 1,
-				 toast_pointer.va_valueid,
-				 RelationGetRelationName(toastrel));
-
-		/*
-		 * Copy the data into proper place in our result
-		 */
-		chcpystrt = 0;
-		chcpyend = chunksize - 1;
-		if (residx == startchunk)
-			chcpystrt = startoffset;
-		if (residx == endchunk)
-			chcpyend = endoffset;
-
-		memcpy(VARDATA(result) +
-			   (residx * TOAST_MAX_CHUNK_SIZE - sliceoffset) + chcpystrt,
-			   chunkdata + chcpystrt,
-			   (chcpyend - chcpystrt) + 1);
-
-		nextidx++;
-	}
-
-	/*
-	 * Final checks that we successfully fetched the datum
-	 */
-	if (nextidx != (endchunk + 1))
-		elog(ERROR, "missing chunk number %d for toast value %u in %s",
-			 nextidx,
-			 toast_pointer.va_valueid,
-			 RelationGetRelationName(toastrel));
-
-	/*
-	 * End scan and close relations
-	 */
-	systable_endscan_ordered(toastscan);
-	toast_close_indexes(toastidxs, num_indexes, AccessShareLock);
-	table_close(toastrel, AccessShareLock);
-
-	return result;
-}
-
-/* ----------
- * toast_decompress_datum -
- *
- * Decompress a compressed version of a varlena datum
- */
-static struct varlena *
-toast_decompress_datum(struct varlena *attr)
-{
-	struct varlena *result;
-
-	Assert(VARATT_IS_COMPRESSED(attr));
-
-	result = (struct varlena *)
-		palloc(TOAST_COMPRESS_RAWSIZE(attr) + VARHDRSZ);
-	SET_VARSIZE(result, TOAST_COMPRESS_RAWSIZE(attr) + VARHDRSZ);
-
-	if (pglz_decompress(TOAST_COMPRESS_RAWDATA(attr),
-						VARSIZE(attr) - TOAST_COMPRESS_HDRSZ,
-						VARDATA(result),
-						TOAST_COMPRESS_RAWSIZE(attr), true) < 0)
-		elog(ERROR, "compressed data is corrupted");
-
-	return result;
-}
-
-
-/* ----------
- * toast_decompress_datum_slice -
- *
- * Decompress the front of a compressed version of a varlena datum.
- * offset handling happens in heap_tuple_untoast_attr_slice.
- * Here we just decompress a slice from the front.
- */
-static struct varlena *
-toast_decompress_datum_slice(struct varlena *attr, int32 slicelength)
-{
-	struct varlena *result;
-	int32		rawsize;
-
-	Assert(VARATT_IS_COMPRESSED(attr));
-
-	result = (struct varlena *) palloc(slicelength + VARHDRSZ);
-
-	rawsize = pglz_decompress(TOAST_COMPRESS_RAWDATA(attr),
-							  VARSIZE(attr) - TOAST_COMPRESS_HDRSZ,
-							  VARDATA(result),
-							  slicelength, false);
-	if (rawsize < 0)
-		elog(ERROR, "compressed data is corrupted");
-
-	SET_VARSIZE(result, rawsize + VARHDRSZ);
-	return result;
-}
-
-
-/* ----------
- * toast_open_indexes
- *
- *	Get an array of the indexes associated to the given toast relation
- *	and return as well the position of the valid index used by the toast
- *	relation in this array. It is the responsibility of the caller of this
- *	function to close the indexes as well as free them.
- */
-static int
-toast_open_indexes(Relation toastrel,
-				   LOCKMODE lock,
-				   Relation **toastidxs,
-				   int *num_indexes)
-{
-	int			i = 0;
-	int			res = 0;
-	bool		found = false;
-	List	   *indexlist;
-	ListCell   *lc;
-
-	/* Get index list of the toast relation */
-	indexlist = RelationGetIndexList(toastrel);
-	Assert(indexlist != NIL);
-
-	*num_indexes = list_length(indexlist);
-
-	/* Open all the index relations */
-	*toastidxs = (Relation *) palloc(*num_indexes * sizeof(Relation));
-	foreach(lc, indexlist)
-		(*toastidxs)[i++] = index_open(lfirst_oid(lc), lock);
-
-	/* Fetch the first valid index in list */
-	for (i = 0; i < *num_indexes; i++)
-	{
-		Relation	toastidx = (*toastidxs)[i];
-
-		if (toastidx->rd_index->indisvalid)
-		{
-			res = i;
-			found = true;
-			break;
-		}
-	}
-
-	/*
-	 * Free index list, not necessary anymore as relations are opened and a
-	 * valid index has been found.
-	 */
-	list_free(indexlist);
-
-	/*
-	 * The toast relation should have one valid index, so something is going
-	 * wrong if there is nothing.
-	 */
-	if (!found)
-		elog(ERROR, "no valid index found for toast relation with Oid %u",
-			 RelationGetRelid(toastrel));
-
-	return res;
-}
-
-/* ----------
- * toast_close_indexes
- *
- *	Close an array of indexes for a toast relation and free it. This should
- *	be called for a set of indexes opened previously with toast_open_indexes.
- */
-static void
-toast_close_indexes(Relation *toastidxs, int num_indexes, LOCKMODE lock)
-{
-	int			i;
-
-	/* Close relations and clean up things */
-	for (i = 0; i < num_indexes; i++)
-		index_close(toastidxs[i], lock);
-	pfree(toastidxs);
-}
-
-/* ----------
- * init_toast_snapshot
- *
- *	Initialize an appropriate TOAST snapshot.  We must use an MVCC snapshot
- *	to initialize the TOAST snapshot; since we don't know which one to use,
- *	just use the oldest one.  This is safe: at worst, we will get a "snapshot
- *	too old" error that might have been avoided otherwise.
- */
-static void
-init_toast_snapshot(Snapshot toast_snapshot)
-{
-	Snapshot	snapshot = GetOldestSnapshot();
-
-	if (snapshot == NULL)
-		elog(ERROR, "no known snapshots");
-
-	InitToastSnapshot(*toast_snapshot, snapshot->lsn, snapshot->whenTaken);
-}
diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c
index e651a841bb..6876537b62 100644
--- a/src/backend/access/transam/xlog.c
+++ b/src/backend/access/transam/xlog.c
@@ -24,12 +24,12 @@
 
 #include "access/clog.h"
 #include "access/commit_ts.h"
+#include "access/heaptoast.h"
 #include "access/multixact.h"
 #include "access/rewriteheap.h"
 #include "access/subtrans.h"
 #include "access/timeline.h"
 #include "access/transam.h"
-#include "access/tuptoaster.h"
 #include "access/twophase.h"
 #include "access/xact.h"
 #include "access/xlog_internal.h"
diff --git a/src/backend/commands/analyze.c b/src/backend/commands/analyze.c
index d2fdf447b6..ed0d4e6d4f 100644
--- a/src/backend/commands/analyze.c
+++ b/src/backend/commands/analyze.c
@@ -16,6 +16,7 @@
 
 #include <math.h>
 
+#include "access/detoast.h"
 #include "access/genam.h"
 #include "access/multixact.h"
 #include "access/relation.h"
@@ -24,7 +25,6 @@
 #include "access/tableam.h"
 #include "access/transam.h"
 #include "access/tupconvert.h"
-#include "access/tuptoaster.h"
 #include "access/visibilitymap.h"
 #include "access/xact.h"
 #include "catalog/catalog.h"
diff --git a/src/backend/commands/cluster.c b/src/backend/commands/cluster.c
index 28985a07ec..a23128d7a0 100644
--- a/src/backend/commands/cluster.c
+++ b/src/backend/commands/cluster.c
@@ -23,7 +23,7 @@
 #include "access/relscan.h"
 #include "access/tableam.h"
 #include "access/transam.h"
-#include "access/tuptoaster.h"
+#include "access/toast_internals.h"
 #include "access/xact.h"
 #include "access/xlog.h"
 #include "catalog/pg_am.h"
diff --git a/src/backend/executor/execExprInterp.c b/src/backend/executor/execExprInterp.c
index 9731dd59ca..293bfb61c3 100644
--- a/src/backend/executor/execExprInterp.c
+++ b/src/backend/executor/execExprInterp.c
@@ -56,7 +56,7 @@
  */
 #include "postgres.h"
 
-#include "access/tuptoaster.h"
+#include "access/heaptoast.h"
 #include "catalog/pg_type.h"
 #include "commands/sequence.h"
 #include "executor/execExpr.h"
diff --git a/src/backend/executor/execTuples.c b/src/backend/executor/execTuples.c
index 697f1fed71..5900d967a2 100644
--- a/src/backend/executor/execTuples.c
+++ b/src/backend/executor/execTuples.c
@@ -57,9 +57,9 @@
  */
 #include "postgres.h"
 
+#include "access/heaptoast.h"
 #include "access/htup_details.h"
 #include "access/tupdesc_details.h"
-#include "access/tuptoaster.h"
 #include "funcapi.h"
 #include "catalog/pg_type.h"
 #include "nodes/nodeFuncs.h"
diff --git a/src/backend/executor/tstoreReceiver.c b/src/backend/executor/tstoreReceiver.c
index cf79feb6bd..c0c81c82da 100644
--- a/src/backend/executor/tstoreReceiver.c
+++ b/src/backend/executor/tstoreReceiver.c
@@ -20,7 +20,7 @@
 
 #include "postgres.h"
 
-#include "access/tuptoaster.h"
+#include "access/detoast.h"
 #include "executor/tstoreReceiver.h"
 
 
diff --git a/src/backend/replication/logical/reorderbuffer.c b/src/backend/replication/logical/reorderbuffer.c
index 409f787ac3..85472a98c5 100644
--- a/src/backend/replication/logical/reorderbuffer.c
+++ b/src/backend/replication/logical/reorderbuffer.c
@@ -56,10 +56,10 @@
 #include <unistd.h>
 #include <sys/stat.h>
 
+#include "access/detoast.h"
 #include "access/heapam.h"
 #include "access/rewriteheap.h"
 #include "access/transam.h"
-#include "access/tuptoaster.h"
 #include "access/xact.h"
 #include "access/xlog_internal.h"
 #include "catalog/catalog.h"
diff --git a/src/backend/statistics/extended_stats.c b/src/backend/statistics/extended_stats.c
index bde13e631c..dd29b2f9ff 100644
--- a/src/backend/statistics/extended_stats.c
+++ b/src/backend/statistics/extended_stats.c
@@ -16,10 +16,10 @@
  */
 #include "postgres.h"
 
+#include "access/detoast.h"
 #include "access/genam.h"
 #include "access/htup_details.h"
 #include "access/table.h"
-#include "access/tuptoaster.h"
 #include "catalog/indexing.h"
 #include "catalog/pg_collation.h"
 #include "catalog/pg_statistic_ext.h"
diff --git a/src/backend/storage/large_object/inv_api.c b/src/backend/storage/large_object/inv_api.c
index a477cb9200..e591236343 100644
--- a/src/backend/storage/large_object/inv_api.c
+++ b/src/backend/storage/large_object/inv_api.c
@@ -32,10 +32,11 @@
 
 #include <limits.h>
 
+#include "access/detoast.h"
 #include "access/genam.h"
+#include "access/htup_details.h"
 #include "access/sysattr.h"
 #include "access/table.h"
-#include "access/tuptoaster.h"
 #include "access/xact.h"
 #include "catalog/dependency.h"
 #include "catalog/indexing.h"
diff --git a/src/backend/utils/adt/array_typanalyze.c b/src/backend/utils/adt/array_typanalyze.c
index eafb94b697..54f5849629 100644
--- a/src/backend/utils/adt/array_typanalyze.c
+++ b/src/backend/utils/adt/array_typanalyze.c
@@ -14,7 +14,7 @@
  */
 #include "postgres.h"
 
-#include "access/tuptoaster.h"
+#include "access/detoast.h"
 #include "commands/vacuum.h"
 #include "utils/array.h"
 #include "utils/builtins.h"
diff --git a/src/backend/utils/adt/datum.c b/src/backend/utils/adt/datum.c
index 81ea5a48e5..1568658bc9 100644
--- a/src/backend/utils/adt/datum.c
+++ b/src/backend/utils/adt/datum.c
@@ -42,7 +42,7 @@
 
 #include "postgres.h"
 
-#include "access/tuptoaster.h"
+#include "access/detoast.h"
 #include "fmgr.h"
 #include "utils/datum.h"
 #include "utils/expandeddatum.h"
diff --git a/src/backend/utils/adt/expandedrecord.c b/src/backend/utils/adt/expandedrecord.c
index 166c863026..369432d53c 100644
--- a/src/backend/utils/adt/expandedrecord.c
+++ b/src/backend/utils/adt/expandedrecord.c
@@ -18,8 +18,9 @@
  */
 #include "postgres.h"
 
+#include "access/detoast.h"
+#include "access/heaptoast.h"
 #include "access/htup_details.h"
-#include "access/tuptoaster.h"
 #include "catalog/heap.h"
 #include "catalog/pg_type.h"
 #include "utils/builtins.h"
diff --git a/src/backend/utils/adt/rowtypes.c b/src/backend/utils/adt/rowtypes.c
index aa7ec8735c..ea3e40a369 100644
--- a/src/backend/utils/adt/rowtypes.c
+++ b/src/backend/utils/adt/rowtypes.c
@@ -16,8 +16,8 @@
 
 #include <ctype.h>
 
+#include "access/detoast.h"
 #include "access/htup_details.h"
-#include "access/tuptoaster.h"
 #include "catalog/pg_type.h"
 #include "funcapi.h"
 #include "libpq/pqformat.h"
diff --git a/src/backend/utils/adt/tsgistidx.c b/src/backend/utils/adt/tsgistidx.c
index 4f256260fd..6ff71a49b8 100644
--- a/src/backend/utils/adt/tsgistidx.c
+++ b/src/backend/utils/adt/tsgistidx.c
@@ -15,7 +15,7 @@
 #include "postgres.h"
 
 #include "access/gist.h"
-#include "access/tuptoaster.h"
+#include "access/heaptoast.h"
 #include "port/pg_bitutils.h"
 #include "tsearch/ts_utils.h"
 #include "utils/builtins.h"
diff --git a/src/backend/utils/adt/varchar.c b/src/backend/utils/adt/varchar.c
index 332dc860c4..9d94399323 100644
--- a/src/backend/utils/adt/varchar.c
+++ b/src/backend/utils/adt/varchar.c
@@ -14,7 +14,7 @@
  */
 #include "postgres.h"
 
-#include "access/tuptoaster.h"
+#include "access/detoast.h"
 #include "catalog/pg_collation.h"
 #include "catalog/pg_type.h"
 #include "libpq/pqformat.h"
diff --git a/src/backend/utils/adt/varlena.c b/src/backend/utils/adt/varlena.c
index fa08b55eb6..d36156f4e4 100644
--- a/src/backend/utils/adt/varlena.c
+++ b/src/backend/utils/adt/varlena.c
@@ -17,7 +17,7 @@
 #include <ctype.h>
 #include <limits.h>
 
-#include "access/tuptoaster.h"
+#include "access/detoast.h"
 #include "catalog/pg_collation.h"
 #include "catalog/pg_type.h"
 #include "common/int.h"
diff --git a/src/backend/utils/cache/catcache.c b/src/backend/utils/cache/catcache.c
index 00def27881..c3e7d94aa5 100644
--- a/src/backend/utils/cache/catcache.c
+++ b/src/backend/utils/cache/catcache.c
@@ -15,10 +15,10 @@
 #include "postgres.h"
 
 #include "access/genam.h"
+#include "access/heaptoast.h"
 #include "access/relscan.h"
 #include "access/sysattr.h"
 #include "access/table.h"
-#include "access/tuptoaster.h"
 #include "access/valid.h"
 #include "access/xact.h"
 #include "catalog/pg_collation.h"
diff --git a/src/backend/utils/fmgr/fmgr.c b/src/backend/utils/fmgr/fmgr.c
index 99c34516bd..0484adb984 100644
--- a/src/backend/utils/fmgr/fmgr.c
+++ b/src/backend/utils/fmgr/fmgr.c
@@ -15,7 +15,7 @@
 
 #include "postgres.h"
 
-#include "access/tuptoaster.h"
+#include "access/detoast.h"
 #include "catalog/pg_language.h"
 #include "catalog/pg_proc.h"
 #include "executor/functions.h"
diff --git a/src/bin/pg_resetwal/pg_resetwal.c b/src/bin/pg_resetwal/pg_resetwal.c
index 159a30b520..f85ea2db52 100644
--- a/src/bin/pg_resetwal/pg_resetwal.c
+++ b/src/bin/pg_resetwal/pg_resetwal.c
@@ -45,7 +45,7 @@
 #include <unistd.h>
 
 #include "access/transam.h"
-#include "access/tuptoaster.h"
+#include "access/heaptoast.h"
 #include "access/multixact.h"
 #include "access/xlog.h"
 #include "access/xlog_internal.h"
diff --git a/src/include/access/detoast.h b/src/include/access/detoast.h
new file mode 100644
index 0000000000..02029a991f
--- /dev/null
+++ b/src/include/access/detoast.h
@@ -0,0 +1,92 @@
+/*-------------------------------------------------------------------------
+ *
+ * detoast.h
+ *	  Access to compressed and external varlena values.
+ *
+ * Copyright (c) 2000-2019, PostgreSQL Global Development Group
+ *
+ * src/include/access/detoast.h
+ *
+ *-------------------------------------------------------------------------
+ */
+#ifndef DETOAST_H
+#define DETOAST_H
+
+/*
+ * Testing whether an externally-stored value is compressed now requires
+ * comparing extsize (the actual length of the external data) to rawsize
+ * (the original uncompressed datum's size).  The latter includes VARHDRSZ
+ * overhead, the former doesn't.  We never use compression unless it actually
+ * saves space, so we expect either equality or less-than.
+ */
+#define VARATT_EXTERNAL_IS_COMPRESSED(toast_pointer) \
+	((toast_pointer).va_extsize < (toast_pointer).va_rawsize - VARHDRSZ)
+
+/*
+ * Macro to fetch the possibly-unaligned contents of an EXTERNAL datum
+ * into a local "struct varatt_external" toast pointer.  This should be
+ * just a memcpy, but some versions of gcc seem to produce broken code
+ * that assumes the datum contents are aligned.  Introducing an explicit
+ * intermediate "varattrib_1b_e *" variable seems to fix it.
+ */
+#define VARATT_EXTERNAL_GET_POINTER(toast_pointer, attr) \
+do { \
+	varattrib_1b_e *attre = (varattrib_1b_e *) (attr); \
+	Assert(VARATT_IS_EXTERNAL(attre)); \
+	Assert(VARSIZE_EXTERNAL(attre) == sizeof(toast_pointer) + VARHDRSZ_EXTERNAL); \
+	memcpy(&(toast_pointer), VARDATA_EXTERNAL(attre), sizeof(toast_pointer)); \
+} while (0)
+
+/* Size of an EXTERNAL datum that contains a standard TOAST pointer */
+#define TOAST_POINTER_SIZE (VARHDRSZ_EXTERNAL + sizeof(varatt_external))
+
+/* Size of an EXTERNAL datum that contains an indirection pointer */
+#define INDIRECT_POINTER_SIZE (VARHDRSZ_EXTERNAL + sizeof(varatt_indirect))
+
+/* ----------
+ * heap_tuple_fetch_attr() -
+ *
+ *		Fetches an external stored attribute from the toast
+ *		relation. Does NOT decompress it, if stored external
+ *		in compressed format.
+ * ----------
+ */
+extern struct varlena *heap_tuple_fetch_attr(struct varlena *attr);
+
+/* ----------
+ * heap_tuple_untoast_attr() -
+ *
+ *		Fully detoasts one attribute, fetching and/or decompressing
+ *		it as needed.
+ * ----------
+ */
+extern struct varlena *heap_tuple_untoast_attr(struct varlena *attr);
+
+/* ----------
+ * heap_tuple_untoast_attr_slice() -
+ *
+ *		Fetches only the specified portion of an attribute.
+ *		(Handles all cases for attribute storage)
+ * ----------
+ */
+extern struct varlena *heap_tuple_untoast_attr_slice(struct varlena *attr,
+							  int32 sliceoffset,
+							  int32 slicelength);
+
+/* ----------
+ * toast_raw_datum_size -
+ *
+ *	Return the raw (detoasted) size of a varlena datum
+ * ----------
+ */
+extern Size toast_raw_datum_size(Datum value);
+
+/* ----------
+ * toast_datum_size -
+ *
+ *	Return the storage size of a varlena datum
+ * ----------
+ */
+extern Size toast_datum_size(Datum value);
+
+#endif							/* DETOAST_H */
diff --git a/src/include/access/tuptoaster.h b/src/include/access/heaptoast.h
similarity index 57%
rename from src/include/access/tuptoaster.h
rename to src/include/access/heaptoast.h
index f0aea2496b..bf02d2c600 100644
--- a/src/include/access/tuptoaster.h
+++ b/src/include/access/heaptoast.h
@@ -1,29 +1,22 @@
 /*-------------------------------------------------------------------------
  *
- * tuptoaster.h
- *	  POSTGRES definitions for external and compressed storage
+ * heaptoast.h
+ *	  Heap-specific definitions for external and compressed storage
  *	  of variable size attributes.
  *
  * Copyright (c) 2000-2019, PostgreSQL Global Development Group
  *
- * src/include/access/tuptoaster.h
+ * src/include/access/heaptoast.h
  *
  *-------------------------------------------------------------------------
  */
-#ifndef TUPTOASTER_H
-#define TUPTOASTER_H
+#ifndef HEAPTOAST_H
+#define HEAPTOAST_H
 
 #include "access/htup_details.h"
 #include "storage/lockdefs.h"
 #include "utils/relcache.h"
 
-/*
- * This enables de-toasting of index entries.  Needed until VACUUM is
- * smart enough to rebuild indexes from scratch.
- */
-#define TOAST_INDEX_HACK
-
-
 /*
  * Find the maximum size of a tuple if there are to be N tuples per page.
  */
@@ -95,37 +88,6 @@
 	 sizeof(int32) -									\
 	 VARHDRSZ)
 
-/* Size of an EXTERNAL datum that contains a standard TOAST pointer */
-#define TOAST_POINTER_SIZE (VARHDRSZ_EXTERNAL + sizeof(varatt_external))
-
-/* Size of an EXTERNAL datum that contains an indirection pointer */
-#define INDIRECT_POINTER_SIZE (VARHDRSZ_EXTERNAL + sizeof(varatt_indirect))
-
-/*
- * Testing whether an externally-stored value is compressed now requires
- * comparing extsize (the actual length of the external data) to rawsize
- * (the original uncompressed datum's size).  The latter includes VARHDRSZ
- * overhead, the former doesn't.  We never use compression unless it actually
- * saves space, so we expect either equality or less-than.
- */
-#define VARATT_EXTERNAL_IS_COMPRESSED(toast_pointer) \
-	((toast_pointer).va_extsize < (toast_pointer).va_rawsize - VARHDRSZ)
-
-/*
- * Macro to fetch the possibly-unaligned contents of an EXTERNAL datum
- * into a local "struct varatt_external" toast pointer.  This should be
- * just a memcpy, but some versions of gcc seem to produce broken code
- * that assumes the datum contents are aligned.  Introducing an explicit
- * intermediate "varattrib_1b_e *" variable seems to fix it.
- */
-#define VARATT_EXTERNAL_GET_POINTER(toast_pointer, attr) \
-do { \
-	varattrib_1b_e *attre = (varattrib_1b_e *) (attr); \
-	Assert(VARATT_IS_EXTERNAL(attre)); \
-	Assert(VARSIZE_EXTERNAL(attre) == sizeof(toast_pointer) + VARHDRSZ_EXTERNAL); \
-	memcpy(&(toast_pointer), VARDATA_EXTERNAL(attre), sizeof(toast_pointer)); \
-} while (0)
-
 /* ----------
  * toast_insert_or_update -
  *
@@ -144,36 +106,6 @@ extern HeapTuple toast_insert_or_update(Relation rel,
  */
 extern void toast_delete(Relation rel, HeapTuple oldtup, bool is_speculative);
 
-/* ----------
- * heap_tuple_fetch_attr() -
- *
- *		Fetches an external stored attribute from the toast
- *		relation. Does NOT decompress it, if stored external
- *		in compressed format.
- * ----------
- */
-extern struct varlena *heap_tuple_fetch_attr(struct varlena *attr);
-
-/* ----------
- * heap_tuple_untoast_attr() -
- *
- *		Fully detoasts one attribute, fetching and/or decompressing
- *		it as needed.
- * ----------
- */
-extern struct varlena *heap_tuple_untoast_attr(struct varlena *attr);
-
-/* ----------
- * heap_tuple_untoast_attr_slice() -
- *
- *		Fetches only the specified portion of an attribute.
- *		(Handles all cases for attribute storage)
- * ----------
- */
-extern struct varlena *heap_tuple_untoast_attr_slice(struct varlena *attr,
-													 int32 sliceoffset,
-													 int32 slicelength);
-
 /* ----------
  * toast_flatten_tuple -
  *
@@ -204,36 +136,4 @@ extern HeapTuple toast_build_flattened_tuple(TupleDesc tupleDesc,
 											 Datum *values,
 											 bool *isnull);
 
-/* ----------
- * toast_compress_datum -
- *
- *	Create a compressed version of a varlena datum, if possible
- * ----------
- */
-extern Datum toast_compress_datum(Datum value);
-
-/* ----------
- * toast_raw_datum_size -
- *
- *	Return the raw (detoasted) size of a varlena datum
- * ----------
- */
-extern Size toast_raw_datum_size(Datum value);
-
-/* ----------
- * toast_datum_size -
- *
- *	Return the storage size of a varlena datum
- * ----------
- */
-extern Size toast_datum_size(Datum value);
-
-/* ----------
- * toast_get_valid_index -
- *
- *	Return OID of valid index associated to a toast relation
- * ----------
- */
-extern Oid	toast_get_valid_index(Oid toastoid, LOCKMODE lock);
-
-#endif							/* TUPTOASTER_H */
+#endif							/* HEAPTOAST_H */
diff --git a/src/include/access/toast_internals.h b/src/include/access/toast_internals.h
new file mode 100644
index 0000000000..494b07a4b1
--- /dev/null
+++ b/src/include/access/toast_internals.h
@@ -0,0 +1,54 @@
+/*-------------------------------------------------------------------------
+ *
+ * toast_internals.h
+ *	  Internal definitions for the TOAST system.
+ *
+ * Copyright (c) 2000-2019, PostgreSQL Global Development Group
+ *
+ * src/include/access/toast_internals.h
+ *
+ *-------------------------------------------------------------------------
+ */
+#ifndef TOAST_INTERNALS_H
+#define TOAST_INTERNALS_H
+
+#include "storage/lockdefs.h"
+#include "utils/relcache.h"
+#include "utils/snapshot.h"
+
+/*
+ *	The information at the start of the compressed toast data.
+ */
+typedef struct toast_compress_header
+{
+	int32		vl_len_;		/* varlena header (do not touch directly!) */
+	int32		rawsize;
+} toast_compress_header;
+
+/*
+ * Utilities for manipulation of header information for compressed
+ * toast entries.
+ */
+#define TOAST_COMPRESS_HDRSZ		((int32) sizeof(toast_compress_header))
+#define TOAST_COMPRESS_RAWSIZE(ptr) (((toast_compress_header *) (ptr))->rawsize)
+#define TOAST_COMPRESS_RAWDATA(ptr) \
+	(((char *) (ptr)) + TOAST_COMPRESS_HDRSZ)
+#define TOAST_COMPRESS_SET_RAWSIZE(ptr, len) \
+	(((toast_compress_header *) (ptr))->rawsize = (len))
+
+extern Datum toast_compress_datum(Datum value);
+extern Oid	toast_get_valid_index(Oid toastoid, LOCKMODE lock);
+
+extern void toast_delete_datum(Relation rel, Datum value, bool is_speculative);
+extern Datum toast_save_datum(Relation rel, Datum value,
+							  struct varlena *oldexternal, int options);
+
+extern int	toast_open_indexes(Relation toastrel,
+							   LOCKMODE lock,
+							   Relation **toastidxs,
+							   int *num_indexes);
+extern void toast_close_indexes(Relation *toastidxs, int num_indexes,
+								LOCKMODE lock);
+extern void init_toast_snapshot(Snapshot toast_snapshot);
+
+#endif							/* TOAST_INTERNALS_H */
diff --git a/src/pl/plpgsql/src/pl_exec.c b/src/pl/plpgsql/src/pl_exec.c
index a4697dc9b8..cb2e19cda4 100644
--- a/src/pl/plpgsql/src/pl_exec.c
+++ b/src/pl/plpgsql/src/pl_exec.c
@@ -17,10 +17,10 @@
 
 #include <ctype.h>
 
+#include "access/detoast.h"
 #include "access/htup_details.h"
 #include "access/transam.h"
 #include "access/tupconvert.h"
-#include "access/tuptoaster.h"
 #include "catalog/pg_proc.h"
 #include "catalog/pg_type.h"
 #include "commands/defrem.h"
diff --git a/src/test/regress/regress.c b/src/test/regress/regress.c
index 7f03b7e857..826556eb29 100644
--- a/src/test/regress/regress.c
+++ b/src/test/regress/regress.c
@@ -19,9 +19,9 @@
 #include <math.h>
 #include <signal.h>
 
+#include "access/detoast.h"
 #include "access/htup_details.h"
 #include "access/transam.h"
-#include "access/tuptoaster.h"
 #include "access/xact.h"
 #include "catalog/pg_operator.h"
 #include "catalog/pg_type.h"
-- 
2.17.1

From a1e90893dec0f7ea8635ecdadf5aa7d2f66a234d Mon Sep 17 00:00:00 2001
From: Robert Haas <rhaas@postgresql.org>
Date: Thu, 1 Aug 2019 10:37:02 -0400
Subject: [PATCH v5 2/3] Allow TOAST tables to be implemented using table AMs
 other than heap.
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

toast_fetch_datum, toast_save_datum, and toast_delete_datum are
adjusted to use tableam rather than heap-specific functions.  This
might have some performance impact, but this patch attempts to
mitigate that by restructuring things so that we don't open and close
the toast table and indexes multiple times per tuple.

tableam now exposes an integer value (not a callback) for the
maximum TOAST chunk size, and has a new callback allowing table
AMs to specify the AM that should be used to implement the TOAST
table. Previously, the toast AM was always the same as the table AM.

Patch by me, reviewed and tested by Prabhat Sabu, Thomas Munro,
Andres Freund, and Álvaro Herrera.

Discussion: http://postgr.es/m/CA+TgmoZv-=2iWM4jcw5ZhJeL18HF96+W1yJeYrnGMYdkFFnEpQ@mail.gmail.com
---
 src/backend/access/common/detoast.c         |  62 +++++-----
 src/backend/access/common/toast_internals.c | 127 +++++++-------------
 src/backend/access/heap/heapam.c            |   6 +-
 src/backend/access/heap/heapam_handler.c    |  14 ++-
 src/backend/access/heap/heaptoast.c         |  19 ++-
 src/backend/access/index/genam.c            |  20 +++
 src/backend/access/table/toast_helper.c     | 107 ++++++++++++++---
 src/backend/catalog/toasting.c              |   2 +-
 src/include/access/genam.h                  |   5 +-
 src/include/access/heapam.h                 |   3 +-
 src/include/access/heaptoast.h              |   3 +-
 src/include/access/tableam.h                |  31 +++++
 src/include/access/toast_helper.h           |  18 ++-
 src/include/access/toast_internals.h        |  15 ++-
 14 files changed, 284 insertions(+), 148 deletions(-)

diff --git a/src/backend/access/common/detoast.c b/src/backend/access/common/detoast.c
index c8b49d6a12..36b68e35fb 100644
--- a/src/backend/access/common/detoast.c
+++ b/src/backend/access/common/detoast.c
@@ -15,10 +15,11 @@
 
 #include "access/detoast.h"
 #include "access/genam.h"
-#include "access/heaptoast.h"
 #include "access/table.h"
 #include "access/toast_internals.h"
+#include "access/tableam.h"
 #include "common/pg_lzcompress.h"
+#include "executor/tuptable.h"
 #include "utils/expandeddatum.h"
 #include "utils/fmgroids.h"
 #include "utils/rel.h"
@@ -303,8 +304,7 @@ toast_fetch_datum(struct varlena *attr)
 	Relation   *toastidxs;
 	ScanKeyData toastkey;
 	SysScanDesc toastscan;
-	HeapTuple	ttup;
-	TupleDesc	toasttupDesc;
+	TupleTableSlot *slot;
 	struct varlena *result;
 	struct varatt_external toast_pointer;
 	int32		ressize;
@@ -312,11 +312,11 @@ toast_fetch_datum(struct varlena *attr)
 				nextidx;
 	int32		numchunks;
 	Pointer		chunk;
-	bool		isnull;
 	char	   *chunkdata;
 	int32		chunksize;
 	int			num_indexes;
 	int			validIndex;
+	int			max_chunk_size;
 	SnapshotData SnapshotToast;
 
 	if (!VARATT_IS_EXTERNAL_ONDISK(attr))
@@ -326,7 +326,6 @@ toast_fetch_datum(struct varlena *attr)
 	VARATT_EXTERNAL_GET_POINTER(toast_pointer, attr);
 
 	ressize = toast_pointer.va_extsize;
-	numchunks = ((ressize - 1) / TOAST_MAX_CHUNK_SIZE) + 1;
 
 	result = (struct varlena *) palloc(ressize + VARHDRSZ);
 
@@ -339,7 +338,9 @@ toast_fetch_datum(struct varlena *attr)
 	 * Open the toast relation and its indexes
 	 */
 	toastrel = table_open(toast_pointer.va_toastrelid, AccessShareLock);
-	toasttupDesc = toastrel->rd_att;
+
+	max_chunk_size = toastrel->rd_tableam->toast_max_chunk_size;
+	numchunks = ((ressize - 1) / max_chunk_size) + 1;
 
 	/* Look for the valid index of the toast relation */
 	validIndex = toast_open_indexes(toastrel,
@@ -367,15 +368,15 @@ toast_fetch_datum(struct varlena *attr)
 	init_toast_snapshot(&SnapshotToast);
 	toastscan = systable_beginscan_ordered(toastrel, toastidxs[validIndex],
 										   &SnapshotToast, 1, &toastkey);
-	while ((ttup = systable_getnext_ordered(toastscan, ForwardScanDirection)) != NULL)
+	while ((slot = systable_getnextslot_ordered(toastscan, ForwardScanDirection)) != NULL)
 	{
 		/*
 		 * Have a chunk, extract the sequence number and the data
 		 */
-		residx = DatumGetInt32(fastgetattr(ttup, 2, toasttupDesc, &isnull));
-		Assert(!isnull);
-		chunk = DatumGetPointer(fastgetattr(ttup, 3, toasttupDesc, &isnull));
-		Assert(!isnull);
+		slot_getsomeattrs(slot, 3);
+		Assert(!slot->tts_isnull[1] && !slot->tts_isnull[2]);
+		residx = DatumGetInt32(slot->tts_values[1]);
+		chunk = DatumGetPointer(slot->tts_values[2]);
 		if (!VARATT_IS_EXTENDED(chunk))
 		{
 			chunksize = VARSIZE(chunk) - VARHDRSZ;
@@ -409,23 +410,23 @@ toast_fetch_datum(struct varlena *attr)
 									 RelationGetRelationName(toastrel))));
 		if (residx < numchunks - 1)
 		{
-			if (chunksize != TOAST_MAX_CHUNK_SIZE)
+			if (chunksize != max_chunk_size)
 				ereport(ERROR,
 						(errcode(ERRCODE_DATA_CORRUPTED),
 						 errmsg_internal("unexpected chunk size %d (expected %d) in chunk %d of %d for toast value %u in %s",
-										 chunksize, (int) TOAST_MAX_CHUNK_SIZE,
+										 chunksize, max_chunk_size,
 										 residx, numchunks,
 										 toast_pointer.va_valueid,
 										 RelationGetRelationName(toastrel))));
 		}
 		else if (residx == numchunks - 1)
 		{
-			if ((residx * TOAST_MAX_CHUNK_SIZE + chunksize) != ressize)
+			if ((residx * max_chunk_size + chunksize) != ressize)
 				ereport(ERROR,
 						(errcode(ERRCODE_DATA_CORRUPTED),
 						 errmsg_internal("unexpected chunk size %d (expected %d) in final chunk %d for toast value %u in %s",
 										 chunksize,
-										 (int) (ressize - residx * TOAST_MAX_CHUNK_SIZE),
+										 (int) (ressize - residx * max_chunk_size),
 										 residx,
 										 toast_pointer.va_valueid,
 										 RelationGetRelationName(toastrel))));
@@ -442,7 +443,7 @@ toast_fetch_datum(struct varlena *attr)
 		/*
 		 * Copy the data into proper place in our result
 		 */
-		memcpy(VARDATA(result) + residx * TOAST_MAX_CHUNK_SIZE,
+		memcpy(VARDATA(result) + residx * max_chunk_size,
 			   chunkdata,
 			   chunksize);
 
@@ -508,6 +509,7 @@ toast_fetch_datum_slice(struct varlena *attr, int32 sliceoffset, int32 length)
 	int32		chcpyend;
 	int			num_indexes;
 	int			validIndex;
+	int			max_chunk_size;
 	SnapshotData SnapshotToast;
 
 	if (!VARATT_IS_EXTERNAL_ONDISK(attr))
@@ -523,7 +525,6 @@ toast_fetch_datum_slice(struct varlena *attr, int32 sliceoffset, int32 length)
 	Assert(!VARATT_EXTERNAL_IS_COMPRESSED(toast_pointer));
 
 	attrsize = toast_pointer.va_extsize;
-	totalchunks = ((attrsize - 1) / TOAST_MAX_CHUNK_SIZE) + 1;
 
 	if (sliceoffset >= attrsize)
 	{
@@ -541,19 +542,22 @@ toast_fetch_datum_slice(struct varlena *attr, int32 sliceoffset, int32 length)
 	if (length == 0)
 		return result;			/* Can save a lot of work at this point! */
 
-	startchunk = sliceoffset / TOAST_MAX_CHUNK_SIZE;
-	endchunk = (sliceoffset + length - 1) / TOAST_MAX_CHUNK_SIZE;
-	numchunks = (endchunk - startchunk) + 1;
-
-	startoffset = sliceoffset % TOAST_MAX_CHUNK_SIZE;
-	endoffset = (sliceoffset + length - 1) % TOAST_MAX_CHUNK_SIZE;
-
 	/*
 	 * Open the toast relation and its indexes
 	 */
 	toastrel = table_open(toast_pointer.va_toastrelid, AccessShareLock);
 	toasttupDesc = toastrel->rd_att;
 
+	max_chunk_size = toastrel->rd_tableam->toast_max_chunk_size;
+	totalchunks = ((attrsize - 1) / max_chunk_size) + 1;
+
+	startchunk = sliceoffset / max_chunk_size;
+	endchunk = (sliceoffset + length - 1) / max_chunk_size;
+	numchunks = (endchunk - startchunk) + 1;
+
+	startoffset = sliceoffset % max_chunk_size;
+	endoffset = (sliceoffset + length - 1) % max_chunk_size;
+
 	/* Look for the valid index of toast relation */
 	validIndex = toast_open_indexes(toastrel,
 									AccessShareLock,
@@ -642,19 +646,19 @@ toast_fetch_datum_slice(struct varlena *attr, int32 sliceoffset, int32 length)
 				 RelationGetRelationName(toastrel));
 		if (residx < totalchunks - 1)
 		{
-			if (chunksize != TOAST_MAX_CHUNK_SIZE)
+			if (chunksize != max_chunk_size)
 				elog(ERROR, "unexpected chunk size %d (expected %d) in chunk %d of %d for toast value %u in %s when fetching slice",
-					 chunksize, (int) TOAST_MAX_CHUNK_SIZE,
+					 chunksize, max_chunk_size,
 					 residx, totalchunks,
 					 toast_pointer.va_valueid,
 					 RelationGetRelationName(toastrel));
 		}
 		else if (residx == totalchunks - 1)
 		{
-			if ((residx * TOAST_MAX_CHUNK_SIZE + chunksize) != attrsize)
+			if ((residx * max_chunk_size + chunksize) != attrsize)
 				elog(ERROR, "unexpected chunk size %d (expected %d) in final chunk %d for toast value %u in %s when fetching slice",
 					 chunksize,
-					 (int) (attrsize - residx * TOAST_MAX_CHUNK_SIZE),
+					 (int) (attrsize - residx * max_chunk_size),
 					 residx,
 					 toast_pointer.va_valueid,
 					 RelationGetRelationName(toastrel));
@@ -677,7 +681,7 @@ toast_fetch_datum_slice(struct varlena *attr, int32 sliceoffset, int32 length)
 			chcpyend = endoffset;
 
 		memcpy(VARDATA(result) +
-			   (residx * TOAST_MAX_CHUNK_SIZE - sliceoffset) + chcpystrt,
+			   (residx * max_chunk_size - sliceoffset) + chcpystrt,
 			   chunkdata + chcpystrt,
 			   (chcpyend - chcpystrt) + 1);
 
diff --git a/src/backend/access/common/toast_internals.c b/src/backend/access/common/toast_internals.c
index a971242490..beb303034d 100644
--- a/src/backend/access/common/toast_internals.c
+++ b/src/backend/access/common/toast_internals.c
@@ -15,9 +15,8 @@
 
 #include "access/detoast.h"
 #include "access/genam.h"
-#include "access/heapam.h"
-#include "access/heaptoast.h"
 #include "access/table.h"
+#include "access/tableam.h"
 #include "access/toast_internals.h"
 #include "access/xact.h"
 #include "catalog/catalog.h"
@@ -100,22 +99,21 @@ toast_compress_datum(Datum value)
  *	Save one single datum into the secondary relation and return
  *	a Datum reference for it.
  *
- * rel: the main relation we're working with (not the toast rel!)
+ * toastrel: the TOAST relation we're working with (not the main rel!)
+ * toastslot: a slot corresponding to 'toastrel'
+ * num_indexes, toastidxs, validIndex: as returned by toast_open_indexes
+ * toastoid: the toast OID that should be inserted into the new TOAST pointer
  * value: datum to be pushed to toast storage
  * oldexternal: if not NULL, toast pointer previously representing the datum
- * options: options to be passed to heap_insert() for toast rows
+ * options: options to be passed to table_tuple_insert() for toast rows
  * ----------
  */
 Datum
-toast_save_datum(Relation rel, Datum value,
-				 struct varlena *oldexternal, int options)
+toast_save_datum(Relation toastrel, TupleTableSlot *toastslot,
+				 int num_indexes, Relation *toastidxs, int validIndex,
+				 Oid toastoid, Datum value, struct varlena *oldexternal,
+				 int options, int max_chunk_size)
 {
-	Relation	toastrel;
-	Relation   *toastidxs;
-	HeapTuple	toasttup;
-	TupleDesc	toasttupDesc;
-	Datum		t_values[3];
-	bool		t_isnull[3];
 	CommandId	mycid = GetCurrentCommandId(true);
 	struct varlena *result;
 	struct varatt_external toast_pointer;
@@ -123,7 +121,7 @@ toast_save_datum(Relation rel, Datum value,
 	{
 		struct varlena hdr;
 		/* this is to make the union big enough for a chunk: */
-		char		data[TOAST_MAX_CHUNK_SIZE + VARHDRSZ];
+		char		data[BLCKSZ + VARHDRSZ];
 		/* ensure union is aligned well enough: */
 		int32		align_it;
 	}			chunk_data;
@@ -132,24 +130,9 @@ toast_save_datum(Relation rel, Datum value,
 	char	   *data_p;
 	int32		data_todo;
 	Pointer		dval = DatumGetPointer(value);
-	int			num_indexes;
-	int			validIndex;
 
 	Assert(!VARATT_IS_EXTERNAL(value));
-
-	/*
-	 * Open the toast relation and its indexes.  We can use the index to check
-	 * uniqueness of the OID we assign to the toasted item, even though it has
-	 * additional columns besides OID.
-	 */
-	toastrel = table_open(rel->rd_rel->reltoastrelid, RowExclusiveLock);
-	toasttupDesc = toastrel->rd_att;
-
-	/* Open all the toast indexes and look for the valid one */
-	validIndex = toast_open_indexes(toastrel,
-									RowExclusiveLock,
-									&toastidxs,
-									&num_indexes);
+	Assert(max_chunk_size <= BLCKSZ);
 
 	/*
 	 * Get the data pointer and length, and compute va_rawsize and va_extsize.
@@ -189,11 +172,11 @@ toast_save_datum(Relation rel, Datum value,
 	 *
 	 * Normally this is the actual OID of the target toast table, but during
 	 * table-rewriting operations such as CLUSTER, we have to insert the OID
-	 * of the table's real permanent toast table instead.  rd_toastoid is set
+	 * of the table's real permanent toast table instead.  toastoid is set
 	 * if we have to substitute such an OID.
 	 */
-	if (OidIsValid(rel->rd_toastoid))
-		toast_pointer.va_toastrelid = rel->rd_toastoid;
+	if (OidIsValid(toastoid))
+		toast_pointer.va_toastrelid = toastoid;
 	else
 		toast_pointer.va_toastrelid = RelationGetRelid(toastrel);
 
@@ -209,7 +192,7 @@ toast_save_datum(Relation rel, Datum value,
 	 * options have been changed), we have to pick a value ID that doesn't
 	 * conflict with either new or existing toast value OIDs.
 	 */
-	if (!OidIsValid(rel->rd_toastoid))
+	if (!OidIsValid(toastoid))
 	{
 		/* normal case: just choose an unused OID */
 		toast_pointer.va_valueid =
@@ -228,7 +211,7 @@ toast_save_datum(Relation rel, Datum value,
 			Assert(VARATT_IS_EXTERNAL_ONDISK(oldexternal));
 			/* Must copy to access aligned fields */
 			VARATT_EXTERNAL_GET_POINTER(old_toast_pointer, oldexternal);
-			if (old_toast_pointer.va_toastrelid == rel->rd_toastoid)
+			if (old_toast_pointer.va_toastrelid == toastoid)
 			{
 				/* This value came from the old toast table; reuse its OID */
 				toast_pointer.va_valueid = old_toast_pointer.va_valueid;
@@ -270,20 +253,11 @@ toast_save_datum(Relation rel, Datum value,
 					GetNewOidWithIndex(toastrel,
 									   RelationGetRelid(toastidxs[validIndex]),
 									   (AttrNumber) 1);
-			} while (toastid_valueid_exists(rel->rd_toastoid,
+			} while (toastid_valueid_exists(toastoid,
 											toast_pointer.va_valueid));
 		}
 	}
 
-	/*
-	 * Initialize constant parts of the tuple data
-	 */
-	t_values[0] = ObjectIdGetDatum(toast_pointer.va_valueid);
-	t_values[2] = PointerGetDatum(&chunk_data);
-	t_isnull[0] = false;
-	t_isnull[1] = false;
-	t_isnull[2] = false;
-
 	/*
 	 * Split up the item into chunks
 	 */
@@ -296,17 +270,22 @@ toast_save_datum(Relation rel, Datum value,
 		/*
 		 * Calculate the size of this chunk
 		 */
-		chunk_size = Min(TOAST_MAX_CHUNK_SIZE, data_todo);
+		chunk_size = Min(max_chunk_size, data_todo);
 
 		/*
 		 * Build a tuple and store it
 		 */
-		t_values[1] = Int32GetDatum(chunk_seq++);
+		toastslot->tts_values[0] = ObjectIdGetDatum(toast_pointer.va_valueid);
+		toastslot->tts_values[1] = Int32GetDatum(chunk_seq++);
 		SET_VARSIZE(&chunk_data, chunk_size + VARHDRSZ);
 		memcpy(VARDATA(&chunk_data), data_p, chunk_size);
-		toasttup = heap_form_tuple(toasttupDesc, t_values, t_isnull);
+		toastslot->tts_values[2] = PointerGetDatum(&chunk_data);
+		toastslot->tts_isnull[0] = false;
+		toastslot->tts_isnull[1] = false;
+		toastslot->tts_isnull[2] = false;
+		ExecStoreVirtualTuple(toastslot);
 
-		heap_insert(toastrel, toasttup, mycid, options, NULL);
+		table_tuple_insert(toastrel, toastslot, mycid, options, NULL);
 
 		/*
 		 * Create the index entry.  We cheat a little here by not using
@@ -323,8 +302,9 @@ toast_save_datum(Relation rel, Datum value,
 		{
 			/* Only index relations marked as ready can be updated */
 			if (toastidxs[i]->rd_index->indisready)
-				index_insert(toastidxs[i], t_values, t_isnull,
-							 &(toasttup->t_self),
+				index_insert(toastidxs[i], toastslot->tts_values,
+							 toastslot->tts_isnull,
+							 &(toastslot->tts_tid),
 							 toastrel,
 							 toastidxs[i]->rd_index->indisunique ?
 							 UNIQUE_CHECK_YES : UNIQUE_CHECK_NO,
@@ -332,9 +312,9 @@ toast_save_datum(Relation rel, Datum value,
 		}
 
 		/*
-		 * Free memory
+		 * Clear slot
 		 */
-		heap_freetuple(toasttup);
+		ExecClearTuple(toastslot);
 
 		/*
 		 * Move on to next chunk
@@ -343,12 +323,6 @@ toast_save_datum(Relation rel, Datum value,
 		data_p += chunk_size;
 	}
 
-	/*
-	 * Done - close toast relation and its indexes
-	 */
-	toast_close_indexes(toastidxs, num_indexes, RowExclusiveLock);
-	table_close(toastrel, RowExclusiveLock);
-
 	/*
 	 * Create the TOAST pointer value that we'll return
 	 */
@@ -366,35 +340,24 @@ toast_save_datum(Relation rel, Datum value,
  * ----------
  */
 void
-toast_delete_datum(Relation rel, Datum value, bool is_speculative)
+toast_delete_datum(Relation toastrel, int num_indexes, Relation *toastidxs,
+				   int validIndex, Datum value, bool is_speculative,
+				   uint32 specToken)
 {
 	struct varlena *attr = (struct varlena *) DatumGetPointer(value);
 	struct varatt_external toast_pointer;
-	Relation	toastrel;
-	Relation   *toastidxs;
 	ScanKeyData toastkey;
 	SysScanDesc toastscan;
-	HeapTuple	toasttup;
-	int			num_indexes;
-	int			validIndex;
+	TupleTableSlot *slot;
 	SnapshotData SnapshotToast;
 
-	if (!VARATT_IS_EXTERNAL_ONDISK(attr))
-		return;
+	Assert(VARATT_IS_EXTERNAL_ONDISK(attr));
 
 	/* Must copy to access aligned fields */
 	VARATT_EXTERNAL_GET_POINTER(toast_pointer, attr);
 
-	/*
-	 * Open the toast relation and its indexes
-	 */
-	toastrel = table_open(toast_pointer.va_toastrelid, RowExclusiveLock);
-
-	/* Fetch valid relation used for process */
-	validIndex = toast_open_indexes(toastrel,
-									RowExclusiveLock,
-									&toastidxs,
-									&num_indexes);
+	/* Check that caller gave us the correct TOAST relation. */
+	Assert(toast_pointer.va_toastrelid == RelationGetRelid(toastrel));
 
 	/*
 	 * Setup a scan key to find chunks with matching va_valueid
@@ -412,23 +375,19 @@ toast_delete_datum(Relation rel, Datum value, bool is_speculative)
 	init_toast_snapshot(&SnapshotToast);
 	toastscan = systable_beginscan_ordered(toastrel, toastidxs[validIndex],
 										   &SnapshotToast, 1, &toastkey);
-	while ((toasttup = systable_getnext_ordered(toastscan, ForwardScanDirection)) != NULL)
+	while ((slot = systable_getnextslot_ordered(toastscan, ForwardScanDirection)) != NULL)
 	{
 		/*
 		 * Have a chunk, delete it
 		 */
 		if (is_speculative)
-			heap_abort_speculative(toastrel, &toasttup->t_self);
+			table_tuple_complete_speculative(toastrel, slot, specToken, false);
 		else
-			simple_heap_delete(toastrel, &toasttup->t_self);
+			simple_table_tuple_delete(toastrel, &slot->tts_tid, &SnapshotToast);
 	}
 
-	/*
-	 * End scan and close relations
-	 */
+	/* End scan */
 	systable_endscan_ordered(toastscan);
-	toast_close_indexes(toastidxs, num_indexes, RowExclusiveLock);
-	table_close(toastrel, RowExclusiveLock);
 }
 
 /* ----------
diff --git a/src/backend/access/heap/heapam.c b/src/backend/access/heap/heapam.c
index e9544822bf..9e7cafa8e6 100644
--- a/src/backend/access/heap/heapam.c
+++ b/src/backend/access/heap/heapam.c
@@ -2809,7 +2809,7 @@ l1:
 		Assert(!HeapTupleHasExternal(&tp));
 	}
 	else if (HeapTupleHasExternal(&tp))
-		toast_delete(relation, &tp, false);
+		toast_delete(relation, &tp, false, 0);
 
 	/*
 	 * Mark tuple for invalidation from system caches at next command
@@ -5564,7 +5564,7 @@ heap_finish_speculative(Relation relation, ItemPointer tid)
  * confirmation records.
  */
 void
-heap_abort_speculative(Relation relation, ItemPointer tid)
+heap_abort_speculative(Relation relation, ItemPointer tid, uint32 specToken)
 {
 	TransactionId xid = GetCurrentTransactionId();
 	ItemId		lp;
@@ -5673,7 +5673,7 @@ heap_abort_speculative(Relation relation, ItemPointer tid)
 	if (HeapTupleHasExternal(&tp))
 	{
 		Assert(!IsToastRelation(relation));
-		toast_delete(relation, &tp, true);
+		toast_delete(relation, &tp, true, specToken);
 	}
 
 	/*
diff --git a/src/backend/access/heap/heapam_handler.c b/src/backend/access/heap/heapam_handler.c
index 2dd8821fac..97a7433092 100644
--- a/src/backend/access/heap/heapam_handler.c
+++ b/src/backend/access/heap/heapam_handler.c
@@ -28,6 +28,7 @@
 #include "access/rewriteheap.h"
 #include "access/tableam.h"
 #include "access/tsmapi.h"
+#include "access/heaptoast.h"
 #include "access/xact.h"
 #include "catalog/catalog.h"
 #include "catalog/index.h"
@@ -292,7 +293,7 @@ heapam_tuple_complete_speculative(Relation relation, TupleTableSlot *slot,
 	if (succeeded)
 		heap_finish_speculative(relation, &slot->tts_tid);
 	else
-		heap_abort_speculative(relation, &slot->tts_tid);
+		heap_abort_speculative(relation, &slot->tts_tid, specToken);
 
 	if (shouldFree)
 		pfree(tuple);
@@ -2041,6 +2042,15 @@ heapam_relation_needs_toast_table(Relation rel)
 	return (tuple_length > TOAST_TUPLE_THRESHOLD);
 }
 
+/*
+ * TOAST tables for heap relations are just heap relations.
+ */
+static Oid
+heapam_relation_toast_am(Relation rel)
+{
+	return rel->rd_rel->relam;
+}
+
 
 /* ------------------------------------------------------------------------
  * Planner related callbacks for the heap AM
@@ -2539,6 +2549,8 @@ static const TableAmRoutine heapam_methods = {
 
 	.relation_size = table_block_relation_size,
 	.relation_needs_toast_table = heapam_relation_needs_toast_table,
+	.relation_toast_am = heapam_relation_toast_am,
+	.toast_max_chunk_size = TOAST_MAX_CHUNK_SIZE,
 
 	.relation_estimate_size = heapam_estimate_rel_size,
 
diff --git a/src/backend/access/heap/heaptoast.c b/src/backend/access/heap/heaptoast.c
index fbf9294598..c0acefc97e 100644
--- a/src/backend/access/heap/heaptoast.c
+++ b/src/backend/access/heap/heaptoast.c
@@ -38,7 +38,8 @@
  * ----------
  */
 void
-toast_delete(Relation rel, HeapTuple oldtup, bool is_speculative)
+toast_delete(Relation rel, HeapTuple oldtup, bool is_speculative,
+			 uint32 specToken)
 {
 	TupleDesc	tupleDesc;
 	Datum		toast_values[MaxHeapAttributeNumber];
@@ -68,7 +69,8 @@ toast_delete(Relation rel, HeapTuple oldtup, bool is_speculative)
 	heap_deform_tuple(oldtup, tupleDesc, toast_values, toast_isnull);
 
 	/* Do the real work. */
-	toast_delete_external(rel, toast_values, toast_isnull, is_speculative);
+	toast_delete_external(rel, toast_values, toast_isnull, is_speculative,
+						  specToken);
 }
 
 
@@ -151,6 +153,8 @@ toast_insert_or_update(Relation rel, HeapTuple newtup, HeapTuple oldtup,
 		ttc.ttc_oldvalues = toast_oldvalues;
 		ttc.ttc_oldisnull = toast_oldisnull;
 	}
+	ttc.ttc_toastrel = NULL;
+	ttc.ttc_toastslot = NULL;
 	ttc.ttc_attr = toast_attr;
 	toast_tuple_init(&ttc);
 
@@ -207,7 +211,8 @@ toast_insert_or_update(Relation rel, HeapTuple newtup, HeapTuple oldtup,
 		 */
 		if (toast_attr[biggest_attno].tai_size > maxDataLen &&
 			rel->rd_rel->reltoastrelid != InvalidOid)
-			toast_tuple_externalize(&ttc, biggest_attno, options);
+			toast_tuple_externalize(&ttc, biggest_attno, options,
+									TOAST_MAX_CHUNK_SIZE);
 	}
 
 	/*
@@ -224,7 +229,8 @@ toast_insert_or_update(Relation rel, HeapTuple newtup, HeapTuple oldtup,
 		biggest_attno = toast_tuple_find_biggest_attribute(&ttc, false, false);
 		if (biggest_attno < 0)
 			break;
-		toast_tuple_externalize(&ttc, biggest_attno, options);
+		toast_tuple_externalize(&ttc, biggest_attno, options,
+								TOAST_MAX_CHUNK_SIZE);
 	}
 
 	/*
@@ -260,7 +266,8 @@ toast_insert_or_update(Relation rel, HeapTuple newtup, HeapTuple oldtup,
 		if (biggest_attno < 0)
 			break;
 
-		toast_tuple_externalize(&ttc, biggest_attno, options);
+		toast_tuple_externalize(&ttc, biggest_attno, options,
+								TOAST_MAX_CHUNK_SIZE);
 	}
 
 	/*
@@ -323,7 +330,7 @@ toast_insert_or_update(Relation rel, HeapTuple newtup, HeapTuple oldtup,
 	else
 		result_tuple = newtup;
 
-	toast_tuple_cleanup(&ttc);
+	toast_tuple_cleanup(&ttc, true);
 
 	return result_tuple;
 }
diff --git a/src/backend/access/index/genam.c b/src/backend/access/index/genam.c
index 2599b5d342..233ba24261 100644
--- a/src/backend/access/index/genam.c
+++ b/src/backend/access/index/genam.c
@@ -642,6 +642,26 @@ systable_getnext_ordered(SysScanDesc sysscan, ScanDirection direction)
 	return htup;
 }
 
+/*
+ * systable_getnextslot_ordered
+ *
+ * Return a slot containing the next tuple from an ordered catalog scan,
+ * or NULL if there are no more tuples.
+ */
+TupleTableSlot *
+systable_getnextslot_ordered(SysScanDesc sysscan, ScanDirection direction)
+{
+	Assert(sysscan->irel);
+	if (!index_getnext_slot(sysscan->iscan, direction, sysscan->slot))
+		return NULL;
+
+	/* See notes in systable_getnext */
+	if (sysscan->iscan->xs_recheck)
+		elog(ERROR, "system catalog scans with lossy index conditions are not implemented");
+
+	return sysscan->slot;
+}
+
 /*
  * systable_endscan_ordered --- close scan, release resources
  */
diff --git a/src/backend/access/table/toast_helper.c b/src/backend/access/table/toast_helper.c
index 7532b4f865..e33918a7f4 100644
--- a/src/backend/access/table/toast_helper.c
+++ b/src/backend/access/table/toast_helper.c
@@ -17,6 +17,7 @@
 #include "access/detoast.h"
 #include "access/table.h"
 #include "access/toast_helper.h"
+#include "access/tableam.h"
 #include "access/toast_internals.h"
 
 /*
@@ -247,26 +248,49 @@ toast_tuple_try_compression(ToastTupleContext *ttc, int attribute)
  * Move an attribute to external storage.
  */
 void
-toast_tuple_externalize(ToastTupleContext *ttc, int attribute, int options)
+toast_tuple_externalize(ToastTupleContext *ttc, int attribute, int options,
+						int max_chunk_size)
 {
 	Datum	   *value = &ttc->ttc_values[attribute];
 	Datum		old_value = *value;
 	ToastAttrInfo *attr = &ttc->ttc_attr[attribute];
 
-	attr->tai_colflags |= TOASTCOL_IGNORE;
-	*value = toast_save_datum(ttc->ttc_rel, old_value, attr->tai_oldexternal,
-							  options);
+	/* Initialize for TOAST table access, if not yet done. */
+	if (ttc->ttc_toastrel == NULL)
+	{
+		ttc->ttc_toastrel =
+			table_open(ttc->ttc_rel->rd_rel->reltoastrelid, RowExclusiveLock);
+		ttc->ttc_validtoastidx = toast_open_indexes(ttc->ttc_toastrel,
+													RowExclusiveLock,
+													&ttc->ttc_toastidxs,
+													&ttc->ttc_ntoastidxs);
+	}
+	if (ttc->ttc_toastslot == NULL)
+		ttc->ttc_toastslot = table_slot_create(ttc->ttc_toastrel, NULL);
+
+	/* Do the real work. */
+	*value = toast_save_datum(ttc->ttc_toastrel, ttc->ttc_toastslot,
+							  ttc->ttc_ntoastidxs, ttc->ttc_toastidxs,
+							  ttc->ttc_validtoastidx,
+							  ttc->ttc_rel->rd_toastoid,
+							  old_value, attr->tai_oldexternal,
+							  options, max_chunk_size);
+
+	/* Update bookkeeping information. */
 	if ((attr->tai_colflags & TOASTCOL_NEEDS_FREE) != 0)
 		pfree(DatumGetPointer(old_value));
-	attr->tai_colflags |= TOASTCOL_NEEDS_FREE;
+	attr->tai_colflags |= (TOASTCOL_NEEDS_FREE | TOASTCOL_IGNORE);
 	ttc->ttc_flags |= (TOAST_NEEDS_CHANGE | TOAST_NEEDS_FREE);
 }
 
 /*
  * Perform appropriate cleanup after one tuple has been subjected to TOAST.
+ *
+ * Pass cleanup_toastrel as true to destroy and clear ttc_toastrel and
+ * ttc_toastslot, or false if caller will do it.
  */
 void
-toast_tuple_cleanup(ToastTupleContext *ttc)
+toast_tuple_cleanup(ToastTupleContext *ttc, bool cleanup_toastrel)
 {
 	TupleDesc	tupleDesc = ttc->ttc_rel->rd_att;
 	int			numAttrs = tupleDesc->natts;
@@ -294,14 +318,46 @@ toast_tuple_cleanup(ToastTupleContext *ttc)
 	{
 		int			i;
 
+		/* Initialize for TOAST table access, if not yet done. */
+		if (ttc->ttc_toastrel == NULL)
+		{
+			ttc->ttc_toastrel =
+				table_open(ttc->ttc_rel->rd_rel->reltoastrelid,
+						   RowExclusiveLock);
+			ttc->ttc_validtoastidx = toast_open_indexes(ttc->ttc_toastrel,
+														RowExclusiveLock,
+														&ttc->ttc_toastidxs,
+														&ttc->ttc_ntoastidxs);
+		}
+
+		/* Delete those attributes which require it. */
 		for (i = 0; i < numAttrs; i++)
 		{
 			ToastAttrInfo *attr = &ttc->ttc_attr[i];
 
 			if ((attr->tai_colflags & TOASTCOL_NEEDS_DELETE_OLD) != 0)
-				toast_delete_datum(ttc->ttc_rel, ttc->ttc_oldvalues[i], false);
+				toast_delete_datum(ttc->ttc_toastrel, ttc->ttc_ntoastidxs,
+								   ttc->ttc_toastidxs, ttc->ttc_validtoastidx,
+								   ttc->ttc_oldvalues[i], false, 0);
 		}
 	}
+
+	/*
+	 * Close toast table and indexes and drop slot, if previously done and
+	 * if caller requests it.
+	 */
+	if (cleanup_toastrel && ttc->ttc_toastrel != NULL)
+	{
+		if (ttc->ttc_toastslot != NULL)
+		{
+			ExecDropSingleTupleTableSlot(ttc->ttc_toastslot);
+			ttc->ttc_toastslot = NULL;
+		}
+		toast_close_indexes(ttc->ttc_toastidxs, ttc->ttc_ntoastidxs,
+							RowExclusiveLock);
+		table_close(ttc->ttc_toastrel, RowExclusiveLock);
+		ttc->ttc_toastrel = NULL;
+	}
 }
 
 /*
@@ -310,22 +366,43 @@ toast_tuple_cleanup(ToastTupleContext *ttc)
  */
 void
 toast_delete_external(Relation rel, Datum *values, bool *isnull,
-					  bool is_speculative)
+					  bool is_speculative, uint32 specToken)
 {
 	TupleDesc	tupleDesc = rel->rd_att;
 	int			numAttrs = tupleDesc->natts;
 	int			i;
+	Relation    toastrel = NULL;
+	Relation   *toastidxs;
+	int         num_indexes;
+	int         validIndex;
 
 	for (i = 0; i < numAttrs; i++)
 	{
-		if (TupleDescAttr(tupleDesc, i)->attlen == -1)
-		{
-			Datum		value = values[i];
+		Datum	value;
+
+		if (isnull[i] || TupleDescAttr(tupleDesc, i)->attlen != -1)
+			continue;
+
+		value = values[i];
+		if (!VARATT_IS_EXTERNAL_ONDISK(PointerGetDatum(value)))
+			continue;
 
-			if (isnull[i])
-				continue;
-			else if (VARATT_IS_EXTERNAL_ONDISK(PointerGetDatum(value)))
-				toast_delete_datum(rel, value, is_speculative);
+		/* Initialize for TOAST table access, if not yet done. */
+		if (toastrel == NULL)
+		{
+			toastrel = table_open(rel->rd_rel->reltoastrelid,
+								  RowExclusiveLock);
+			validIndex = toast_open_indexes(toastrel, RowExclusiveLock,
+											&toastidxs, &num_indexes);
 		}
+
+		toast_delete_datum(toastrel, num_indexes, toastidxs, validIndex,
+						   value, is_speculative, specToken);
+	}
+
+	if (toastrel != NULL)
+	{
+		toast_close_indexes(toastidxs, num_indexes, RowExclusiveLock);
+		table_close(toastrel, RowExclusiveLock);
 	}
 }
diff --git a/src/backend/catalog/toasting.c b/src/backend/catalog/toasting.c
index de6282a667..f082463bf6 100644
--- a/src/backend/catalog/toasting.c
+++ b/src/backend/catalog/toasting.c
@@ -258,7 +258,7 @@ create_toast_table(Relation rel, Oid toastOid, Oid toastIndexOid,
 										   toast_typid,
 										   InvalidOid,
 										   rel->rd_rel->relowner,
-										   rel->rd_rel->relam,
+										   table_relation_toast_am(rel),
 										   tupdesc,
 										   NIL,
 										   RELKIND_TOASTVALUE,
diff --git a/src/include/access/genam.h b/src/include/access/genam.h
index 8c053be2ca..a8f5076420 100644
--- a/src/include/access/genam.h
+++ b/src/include/access/genam.h
@@ -21,8 +21,9 @@
 #include "utils/relcache.h"
 #include "utils/snapshot.h"
 
-/* We don't want this file to depend on execnodes.h. */
+/* We don't want this file to depend on execnodes.h or tuptable.h. */
 struct IndexInfo;
+struct TupleTableSlot;
 
 /*
  * Struct for statistics returned by ambuild
@@ -212,6 +213,8 @@ extern SysScanDesc systable_beginscan_ordered(Relation heapRelation,
 											  int nkeys, ScanKey key);
 extern HeapTuple systable_getnext_ordered(SysScanDesc sysscan,
 										  ScanDirection direction);
+extern struct TupleTableSlot *systable_getnextslot_ordered(SysScanDesc sysscan,
+														   ScanDirection direction);
 extern void systable_endscan_ordered(SysScanDesc sysscan);
 
 #endif							/* GENAM_H */
diff --git a/src/include/access/heapam.h b/src/include/access/heapam.h
index 858bcb6bc9..6ee0c6efa7 100644
--- a/src/include/access/heapam.h
+++ b/src/include/access/heapam.h
@@ -143,7 +143,8 @@ extern TM_Result heap_delete(Relation relation, ItemPointer tid,
 							 CommandId cid, Snapshot crosscheck, bool wait,
 							 struct TM_FailureData *tmfd, bool changingPart);
 extern void heap_finish_speculative(Relation relation, ItemPointer tid);
-extern void heap_abort_speculative(Relation relation, ItemPointer tid);
+extern void heap_abort_speculative(Relation relation, ItemPointer tid,
+					   uint32 specToken);
 extern TM_Result heap_update(Relation relation, ItemPointer otid,
 							 HeapTuple newtup,
 							 CommandId cid, Snapshot crosscheck, bool wait,
diff --git a/src/include/access/heaptoast.h b/src/include/access/heaptoast.h
index bf02d2c600..07d36ac968 100644
--- a/src/include/access/heaptoast.h
+++ b/src/include/access/heaptoast.h
@@ -104,7 +104,8 @@ extern HeapTuple toast_insert_or_update(Relation rel,
  *	Called by heap_delete().
  * ----------
  */
-extern void toast_delete(Relation rel, HeapTuple oldtup, bool is_speculative);
+extern void toast_delete(Relation rel, HeapTuple oldtup,
+			 bool is_speculative, uint32 specToken);
 
 /* ----------
  * toast_flatten_tuple -
diff --git a/src/include/access/tableam.h b/src/include/access/tableam.h
index 7f81703b78..521fd6232d 100644
--- a/src/include/access/tableam.h
+++ b/src/include/access/tableam.h
@@ -581,6 +581,27 @@ typedef struct TableAmRoutine
 	 */
 	bool		(*relation_needs_toast_table) (Relation rel);
 
+	/*
+	 * This callback should return the OID of the table AM that implements
+	 * TOAST tables for this AM.  If the relation_needs_toast_table callback
+	 * always returns false, this callback is not required.
+	 */
+	Oid		    (*relation_toast_am) (Relation rel);
+
+	/*
+	 * If this table AM can be used to implement a TOAST table, the following
+	 * field should be set to the maximum number of bytes that can be stored
+	 * in a single TOAST chunk.  It must not be set to a value greater than
+	 * BLCKSZ.  If this table AM is not used to implement a TOAST table, this
+	 * value is ignored.
+	 *
+	 * (Note that there is no requirement that the TOAST table be implemented
+	 * using the same AM as the table to which it is attached.  If this AM
+	 * has TOAST tables but uses some other AM to implement them, this value
+	 * is ignored; it is a property of the TOAST table, not the parent table.)
+	 */
+	int			toast_max_chunk_size;
+
 
 	/* ------------------------------------------------------------------------
 	 * Planner related functions.
@@ -1603,6 +1624,16 @@ table_relation_needs_toast_table(Relation rel)
 	return rel->rd_tableam->relation_needs_toast_table(rel);
 }
 
+/*
+ * Return the OID of the AM that should be used to implement the TOAST table
+ * for this relation.
+ */
+static inline Oid
+table_relation_toast_am(Relation rel)
+{
+	return rel->rd_tableam->relation_toast_am(rel);
+}
+
 
 /* ----------------------------------------------------------------------------
  * Planner related functionality
diff --git a/src/include/access/toast_helper.h b/src/include/access/toast_helper.h
index 7cefacb0ea..cfb4ae0385 100644
--- a/src/include/access/toast_helper.h
+++ b/src/include/access/toast_helper.h
@@ -14,6 +14,7 @@
 #ifndef TOAST_HELPER_H
 #define TOAST_HELPER_H
 
+#include "executor/tuptable.h"
 #include "utils/rel.h"
 
 /*
@@ -51,6 +52,17 @@ typedef struct
 	Datum	   *ttc_oldvalues;	/* values from previous tuple */
 	bool	   *ttc_oldisnull;	/* null flags from previous tuple */
 
+	/*
+	 * Before calling toast_tuple_init, the caller should either initialize
+	 * all of these fields or else set ttc_toastrel and ttc_toastslot to NULL.
+	 * In the latter case, all of the fields will be initialized as required.
+	 */
+	Relation	ttc_toastrel;	/* the toast table for the relation */
+	TupleTableSlot *ttc_toastslot;	/* a slot for the toast table */
+	int			ttc_ntoastidxs; /* # of toast indexes for toast table */
+	Relation   *ttc_toastidxs;	/* array of those toast indexes */
+	int			ttc_validtoastidx;	/* the valid toast index */
+
 	/*
 	 * Before calling toast_tuple_init, the caller should set tts_attr to
 	 * point to an array of ToastAttrInfo structures of a length equal to
@@ -106,10 +118,10 @@ extern int	toast_tuple_find_biggest_attribute(ToastTupleContext *ttc,
 											   bool check_main);
 extern void toast_tuple_try_compression(ToastTupleContext *ttc, int attribute);
 extern void toast_tuple_externalize(ToastTupleContext *ttc, int attribute,
-									int options);
-extern void toast_tuple_cleanup(ToastTupleContext *ttc);
+									int options, int max_chunk_size);
+extern void toast_tuple_cleanup(ToastTupleContext *ttc, bool cleanup_toastrel);
 
 extern void toast_delete_external(Relation rel, Datum *values, bool *isnull,
-								  bool is_speculative);
+								  bool is_speculative, uint32 specToken);
 
 #endif
diff --git a/src/include/access/toast_internals.h b/src/include/access/toast_internals.h
index 494b07a4b1..96f61baf80 100644
--- a/src/include/access/toast_internals.h
+++ b/src/include/access/toast_internals.h
@@ -16,6 +16,8 @@
 #include "utils/relcache.h"
 #include "utils/snapshot.h"
 
+struct TupleTableSlot;
+
 /*
  *	The information at the start of the compressed toast data.
  */
@@ -39,9 +41,16 @@ typedef struct toast_compress_header
 extern Datum toast_compress_datum(Datum value);
 extern Oid	toast_get_valid_index(Oid toastoid, LOCKMODE lock);
 
-extern void toast_delete_datum(Relation rel, Datum value, bool is_speculative);
-extern Datum toast_save_datum(Relation rel, Datum value,
-							  struct varlena *oldexternal, int options);
+extern void toast_delete_datum(Relation toastrel, int num_indexes,
+							   Relation *toastidxs, int validIndex,
+							   Datum value, bool is_speculative,
+							   uint32 specToken);
+extern Datum toast_save_datum(Relation toastrel,
+							  struct TupleTableSlot *toastslot,
+							  int num_indexes, Relation *toastidxs,
+							  int validIndex, Oid toastoid,
+							  Datum value, struct varlena *oldexternal,
+							  int options, int max_chunk_size);
 
 extern int	toast_open_indexes(Relation toastrel,
 							   LOCKMODE lock,
-- 
2.17.2 (Apple Git-113)

From 4c3ae35d6ec84ef793d31acb6af94b702f64199b Mon Sep 17 00:00:00 2001
From: Robert Haas <rhaas@postgresql.org>
Date: Mon, 8 Jul 2019 12:02:16 -0400
Subject: [PATCH v5 1/3] Create an API for inserting and deleting rows in TOAST
 tables.
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

This moves much of the non-heap-specific logic from toast_delete and
toast_insert_or_update into a helper functions accessible via a new
header, toast_helper.h.  Using the functions in this module, a table
AM can implement creation and deletion of TOAST table rows with
much less code duplication than was possible heretofore.  Some
table AMs won't want to use the TOAST logic at all, but for those
that do this will make that easier.

Patch by me, reviewed and tested by Prabhat Sabu, Thomas Munro,
Andres Freund, and Álvaro Herrera.

Discussion: http://postgr.es/m/CA+TgmoZv-=2iWM4jcw5ZhJeL18HF96+W1yJeYrnGMYdkFFnEpQ@mail.gmail.com
---
 src/backend/access/heap/heaptoast.c     | 400 +++---------------------
 src/backend/access/table/Makefile       |   2 +-
 src/backend/access/table/toast_helper.c | 331 ++++++++++++++++++++
 src/include/access/toast_helper.h       | 115 +++++++
 src/tools/pgindent/typedefs.list        |   2 +
 5 files changed, 493 insertions(+), 357 deletions(-)
 create mode 100644 src/backend/access/table/toast_helper.c
 create mode 100644 src/include/access/toast_helper.h

diff --git a/src/backend/access/heap/heaptoast.c b/src/backend/access/heap/heaptoast.c
index 5d105e3517..fbf9294598 100644
--- a/src/backend/access/heap/heaptoast.c
+++ b/src/backend/access/heap/heaptoast.c
@@ -27,6 +27,7 @@
 #include "access/detoast.h"
 #include "access/heapam.h"
 #include "access/heaptoast.h"
+#include "access/toast_helper.h"
 #include "access/toast_internals.h"
 
 
@@ -40,8 +41,6 @@ void
 toast_delete(Relation rel, HeapTuple oldtup, bool is_speculative)
 {
 	TupleDesc	tupleDesc;
-	int			numAttrs;
-	int			i;
 	Datum		toast_values[MaxHeapAttributeNumber];
 	bool		toast_isnull[MaxHeapAttributeNumber];
 
@@ -64,27 +63,12 @@ toast_delete(Relation rel, HeapTuple oldtup, bool is_speculative)
 	 * least one varlena column, by the way.)
 	 */
 	tupleDesc = rel->rd_att;
-	numAttrs = tupleDesc->natts;
 
-	Assert(numAttrs <= MaxHeapAttributeNumber);
+	Assert(tupleDesc->natts <= MaxHeapAttributeNumber);
 	heap_deform_tuple(oldtup, tupleDesc, toast_values, toast_isnull);
 
-	/*
-	 * Check for external stored attributes and delete them from the secondary
-	 * relation.
-	 */
-	for (i = 0; i < numAttrs; i++)
-	{
-		if (TupleDescAttr(tupleDesc, i)->attlen == -1)
-		{
-			Datum		value = toast_values[i];
-
-			if (toast_isnull[i])
-				continue;
-			else if (VARATT_IS_EXTERNAL_ONDISK(PointerGetDatum(value)))
-				toast_delete_datum(rel, value, is_speculative);
-		}
-	}
+	/* Do the real work. */
+	toast_delete_external(rel, toast_values, toast_isnull, is_speculative);
 }
 
 
@@ -113,25 +97,16 @@ toast_insert_or_update(Relation rel, HeapTuple newtup, HeapTuple oldtup,
 	HeapTuple	result_tuple;
 	TupleDesc	tupleDesc;
 	int			numAttrs;
-	int			i;
-
-	bool		need_change = false;
-	bool		need_free = false;
-	bool		need_delold = false;
-	bool		has_nulls = false;
 
 	Size		maxDataLen;
 	Size		hoff;
 
-	char		toast_action[MaxHeapAttributeNumber];
 	bool		toast_isnull[MaxHeapAttributeNumber];
 	bool		toast_oldisnull[MaxHeapAttributeNumber];
 	Datum		toast_values[MaxHeapAttributeNumber];
 	Datum		toast_oldvalues[MaxHeapAttributeNumber];
-	struct varlena *toast_oldexternal[MaxHeapAttributeNumber];
-	int32		toast_sizes[MaxHeapAttributeNumber];
-	bool		toast_free[MaxHeapAttributeNumber];
-	bool		toast_delold[MaxHeapAttributeNumber];
+	ToastAttrInfo toast_attr[MaxHeapAttributeNumber];
+	ToastTupleContext ttc;
 
 	/*
 	 * Ignore the INSERT_SPECULATIVE option. Speculative insertions/super
@@ -160,129 +135,24 @@ toast_insert_or_update(Relation rel, HeapTuple newtup, HeapTuple oldtup,
 		heap_deform_tuple(oldtup, tupleDesc, toast_oldvalues, toast_oldisnull);
 
 	/* ----------
-	 * Then collect information about the values given
-	 *
-	 * NOTE: toast_action[i] can have these values:
-	 *		' '		default handling
-	 *		'p'		already processed --- don't touch it
-	 *		'x'		incompressible, but OK to move off
-	 *
-	 * NOTE: toast_sizes[i] is only made valid for varlena attributes with
-	 *		toast_action[i] different from 'p'.
+	 * Prepare for toasting
 	 * ----------
 	 */
-	memset(toast_action, ' ', numAttrs * sizeof(char));
-	memset(toast_oldexternal, 0, numAttrs * sizeof(struct varlena *));
-	memset(toast_free, 0, numAttrs * sizeof(bool));
-	memset(toast_delold, 0, numAttrs * sizeof(bool));
-
-	for (i = 0; i < numAttrs; i++)
+	ttc.ttc_rel = rel;
+	ttc.ttc_values = toast_values;
+	ttc.ttc_isnull = toast_isnull;
+	if (oldtup == NULL)
 	{
-		Form_pg_attribute att = TupleDescAttr(tupleDesc, i);
-		struct varlena *old_value;
-		struct varlena *new_value;
-
-		if (oldtup != NULL)
-		{
-			/*
-			 * For UPDATE get the old and new values of this attribute
-			 */
-			old_value = (struct varlena *) DatumGetPointer(toast_oldvalues[i]);
-			new_value = (struct varlena *) DatumGetPointer(toast_values[i]);
-
-			/*
-			 * If the old value is stored on disk, check if it has changed so
-			 * we have to delete it later.
-			 */
-			if (att->attlen == -1 && !toast_oldisnull[i] &&
-				VARATT_IS_EXTERNAL_ONDISK(old_value))
-			{
-				if (toast_isnull[i] || !VARATT_IS_EXTERNAL_ONDISK(new_value) ||
-					memcmp((char *) old_value, (char *) new_value,
-						   VARSIZE_EXTERNAL(old_value)) != 0)
-				{
-					/*
-					 * The old external stored value isn't needed any more
-					 * after the update
-					 */
-					toast_delold[i] = true;
-					need_delold = true;
-				}
-				else
-				{
-					/*
-					 * This attribute isn't changed by this update so we reuse
-					 * the original reference to the old value in the new
-					 * tuple.
-					 */
-					toast_action[i] = 'p';
-					continue;
-				}
-			}
-		}
-		else
-		{
-			/*
-			 * For INSERT simply get the new value
-			 */
-			new_value = (struct varlena *) DatumGetPointer(toast_values[i]);
-		}
-
-		/*
-		 * Handle NULL attributes
-		 */
-		if (toast_isnull[i])
-		{
-			toast_action[i] = 'p';
-			has_nulls = true;
-			continue;
-		}
-
-		/*
-		 * Now look at varlena attributes
-		 */
-		if (att->attlen == -1)
-		{
-			/*
-			 * If the table's attribute says PLAIN always, force it so.
-			 */
-			if (att->attstorage == 'p')
-				toast_action[i] = 'p';
-
-			/*
-			 * We took care of UPDATE above, so any external value we find
-			 * still in the tuple must be someone else's that we cannot reuse
-			 * (this includes the case of an out-of-line in-memory datum).
-			 * Fetch it back (without decompression, unless we are forcing
-			 * PLAIN storage).  If necessary, we'll push it out as a new
-			 * external value below.
-			 */
-			if (VARATT_IS_EXTERNAL(new_value))
-			{
-				toast_oldexternal[i] = new_value;
-				if (att->attstorage == 'p')
-					new_value = heap_tuple_untoast_attr(new_value);
-				else
-					new_value = heap_tuple_fetch_attr(new_value);
-				toast_values[i] = PointerGetDatum(new_value);
-				toast_free[i] = true;
-				need_change = true;
-				need_free = true;
-			}
-
-			/*
-			 * Remember the size of this attribute
-			 */
-			toast_sizes[i] = VARSIZE_ANY(new_value);
-		}
-		else
-		{
-			/*
-			 * Not a varlena attribute, plain storage always
-			 */
-			toast_action[i] = 'p';
-		}
+		ttc.ttc_oldvalues = NULL;
+		ttc.ttc_oldisnull = NULL;
 	}
+	else
+	{
+		ttc.ttc_oldvalues = toast_oldvalues;
+		ttc.ttc_oldisnull = toast_oldisnull;
+	}
+	ttc.ttc_attr = toast_attr;
+	toast_tuple_init(&ttc);
 
 	/* ----------
 	 * Compress and/or save external until data fits into target length
@@ -297,7 +167,7 @@ toast_insert_or_update(Relation rel, HeapTuple newtup, HeapTuple oldtup,
 
 	/* compute header overhead --- this should match heap_form_tuple() */
 	hoff = SizeofHeapTupleHeader;
-	if (has_nulls)
+	if ((ttc.ttc_flags & TOAST_HAS_NULLS) != 0)
 		hoff += BITMAPLEN(numAttrs);
 	hoff = MAXALIGN(hoff);
 	/* now convert to a limit on the tuple data size */
@@ -310,66 +180,21 @@ toast_insert_or_update(Relation rel, HeapTuple newtup, HeapTuple oldtup,
 	while (heap_compute_data_size(tupleDesc,
 								  toast_values, toast_isnull) > maxDataLen)
 	{
-		int			biggest_attno = -1;
-		int32		biggest_size = MAXALIGN(TOAST_POINTER_SIZE);
-		Datum		old_value;
-		Datum		new_value;
-
-		/*
-		 * Search for the biggest yet unprocessed internal attribute
-		 */
-		for (i = 0; i < numAttrs; i++)
-		{
-			Form_pg_attribute att = TupleDescAttr(tupleDesc, i);
-
-			if (toast_action[i] != ' ')
-				continue;
-			if (VARATT_IS_EXTERNAL(DatumGetPointer(toast_values[i])))
-				continue;		/* can't happen, toast_action would be 'p' */
-			if (VARATT_IS_COMPRESSED(DatumGetPointer(toast_values[i])))
-				continue;
-			if (att->attstorage != 'x' && att->attstorage != 'e')
-				continue;
-			if (toast_sizes[i] > biggest_size)
-			{
-				biggest_attno = i;
-				biggest_size = toast_sizes[i];
-			}
-		}
+		int			biggest_attno;
 
+		biggest_attno = toast_tuple_find_biggest_attribute(&ttc, true, false);
 		if (biggest_attno < 0)
 			break;
 
 		/*
 		 * Attempt to compress it inline, if it has attstorage 'x'
 		 */
-		i = biggest_attno;
-		if (TupleDescAttr(tupleDesc, i)->attstorage == 'x')
-		{
-			old_value = toast_values[i];
-			new_value = toast_compress_datum(old_value);
-
-			if (DatumGetPointer(new_value) != NULL)
-			{
-				/* successful compression */
-				if (toast_free[i])
-					pfree(DatumGetPointer(old_value));
-				toast_values[i] = new_value;
-				toast_free[i] = true;
-				toast_sizes[i] = VARSIZE(DatumGetPointer(toast_values[i]));
-				need_change = true;
-				need_free = true;
-			}
-			else
-			{
-				/* incompressible, ignore on subsequent compression passes */
-				toast_action[i] = 'x';
-			}
-		}
+		if (TupleDescAttr(tupleDesc, biggest_attno)->attstorage == 'x')
+			toast_tuple_try_compression(&ttc, biggest_attno);
 		else
 		{
 			/* has attstorage 'e', ignore on subsequent compression passes */
-			toast_action[i] = 'x';
+			toast_attr[biggest_attno].tai_colflags |= TOASTCOL_INCOMPRESSIBLE;
 		}
 
 		/*
@@ -380,72 +205,26 @@ toast_insert_or_update(Relation rel, HeapTuple newtup, HeapTuple oldtup,
 		 *
 		 * XXX maybe the threshold should be less than maxDataLen?
 		 */
-		if (toast_sizes[i] > maxDataLen &&
+		if (toast_attr[biggest_attno].tai_size > maxDataLen &&
 			rel->rd_rel->reltoastrelid != InvalidOid)
-		{
-			old_value = toast_values[i];
-			toast_action[i] = 'p';
-			toast_values[i] = toast_save_datum(rel, toast_values[i],
-											   toast_oldexternal[i], options);
-			if (toast_free[i])
-				pfree(DatumGetPointer(old_value));
-			toast_free[i] = true;
-			need_change = true;
-			need_free = true;
-		}
+			toast_tuple_externalize(&ttc, biggest_attno, options);
 	}
 
 	/*
 	 * Second we look for attributes of attstorage 'x' or 'e' that are still
-	 * inline.  But skip this if there's no toast table to push them to.
+	 * inline, and make them external.  But skip this if there's no toast
+	 * table to push them to.
 	 */
 	while (heap_compute_data_size(tupleDesc,
 								  toast_values, toast_isnull) > maxDataLen &&
 		   rel->rd_rel->reltoastrelid != InvalidOid)
 	{
-		int			biggest_attno = -1;
-		int32		biggest_size = MAXALIGN(TOAST_POINTER_SIZE);
-		Datum		old_value;
-
-		/*------
-		 * Search for the biggest yet inlined attribute with
-		 * attstorage equals 'x' or 'e'
-		 *------
-		 */
-		for (i = 0; i < numAttrs; i++)
-		{
-			Form_pg_attribute att = TupleDescAttr(tupleDesc, i);
-
-			if (toast_action[i] == 'p')
-				continue;
-			if (VARATT_IS_EXTERNAL(DatumGetPointer(toast_values[i])))
-				continue;		/* can't happen, toast_action would be 'p' */
-			if (att->attstorage != 'x' && att->attstorage != 'e')
-				continue;
-			if (toast_sizes[i] > biggest_size)
-			{
-				biggest_attno = i;
-				biggest_size = toast_sizes[i];
-			}
-		}
+		int			biggest_attno;
 
+		biggest_attno = toast_tuple_find_biggest_attribute(&ttc, false, false);
 		if (biggest_attno < 0)
 			break;
-
-		/*
-		 * Store this external
-		 */
-		i = biggest_attno;
-		old_value = toast_values[i];
-		toast_action[i] = 'p';
-		toast_values[i] = toast_save_datum(rel, toast_values[i],
-										   toast_oldexternal[i], options);
-		if (toast_free[i])
-			pfree(DatumGetPointer(old_value));
-		toast_free[i] = true;
-
-		need_change = true;
-		need_free = true;
+		toast_tuple_externalize(&ttc, biggest_attno, options);
 	}
 
 	/*
@@ -455,57 +234,13 @@ toast_insert_or_update(Relation rel, HeapTuple newtup, HeapTuple oldtup,
 	while (heap_compute_data_size(tupleDesc,
 								  toast_values, toast_isnull) > maxDataLen)
 	{
-		int			biggest_attno = -1;
-		int32		biggest_size = MAXALIGN(TOAST_POINTER_SIZE);
-		Datum		old_value;
-		Datum		new_value;
-
-		/*
-		 * Search for the biggest yet uncompressed internal attribute
-		 */
-		for (i = 0; i < numAttrs; i++)
-		{
-			if (toast_action[i] != ' ')
-				continue;
-			if (VARATT_IS_EXTERNAL(DatumGetPointer(toast_values[i])))
-				continue;		/* can't happen, toast_action would be 'p' */
-			if (VARATT_IS_COMPRESSED(DatumGetPointer(toast_values[i])))
-				continue;
-			if (TupleDescAttr(tupleDesc, i)->attstorage != 'm')
-				continue;
-			if (toast_sizes[i] > biggest_size)
-			{
-				biggest_attno = i;
-				biggest_size = toast_sizes[i];
-			}
-		}
+		int			biggest_attno;
 
+		biggest_attno = toast_tuple_find_biggest_attribute(&ttc, true, true);
 		if (biggest_attno < 0)
 			break;
 
-		/*
-		 * Attempt to compress it inline
-		 */
-		i = biggest_attno;
-		old_value = toast_values[i];
-		new_value = toast_compress_datum(old_value);
-
-		if (DatumGetPointer(new_value) != NULL)
-		{
-			/* successful compression */
-			if (toast_free[i])
-				pfree(DatumGetPointer(old_value));
-			toast_values[i] = new_value;
-			toast_free[i] = true;
-			toast_sizes[i] = VARSIZE(DatumGetPointer(toast_values[i]));
-			need_change = true;
-			need_free = true;
-		}
-		else
-		{
-			/* incompressible, ignore on subsequent compression passes */
-			toast_action[i] = 'x';
-		}
+		toast_tuple_try_compression(&ttc, biggest_attno);
 	}
 
 	/*
@@ -519,54 +254,20 @@ toast_insert_or_update(Relation rel, HeapTuple newtup, HeapTuple oldtup,
 								  toast_values, toast_isnull) > maxDataLen &&
 		   rel->rd_rel->reltoastrelid != InvalidOid)
 	{
-		int			biggest_attno = -1;
-		int32		biggest_size = MAXALIGN(TOAST_POINTER_SIZE);
-		Datum		old_value;
-
-		/*--------
-		 * Search for the biggest yet inlined attribute with
-		 * attstorage = 'm'
-		 *--------
-		 */
-		for (i = 0; i < numAttrs; i++)
-		{
-			if (toast_action[i] == 'p')
-				continue;
-			if (VARATT_IS_EXTERNAL(DatumGetPointer(toast_values[i])))
-				continue;		/* can't happen, toast_action would be 'p' */
-			if (TupleDescAttr(tupleDesc, i)->attstorage != 'm')
-				continue;
-			if (toast_sizes[i] > biggest_size)
-			{
-				biggest_attno = i;
-				biggest_size = toast_sizes[i];
-			}
-		}
+		int			biggest_attno;
 
+		biggest_attno = toast_tuple_find_biggest_attribute(&ttc, false, true);
 		if (biggest_attno < 0)
 			break;
 
-		/*
-		 * Store this external
-		 */
-		i = biggest_attno;
-		old_value = toast_values[i];
-		toast_action[i] = 'p';
-		toast_values[i] = toast_save_datum(rel, toast_values[i],
-										   toast_oldexternal[i], options);
-		if (toast_free[i])
-			pfree(DatumGetPointer(old_value));
-		toast_free[i] = true;
-
-		need_change = true;
-		need_free = true;
+		toast_tuple_externalize(&ttc, biggest_attno, options);
 	}
 
 	/*
 	 * In the case we toasted any values, we need to build a new heap tuple
 	 * with the changed values.
 	 */
-	if (need_change)
+	if ((ttc.ttc_flags & TOAST_NEEDS_CHANGE) != 0)
 	{
 		HeapTupleHeader olddata = newtup->t_data;
 		HeapTupleHeader new_data;
@@ -585,7 +286,7 @@ toast_insert_or_update(Relation rel, HeapTuple newtup, HeapTuple oldtup,
 		 * whether there needs to be one at all.
 		 */
 		new_header_len = SizeofHeapTupleHeader;
-		if (has_nulls)
+		if ((ttc.ttc_flags & TOAST_HAS_NULLS) != 0)
 			new_header_len += BITMAPLEN(numAttrs);
 		new_header_len = MAXALIGN(new_header_len);
 		new_data_len = heap_compute_data_size(tupleDesc,
@@ -616,26 +317,13 @@ toast_insert_or_update(Relation rel, HeapTuple newtup, HeapTuple oldtup,
 						(char *) new_data + new_header_len,
 						new_data_len,
 						&(new_data->t_infomask),
-						has_nulls ? new_data->t_bits : NULL);
+						((ttc.ttc_flags & TOAST_HAS_NULLS) != 0) ?
+						new_data->t_bits : NULL);
 	}
 	else
 		result_tuple = newtup;
 
-	/*
-	 * Free allocated temp values
-	 */
-	if (need_free)
-		for (i = 0; i < numAttrs; i++)
-			if (toast_free[i])
-				pfree(DatumGetPointer(toast_values[i]));
-
-	/*
-	 * Delete external values from the old tuple
-	 */
-	if (need_delold)
-		for (i = 0; i < numAttrs; i++)
-			if (toast_delold[i])
-				toast_delete_datum(rel, toast_oldvalues[i], false);
+	toast_tuple_cleanup(&ttc);
 
 	return result_tuple;
 }
diff --git a/src/backend/access/table/Makefile b/src/backend/access/table/Makefile
index 55a0e5efad..b29df3f333 100644
--- a/src/backend/access/table/Makefile
+++ b/src/backend/access/table/Makefile
@@ -12,6 +12,6 @@ subdir = src/backend/access/table
 top_builddir = ../../../..
 include $(top_builddir)/src/Makefile.global
 
-OBJS = table.o tableam.o tableamapi.o
+OBJS = table.o tableam.o tableamapi.o toast_helper.o
 
 include $(top_srcdir)/src/backend/common.mk
diff --git a/src/backend/access/table/toast_helper.c b/src/backend/access/table/toast_helper.c
new file mode 100644
index 0000000000..7532b4f865
--- /dev/null
+++ b/src/backend/access/table/toast_helper.c
@@ -0,0 +1,331 @@
+/*-------------------------------------------------------------------------
+ *
+ * toast_helper.c
+ *	  Helper functions for table AMs implementing compressed or
+ *    out-of-line storage of varlena attributes.
+ *
+ * Copyright (c) 2000-2019, PostgreSQL Global Development Group
+ *
+ * IDENTIFICATION
+ *	  src/backend/access/common/toast_helper.c
+ *
+ *-------------------------------------------------------------------------
+ */
+
+#include "postgres.h"
+
+#include "access/detoast.h"
+#include "access/table.h"
+#include "access/toast_helper.h"
+#include "access/toast_internals.h"
+
+/*
+ * Prepare to TOAST a tuple.
+ *
+ * tupleDesc, toast_values, and toast_isnull are required parameters; they
+ * provide the necessary details about the tuple to be toasted.
+ *
+ * toast_oldvalues and toast_oldisnull should be NULL for a newly-inserted
+ * tuple; for an update, they should describe the existing tuple.
+ *
+ * All of these arrays should have a length equal to tupleDesc->natts.
+ *
+ * On return, toast_flags and toast_attr will have been initialized.
+ * toast_flags is just a single uint8, but toast_attr is an caller-provided
+ * array with a length equal to tupleDesc->natts.  The caller need not
+ * perform any initialization of the array before calling this function.
+ */
+void
+toast_tuple_init(ToastTupleContext *ttc)
+{
+	TupleDesc	tupleDesc = ttc->ttc_rel->rd_att;
+	int			numAttrs = tupleDesc->natts;
+	int			i;
+
+	ttc->ttc_flags = 0;
+
+	for (i = 0; i < numAttrs; i++)
+	{
+		Form_pg_attribute att = TupleDescAttr(tupleDesc, i);
+		struct varlena *old_value;
+		struct varlena *new_value;
+
+		ttc->ttc_attr[i].tai_colflags = 0;
+		ttc->ttc_attr[i].tai_oldexternal = NULL;
+
+		if (ttc->ttc_oldvalues != NULL)
+		{
+			/*
+			 * For UPDATE get the old and new values of this attribute
+			 */
+			old_value =
+				(struct varlena *) DatumGetPointer(ttc->ttc_oldvalues[i]);
+			new_value =
+				(struct varlena *) DatumGetPointer(ttc->ttc_values[i]);
+
+			/*
+			 * If the old value is stored on disk, check if it has changed so
+			 * we have to delete it later.
+			 */
+			if (att->attlen == -1 && !ttc->ttc_oldisnull[i] &&
+				VARATT_IS_EXTERNAL_ONDISK(old_value))
+			{
+				if (ttc->ttc_isnull[i] ||
+					!VARATT_IS_EXTERNAL_ONDISK(new_value) ||
+					memcmp((char *) old_value, (char *) new_value,
+						   VARSIZE_EXTERNAL(old_value)) != 0)
+				{
+					/*
+					 * The old external stored value isn't needed any more
+					 * after the update
+					 */
+					ttc->ttc_attr[i].tai_colflags |= TOASTCOL_NEEDS_DELETE_OLD;
+					ttc->ttc_flags |= TOAST_NEEDS_DELETE_OLD;
+				}
+				else
+				{
+					/*
+					 * This attribute isn't changed by this update so we reuse
+					 * the original reference to the old value in the new
+					 * tuple.
+					 */
+					ttc->ttc_attr[i].tai_colflags |= TOASTCOL_IGNORE;
+					continue;
+				}
+			}
+		}
+		else
+		{
+			/*
+			 * For INSERT simply get the new value
+			 */
+			new_value = (struct varlena *) DatumGetPointer(ttc->ttc_values[i]);
+		}
+
+		/*
+		 * Handle NULL attributes
+		 */
+		if (ttc->ttc_isnull[i])
+		{
+			ttc->ttc_attr[i].tai_colflags |= TOASTCOL_IGNORE;
+			ttc->ttc_flags |= TOAST_HAS_NULLS;
+			continue;
+		}
+
+		/*
+		 * Now look at varlena attributes
+		 */
+		if (att->attlen == -1)
+		{
+			/*
+			 * If the table's attribute says PLAIN always, force it so.
+			 */
+			if (att->attstorage == 'p')
+				ttc->ttc_attr[i].tai_colflags |= TOASTCOL_IGNORE;
+
+			/*
+			 * We took care of UPDATE above, so any external value we find
+			 * still in the tuple must be someone else's that we cannot reuse
+			 * (this includes the case of an out-of-line in-memory datum).
+			 * Fetch it back (without decompression, unless we are forcing
+			 * PLAIN storage).  If necessary, we'll push it out as a new
+			 * external value below.
+			 */
+			if (VARATT_IS_EXTERNAL(new_value))
+			{
+				ttc->ttc_attr[i].tai_oldexternal = new_value;
+				if (att->attstorage == 'p')
+					new_value = heap_tuple_untoast_attr(new_value);
+				else
+					new_value = heap_tuple_fetch_attr(new_value);
+				ttc->ttc_values[i] = PointerGetDatum(new_value);
+				ttc->ttc_attr[i].tai_colflags |= TOASTCOL_NEEDS_FREE;
+				ttc->ttc_flags |= (TOAST_NEEDS_CHANGE | TOAST_NEEDS_FREE);
+			}
+
+			/*
+			 * Remember the size of this attribute
+			 */
+			ttc->ttc_attr[i].tai_size = VARSIZE_ANY(new_value);
+		}
+		else
+		{
+			/*
+			 * Not a varlena attribute, plain storage always
+			 */
+			ttc->ttc_attr[i].tai_colflags |= TOASTCOL_IGNORE;
+		}
+	}
+}
+
+/*
+ * Find the largest varlena attribute that satisfies certain criteria.
+ *
+ * The relevant column must not be marked TOASTCOL_IGNORE, and if the
+ * for_compression flag is passed as true, it must also not be marked
+ * TOASTCOL_INCOMPRESSIBLE.
+ *
+ * The column must have attstorage 'e' or 'x' if check_main is false, and
+ * must have attstorage 'm' if check_main is true.
+ *
+ * The column must have a minimum size of MAXALIGN(TOAST_POINTER_SIZE);
+ * if not, no benefit is to be expected by compressing it.
+ *
+ * The return value is the index of the biggest suitable column, or
+ * -1 if there is none.
+ */
+int
+toast_tuple_find_biggest_attribute(ToastTupleContext *ttc,
+								   bool for_compression, bool check_main)
+{
+	TupleDesc	tupleDesc = ttc->ttc_rel->rd_att;
+	int			numAttrs = tupleDesc->natts;
+	int			biggest_attno = -1;
+	int32		biggest_size = MAXALIGN(TOAST_POINTER_SIZE);
+	int32		skip_colflags = TOASTCOL_IGNORE;
+	int			i;
+
+	if (for_compression)
+		skip_colflags |= TOASTCOL_INCOMPRESSIBLE;
+
+	for (i = 0; i < numAttrs; i++)
+	{
+		Form_pg_attribute att = TupleDescAttr(tupleDesc, i);
+
+		if ((ttc->ttc_attr[i].tai_colflags & skip_colflags) != 0)
+			continue;
+		if (VARATT_IS_EXTERNAL(DatumGetPointer(ttc->ttc_values[i])))
+			continue;			/* can't happen, toast_action would be 'p' */
+		if (for_compression &&
+			VARATT_IS_COMPRESSED(DatumGetPointer(ttc->ttc_values[i])))
+			continue;
+		if (check_main && att->attstorage != 'm')
+			continue;
+		if (!check_main && att->attstorage != 'x' && att->attstorage != 'e')
+			continue;
+
+		if (ttc->ttc_attr[i].tai_size > biggest_size)
+		{
+			biggest_attno = i;
+			biggest_size = ttc->ttc_attr[i].tai_size;
+		}
+	}
+
+	return biggest_attno;
+}
+
+/*
+ * Try compression for an attribute.
+ *
+ * If we find that the attribute is not compressible, mark it so.
+ */
+void
+toast_tuple_try_compression(ToastTupleContext *ttc, int attribute)
+{
+	Datum	   *value = &ttc->ttc_values[attribute];
+	Datum		new_value = toast_compress_datum(*value);
+	ToastAttrInfo *attr = &ttc->ttc_attr[attribute];
+
+	if (DatumGetPointer(new_value) != NULL)
+	{
+		/* successful compression */
+		if ((attr->tai_colflags & TOASTCOL_NEEDS_FREE) != 0)
+			pfree(DatumGetPointer(*value));
+		*value = new_value;
+		attr->tai_colflags |= TOASTCOL_NEEDS_FREE;
+		attr->tai_size = VARSIZE(DatumGetPointer(*value));
+		ttc->ttc_flags |= (TOAST_NEEDS_CHANGE | TOAST_NEEDS_FREE);
+	}
+	else
+	{
+		/* incompressible, ignore on subsequent compression passes */
+		attr->tai_colflags |= TOASTCOL_INCOMPRESSIBLE;
+	}
+}
+
+/*
+ * Move an attribute to external storage.
+ */
+void
+toast_tuple_externalize(ToastTupleContext *ttc, int attribute, int options)
+{
+	Datum	   *value = &ttc->ttc_values[attribute];
+	Datum		old_value = *value;
+	ToastAttrInfo *attr = &ttc->ttc_attr[attribute];
+
+	attr->tai_colflags |= TOASTCOL_IGNORE;
+	*value = toast_save_datum(ttc->ttc_rel, old_value, attr->tai_oldexternal,
+							  options);
+	if ((attr->tai_colflags & TOASTCOL_NEEDS_FREE) != 0)
+		pfree(DatumGetPointer(old_value));
+	attr->tai_colflags |= TOASTCOL_NEEDS_FREE;
+	ttc->ttc_flags |= (TOAST_NEEDS_CHANGE | TOAST_NEEDS_FREE);
+}
+
+/*
+ * Perform appropriate cleanup after one tuple has been subjected to TOAST.
+ */
+void
+toast_tuple_cleanup(ToastTupleContext *ttc)
+{
+	TupleDesc	tupleDesc = ttc->ttc_rel->rd_att;
+	int			numAttrs = tupleDesc->natts;
+
+	/*
+	 * Free allocated temp values
+	 */
+	if ((ttc->ttc_flags & TOAST_NEEDS_FREE) != 0)
+	{
+		int			i;
+
+		for (i = 0; i < numAttrs; i++)
+		{
+			ToastAttrInfo *attr = &ttc->ttc_attr[i];
+
+			if ((attr->tai_colflags & TOASTCOL_NEEDS_FREE) != 0)
+				pfree(DatumGetPointer(ttc->ttc_values[i]));
+		}
+	}
+
+	/*
+	 * Delete external values from the old tuple
+	 */
+	if ((ttc->ttc_flags & TOAST_NEEDS_DELETE_OLD) != 0)
+	{
+		int			i;
+
+		for (i = 0; i < numAttrs; i++)
+		{
+			ToastAttrInfo *attr = &ttc->ttc_attr[i];
+
+			if ((attr->tai_colflags & TOASTCOL_NEEDS_DELETE_OLD) != 0)
+				toast_delete_datum(ttc->ttc_rel, ttc->ttc_oldvalues[i], false);
+		}
+	}
+}
+
+/*
+ * Check for external stored attributes and delete them from the secondary
+ * relation.
+ */
+void
+toast_delete_external(Relation rel, Datum *values, bool *isnull,
+					  bool is_speculative)
+{
+	TupleDesc	tupleDesc = rel->rd_att;
+	int			numAttrs = tupleDesc->natts;
+	int			i;
+
+	for (i = 0; i < numAttrs; i++)
+	{
+		if (TupleDescAttr(tupleDesc, i)->attlen == -1)
+		{
+			Datum		value = values[i];
+
+			if (isnull[i])
+				continue;
+			else if (VARATT_IS_EXTERNAL_ONDISK(PointerGetDatum(value)))
+				toast_delete_datum(rel, value, is_speculative);
+		}
+	}
+}
diff --git a/src/include/access/toast_helper.h b/src/include/access/toast_helper.h
new file mode 100644
index 0000000000..7cefacb0ea
--- /dev/null
+++ b/src/include/access/toast_helper.h
@@ -0,0 +1,115 @@
+/*-------------------------------------------------------------------------
+ *
+ * toast_helper.h
+ *	  Helper functions for table AMs implementing compressed or
+ *    out-of-line storage of varlena attributes.
+ *
+ * Copyright (c) 2000-2019, PostgreSQL Global Development Group
+ *
+ * src/include/access/toast_helper.h
+ *
+ *-------------------------------------------------------------------------
+ */
+
+#ifndef TOAST_HELPER_H
+#define TOAST_HELPER_H
+
+#include "utils/rel.h"
+
+/*
+ * Information about one column of a tuple being toasted.
+ *
+ * NOTE: toast_action[i] can have these values:
+ *		' '		default handling
+ *		'p'		already processed --- don't touch it
+ *		'x'		incompressible, but OK to move off
+ *
+ * NOTE: toast_attr[i].tai_size is only made valid for varlena attributes with
+ * toast_action[i] different from 'p'.
+ */
+typedef struct
+{
+	struct varlena *tai_oldexternal;
+	int32		tai_size;
+	uint8		tai_colflags;
+} ToastAttrInfo;
+
+/*
+ * Information about one tuple being toasted.
+ */
+typedef struct
+{
+	/*
+	 * Before calling toast_tuple_init, the caller must initialize the
+	 * following fields.  Each array must have a length equal to
+	 * ttc_rel->rd_att->natts.  The tts_oldvalues and tts_oldisnull fields
+	 * should be NULL in the case of an insert.
+	 */
+	Relation	ttc_rel;		/* the relation that contains the tuple */
+	Datum	   *ttc_values;		/* values from the tuple columns */
+	bool	   *ttc_isnull;		/* null flags for the tuple columns */
+	Datum	   *ttc_oldvalues;	/* values from previous tuple */
+	bool	   *ttc_oldisnull;	/* null flags from previous tuple */
+
+	/*
+	 * Before calling toast_tuple_init, the caller should set tts_attr to
+	 * point to an array of ToastAttrInfo structures of a length equal to
+	 * tts_rel->rd_att->natts.  The contents of the array need not be
+	 * initialized.  ttc_flags also does not need to be initialized.
+	 */
+	uint8		ttc_flags;
+	ToastAttrInfo *ttc_attr;
+} ToastTupleContext;
+
+/*
+ * Flags indicating the overall state of a TOAST operation.
+ *
+ * TOAST_NEEDS_DELETE_OLD indicates that one or more old TOAST datums need
+ * to be deleted.
+ *
+ * TOAST_NEEDS_FREE indicates that one or more TOAST values need to be freed.
+ *
+ * TOAST_HAS_NULLS indicates that nulls were found in the tuple being toasted.
+ *
+ * TOAST_NEEDS_CHANGE indicates that a new tuple needs to built; in other
+ * words, the toaster did something.
+ */
+#define TOAST_NEEDS_DELETE_OLD				0x0001
+#define TOAST_NEEDS_FREE					0x0002
+#define TOAST_HAS_NULLS						0x0004
+#define TOAST_NEEDS_CHANGE					0x0008
+
+/*
+ * Flags indicating the status of a TOAST operation with respect to a
+ * particular column.
+ *
+ * TOASTCOL_NEEDS_DELETE_OLD indicates that the old TOAST datums for this
+ * column need to be deleted.
+ *
+ * TOASTCOL_NEEDS_FREE indicates that the value for this column needs to
+ * be freed.
+ *
+ * TOASTCOL_IGNORE indicates that the toaster should not further process
+ * this column.
+ *
+ * TOASTCOL_INCOMPRESSIBLE indicates that this column has been found to
+ * be incompressible, but could be moved out-of-line.
+ */
+#define TOASTCOL_NEEDS_DELETE_OLD			TOAST_NEEDS_DELETE_OLD
+#define TOASTCOL_NEEDS_FREE					TOAST_NEEDS_FREE
+#define TOASTCOL_IGNORE						0x0010
+#define TOASTCOL_INCOMPRESSIBLE				0x0020
+
+extern void toast_tuple_init(ToastTupleContext *ttc);
+extern int	toast_tuple_find_biggest_attribute(ToastTupleContext *ttc,
+											   bool for_compression,
+											   bool check_main);
+extern void toast_tuple_try_compression(ToastTupleContext *ttc, int attribute);
+extern void toast_tuple_externalize(ToastTupleContext *ttc, int attribute,
+									int options);
+extern void toast_tuple_cleanup(ToastTupleContext *ttc);
+
+extern void toast_delete_external(Relation rel, Datum *values, bool *isnull,
+								  bool is_speculative);
+
+#endif
diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list
index 432d2d812e..f3cdfa8a22 100644
--- a/src/tools/pgindent/typedefs.list
+++ b/src/tools/pgindent/typedefs.list
@@ -2349,6 +2349,8 @@ TBlockState
 TIDBitmap
 TM_FailureData
 TM_Result
+ToastAttrInfo
+ToastTupleContext
 TOKEN_DEFAULT_DACL
 TOKEN_INFORMATION_CLASS
 TOKEN_PRIVILEGES
-- 
2.17.2 (Apple Git-113)

From 478afef9cd49c66a9ae09f4a800773a8926e4957 Mon Sep 17 00:00:00 2001
From: Robert Haas <rhaas@postgresql.org>
Date: Mon, 8 Jul 2019 12:34:37 -0400
Subject: [PATCH v5 3/3] Rename some toasting functions based on whether they
 are heap-specific.
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

The old names for the attribute-detoasting functions names included the
word "heap," which seems outdated now that the heap is only one of
potentially many table access methods.

On the other hand, toast_insert_or_update is heap-specific, so rename
it to heap_toast_insert_or_update.

Patch by me, reviewed and tested by Prabhat Sabu, Thomas Munro,
Andres Freund, and Álvaro Herrera.

Discussion: http://postgr.es/m/CA+TgmoZv-=2iWM4jcw5ZhJeL18HF96+W1yJeYrnGMYdkFFnEpQ@mail.gmail.com
---
 src/backend/access/common/detoast.c        | 26 +++++++++++-----------
 src/backend/access/common/indextuple.c     |  2 +-
 src/backend/access/heap/heapam.c           |  4 ++--
 src/backend/access/heap/heaptoast.c        | 17 +++++++-------
 src/backend/access/heap/rewriteheap.c      |  4 ++--
 src/backend/access/table/toast_helper.c    |  4 ++--
 src/backend/executor/tstoreReceiver.c      |  2 +-
 src/backend/storage/large_object/inv_api.c |  2 +-
 src/backend/utils/adt/expandedrecord.c     |  4 ++--
 src/backend/utils/fmgr/fmgr.c              |  8 +++----
 src/include/access/detoast.h               | 16 ++++++-------
 src/include/access/heaptoast.h             |  7 +++---
 src/pl/plpgsql/src/pl_exec.c               |  2 +-
 src/test/regress/regress.c                 |  2 +-
 14 files changed, 50 insertions(+), 50 deletions(-)

diff --git a/src/backend/access/common/detoast.c b/src/backend/access/common/detoast.c
index 36b68e35fb..78256f91ca 100644
--- a/src/backend/access/common/detoast.c
+++ b/src/backend/access/common/detoast.c
@@ -31,7 +31,7 @@ static struct varlena *toast_decompress_datum(struct varlena *attr);
 static struct varlena *toast_decompress_datum_slice(struct varlena *attr, int32 slicelength);
 
 /* ----------
- * heap_tuple_fetch_attr -
+ * detoast_external_attr -
  *
  *	Public entry point to get back a toasted value from
  *	external source (possibly still in compressed format).
@@ -43,7 +43,7 @@ static struct varlena *toast_decompress_datum_slice(struct varlena *attr, int32
  * ----------
  */
 struct varlena *
-heap_tuple_fetch_attr(struct varlena *attr)
+detoast_external_attr(struct varlena *attr)
 {
 	struct varlena *result;
 
@@ -69,7 +69,7 @@ heap_tuple_fetch_attr(struct varlena *attr)
 
 		/* recurse if value is still external in some other way */
 		if (VARATT_IS_EXTERNAL(attr))
-			return heap_tuple_fetch_attr(attr);
+			return detoast_external_attr(attr);
 
 		/*
 		 * Copy into the caller's memory context, in case caller tries to
@@ -104,7 +104,7 @@ heap_tuple_fetch_attr(struct varlena *attr)
 
 
 /* ----------
- * heap_tuple_untoast_attr -
+ * detoast_attr -
  *
  *	Public entry point to get back a toasted value from compression
  *	or external storage.  The result is always non-extended varlena form.
@@ -114,7 +114,7 @@ heap_tuple_fetch_attr(struct varlena *attr)
  * ----------
  */
 struct varlena *
-heap_tuple_untoast_attr(struct varlena *attr)
+detoast_attr(struct varlena *attr)
 {
 	if (VARATT_IS_EXTERNAL_ONDISK(attr))
 	{
@@ -145,7 +145,7 @@ heap_tuple_untoast_attr(struct varlena *attr)
 		Assert(!VARATT_IS_EXTERNAL_INDIRECT(attr));
 
 		/* recurse in case value is still extended in some other way */
-		attr = heap_tuple_untoast_attr(attr);
+		attr = detoast_attr(attr);
 
 		/* if it isn't, we'd better copy it */
 		if (attr == (struct varlena *) redirect.pointer)
@@ -162,7 +162,7 @@ heap_tuple_untoast_attr(struct varlena *attr)
 		/*
 		 * This is an expanded-object pointer --- get flat format
 		 */
-		attr = heap_tuple_fetch_attr(attr);
+		attr = detoast_external_attr(attr);
 		/* flatteners are not allowed to produce compressed/short output */
 		Assert(!VARATT_IS_EXTENDED(attr));
 	}
@@ -193,14 +193,14 @@ heap_tuple_untoast_attr(struct varlena *attr)
 
 
 /* ----------
- * heap_tuple_untoast_attr_slice -
+ * detoast_attr_slice -
  *
  *		Public entry point to get back part of a toasted value
  *		from compression or external storage.
  * ----------
  */
 struct varlena *
-heap_tuple_untoast_attr_slice(struct varlena *attr,
+detoast_attr_slice(struct varlena *attr,
 							  int32 sliceoffset, int32 slicelength)
 {
 	struct varlena *preslice;
@@ -230,13 +230,13 @@ heap_tuple_untoast_attr_slice(struct varlena *attr,
 		/* nested indirect Datums aren't allowed */
 		Assert(!VARATT_IS_EXTERNAL_INDIRECT(redirect.pointer));
 
-		return heap_tuple_untoast_attr_slice(redirect.pointer,
+		return detoast_attr_slice(redirect.pointer,
 											 sliceoffset, slicelength);
 	}
 	else if (VARATT_IS_EXTERNAL_EXPANDED(attr))
 	{
-		/* pass it off to heap_tuple_fetch_attr to flatten */
-		preslice = heap_tuple_fetch_attr(attr);
+		/* pass it off to detoast_external_attr to flatten */
+		preslice = detoast_external_attr(attr);
 	}
 	else
 		preslice = attr;
@@ -737,7 +737,7 @@ toast_decompress_datum(struct varlena *attr)
  * toast_decompress_datum_slice -
  *
  * Decompress the front of a compressed version of a varlena datum.
- * offset handling happens in heap_tuple_untoast_attr_slice.
+ * offset handling happens in detoast_attr_slice.
  * Here we just decompress a slice from the front.
  */
 static struct varlena *
diff --git a/src/backend/access/common/indextuple.c b/src/backend/access/common/indextuple.c
index 07586201b9..8a5f5227a3 100644
--- a/src/backend/access/common/indextuple.c
+++ b/src/backend/access/common/indextuple.c
@@ -89,7 +89,7 @@ index_form_tuple(TupleDesc tupleDescriptor,
 		if (VARATT_IS_EXTERNAL(DatumGetPointer(values[i])))
 		{
 			untoasted_values[i] =
-				PointerGetDatum(heap_tuple_fetch_attr((struct varlena *)
+				PointerGetDatum(detoast_external_attr((struct varlena *)
 													  DatumGetPointer(values[i])));
 			untoasted_free[i] = true;
 		}
diff --git a/src/backend/access/heap/heapam.c b/src/backend/access/heap/heapam.c
index 9e7cafa8e6..3b0aa08a36 100644
--- a/src/backend/access/heap/heapam.c
+++ b/src/backend/access/heap/heapam.c
@@ -2085,7 +2085,7 @@ heap_prepare_insert(Relation relation, HeapTuple tup, TransactionId xid,
 		return tup;
 	}
 	else if (HeapTupleHasExternal(tup) || tup->t_len > TOAST_TUPLE_THRESHOLD)
-		return toast_insert_or_update(relation, tup, NULL, options);
+		return heap_toast_insert_or_update(relation, tup, NULL, options);
 	else
 		return tup;
 }
@@ -3504,7 +3504,7 @@ l2:
 		if (need_toast)
 		{
 			/* Note we always use WAL and FSM during updates */
-			heaptup = toast_insert_or_update(relation, newtup, &oldtup, 0);
+			heaptup = heap_toast_insert_or_update(relation, newtup, &oldtup, 0);
 			newtupsize = MAXALIGN(heaptup->t_len);
 		}
 		else
diff --git a/src/backend/access/heap/heaptoast.c b/src/backend/access/heap/heaptoast.c
index c0acefc97e..defa6fb3bb 100644
--- a/src/backend/access/heap/heaptoast.c
+++ b/src/backend/access/heap/heaptoast.c
@@ -12,7 +12,7 @@
  *
  *
  * INTERFACE ROUTINES
- *		toast_insert_or_update -
+ *		heap_toast_insert_or_update -
  *			Try to make a given tuple fit into one page by compressing
  *			or moving off attributes
  *
@@ -75,7 +75,7 @@ toast_delete(Relation rel, HeapTuple oldtup, bool is_speculative,
 
 
 /* ----------
- * toast_insert_or_update -
+ * heap_toast_insert_or_update -
  *
  *	Delete no-longer-used toast-entries and create new ones to
  *	make the new tuple fit on INSERT or UPDATE
@@ -93,8 +93,8 @@ toast_delete(Relation rel, HeapTuple oldtup, bool is_speculative,
  * ----------
  */
 HeapTuple
-toast_insert_or_update(Relation rel, HeapTuple newtup, HeapTuple oldtup,
-					   int options)
+heap_toast_insert_or_update(Relation rel, HeapTuple newtup, HeapTuple oldtup,
+							int options)
 {
 	HeapTuple	result_tuple;
 	TupleDesc	tupleDesc;
@@ -376,7 +376,7 @@ toast_flatten_tuple(HeapTuple tup, TupleDesc tupleDesc)
 			new_value = (struct varlena *) DatumGetPointer(toast_values[i]);
 			if (VARATT_IS_EXTERNAL(new_value))
 			{
-				new_value = heap_tuple_fetch_attr(new_value);
+				new_value = detoast_external_attr(new_value);
 				toast_values[i] = PointerGetDatum(new_value);
 				toast_free[i] = true;
 			}
@@ -491,7 +491,7 @@ toast_flatten_tuple_to_datum(HeapTupleHeader tup,
 			if (VARATT_IS_EXTERNAL(new_value) ||
 				VARATT_IS_COMPRESSED(new_value))
 			{
-				new_value = heap_tuple_untoast_attr(new_value);
+				new_value = detoast_attr(new_value);
 				toast_values[i] = PointerGetDatum(new_value);
 				toast_free[i] = true;
 			}
@@ -501,7 +501,8 @@ toast_flatten_tuple_to_datum(HeapTupleHeader tup,
 	/*
 	 * Calculate the new size of the tuple.
 	 *
-	 * This should match the reconstruction code in toast_insert_or_update.
+	 * This should match the reconstruction code in
+	 * heap_toast_insert_or_update.
 	 */
 	new_header_len = SizeofHeapTupleHeader;
 	if (has_nulls)
@@ -590,7 +591,7 @@ toast_build_flattened_tuple(TupleDesc tupleDesc,
 			new_value = (struct varlena *) DatumGetPointer(new_values[i]);
 			if (VARATT_IS_EXTERNAL(new_value))
 			{
-				new_value = heap_tuple_fetch_attr(new_value);
+				new_value = detoast_external_attr(new_value);
 				new_values[i] = PointerGetDatum(new_value);
 				freeable_values[num_to_free++] = (Pointer) new_value;
 			}
diff --git a/src/backend/access/heap/rewriteheap.c b/src/backend/access/heap/rewriteheap.c
index 0172a13957..7c98a42b8b 100644
--- a/src/backend/access/heap/rewriteheap.c
+++ b/src/backend/access/heap/rewriteheap.c
@@ -664,8 +664,8 @@ raw_heap_insert(RewriteState state, HeapTuple tup)
 		 */
 		options |= HEAP_INSERT_NO_LOGICAL;
 
-		heaptup = toast_insert_or_update(state->rs_new_rel, tup, NULL,
-										 options);
+		heaptup = heap_toast_insert_or_update(state->rs_new_rel, tup, NULL,
+											  options);
 	}
 	else
 		heaptup = tup;
diff --git a/src/backend/access/table/toast_helper.c b/src/backend/access/table/toast_helper.c
index e33918a7f4..dedc123e31 100644
--- a/src/backend/access/table/toast_helper.c
+++ b/src/backend/access/table/toast_helper.c
@@ -136,9 +136,9 @@ toast_tuple_init(ToastTupleContext *ttc)
 			{
 				ttc->ttc_attr[i].tai_oldexternal = new_value;
 				if (att->attstorage == 'p')
-					new_value = heap_tuple_untoast_attr(new_value);
+					new_value = detoast_attr(new_value);
 				else
-					new_value = heap_tuple_fetch_attr(new_value);
+					new_value = detoast_external_attr(new_value);
 				ttc->ttc_values[i] = PointerGetDatum(new_value);
 				ttc->ttc_attr[i].tai_colflags |= TOASTCOL_NEEDS_FREE;
 				ttc->ttc_flags |= (TOAST_NEEDS_CHANGE | TOAST_NEEDS_FREE);
diff --git a/src/backend/executor/tstoreReceiver.c b/src/backend/executor/tstoreReceiver.c
index c0c81c82da..6306b7d0bd 100644
--- a/src/backend/executor/tstoreReceiver.c
+++ b/src/backend/executor/tstoreReceiver.c
@@ -133,7 +133,7 @@ tstoreReceiveSlot_detoast(TupleTableSlot *slot, DestReceiver *self)
 		{
 			if (VARATT_IS_EXTERNAL(DatumGetPointer(val)))
 			{
-				val = PointerGetDatum(heap_tuple_fetch_attr((struct varlena *)
+				val = PointerGetDatum(detoast_external_attr((struct varlena *)
 															DatumGetPointer(val)));
 				myState->tofree[nfree++] = val;
 			}
diff --git a/src/backend/storage/large_object/inv_api.c b/src/backend/storage/large_object/inv_api.c
index e591236343..263d5be12e 100644
--- a/src/backend/storage/large_object/inv_api.c
+++ b/src/backend/storage/large_object/inv_api.c
@@ -180,7 +180,7 @@ getdatafield(Form_pg_largeobject tuple,
 	if (VARATT_IS_EXTENDED(datafield))
 	{
 		datafield = (bytea *)
-			heap_tuple_untoast_attr((struct varlena *) datafield);
+			detoast_attr((struct varlena *) datafield);
 		freeit = true;
 	}
 	len = VARSIZE(datafield) - VARHDRSZ;
diff --git a/src/backend/utils/adt/expandedrecord.c b/src/backend/utils/adt/expandedrecord.c
index 369432d53c..d99d370b17 100644
--- a/src/backend/utils/adt/expandedrecord.c
+++ b/src/backend/utils/adt/expandedrecord.c
@@ -1159,7 +1159,7 @@ expanded_record_set_field_internal(ExpandedRecordHeader *erh, int fnumber,
 			{
 				/* Detoasting should be done in short-lived context. */
 				oldcxt = MemoryContextSwitchTo(get_short_term_cxt(erh));
-				newValue = PointerGetDatum(heap_tuple_fetch_attr((struct varlena *) DatumGetPointer(newValue)));
+				newValue = PointerGetDatum(detoast_external_attr((struct varlena *) DatumGetPointer(newValue)));
 				MemoryContextSwitchTo(oldcxt);
 			}
 			else
@@ -1305,7 +1305,7 @@ expanded_record_set_fields(ExpandedRecordHeader *erh,
 					if (expand_external)
 					{
 						/* Detoast as requested while copying the value */
-						newValue = PointerGetDatum(heap_tuple_fetch_attr((struct varlena *) DatumGetPointer(newValue)));
+						newValue = PointerGetDatum(detoast_external_attr((struct varlena *) DatumGetPointer(newValue)));
 					}
 					else
 					{
diff --git a/src/backend/utils/fmgr/fmgr.c b/src/backend/utils/fmgr/fmgr.c
index 0484adb984..099ebd779b 100644
--- a/src/backend/utils/fmgr/fmgr.c
+++ b/src/backend/utils/fmgr/fmgr.c
@@ -1739,7 +1739,7 @@ struct varlena *
 pg_detoast_datum(struct varlena *datum)
 {
 	if (VARATT_IS_EXTENDED(datum))
-		return heap_tuple_untoast_attr(datum);
+		return detoast_attr(datum);
 	else
 		return datum;
 }
@@ -1748,7 +1748,7 @@ struct varlena *
 pg_detoast_datum_copy(struct varlena *datum)
 {
 	if (VARATT_IS_EXTENDED(datum))
-		return heap_tuple_untoast_attr(datum);
+		return detoast_attr(datum);
 	else
 	{
 		/* Make a modifiable copy of the varlena object */
@@ -1764,14 +1764,14 @@ struct varlena *
 pg_detoast_datum_slice(struct varlena *datum, int32 first, int32 count)
 {
 	/* Only get the specified portion from the toast rel */
-	return heap_tuple_untoast_attr_slice(datum, first, count);
+	return detoast_attr_slice(datum, first, count);
 }
 
 struct varlena *
 pg_detoast_datum_packed(struct varlena *datum)
 {
 	if (VARATT_IS_COMPRESSED(datum) || VARATT_IS_EXTERNAL(datum))
-		return heap_tuple_untoast_attr(datum);
+		return detoast_attr(datum);
 	else
 		return datum;
 }
diff --git a/src/include/access/detoast.h b/src/include/access/detoast.h
index 02029a991f..baf3dc2591 100644
--- a/src/include/access/detoast.h
+++ b/src/include/access/detoast.h
@@ -44,34 +44,34 @@ do { \
 #define INDIRECT_POINTER_SIZE (VARHDRSZ_EXTERNAL + sizeof(varatt_indirect))
 
 /* ----------
- * heap_tuple_fetch_attr() -
+ * detoast_external_attr() -
  *
  *		Fetches an external stored attribute from the toast
  *		relation. Does NOT decompress it, if stored external
  *		in compressed format.
  * ----------
  */
-extern struct varlena *heap_tuple_fetch_attr(struct varlena *attr);
+extern struct varlena *detoast_external_attr(struct varlena *attr);
 
 /* ----------
- * heap_tuple_untoast_attr() -
+ * detoast_attr() -
  *
  *		Fully detoasts one attribute, fetching and/or decompressing
  *		it as needed.
  * ----------
  */
-extern struct varlena *heap_tuple_untoast_attr(struct varlena *attr);
+extern struct varlena *detoast_attr(struct varlena *attr);
 
 /* ----------
- * heap_tuple_untoast_attr_slice() -
+ * detoast_attr_slice() -
  *
  *		Fetches only the specified portion of an attribute.
  *		(Handles all cases for attribute storage)
  * ----------
  */
-extern struct varlena *heap_tuple_untoast_attr_slice(struct varlena *attr,
-							  int32 sliceoffset,
-							  int32 slicelength);
+extern struct varlena *detoast_attr_slice(struct varlena *attr,
+										  int32 sliceoffset,
+										  int32 slicelength);
 
 /* ----------
  * toast_raw_datum_size -
diff --git a/src/include/access/heaptoast.h b/src/include/access/heaptoast.h
index 07d36ac968..65765088d6 100644
--- a/src/include/access/heaptoast.h
+++ b/src/include/access/heaptoast.h
@@ -89,14 +89,13 @@
 	 VARHDRSZ)
 
 /* ----------
- * toast_insert_or_update -
+ * heap_toast_insert_or_update -
  *
  *	Called by heap_insert() and heap_update().
  * ----------
  */
-extern HeapTuple toast_insert_or_update(Relation rel,
-										HeapTuple newtup, HeapTuple oldtup,
-										int options);
+extern HeapTuple heap_toast_insert_or_update(Relation rel, HeapTuple newtup,
+											 HeapTuple oldtup, int options);
 
 /* ----------
  * toast_delete -
diff --git a/src/pl/plpgsql/src/pl_exec.c b/src/pl/plpgsql/src/pl_exec.c
index cb2e19cda4..345065e305 100644
--- a/src/pl/plpgsql/src/pl_exec.c
+++ b/src/pl/plpgsql/src/pl_exec.c
@@ -8344,7 +8344,7 @@ assign_simple_var(PLpgSQL_execstate *estate, PLpgSQL_var *var,
 		 * pain, but there's little choice.
 		 */
 		oldcxt = MemoryContextSwitchTo(get_eval_mcontext(estate));
-		detoasted = PointerGetDatum(heap_tuple_fetch_attr((struct varlena *) DatumGetPointer(newvalue)));
+		detoasted = PointerGetDatum(detoast_external_attr((struct varlena *) DatumGetPointer(newvalue)));
 		MemoryContextSwitchTo(oldcxt);
 		/* Now's a good time to not leak the input value if it's freeable */
 		if (freeable)
diff --git a/src/test/regress/regress.c b/src/test/regress/regress.c
index 826556eb29..2bbeaa0460 100644
--- a/src/test/regress/regress.c
+++ b/src/test/regress/regress.c
@@ -558,7 +558,7 @@ make_tuple_indirect(PG_FUNCTION_ARGS)
 
 		/* copy datum, so it still lives later */
 		if (VARATT_IS_EXTERNAL_ONDISK(attr))
-			attr = heap_tuple_fetch_attr(attr);
+			attr = detoast_external_attr(attr);
 		else
 		{
 			struct varlena *oldattr = attr;
-- 
2.17.2 (Apple Git-113)

From 227ddd67a57758d9fa55c1b4b0dea33e297f454b Mon Sep 17 00:00:00 2001
From: Robert Haas <rhaas@postgresql.org>
Date: Mon, 8 Jul 2019 12:34:37 -0400
Subject: [PATCH v6 2/2] Rename some toasting functions based on whether they
 are heap-specific.
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

The old names for the attribute-detoasting functions names included the
word "heap," which seems outdated now that the heap is only one of
potentially many table access methods.

On the other hand, toast_insert_or_update and toast_delete are
heap-specific, so rename them by adding "heap_" as a prefix.

Patch by me, reviewed and tested by Prabhat Sabu, Thomas Munro,
Andres Freund, and Álvaro Herrera.

Discussion: http://postgr.es/m/CA+TgmoZv-=2iWM4jcw5ZhJeL18HF96+W1yJeYrnGMYdkFFnEpQ@mail.gmail.com
---
 src/backend/access/common/detoast.c        | 26 +++++++++++-----------
 src/backend/access/common/indextuple.c     |  2 +-
 src/backend/access/heap/heapam.c           |  8 +++----
 src/backend/access/heap/heaptoast.c        | 25 +++++++++++----------
 src/backend/access/heap/rewriteheap.c      |  4 ++--
 src/backend/access/table/toast_helper.c    |  4 ++--
 src/backend/executor/tstoreReceiver.c      |  2 +-
 src/backend/storage/large_object/inv_api.c |  2 +-
 src/backend/utils/adt/expandedrecord.c     |  4 ++--
 src/backend/utils/fmgr/fmgr.c              |  8 +++----
 src/include/access/detoast.h               | 16 ++++++-------
 src/include/access/heaptoast.h             | 13 +++++------
 src/pl/plpgsql/src/pl_exec.c               |  2 +-
 src/test/regress/regress.c                 |  2 +-
 14 files changed, 59 insertions(+), 59 deletions(-)

diff --git a/src/backend/access/common/detoast.c b/src/backend/access/common/detoast.c
index 36b68e35fb..78256f91ca 100644
--- a/src/backend/access/common/detoast.c
+++ b/src/backend/access/common/detoast.c
@@ -31,7 +31,7 @@ static struct varlena *toast_decompress_datum(struct varlena *attr);
 static struct varlena *toast_decompress_datum_slice(struct varlena *attr, int32 slicelength);
 
 /* ----------
- * heap_tuple_fetch_attr -
+ * detoast_external_attr -
  *
  *	Public entry point to get back a toasted value from
  *	external source (possibly still in compressed format).
@@ -43,7 +43,7 @@ static struct varlena *toast_decompress_datum_slice(struct varlena *attr, int32
  * ----------
  */
 struct varlena *
-heap_tuple_fetch_attr(struct varlena *attr)
+detoast_external_attr(struct varlena *attr)
 {
 	struct varlena *result;
 
@@ -69,7 +69,7 @@ heap_tuple_fetch_attr(struct varlena *attr)
 
 		/* recurse if value is still external in some other way */
 		if (VARATT_IS_EXTERNAL(attr))
-			return heap_tuple_fetch_attr(attr);
+			return detoast_external_attr(attr);
 
 		/*
 		 * Copy into the caller's memory context, in case caller tries to
@@ -104,7 +104,7 @@ heap_tuple_fetch_attr(struct varlena *attr)
 
 
 /* ----------
- * heap_tuple_untoast_attr -
+ * detoast_attr -
  *
  *	Public entry point to get back a toasted value from compression
  *	or external storage.  The result is always non-extended varlena form.
@@ -114,7 +114,7 @@ heap_tuple_fetch_attr(struct varlena *attr)
  * ----------
  */
 struct varlena *
-heap_tuple_untoast_attr(struct varlena *attr)
+detoast_attr(struct varlena *attr)
 {
 	if (VARATT_IS_EXTERNAL_ONDISK(attr))
 	{
@@ -145,7 +145,7 @@ heap_tuple_untoast_attr(struct varlena *attr)
 		Assert(!VARATT_IS_EXTERNAL_INDIRECT(attr));
 
 		/* recurse in case value is still extended in some other way */
-		attr = heap_tuple_untoast_attr(attr);
+		attr = detoast_attr(attr);
 
 		/* if it isn't, we'd better copy it */
 		if (attr == (struct varlena *) redirect.pointer)
@@ -162,7 +162,7 @@ heap_tuple_untoast_attr(struct varlena *attr)
 		/*
 		 * This is an expanded-object pointer --- get flat format
 		 */
-		attr = heap_tuple_fetch_attr(attr);
+		attr = detoast_external_attr(attr);
 		/* flatteners are not allowed to produce compressed/short output */
 		Assert(!VARATT_IS_EXTENDED(attr));
 	}
@@ -193,14 +193,14 @@ heap_tuple_untoast_attr(struct varlena *attr)
 
 
 /* ----------
- * heap_tuple_untoast_attr_slice -
+ * detoast_attr_slice -
  *
  *		Public entry point to get back part of a toasted value
  *		from compression or external storage.
  * ----------
  */
 struct varlena *
-heap_tuple_untoast_attr_slice(struct varlena *attr,
+detoast_attr_slice(struct varlena *attr,
 							  int32 sliceoffset, int32 slicelength)
 {
 	struct varlena *preslice;
@@ -230,13 +230,13 @@ heap_tuple_untoast_attr_slice(struct varlena *attr,
 		/* nested indirect Datums aren't allowed */
 		Assert(!VARATT_IS_EXTERNAL_INDIRECT(redirect.pointer));
 
-		return heap_tuple_untoast_attr_slice(redirect.pointer,
+		return detoast_attr_slice(redirect.pointer,
 											 sliceoffset, slicelength);
 	}
 	else if (VARATT_IS_EXTERNAL_EXPANDED(attr))
 	{
-		/* pass it off to heap_tuple_fetch_attr to flatten */
-		preslice = heap_tuple_fetch_attr(attr);
+		/* pass it off to detoast_external_attr to flatten */
+		preslice = detoast_external_attr(attr);
 	}
 	else
 		preslice = attr;
@@ -737,7 +737,7 @@ toast_decompress_datum(struct varlena *attr)
  * toast_decompress_datum_slice -
  *
  * Decompress the front of a compressed version of a varlena datum.
- * offset handling happens in heap_tuple_untoast_attr_slice.
+ * offset handling happens in detoast_attr_slice.
  * Here we just decompress a slice from the front.
  */
 static struct varlena *
diff --git a/src/backend/access/common/indextuple.c b/src/backend/access/common/indextuple.c
index 07586201b9..8a5f5227a3 100644
--- a/src/backend/access/common/indextuple.c
+++ b/src/backend/access/common/indextuple.c
@@ -89,7 +89,7 @@ index_form_tuple(TupleDesc tupleDescriptor,
 		if (VARATT_IS_EXTERNAL(DatumGetPointer(values[i])))
 		{
 			untoasted_values[i] =
-				PointerGetDatum(heap_tuple_fetch_attr((struct varlena *)
+				PointerGetDatum(detoast_external_attr((struct varlena *)
 													  DatumGetPointer(values[i])));
 			untoasted_free[i] = true;
 		}
diff --git a/src/backend/access/heap/heapam.c b/src/backend/access/heap/heapam.c
index 9e7cafa8e6..08bd087bc8 100644
--- a/src/backend/access/heap/heapam.c
+++ b/src/backend/access/heap/heapam.c
@@ -2085,7 +2085,7 @@ heap_prepare_insert(Relation relation, HeapTuple tup, TransactionId xid,
 		return tup;
 	}
 	else if (HeapTupleHasExternal(tup) || tup->t_len > TOAST_TUPLE_THRESHOLD)
-		return toast_insert_or_update(relation, tup, NULL, options);
+		return heap_toast_insert_or_update(relation, tup, NULL, options);
 	else
 		return tup;
 }
@@ -2809,7 +2809,7 @@ l1:
 		Assert(!HeapTupleHasExternal(&tp));
 	}
 	else if (HeapTupleHasExternal(&tp))
-		toast_delete(relation, &tp, false, 0);
+		heap_toast_delete(relation, &tp, false, 0);
 
 	/*
 	 * Mark tuple for invalidation from system caches at next command
@@ -3504,7 +3504,7 @@ l2:
 		if (need_toast)
 		{
 			/* Note we always use WAL and FSM during updates */
-			heaptup = toast_insert_or_update(relation, newtup, &oldtup, 0);
+			heaptup = heap_toast_insert_or_update(relation, newtup, &oldtup, 0);
 			newtupsize = MAXALIGN(heaptup->t_len);
 		}
 		else
@@ -5673,7 +5673,7 @@ heap_abort_speculative(Relation relation, ItemPointer tid, uint32 specToken)
 	if (HeapTupleHasExternal(&tp))
 	{
 		Assert(!IsToastRelation(relation));
-		toast_delete(relation, &tp, true, specToken);
+		heap_toast_delete(relation, &tp, true, specToken);
 	}
 
 	/*
diff --git a/src/backend/access/heap/heaptoast.c b/src/backend/access/heap/heaptoast.c
index c0acefc97e..cca916a39f 100644
--- a/src/backend/access/heap/heaptoast.c
+++ b/src/backend/access/heap/heaptoast.c
@@ -12,11 +12,11 @@
  *
  *
  * INTERFACE ROUTINES
- *		toast_insert_or_update -
+ *		heap_toast_insert_or_update -
  *			Try to make a given tuple fit into one page by compressing
  *			or moving off attributes
  *
- *		toast_delete -
+ *		heap_toast_delete -
  *			Reclaim toast storage when a tuple is deleted
  *
  *-------------------------------------------------------------------------
@@ -32,14 +32,14 @@
 
 
 /* ----------
- * toast_delete -
+ * heap_toast_delete -
  *
  *	Cascaded delete toast-entries on DELETE
  * ----------
  */
 void
-toast_delete(Relation rel, HeapTuple oldtup, bool is_speculative,
-			 uint32 specToken)
+heap_toast_delete(Relation rel, HeapTuple oldtup, bool is_speculative,
+				  uint32 specToken)
 {
 	TupleDesc	tupleDesc;
 	Datum		toast_values[MaxHeapAttributeNumber];
@@ -75,7 +75,7 @@ toast_delete(Relation rel, HeapTuple oldtup, bool is_speculative,
 
 
 /* ----------
- * toast_insert_or_update -
+ * heap_toast_insert_or_update -
  *
  *	Delete no-longer-used toast-entries and create new ones to
  *	make the new tuple fit on INSERT or UPDATE
@@ -93,8 +93,8 @@ toast_delete(Relation rel, HeapTuple oldtup, bool is_speculative,
  * ----------
  */
 HeapTuple
-toast_insert_or_update(Relation rel, HeapTuple newtup, HeapTuple oldtup,
-					   int options)
+heap_toast_insert_or_update(Relation rel, HeapTuple newtup, HeapTuple oldtup,
+							int options)
 {
 	HeapTuple	result_tuple;
 	TupleDesc	tupleDesc;
@@ -376,7 +376,7 @@ toast_flatten_tuple(HeapTuple tup, TupleDesc tupleDesc)
 			new_value = (struct varlena *) DatumGetPointer(toast_values[i]);
 			if (VARATT_IS_EXTERNAL(new_value))
 			{
-				new_value = heap_tuple_fetch_attr(new_value);
+				new_value = detoast_external_attr(new_value);
 				toast_values[i] = PointerGetDatum(new_value);
 				toast_free[i] = true;
 			}
@@ -491,7 +491,7 @@ toast_flatten_tuple_to_datum(HeapTupleHeader tup,
 			if (VARATT_IS_EXTERNAL(new_value) ||
 				VARATT_IS_COMPRESSED(new_value))
 			{
-				new_value = heap_tuple_untoast_attr(new_value);
+				new_value = detoast_attr(new_value);
 				toast_values[i] = PointerGetDatum(new_value);
 				toast_free[i] = true;
 			}
@@ -501,7 +501,8 @@ toast_flatten_tuple_to_datum(HeapTupleHeader tup,
 	/*
 	 * Calculate the new size of the tuple.
 	 *
-	 * This should match the reconstruction code in toast_insert_or_update.
+	 * This should match the reconstruction code in
+	 * heap_toast_insert_or_update.
 	 */
 	new_header_len = SizeofHeapTupleHeader;
 	if (has_nulls)
@@ -590,7 +591,7 @@ toast_build_flattened_tuple(TupleDesc tupleDesc,
 			new_value = (struct varlena *) DatumGetPointer(new_values[i]);
 			if (VARATT_IS_EXTERNAL(new_value))
 			{
-				new_value = heap_tuple_fetch_attr(new_value);
+				new_value = detoast_external_attr(new_value);
 				new_values[i] = PointerGetDatum(new_value);
 				freeable_values[num_to_free++] = (Pointer) new_value;
 			}
diff --git a/src/backend/access/heap/rewriteheap.c b/src/backend/access/heap/rewriteheap.c
index 0172a13957..7c98a42b8b 100644
--- a/src/backend/access/heap/rewriteheap.c
+++ b/src/backend/access/heap/rewriteheap.c
@@ -664,8 +664,8 @@ raw_heap_insert(RewriteState state, HeapTuple tup)
 		 */
 		options |= HEAP_INSERT_NO_LOGICAL;
 
-		heaptup = toast_insert_or_update(state->rs_new_rel, tup, NULL,
-										 options);
+		heaptup = heap_toast_insert_or_update(state->rs_new_rel, tup, NULL,
+											  options);
 	}
 	else
 		heaptup = tup;
diff --git a/src/backend/access/table/toast_helper.c b/src/backend/access/table/toast_helper.c
index e33918a7f4..dedc123e31 100644
--- a/src/backend/access/table/toast_helper.c
+++ b/src/backend/access/table/toast_helper.c
@@ -136,9 +136,9 @@ toast_tuple_init(ToastTupleContext *ttc)
 			{
 				ttc->ttc_attr[i].tai_oldexternal = new_value;
 				if (att->attstorage == 'p')
-					new_value = heap_tuple_untoast_attr(new_value);
+					new_value = detoast_attr(new_value);
 				else
-					new_value = heap_tuple_fetch_attr(new_value);
+					new_value = detoast_external_attr(new_value);
 				ttc->ttc_values[i] = PointerGetDatum(new_value);
 				ttc->ttc_attr[i].tai_colflags |= TOASTCOL_NEEDS_FREE;
 				ttc->ttc_flags |= (TOAST_NEEDS_CHANGE | TOAST_NEEDS_FREE);
diff --git a/src/backend/executor/tstoreReceiver.c b/src/backend/executor/tstoreReceiver.c
index c0c81c82da..6306b7d0bd 100644
--- a/src/backend/executor/tstoreReceiver.c
+++ b/src/backend/executor/tstoreReceiver.c
@@ -133,7 +133,7 @@ tstoreReceiveSlot_detoast(TupleTableSlot *slot, DestReceiver *self)
 		{
 			if (VARATT_IS_EXTERNAL(DatumGetPointer(val)))
 			{
-				val = PointerGetDatum(heap_tuple_fetch_attr((struct varlena *)
+				val = PointerGetDatum(detoast_external_attr((struct varlena *)
 															DatumGetPointer(val)));
 				myState->tofree[nfree++] = val;
 			}
diff --git a/src/backend/storage/large_object/inv_api.c b/src/backend/storage/large_object/inv_api.c
index e591236343..263d5be12e 100644
--- a/src/backend/storage/large_object/inv_api.c
+++ b/src/backend/storage/large_object/inv_api.c
@@ -180,7 +180,7 @@ getdatafield(Form_pg_largeobject tuple,
 	if (VARATT_IS_EXTENDED(datafield))
 	{
 		datafield = (bytea *)
-			heap_tuple_untoast_attr((struct varlena *) datafield);
+			detoast_attr((struct varlena *) datafield);
 		freeit = true;
 	}
 	len = VARSIZE(datafield) - VARHDRSZ;
diff --git a/src/backend/utils/adt/expandedrecord.c b/src/backend/utils/adt/expandedrecord.c
index 369432d53c..d99d370b17 100644
--- a/src/backend/utils/adt/expandedrecord.c
+++ b/src/backend/utils/adt/expandedrecord.c
@@ -1159,7 +1159,7 @@ expanded_record_set_field_internal(ExpandedRecordHeader *erh, int fnumber,
 			{
 				/* Detoasting should be done in short-lived context. */
 				oldcxt = MemoryContextSwitchTo(get_short_term_cxt(erh));
-				newValue = PointerGetDatum(heap_tuple_fetch_attr((struct varlena *) DatumGetPointer(newValue)));
+				newValue = PointerGetDatum(detoast_external_attr((struct varlena *) DatumGetPointer(newValue)));
 				MemoryContextSwitchTo(oldcxt);
 			}
 			else
@@ -1305,7 +1305,7 @@ expanded_record_set_fields(ExpandedRecordHeader *erh,
 					if (expand_external)
 					{
 						/* Detoast as requested while copying the value */
-						newValue = PointerGetDatum(heap_tuple_fetch_attr((struct varlena *) DatumGetPointer(newValue)));
+						newValue = PointerGetDatum(detoast_external_attr((struct varlena *) DatumGetPointer(newValue)));
 					}
 					else
 					{
diff --git a/src/backend/utils/fmgr/fmgr.c b/src/backend/utils/fmgr/fmgr.c
index 0484adb984..099ebd779b 100644
--- a/src/backend/utils/fmgr/fmgr.c
+++ b/src/backend/utils/fmgr/fmgr.c
@@ -1739,7 +1739,7 @@ struct varlena *
 pg_detoast_datum(struct varlena *datum)
 {
 	if (VARATT_IS_EXTENDED(datum))
-		return heap_tuple_untoast_attr(datum);
+		return detoast_attr(datum);
 	else
 		return datum;
 }
@@ -1748,7 +1748,7 @@ struct varlena *
 pg_detoast_datum_copy(struct varlena *datum)
 {
 	if (VARATT_IS_EXTENDED(datum))
-		return heap_tuple_untoast_attr(datum);
+		return detoast_attr(datum);
 	else
 	{
 		/* Make a modifiable copy of the varlena object */
@@ -1764,14 +1764,14 @@ struct varlena *
 pg_detoast_datum_slice(struct varlena *datum, int32 first, int32 count)
 {
 	/* Only get the specified portion from the toast rel */
-	return heap_tuple_untoast_attr_slice(datum, first, count);
+	return detoast_attr_slice(datum, first, count);
 }
 
 struct varlena *
 pg_detoast_datum_packed(struct varlena *datum)
 {
 	if (VARATT_IS_COMPRESSED(datum) || VARATT_IS_EXTERNAL(datum))
-		return heap_tuple_untoast_attr(datum);
+		return detoast_attr(datum);
 	else
 		return datum;
 }
diff --git a/src/include/access/detoast.h b/src/include/access/detoast.h
index 02029a991f..baf3dc2591 100644
--- a/src/include/access/detoast.h
+++ b/src/include/access/detoast.h
@@ -44,34 +44,34 @@ do { \
 #define INDIRECT_POINTER_SIZE (VARHDRSZ_EXTERNAL + sizeof(varatt_indirect))
 
 /* ----------
- * heap_tuple_fetch_attr() -
+ * detoast_external_attr() -
  *
  *		Fetches an external stored attribute from the toast
  *		relation. Does NOT decompress it, if stored external
  *		in compressed format.
  * ----------
  */
-extern struct varlena *heap_tuple_fetch_attr(struct varlena *attr);
+extern struct varlena *detoast_external_attr(struct varlena *attr);
 
 /* ----------
- * heap_tuple_untoast_attr() -
+ * detoast_attr() -
  *
  *		Fully detoasts one attribute, fetching and/or decompressing
  *		it as needed.
  * ----------
  */
-extern struct varlena *heap_tuple_untoast_attr(struct varlena *attr);
+extern struct varlena *detoast_attr(struct varlena *attr);
 
 /* ----------
- * heap_tuple_untoast_attr_slice() -
+ * detoast_attr_slice() -
  *
  *		Fetches only the specified portion of an attribute.
  *		(Handles all cases for attribute storage)
  * ----------
  */
-extern struct varlena *heap_tuple_untoast_attr_slice(struct varlena *attr,
-							  int32 sliceoffset,
-							  int32 slicelength);
+extern struct varlena *detoast_attr_slice(struct varlena *attr,
+										  int32 sliceoffset,
+										  int32 slicelength);
 
 /* ----------
  * toast_raw_datum_size -
diff --git a/src/include/access/heaptoast.h b/src/include/access/heaptoast.h
index 07d36ac968..23f62dc4af 100644
--- a/src/include/access/heaptoast.h
+++ b/src/include/access/heaptoast.h
@@ -89,23 +89,22 @@
 	 VARHDRSZ)
 
 /* ----------
- * toast_insert_or_update -
+ * heap_toast_insert_or_update -
  *
  *	Called by heap_insert() and heap_update().
  * ----------
  */
-extern HeapTuple toast_insert_or_update(Relation rel,
-										HeapTuple newtup, HeapTuple oldtup,
-										int options);
+extern HeapTuple heap_toast_insert_or_update(Relation rel, HeapTuple newtup,
+											 HeapTuple oldtup, int options);
 
 /* ----------
- * toast_delete -
+ * heap_toast_delete -
  *
  *	Called by heap_delete().
  * ----------
  */
-extern void toast_delete(Relation rel, HeapTuple oldtup,
-			 bool is_speculative, uint32 specToken);
+extern void heap_toast_delete(Relation rel, HeapTuple oldtup,
+							  bool is_speculative, uint32 specToken);
 
 /* ----------
  * toast_flatten_tuple -
diff --git a/src/pl/plpgsql/src/pl_exec.c b/src/pl/plpgsql/src/pl_exec.c
index cb2e19cda4..345065e305 100644
--- a/src/pl/plpgsql/src/pl_exec.c
+++ b/src/pl/plpgsql/src/pl_exec.c
@@ -8344,7 +8344,7 @@ assign_simple_var(PLpgSQL_execstate *estate, PLpgSQL_var *var,
 		 * pain, but there's little choice.
 		 */
 		oldcxt = MemoryContextSwitchTo(get_eval_mcontext(estate));
-		detoasted = PointerGetDatum(heap_tuple_fetch_attr((struct varlena *) DatumGetPointer(newvalue)));
+		detoasted = PointerGetDatum(detoast_external_attr((struct varlena *) DatumGetPointer(newvalue)));
 		MemoryContextSwitchTo(oldcxt);
 		/* Now's a good time to not leak the input value if it's freeable */
 		if (freeable)
diff --git a/src/test/regress/regress.c b/src/test/regress/regress.c
index 826556eb29..2bbeaa0460 100644
--- a/src/test/regress/regress.c
+++ b/src/test/regress/regress.c
@@ -558,7 +558,7 @@ make_tuple_indirect(PG_FUNCTION_ARGS)
 
 		/* copy datum, so it still lives later */
 		if (VARATT_IS_EXTERNAL_ONDISK(attr))
-			attr = heap_tuple_fetch_attr(attr);
+			attr = detoast_external_attr(attr);
 		else
 		{
 			struct varlena *oldattr = attr;
-- 
2.17.2 (Apple Git-113)

From 9449efff4983b9650984855863a4ca09bd8c9a2f Mon Sep 17 00:00:00 2001
From: Robert Haas <rhaas@postgresql.org>
Date: Thu, 1 Aug 2019 10:37:02 -0400
Subject: [PATCH v6 1/2] Allow TOAST tables to be implemented using table AMs
 other than heap.
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

toast_fetch_datum, toast_save_datum, and toast_delete_datum are
adjusted to use tableam rather than heap-specific functions.  This
might have some performance impact, but this patch attempts to
mitigate that by restructuring things so that we don't open and close
the toast table and indexes multiple times per tuple.

tableam now exposes an integer value (not a callback) for the
maximum TOAST chunk size, and has a new callback allowing table
AMs to specify the AM that should be used to implement the TOAST
table. Previously, the toast AM was always the same as the table AM.

Patch by me, reviewed and tested by Prabhat Sabu, Thomas Munro,
Andres Freund, and Álvaro Herrera.

Discussion: http://postgr.es/m/CA+TgmoZv-=2iWM4jcw5ZhJeL18HF96+W1yJeYrnGMYdkFFnEpQ@mail.gmail.com
---
 src/backend/access/common/detoast.c         |  62 +++++-----
 src/backend/access/common/toast_internals.c | 127 +++++++-------------
 src/backend/access/heap/heapam.c            |   6 +-
 src/backend/access/heap/heapam_handler.c    |  14 ++-
 src/backend/access/heap/heaptoast.c         |  19 ++-
 src/backend/access/index/genam.c            |  20 +++
 src/backend/access/table/toast_helper.c     | 107 ++++++++++++++---
 src/backend/catalog/toasting.c              |   2 +-
 src/include/access/genam.h                  |   5 +-
 src/include/access/heapam.h                 |   3 +-
 src/include/access/heaptoast.h              |   3 +-
 src/include/access/tableam.h                |  31 +++++
 src/include/access/toast_helper.h           |  18 ++-
 src/include/access/toast_internals.h        |  15 ++-
 14 files changed, 284 insertions(+), 148 deletions(-)

diff --git a/src/backend/access/common/detoast.c b/src/backend/access/common/detoast.c
index c8b49d6a12..36b68e35fb 100644
--- a/src/backend/access/common/detoast.c
+++ b/src/backend/access/common/detoast.c
@@ -15,10 +15,11 @@
 
 #include "access/detoast.h"
 #include "access/genam.h"
-#include "access/heaptoast.h"
 #include "access/table.h"
 #include "access/toast_internals.h"
+#include "access/tableam.h"
 #include "common/pg_lzcompress.h"
+#include "executor/tuptable.h"
 #include "utils/expandeddatum.h"
 #include "utils/fmgroids.h"
 #include "utils/rel.h"
@@ -303,8 +304,7 @@ toast_fetch_datum(struct varlena *attr)
 	Relation   *toastidxs;
 	ScanKeyData toastkey;
 	SysScanDesc toastscan;
-	HeapTuple	ttup;
-	TupleDesc	toasttupDesc;
+	TupleTableSlot *slot;
 	struct varlena *result;
 	struct varatt_external toast_pointer;
 	int32		ressize;
@@ -312,11 +312,11 @@ toast_fetch_datum(struct varlena *attr)
 				nextidx;
 	int32		numchunks;
 	Pointer		chunk;
-	bool		isnull;
 	char	   *chunkdata;
 	int32		chunksize;
 	int			num_indexes;
 	int			validIndex;
+	int			max_chunk_size;
 	SnapshotData SnapshotToast;
 
 	if (!VARATT_IS_EXTERNAL_ONDISK(attr))
@@ -326,7 +326,6 @@ toast_fetch_datum(struct varlena *attr)
 	VARATT_EXTERNAL_GET_POINTER(toast_pointer, attr);
 
 	ressize = toast_pointer.va_extsize;
-	numchunks = ((ressize - 1) / TOAST_MAX_CHUNK_SIZE) + 1;
 
 	result = (struct varlena *) palloc(ressize + VARHDRSZ);
 
@@ -339,7 +338,9 @@ toast_fetch_datum(struct varlena *attr)
 	 * Open the toast relation and its indexes
 	 */
 	toastrel = table_open(toast_pointer.va_toastrelid, AccessShareLock);
-	toasttupDesc = toastrel->rd_att;
+
+	max_chunk_size = toastrel->rd_tableam->toast_max_chunk_size;
+	numchunks = ((ressize - 1) / max_chunk_size) + 1;
 
 	/* Look for the valid index of the toast relation */
 	validIndex = toast_open_indexes(toastrel,
@@ -367,15 +368,15 @@ toast_fetch_datum(struct varlena *attr)
 	init_toast_snapshot(&SnapshotToast);
 	toastscan = systable_beginscan_ordered(toastrel, toastidxs[validIndex],
 										   &SnapshotToast, 1, &toastkey);
-	while ((ttup = systable_getnext_ordered(toastscan, ForwardScanDirection)) != NULL)
+	while ((slot = systable_getnextslot_ordered(toastscan, ForwardScanDirection)) != NULL)
 	{
 		/*
 		 * Have a chunk, extract the sequence number and the data
 		 */
-		residx = DatumGetInt32(fastgetattr(ttup, 2, toasttupDesc, &isnull));
-		Assert(!isnull);
-		chunk = DatumGetPointer(fastgetattr(ttup, 3, toasttupDesc, &isnull));
-		Assert(!isnull);
+		slot_getsomeattrs(slot, 3);
+		Assert(!slot->tts_isnull[1] && !slot->tts_isnull[2]);
+		residx = DatumGetInt32(slot->tts_values[1]);
+		chunk = DatumGetPointer(slot->tts_values[2]);
 		if (!VARATT_IS_EXTENDED(chunk))
 		{
 			chunksize = VARSIZE(chunk) - VARHDRSZ;
@@ -409,23 +410,23 @@ toast_fetch_datum(struct varlena *attr)
 									 RelationGetRelationName(toastrel))));
 		if (residx < numchunks - 1)
 		{
-			if (chunksize != TOAST_MAX_CHUNK_SIZE)
+			if (chunksize != max_chunk_size)
 				ereport(ERROR,
 						(errcode(ERRCODE_DATA_CORRUPTED),
 						 errmsg_internal("unexpected chunk size %d (expected %d) in chunk %d of %d for toast value %u in %s",
-										 chunksize, (int) TOAST_MAX_CHUNK_SIZE,
+										 chunksize, max_chunk_size,
 										 residx, numchunks,
 										 toast_pointer.va_valueid,
 										 RelationGetRelationName(toastrel))));
 		}
 		else if (residx == numchunks - 1)
 		{
-			if ((residx * TOAST_MAX_CHUNK_SIZE + chunksize) != ressize)
+			if ((residx * max_chunk_size + chunksize) != ressize)
 				ereport(ERROR,
 						(errcode(ERRCODE_DATA_CORRUPTED),
 						 errmsg_internal("unexpected chunk size %d (expected %d) in final chunk %d for toast value %u in %s",
 										 chunksize,
-										 (int) (ressize - residx * TOAST_MAX_CHUNK_SIZE),
+										 (int) (ressize - residx * max_chunk_size),
 										 residx,
 										 toast_pointer.va_valueid,
 										 RelationGetRelationName(toastrel))));
@@ -442,7 +443,7 @@ toast_fetch_datum(struct varlena *attr)
 		/*
 		 * Copy the data into proper place in our result
 		 */
-		memcpy(VARDATA(result) + residx * TOAST_MAX_CHUNK_SIZE,
+		memcpy(VARDATA(result) + residx * max_chunk_size,
 			   chunkdata,
 			   chunksize);
 
@@ -508,6 +509,7 @@ toast_fetch_datum_slice(struct varlena *attr, int32 sliceoffset, int32 length)
 	int32		chcpyend;
 	int			num_indexes;
 	int			validIndex;
+	int			max_chunk_size;
 	SnapshotData SnapshotToast;
 
 	if (!VARATT_IS_EXTERNAL_ONDISK(attr))
@@ -523,7 +525,6 @@ toast_fetch_datum_slice(struct varlena *attr, int32 sliceoffset, int32 length)
 	Assert(!VARATT_EXTERNAL_IS_COMPRESSED(toast_pointer));
 
 	attrsize = toast_pointer.va_extsize;
-	totalchunks = ((attrsize - 1) / TOAST_MAX_CHUNK_SIZE) + 1;
 
 	if (sliceoffset >= attrsize)
 	{
@@ -541,19 +542,22 @@ toast_fetch_datum_slice(struct varlena *attr, int32 sliceoffset, int32 length)
 	if (length == 0)
 		return result;			/* Can save a lot of work at this point! */
 
-	startchunk = sliceoffset / TOAST_MAX_CHUNK_SIZE;
-	endchunk = (sliceoffset + length - 1) / TOAST_MAX_CHUNK_SIZE;
-	numchunks = (endchunk - startchunk) + 1;
-
-	startoffset = sliceoffset % TOAST_MAX_CHUNK_SIZE;
-	endoffset = (sliceoffset + length - 1) % TOAST_MAX_CHUNK_SIZE;
-
 	/*
 	 * Open the toast relation and its indexes
 	 */
 	toastrel = table_open(toast_pointer.va_toastrelid, AccessShareLock);
 	toasttupDesc = toastrel->rd_att;
 
+	max_chunk_size = toastrel->rd_tableam->toast_max_chunk_size;
+	totalchunks = ((attrsize - 1) / max_chunk_size) + 1;
+
+	startchunk = sliceoffset / max_chunk_size;
+	endchunk = (sliceoffset + length - 1) / max_chunk_size;
+	numchunks = (endchunk - startchunk) + 1;
+
+	startoffset = sliceoffset % max_chunk_size;
+	endoffset = (sliceoffset + length - 1) % max_chunk_size;
+
 	/* Look for the valid index of toast relation */
 	validIndex = toast_open_indexes(toastrel,
 									AccessShareLock,
@@ -642,19 +646,19 @@ toast_fetch_datum_slice(struct varlena *attr, int32 sliceoffset, int32 length)
 				 RelationGetRelationName(toastrel));
 		if (residx < totalchunks - 1)
 		{
-			if (chunksize != TOAST_MAX_CHUNK_SIZE)
+			if (chunksize != max_chunk_size)
 				elog(ERROR, "unexpected chunk size %d (expected %d) in chunk %d of %d for toast value %u in %s when fetching slice",
-					 chunksize, (int) TOAST_MAX_CHUNK_SIZE,
+					 chunksize, max_chunk_size,
 					 residx, totalchunks,
 					 toast_pointer.va_valueid,
 					 RelationGetRelationName(toastrel));
 		}
 		else if (residx == totalchunks - 1)
 		{
-			if ((residx * TOAST_MAX_CHUNK_SIZE + chunksize) != attrsize)
+			if ((residx * max_chunk_size + chunksize) != attrsize)
 				elog(ERROR, "unexpected chunk size %d (expected %d) in final chunk %d for toast value %u in %s when fetching slice",
 					 chunksize,
-					 (int) (attrsize - residx * TOAST_MAX_CHUNK_SIZE),
+					 (int) (attrsize - residx * max_chunk_size),
 					 residx,
 					 toast_pointer.va_valueid,
 					 RelationGetRelationName(toastrel));
@@ -677,7 +681,7 @@ toast_fetch_datum_slice(struct varlena *attr, int32 sliceoffset, int32 length)
 			chcpyend = endoffset;
 
 		memcpy(VARDATA(result) +
-			   (residx * TOAST_MAX_CHUNK_SIZE - sliceoffset) + chcpystrt,
+			   (residx * max_chunk_size - sliceoffset) + chcpystrt,
 			   chunkdata + chcpystrt,
 			   (chcpyend - chcpystrt) + 1);
 
diff --git a/src/backend/access/common/toast_internals.c b/src/backend/access/common/toast_internals.c
index a971242490..beb303034d 100644
--- a/src/backend/access/common/toast_internals.c
+++ b/src/backend/access/common/toast_internals.c
@@ -15,9 +15,8 @@
 
 #include "access/detoast.h"
 #include "access/genam.h"
-#include "access/heapam.h"
-#include "access/heaptoast.h"
 #include "access/table.h"
+#include "access/tableam.h"
 #include "access/toast_internals.h"
 #include "access/xact.h"
 #include "catalog/catalog.h"
@@ -100,22 +99,21 @@ toast_compress_datum(Datum value)
  *	Save one single datum into the secondary relation and return
  *	a Datum reference for it.
  *
- * rel: the main relation we're working with (not the toast rel!)
+ * toastrel: the TOAST relation we're working with (not the main rel!)
+ * toastslot: a slot corresponding to 'toastrel'
+ * num_indexes, toastidxs, validIndex: as returned by toast_open_indexes
+ * toastoid: the toast OID that should be inserted into the new TOAST pointer
  * value: datum to be pushed to toast storage
  * oldexternal: if not NULL, toast pointer previously representing the datum
- * options: options to be passed to heap_insert() for toast rows
+ * options: options to be passed to table_tuple_insert() for toast rows
  * ----------
  */
 Datum
-toast_save_datum(Relation rel, Datum value,
-				 struct varlena *oldexternal, int options)
+toast_save_datum(Relation toastrel, TupleTableSlot *toastslot,
+				 int num_indexes, Relation *toastidxs, int validIndex,
+				 Oid toastoid, Datum value, struct varlena *oldexternal,
+				 int options, int max_chunk_size)
 {
-	Relation	toastrel;
-	Relation   *toastidxs;
-	HeapTuple	toasttup;
-	TupleDesc	toasttupDesc;
-	Datum		t_values[3];
-	bool		t_isnull[3];
 	CommandId	mycid = GetCurrentCommandId(true);
 	struct varlena *result;
 	struct varatt_external toast_pointer;
@@ -123,7 +121,7 @@ toast_save_datum(Relation rel, Datum value,
 	{
 		struct varlena hdr;
 		/* this is to make the union big enough for a chunk: */
-		char		data[TOAST_MAX_CHUNK_SIZE + VARHDRSZ];
+		char		data[BLCKSZ + VARHDRSZ];
 		/* ensure union is aligned well enough: */
 		int32		align_it;
 	}			chunk_data;
@@ -132,24 +130,9 @@ toast_save_datum(Relation rel, Datum value,
 	char	   *data_p;
 	int32		data_todo;
 	Pointer		dval = DatumGetPointer(value);
-	int			num_indexes;
-	int			validIndex;
 
 	Assert(!VARATT_IS_EXTERNAL(value));
-
-	/*
-	 * Open the toast relation and its indexes.  We can use the index to check
-	 * uniqueness of the OID we assign to the toasted item, even though it has
-	 * additional columns besides OID.
-	 */
-	toastrel = table_open(rel->rd_rel->reltoastrelid, RowExclusiveLock);
-	toasttupDesc = toastrel->rd_att;
-
-	/* Open all the toast indexes and look for the valid one */
-	validIndex = toast_open_indexes(toastrel,
-									RowExclusiveLock,
-									&toastidxs,
-									&num_indexes);
+	Assert(max_chunk_size <= BLCKSZ);
 
 	/*
 	 * Get the data pointer and length, and compute va_rawsize and va_extsize.
@@ -189,11 +172,11 @@ toast_save_datum(Relation rel, Datum value,
 	 *
 	 * Normally this is the actual OID of the target toast table, but during
 	 * table-rewriting operations such as CLUSTER, we have to insert the OID
-	 * of the table's real permanent toast table instead.  rd_toastoid is set
+	 * of the table's real permanent toast table instead.  toastoid is set
 	 * if we have to substitute such an OID.
 	 */
-	if (OidIsValid(rel->rd_toastoid))
-		toast_pointer.va_toastrelid = rel->rd_toastoid;
+	if (OidIsValid(toastoid))
+		toast_pointer.va_toastrelid = toastoid;
 	else
 		toast_pointer.va_toastrelid = RelationGetRelid(toastrel);
 
@@ -209,7 +192,7 @@ toast_save_datum(Relation rel, Datum value,
 	 * options have been changed), we have to pick a value ID that doesn't
 	 * conflict with either new or existing toast value OIDs.
 	 */
-	if (!OidIsValid(rel->rd_toastoid))
+	if (!OidIsValid(toastoid))
 	{
 		/* normal case: just choose an unused OID */
 		toast_pointer.va_valueid =
@@ -228,7 +211,7 @@ toast_save_datum(Relation rel, Datum value,
 			Assert(VARATT_IS_EXTERNAL_ONDISK(oldexternal));
 			/* Must copy to access aligned fields */
 			VARATT_EXTERNAL_GET_POINTER(old_toast_pointer, oldexternal);
-			if (old_toast_pointer.va_toastrelid == rel->rd_toastoid)
+			if (old_toast_pointer.va_toastrelid == toastoid)
 			{
 				/* This value came from the old toast table; reuse its OID */
 				toast_pointer.va_valueid = old_toast_pointer.va_valueid;
@@ -270,20 +253,11 @@ toast_save_datum(Relation rel, Datum value,
 					GetNewOidWithIndex(toastrel,
 									   RelationGetRelid(toastidxs[validIndex]),
 									   (AttrNumber) 1);
-			} while (toastid_valueid_exists(rel->rd_toastoid,
+			} while (toastid_valueid_exists(toastoid,
 											toast_pointer.va_valueid));
 		}
 	}
 
-	/*
-	 * Initialize constant parts of the tuple data
-	 */
-	t_values[0] = ObjectIdGetDatum(toast_pointer.va_valueid);
-	t_values[2] = PointerGetDatum(&chunk_data);
-	t_isnull[0] = false;
-	t_isnull[1] = false;
-	t_isnull[2] = false;
-
 	/*
 	 * Split up the item into chunks
 	 */
@@ -296,17 +270,22 @@ toast_save_datum(Relation rel, Datum value,
 		/*
 		 * Calculate the size of this chunk
 		 */
-		chunk_size = Min(TOAST_MAX_CHUNK_SIZE, data_todo);
+		chunk_size = Min(max_chunk_size, data_todo);
 
 		/*
 		 * Build a tuple and store it
 		 */
-		t_values[1] = Int32GetDatum(chunk_seq++);
+		toastslot->tts_values[0] = ObjectIdGetDatum(toast_pointer.va_valueid);
+		toastslot->tts_values[1] = Int32GetDatum(chunk_seq++);
 		SET_VARSIZE(&chunk_data, chunk_size + VARHDRSZ);
 		memcpy(VARDATA(&chunk_data), data_p, chunk_size);
-		toasttup = heap_form_tuple(toasttupDesc, t_values, t_isnull);
+		toastslot->tts_values[2] = PointerGetDatum(&chunk_data);
+		toastslot->tts_isnull[0] = false;
+		toastslot->tts_isnull[1] = false;
+		toastslot->tts_isnull[2] = false;
+		ExecStoreVirtualTuple(toastslot);
 
-		heap_insert(toastrel, toasttup, mycid, options, NULL);
+		table_tuple_insert(toastrel, toastslot, mycid, options, NULL);
 
 		/*
 		 * Create the index entry.  We cheat a little here by not using
@@ -323,8 +302,9 @@ toast_save_datum(Relation rel, Datum value,
 		{
 			/* Only index relations marked as ready can be updated */
 			if (toastidxs[i]->rd_index->indisready)
-				index_insert(toastidxs[i], t_values, t_isnull,
-							 &(toasttup->t_self),
+				index_insert(toastidxs[i], toastslot->tts_values,
+							 toastslot->tts_isnull,
+							 &(toastslot->tts_tid),
 							 toastrel,
 							 toastidxs[i]->rd_index->indisunique ?
 							 UNIQUE_CHECK_YES : UNIQUE_CHECK_NO,
@@ -332,9 +312,9 @@ toast_save_datum(Relation rel, Datum value,
 		}
 
 		/*
-		 * Free memory
+		 * Clear slot
 		 */
-		heap_freetuple(toasttup);
+		ExecClearTuple(toastslot);
 
 		/*
 		 * Move on to next chunk
@@ -343,12 +323,6 @@ toast_save_datum(Relation rel, Datum value,
 		data_p += chunk_size;
 	}
 
-	/*
-	 * Done - close toast relation and its indexes
-	 */
-	toast_close_indexes(toastidxs, num_indexes, RowExclusiveLock);
-	table_close(toastrel, RowExclusiveLock);
-
 	/*
 	 * Create the TOAST pointer value that we'll return
 	 */
@@ -366,35 +340,24 @@ toast_save_datum(Relation rel, Datum value,
  * ----------
  */
 void
-toast_delete_datum(Relation rel, Datum value, bool is_speculative)
+toast_delete_datum(Relation toastrel, int num_indexes, Relation *toastidxs,
+				   int validIndex, Datum value, bool is_speculative,
+				   uint32 specToken)
 {
 	struct varlena *attr = (struct varlena *) DatumGetPointer(value);
 	struct varatt_external toast_pointer;
-	Relation	toastrel;
-	Relation   *toastidxs;
 	ScanKeyData toastkey;
 	SysScanDesc toastscan;
-	HeapTuple	toasttup;
-	int			num_indexes;
-	int			validIndex;
+	TupleTableSlot *slot;
 	SnapshotData SnapshotToast;
 
-	if (!VARATT_IS_EXTERNAL_ONDISK(attr))
-		return;
+	Assert(VARATT_IS_EXTERNAL_ONDISK(attr));
 
 	/* Must copy to access aligned fields */
 	VARATT_EXTERNAL_GET_POINTER(toast_pointer, attr);
 
-	/*
-	 * Open the toast relation and its indexes
-	 */
-	toastrel = table_open(toast_pointer.va_toastrelid, RowExclusiveLock);
-
-	/* Fetch valid relation used for process */
-	validIndex = toast_open_indexes(toastrel,
-									RowExclusiveLock,
-									&toastidxs,
-									&num_indexes);
+	/* Check that caller gave us the correct TOAST relation. */
+	Assert(toast_pointer.va_toastrelid == RelationGetRelid(toastrel));
 
 	/*
 	 * Setup a scan key to find chunks with matching va_valueid
@@ -412,23 +375,19 @@ toast_delete_datum(Relation rel, Datum value, bool is_speculative)
 	init_toast_snapshot(&SnapshotToast);
 	toastscan = systable_beginscan_ordered(toastrel, toastidxs[validIndex],
 										   &SnapshotToast, 1, &toastkey);
-	while ((toasttup = systable_getnext_ordered(toastscan, ForwardScanDirection)) != NULL)
+	while ((slot = systable_getnextslot_ordered(toastscan, ForwardScanDirection)) != NULL)
 	{
 		/*
 		 * Have a chunk, delete it
 		 */
 		if (is_speculative)
-			heap_abort_speculative(toastrel, &toasttup->t_self);
+			table_tuple_complete_speculative(toastrel, slot, specToken, false);
 		else
-			simple_heap_delete(toastrel, &toasttup->t_self);
+			simple_table_tuple_delete(toastrel, &slot->tts_tid, &SnapshotToast);
 	}
 
-	/*
-	 * End scan and close relations
-	 */
+	/* End scan */
 	systable_endscan_ordered(toastscan);
-	toast_close_indexes(toastidxs, num_indexes, RowExclusiveLock);
-	table_close(toastrel, RowExclusiveLock);
 }
 
 /* ----------
diff --git a/src/backend/access/heap/heapam.c b/src/backend/access/heap/heapam.c
index e9544822bf..9e7cafa8e6 100644
--- a/src/backend/access/heap/heapam.c
+++ b/src/backend/access/heap/heapam.c
@@ -2809,7 +2809,7 @@ l1:
 		Assert(!HeapTupleHasExternal(&tp));
 	}
 	else if (HeapTupleHasExternal(&tp))
-		toast_delete(relation, &tp, false);
+		toast_delete(relation, &tp, false, 0);
 
 	/*
 	 * Mark tuple for invalidation from system caches at next command
@@ -5564,7 +5564,7 @@ heap_finish_speculative(Relation relation, ItemPointer tid)
  * confirmation records.
  */
 void
-heap_abort_speculative(Relation relation, ItemPointer tid)
+heap_abort_speculative(Relation relation, ItemPointer tid, uint32 specToken)
 {
 	TransactionId xid = GetCurrentTransactionId();
 	ItemId		lp;
@@ -5673,7 +5673,7 @@ heap_abort_speculative(Relation relation, ItemPointer tid)
 	if (HeapTupleHasExternal(&tp))
 	{
 		Assert(!IsToastRelation(relation));
-		toast_delete(relation, &tp, true);
+		toast_delete(relation, &tp, true, specToken);
 	}
 
 	/*
diff --git a/src/backend/access/heap/heapam_handler.c b/src/backend/access/heap/heapam_handler.c
index 2dd8821fac..97a7433092 100644
--- a/src/backend/access/heap/heapam_handler.c
+++ b/src/backend/access/heap/heapam_handler.c
@@ -28,6 +28,7 @@
 #include "access/rewriteheap.h"
 #include "access/tableam.h"
 #include "access/tsmapi.h"
+#include "access/heaptoast.h"
 #include "access/xact.h"
 #include "catalog/catalog.h"
 #include "catalog/index.h"
@@ -292,7 +293,7 @@ heapam_tuple_complete_speculative(Relation relation, TupleTableSlot *slot,
 	if (succeeded)
 		heap_finish_speculative(relation, &slot->tts_tid);
 	else
-		heap_abort_speculative(relation, &slot->tts_tid);
+		heap_abort_speculative(relation, &slot->tts_tid, specToken);
 
 	if (shouldFree)
 		pfree(tuple);
@@ -2041,6 +2042,15 @@ heapam_relation_needs_toast_table(Relation rel)
 	return (tuple_length > TOAST_TUPLE_THRESHOLD);
 }
 
+/*
+ * TOAST tables for heap relations are just heap relations.
+ */
+static Oid
+heapam_relation_toast_am(Relation rel)
+{
+	return rel->rd_rel->relam;
+}
+
 
 /* ------------------------------------------------------------------------
  * Planner related callbacks for the heap AM
@@ -2539,6 +2549,8 @@ static const TableAmRoutine heapam_methods = {
 
 	.relation_size = table_block_relation_size,
 	.relation_needs_toast_table = heapam_relation_needs_toast_table,
+	.relation_toast_am = heapam_relation_toast_am,
+	.toast_max_chunk_size = TOAST_MAX_CHUNK_SIZE,
 
 	.relation_estimate_size = heapam_estimate_rel_size,
 
diff --git a/src/backend/access/heap/heaptoast.c b/src/backend/access/heap/heaptoast.c
index fbf9294598..c0acefc97e 100644
--- a/src/backend/access/heap/heaptoast.c
+++ b/src/backend/access/heap/heaptoast.c
@@ -38,7 +38,8 @@
  * ----------
  */
 void
-toast_delete(Relation rel, HeapTuple oldtup, bool is_speculative)
+toast_delete(Relation rel, HeapTuple oldtup, bool is_speculative,
+			 uint32 specToken)
 {
 	TupleDesc	tupleDesc;
 	Datum		toast_values[MaxHeapAttributeNumber];
@@ -68,7 +69,8 @@ toast_delete(Relation rel, HeapTuple oldtup, bool is_speculative)
 	heap_deform_tuple(oldtup, tupleDesc, toast_values, toast_isnull);
 
 	/* Do the real work. */
-	toast_delete_external(rel, toast_values, toast_isnull, is_speculative);
+	toast_delete_external(rel, toast_values, toast_isnull, is_speculative,
+						  specToken);
 }
 
 
@@ -151,6 +153,8 @@ toast_insert_or_update(Relation rel, HeapTuple newtup, HeapTuple oldtup,
 		ttc.ttc_oldvalues = toast_oldvalues;
 		ttc.ttc_oldisnull = toast_oldisnull;
 	}
+	ttc.ttc_toastrel = NULL;
+	ttc.ttc_toastslot = NULL;
 	ttc.ttc_attr = toast_attr;
 	toast_tuple_init(&ttc);
 
@@ -207,7 +211,8 @@ toast_insert_or_update(Relation rel, HeapTuple newtup, HeapTuple oldtup,
 		 */
 		if (toast_attr[biggest_attno].tai_size > maxDataLen &&
 			rel->rd_rel->reltoastrelid != InvalidOid)
-			toast_tuple_externalize(&ttc, biggest_attno, options);
+			toast_tuple_externalize(&ttc, biggest_attno, options,
+									TOAST_MAX_CHUNK_SIZE);
 	}
 
 	/*
@@ -224,7 +229,8 @@ toast_insert_or_update(Relation rel, HeapTuple newtup, HeapTuple oldtup,
 		biggest_attno = toast_tuple_find_biggest_attribute(&ttc, false, false);
 		if (biggest_attno < 0)
 			break;
-		toast_tuple_externalize(&ttc, biggest_attno, options);
+		toast_tuple_externalize(&ttc, biggest_attno, options,
+								TOAST_MAX_CHUNK_SIZE);
 	}
 
 	/*
@@ -260,7 +266,8 @@ toast_insert_or_update(Relation rel, HeapTuple newtup, HeapTuple oldtup,
 		if (biggest_attno < 0)
 			break;
 
-		toast_tuple_externalize(&ttc, biggest_attno, options);
+		toast_tuple_externalize(&ttc, biggest_attno, options,
+								TOAST_MAX_CHUNK_SIZE);
 	}
 
 	/*
@@ -323,7 +330,7 @@ toast_insert_or_update(Relation rel, HeapTuple newtup, HeapTuple oldtup,
 	else
 		result_tuple = newtup;
 
-	toast_tuple_cleanup(&ttc);
+	toast_tuple_cleanup(&ttc, true);
 
 	return result_tuple;
 }
diff --git a/src/backend/access/index/genam.c b/src/backend/access/index/genam.c
index 2599b5d342..233ba24261 100644
--- a/src/backend/access/index/genam.c
+++ b/src/backend/access/index/genam.c
@@ -642,6 +642,26 @@ systable_getnext_ordered(SysScanDesc sysscan, ScanDirection direction)
 	return htup;
 }
 
+/*
+ * systable_getnextslot_ordered
+ *
+ * Return a slot containing the next tuple from an ordered catalog scan,
+ * or NULL if there are no more tuples.
+ */
+TupleTableSlot *
+systable_getnextslot_ordered(SysScanDesc sysscan, ScanDirection direction)
+{
+	Assert(sysscan->irel);
+	if (!index_getnext_slot(sysscan->iscan, direction, sysscan->slot))
+		return NULL;
+
+	/* See notes in systable_getnext */
+	if (sysscan->iscan->xs_recheck)
+		elog(ERROR, "system catalog scans with lossy index conditions are not implemented");
+
+	return sysscan->slot;
+}
+
 /*
  * systable_endscan_ordered --- close scan, release resources
  */
diff --git a/src/backend/access/table/toast_helper.c b/src/backend/access/table/toast_helper.c
index 7532b4f865..e33918a7f4 100644
--- a/src/backend/access/table/toast_helper.c
+++ b/src/backend/access/table/toast_helper.c
@@ -17,6 +17,7 @@
 #include "access/detoast.h"
 #include "access/table.h"
 #include "access/toast_helper.h"
+#include "access/tableam.h"
 #include "access/toast_internals.h"
 
 /*
@@ -247,26 +248,49 @@ toast_tuple_try_compression(ToastTupleContext *ttc, int attribute)
  * Move an attribute to external storage.
  */
 void
-toast_tuple_externalize(ToastTupleContext *ttc, int attribute, int options)
+toast_tuple_externalize(ToastTupleContext *ttc, int attribute, int options,
+						int max_chunk_size)
 {
 	Datum	   *value = &ttc->ttc_values[attribute];
 	Datum		old_value = *value;
 	ToastAttrInfo *attr = &ttc->ttc_attr[attribute];
 
-	attr->tai_colflags |= TOASTCOL_IGNORE;
-	*value = toast_save_datum(ttc->ttc_rel, old_value, attr->tai_oldexternal,
-							  options);
+	/* Initialize for TOAST table access, if not yet done. */
+	if (ttc->ttc_toastrel == NULL)
+	{
+		ttc->ttc_toastrel =
+			table_open(ttc->ttc_rel->rd_rel->reltoastrelid, RowExclusiveLock);
+		ttc->ttc_validtoastidx = toast_open_indexes(ttc->ttc_toastrel,
+													RowExclusiveLock,
+													&ttc->ttc_toastidxs,
+													&ttc->ttc_ntoastidxs);
+	}
+	if (ttc->ttc_toastslot == NULL)
+		ttc->ttc_toastslot = table_slot_create(ttc->ttc_toastrel, NULL);
+
+	/* Do the real work. */
+	*value = toast_save_datum(ttc->ttc_toastrel, ttc->ttc_toastslot,
+							  ttc->ttc_ntoastidxs, ttc->ttc_toastidxs,
+							  ttc->ttc_validtoastidx,
+							  ttc->ttc_rel->rd_toastoid,
+							  old_value, attr->tai_oldexternal,
+							  options, max_chunk_size);
+
+	/* Update bookkeeping information. */
 	if ((attr->tai_colflags & TOASTCOL_NEEDS_FREE) != 0)
 		pfree(DatumGetPointer(old_value));
-	attr->tai_colflags |= TOASTCOL_NEEDS_FREE;
+	attr->tai_colflags |= (TOASTCOL_NEEDS_FREE | TOASTCOL_IGNORE);
 	ttc->ttc_flags |= (TOAST_NEEDS_CHANGE | TOAST_NEEDS_FREE);
 }
 
 /*
  * Perform appropriate cleanup after one tuple has been subjected to TOAST.
+ *
+ * Pass cleanup_toastrel as true to destroy and clear ttc_toastrel and
+ * ttc_toastslot, or false if caller will do it.
  */
 void
-toast_tuple_cleanup(ToastTupleContext *ttc)
+toast_tuple_cleanup(ToastTupleContext *ttc, bool cleanup_toastrel)
 {
 	TupleDesc	tupleDesc = ttc->ttc_rel->rd_att;
 	int			numAttrs = tupleDesc->natts;
@@ -294,14 +318,46 @@ toast_tuple_cleanup(ToastTupleContext *ttc)
 	{
 		int			i;
 
+		/* Initialize for TOAST table access, if not yet done. */
+		if (ttc->ttc_toastrel == NULL)
+		{
+			ttc->ttc_toastrel =
+				table_open(ttc->ttc_rel->rd_rel->reltoastrelid,
+						   RowExclusiveLock);
+			ttc->ttc_validtoastidx = toast_open_indexes(ttc->ttc_toastrel,
+														RowExclusiveLock,
+														&ttc->ttc_toastidxs,
+														&ttc->ttc_ntoastidxs);
+		}
+
+		/* Delete those attributes which require it. */
 		for (i = 0; i < numAttrs; i++)
 		{
 			ToastAttrInfo *attr = &ttc->ttc_attr[i];
 
 			if ((attr->tai_colflags & TOASTCOL_NEEDS_DELETE_OLD) != 0)
-				toast_delete_datum(ttc->ttc_rel, ttc->ttc_oldvalues[i], false);
+				toast_delete_datum(ttc->ttc_toastrel, ttc->ttc_ntoastidxs,
+								   ttc->ttc_toastidxs, ttc->ttc_validtoastidx,
+								   ttc->ttc_oldvalues[i], false, 0);
 		}
 	}
+
+	/*
+	 * Close toast table and indexes and drop slot, if previously done and
+	 * if caller requests it.
+	 */
+	if (cleanup_toastrel && ttc->ttc_toastrel != NULL)
+	{
+		if (ttc->ttc_toastslot != NULL)
+		{
+			ExecDropSingleTupleTableSlot(ttc->ttc_toastslot);
+			ttc->ttc_toastslot = NULL;
+		}
+		toast_close_indexes(ttc->ttc_toastidxs, ttc->ttc_ntoastidxs,
+							RowExclusiveLock);
+		table_close(ttc->ttc_toastrel, RowExclusiveLock);
+		ttc->ttc_toastrel = NULL;
+	}
 }
 
 /*
@@ -310,22 +366,43 @@ toast_tuple_cleanup(ToastTupleContext *ttc)
  */
 void
 toast_delete_external(Relation rel, Datum *values, bool *isnull,
-					  bool is_speculative)
+					  bool is_speculative, uint32 specToken)
 {
 	TupleDesc	tupleDesc = rel->rd_att;
 	int			numAttrs = tupleDesc->natts;
 	int			i;
+	Relation    toastrel = NULL;
+	Relation   *toastidxs;
+	int         num_indexes;
+	int         validIndex;
 
 	for (i = 0; i < numAttrs; i++)
 	{
-		if (TupleDescAttr(tupleDesc, i)->attlen == -1)
-		{
-			Datum		value = values[i];
+		Datum	value;
+
+		if (isnull[i] || TupleDescAttr(tupleDesc, i)->attlen != -1)
+			continue;
+
+		value = values[i];
+		if (!VARATT_IS_EXTERNAL_ONDISK(PointerGetDatum(value)))
+			continue;
 
-			if (isnull[i])
-				continue;
-			else if (VARATT_IS_EXTERNAL_ONDISK(PointerGetDatum(value)))
-				toast_delete_datum(rel, value, is_speculative);
+		/* Initialize for TOAST table access, if not yet done. */
+		if (toastrel == NULL)
+		{
+			toastrel = table_open(rel->rd_rel->reltoastrelid,
+								  RowExclusiveLock);
+			validIndex = toast_open_indexes(toastrel, RowExclusiveLock,
+											&toastidxs, &num_indexes);
 		}
+
+		toast_delete_datum(toastrel, num_indexes, toastidxs, validIndex,
+						   value, is_speculative, specToken);
+	}
+
+	if (toastrel != NULL)
+	{
+		toast_close_indexes(toastidxs, num_indexes, RowExclusiveLock);
+		table_close(toastrel, RowExclusiveLock);
 	}
 }
diff --git a/src/backend/catalog/toasting.c b/src/backend/catalog/toasting.c
index de6282a667..f082463bf6 100644
--- a/src/backend/catalog/toasting.c
+++ b/src/backend/catalog/toasting.c
@@ -258,7 +258,7 @@ create_toast_table(Relation rel, Oid toastOid, Oid toastIndexOid,
 										   toast_typid,
 										   InvalidOid,
 										   rel->rd_rel->relowner,
-										   rel->rd_rel->relam,
+										   table_relation_toast_am(rel),
 										   tupdesc,
 										   NIL,
 										   RELKIND_TOASTVALUE,
diff --git a/src/include/access/genam.h b/src/include/access/genam.h
index 8c053be2ca..a8f5076420 100644
--- a/src/include/access/genam.h
+++ b/src/include/access/genam.h
@@ -21,8 +21,9 @@
 #include "utils/relcache.h"
 #include "utils/snapshot.h"
 
-/* We don't want this file to depend on execnodes.h. */
+/* We don't want this file to depend on execnodes.h or tuptable.h. */
 struct IndexInfo;
+struct TupleTableSlot;
 
 /*
  * Struct for statistics returned by ambuild
@@ -212,6 +213,8 @@ extern SysScanDesc systable_beginscan_ordered(Relation heapRelation,
 											  int nkeys, ScanKey key);
 extern HeapTuple systable_getnext_ordered(SysScanDesc sysscan,
 										  ScanDirection direction);
+extern struct TupleTableSlot *systable_getnextslot_ordered(SysScanDesc sysscan,
+														   ScanDirection direction);
 extern void systable_endscan_ordered(SysScanDesc sysscan);
 
 #endif							/* GENAM_H */
diff --git a/src/include/access/heapam.h b/src/include/access/heapam.h
index 858bcb6bc9..6ee0c6efa7 100644
--- a/src/include/access/heapam.h
+++ b/src/include/access/heapam.h
@@ -143,7 +143,8 @@ extern TM_Result heap_delete(Relation relation, ItemPointer tid,
 							 CommandId cid, Snapshot crosscheck, bool wait,
 							 struct TM_FailureData *tmfd, bool changingPart);
 extern void heap_finish_speculative(Relation relation, ItemPointer tid);
-extern void heap_abort_speculative(Relation relation, ItemPointer tid);
+extern void heap_abort_speculative(Relation relation, ItemPointer tid,
+					   uint32 specToken);
 extern TM_Result heap_update(Relation relation, ItemPointer otid,
 							 HeapTuple newtup,
 							 CommandId cid, Snapshot crosscheck, bool wait,
diff --git a/src/include/access/heaptoast.h b/src/include/access/heaptoast.h
index bf02d2c600..07d36ac968 100644
--- a/src/include/access/heaptoast.h
+++ b/src/include/access/heaptoast.h
@@ -104,7 +104,8 @@ extern HeapTuple toast_insert_or_update(Relation rel,
  *	Called by heap_delete().
  * ----------
  */
-extern void toast_delete(Relation rel, HeapTuple oldtup, bool is_speculative);
+extern void toast_delete(Relation rel, HeapTuple oldtup,
+			 bool is_speculative, uint32 specToken);
 
 /* ----------
  * toast_flatten_tuple -
diff --git a/src/include/access/tableam.h b/src/include/access/tableam.h
index 7f81703b78..521fd6232d 100644
--- a/src/include/access/tableam.h
+++ b/src/include/access/tableam.h
@@ -581,6 +581,27 @@ typedef struct TableAmRoutine
 	 */
 	bool		(*relation_needs_toast_table) (Relation rel);
 
+	/*
+	 * This callback should return the OID of the table AM that implements
+	 * TOAST tables for this AM.  If the relation_needs_toast_table callback
+	 * always returns false, this callback is not required.
+	 */
+	Oid		    (*relation_toast_am) (Relation rel);
+
+	/*
+	 * If this table AM can be used to implement a TOAST table, the following
+	 * field should be set to the maximum number of bytes that can be stored
+	 * in a single TOAST chunk.  It must not be set to a value greater than
+	 * BLCKSZ.  If this table AM is not used to implement a TOAST table, this
+	 * value is ignored.
+	 *
+	 * (Note that there is no requirement that the TOAST table be implemented
+	 * using the same AM as the table to which it is attached.  If this AM
+	 * has TOAST tables but uses some other AM to implement them, this value
+	 * is ignored; it is a property of the TOAST table, not the parent table.)
+	 */
+	int			toast_max_chunk_size;
+
 
 	/* ------------------------------------------------------------------------
 	 * Planner related functions.
@@ -1603,6 +1624,16 @@ table_relation_needs_toast_table(Relation rel)
 	return rel->rd_tableam->relation_needs_toast_table(rel);
 }
 
+/*
+ * Return the OID of the AM that should be used to implement the TOAST table
+ * for this relation.
+ */
+static inline Oid
+table_relation_toast_am(Relation rel)
+{
+	return rel->rd_tableam->relation_toast_am(rel);
+}
+
 
 /* ----------------------------------------------------------------------------
  * Planner related functionality
diff --git a/src/include/access/toast_helper.h b/src/include/access/toast_helper.h
index 7cefacb0ea..cfb4ae0385 100644
--- a/src/include/access/toast_helper.h
+++ b/src/include/access/toast_helper.h
@@ -14,6 +14,7 @@
 #ifndef TOAST_HELPER_H
 #define TOAST_HELPER_H
 
+#include "executor/tuptable.h"
 #include "utils/rel.h"
 
 /*
@@ -51,6 +52,17 @@ typedef struct
 	Datum	   *ttc_oldvalues;	/* values from previous tuple */
 	bool	   *ttc_oldisnull;	/* null flags from previous tuple */
 
+	/*
+	 * Before calling toast_tuple_init, the caller should either initialize
+	 * all of these fields or else set ttc_toastrel and ttc_toastslot to NULL.
+	 * In the latter case, all of the fields will be initialized as required.
+	 */
+	Relation	ttc_toastrel;	/* the toast table for the relation */
+	TupleTableSlot *ttc_toastslot;	/* a slot for the toast table */
+	int			ttc_ntoastidxs; /* # of toast indexes for toast table */
+	Relation   *ttc_toastidxs;	/* array of those toast indexes */
+	int			ttc_validtoastidx;	/* the valid toast index */
+
 	/*
 	 * Before calling toast_tuple_init, the caller should set tts_attr to
 	 * point to an array of ToastAttrInfo structures of a length equal to
@@ -106,10 +118,10 @@ extern int	toast_tuple_find_biggest_attribute(ToastTupleContext *ttc,
 											   bool check_main);
 extern void toast_tuple_try_compression(ToastTupleContext *ttc, int attribute);
 extern void toast_tuple_externalize(ToastTupleContext *ttc, int attribute,
-									int options);
-extern void toast_tuple_cleanup(ToastTupleContext *ttc);
+									int options, int max_chunk_size);
+extern void toast_tuple_cleanup(ToastTupleContext *ttc, bool cleanup_toastrel);
 
 extern void toast_delete_external(Relation rel, Datum *values, bool *isnull,
-								  bool is_speculative);
+								  bool is_speculative, uint32 specToken);
 
 #endif
diff --git a/src/include/access/toast_internals.h b/src/include/access/toast_internals.h
index 494b07a4b1..96f61baf80 100644
--- a/src/include/access/toast_internals.h
+++ b/src/include/access/toast_internals.h
@@ -16,6 +16,8 @@
 #include "utils/relcache.h"
 #include "utils/snapshot.h"
 
+struct TupleTableSlot;
+
 /*
  *	The information at the start of the compressed toast data.
  */
@@ -39,9 +41,16 @@ typedef struct toast_compress_header
 extern Datum toast_compress_datum(Datum value);
 extern Oid	toast_get_valid_index(Oid toastoid, LOCKMODE lock);
 
-extern void toast_delete_datum(Relation rel, Datum value, bool is_speculative);
-extern Datum toast_save_datum(Relation rel, Datum value,
-							  struct varlena *oldexternal, int options);
+extern void toast_delete_datum(Relation toastrel, int num_indexes,
+							   Relation *toastidxs, int validIndex,
+							   Datum value, bool is_speculative,
+							   uint32 specToken);
+extern Datum toast_save_datum(Relation toastrel,
+							  struct TupleTableSlot *toastslot,
+							  int num_indexes, Relation *toastidxs,
+							  int validIndex, Oid toastoid,
+							  Datum value, struct varlena *oldexternal,
+							  int options, int max_chunk_size);
 
 extern int	toast_open_indexes(Relation toastrel,
 							   LOCKMODE lock,
-- 
2.17.2 (Apple Git-113)

From 1d3dc0c37714f7d9ba1f168e0dbc54578fab3c88 Mon Sep 17 00:00:00 2001
From: Robert Haas <rhaas@postgresql.org>
Date: Fri, 4 Oct 2019 14:24:28 -0400
Subject: [PATCH v7] Allow TOAST tables to be implemented using table AMs other
 than heap.
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

toast_fetch_datum, toast_save_datum, and toast_delete_datum are
adjusted to use tableam rather than heap-specific functions.  This
might have some performance impact, but this patch attempts to
mitigate that by restructuring things so that we don't open and close
the toast table and indexes multiple times per tuple.

tableam now exposes an integer value (not a callback) for the
maximum TOAST chunk size, and has a new callback allowing table
AMs to specify the AM that should be used to implement the TOAST
table. Previously, the toast AM was always the same as the table AM.

Patch by me, reviewed and tested by Prabhat Sabu, Thomas Munro,
Andres Freund, and Álvaro Herrera.

Discussion: http://postgr.es/m/CA+TgmoZv-=2iWM4jcw5ZhJeL18HF96+W1yJeYrnGMYdkFFnEpQ@mail.gmail.com
---
 src/backend/access/common/detoast.c         |  62 +++++-----
 src/backend/access/common/toast_internals.c | 127 +++++++-------------
 src/backend/access/heap/heapam.c            |   6 +-
 src/backend/access/heap/heapam_handler.c    |  14 ++-
 src/backend/access/heap/heaptoast.c         |  19 ++-
 src/backend/access/index/genam.c            |  20 +++
 src/backend/access/table/toast_helper.c     | 107 ++++++++++++++---
 src/backend/catalog/toasting.c              |   2 +-
 src/include/access/genam.h                  |   5 +-
 src/include/access/heapam.h                 |   3 +-
 src/include/access/heaptoast.h              |   2 +-
 src/include/access/tableam.h                |  31 +++++
 src/include/access/toast_helper.h           |  18 ++-
 src/include/access/toast_internals.h        |  15 ++-
 14 files changed, 283 insertions(+), 148 deletions(-)

diff --git a/src/backend/access/common/detoast.c b/src/backend/access/common/detoast.c
index b25ca6810b..8550587c08 100644
--- a/src/backend/access/common/detoast.c
+++ b/src/backend/access/common/detoast.c
@@ -15,10 +15,11 @@
 
 #include "access/detoast.h"
 #include "access/genam.h"
-#include "access/heaptoast.h"
 #include "access/table.h"
 #include "access/toast_internals.h"
+#include "access/tableam.h"
 #include "common/pg_lzcompress.h"
+#include "executor/tuptable.h"
 #include "utils/expandeddatum.h"
 #include "utils/fmgroids.h"
 #include "utils/rel.h"
@@ -327,8 +328,7 @@ toast_fetch_datum(struct varlena *attr)
 	Relation   *toastidxs;
 	ScanKeyData toastkey;
 	SysScanDesc toastscan;
-	HeapTuple	ttup;
-	TupleDesc	toasttupDesc;
+	TupleTableSlot *slot;
 	struct varlena *result;
 	struct varatt_external toast_pointer;
 	int32		ressize;
@@ -336,11 +336,11 @@ toast_fetch_datum(struct varlena *attr)
 				nextidx;
 	int32		numchunks;
 	Pointer		chunk;
-	bool		isnull;
 	char	   *chunkdata;
 	int32		chunksize;
 	int			num_indexes;
 	int			validIndex;
+	int			max_chunk_size;
 	SnapshotData SnapshotToast;
 
 	if (!VARATT_IS_EXTERNAL_ONDISK(attr))
@@ -350,7 +350,6 @@ toast_fetch_datum(struct varlena *attr)
 	VARATT_EXTERNAL_GET_POINTER(toast_pointer, attr);
 
 	ressize = toast_pointer.va_extsize;
-	numchunks = ((ressize - 1) / TOAST_MAX_CHUNK_SIZE) + 1;
 
 	result = (struct varlena *) palloc(ressize + VARHDRSZ);
 
@@ -363,7 +362,9 @@ toast_fetch_datum(struct varlena *attr)
 	 * Open the toast relation and its indexes
 	 */
 	toastrel = table_open(toast_pointer.va_toastrelid, AccessShareLock);
-	toasttupDesc = toastrel->rd_att;
+
+	max_chunk_size = toastrel->rd_tableam->toast_max_chunk_size;
+	numchunks = ((ressize - 1) / max_chunk_size) + 1;
 
 	/* Look for the valid index of the toast relation */
 	validIndex = toast_open_indexes(toastrel,
@@ -391,15 +392,15 @@ toast_fetch_datum(struct varlena *attr)
 	init_toast_snapshot(&SnapshotToast);
 	toastscan = systable_beginscan_ordered(toastrel, toastidxs[validIndex],
 										   &SnapshotToast, 1, &toastkey);
-	while ((ttup = systable_getnext_ordered(toastscan, ForwardScanDirection)) != NULL)
+	while ((slot = systable_getnextslot_ordered(toastscan, ForwardScanDirection)) != NULL)
 	{
 		/*
 		 * Have a chunk, extract the sequence number and the data
 		 */
-		residx = DatumGetInt32(fastgetattr(ttup, 2, toasttupDesc, &isnull));
-		Assert(!isnull);
-		chunk = DatumGetPointer(fastgetattr(ttup, 3, toasttupDesc, &isnull));
-		Assert(!isnull);
+		slot_getsomeattrs(slot, 3);
+		Assert(!slot->tts_isnull[1] && !slot->tts_isnull[2]);
+		residx = DatumGetInt32(slot->tts_values[1]);
+		chunk = DatumGetPointer(slot->tts_values[2]);
 		if (!VARATT_IS_EXTENDED(chunk))
 		{
 			chunksize = VARSIZE(chunk) - VARHDRSZ;
@@ -433,23 +434,23 @@ toast_fetch_datum(struct varlena *attr)
 									 RelationGetRelationName(toastrel))));
 		if (residx < numchunks - 1)
 		{
-			if (chunksize != TOAST_MAX_CHUNK_SIZE)
+			if (chunksize != max_chunk_size)
 				ereport(ERROR,
 						(errcode(ERRCODE_DATA_CORRUPTED),
 						 errmsg_internal("unexpected chunk size %d (expected %d) in chunk %d of %d for toast value %u in %s",
-										 chunksize, (int) TOAST_MAX_CHUNK_SIZE,
+										 chunksize, max_chunk_size,
 										 residx, numchunks,
 										 toast_pointer.va_valueid,
 										 RelationGetRelationName(toastrel))));
 		}
 		else if (residx == numchunks - 1)
 		{
-			if ((residx * TOAST_MAX_CHUNK_SIZE + chunksize) != ressize)
+			if ((residx * max_chunk_size + chunksize) != ressize)
 				ereport(ERROR,
 						(errcode(ERRCODE_DATA_CORRUPTED),
 						 errmsg_internal("unexpected chunk size %d (expected %d) in final chunk %d for toast value %u in %s",
 										 chunksize,
-										 (int) (ressize - residx * TOAST_MAX_CHUNK_SIZE),
+										 (int) (ressize - residx * max_chunk_size),
 										 residx,
 										 toast_pointer.va_valueid,
 										 RelationGetRelationName(toastrel))));
@@ -466,7 +467,7 @@ toast_fetch_datum(struct varlena *attr)
 		/*
 		 * Copy the data into proper place in our result
 		 */
-		memcpy(VARDATA(result) + residx * TOAST_MAX_CHUNK_SIZE,
+		memcpy(VARDATA(result) + residx * max_chunk_size,
 			   chunkdata,
 			   chunksize);
 
@@ -534,6 +535,7 @@ toast_fetch_datum_slice(struct varlena *attr, int32 sliceoffset, int32 length)
 	int32		chcpyend;
 	int			num_indexes;
 	int			validIndex;
+	int			max_chunk_size;
 	SnapshotData SnapshotToast;
 
 	if (!VARATT_IS_EXTERNAL_ONDISK(attr))
@@ -550,7 +552,6 @@ toast_fetch_datum_slice(struct varlena *attr, int32 sliceoffset, int32 length)
 	Assert(!VARATT_EXTERNAL_IS_COMPRESSED(toast_pointer) || 0 == sliceoffset);
 
 	attrsize = toast_pointer.va_extsize;
-	totalchunks = ((attrsize - 1) / TOAST_MAX_CHUNK_SIZE) + 1;
 
 	if (sliceoffset >= attrsize)
 	{
@@ -579,19 +580,22 @@ toast_fetch_datum_slice(struct varlena *attr, int32 sliceoffset, int32 length)
 	if (length == 0)
 		return result;			/* Can save a lot of work at this point! */
 
-	startchunk = sliceoffset / TOAST_MAX_CHUNK_SIZE;
-	endchunk = (sliceoffset + length - 1) / TOAST_MAX_CHUNK_SIZE;
-	numchunks = (endchunk - startchunk) + 1;
-
-	startoffset = sliceoffset % TOAST_MAX_CHUNK_SIZE;
-	endoffset = (sliceoffset + length - 1) % TOAST_MAX_CHUNK_SIZE;
-
 	/*
 	 * Open the toast relation and its indexes
 	 */
 	toastrel = table_open(toast_pointer.va_toastrelid, AccessShareLock);
 	toasttupDesc = toastrel->rd_att;
 
+	max_chunk_size = toastrel->rd_tableam->toast_max_chunk_size;
+	totalchunks = ((attrsize - 1) / max_chunk_size) + 1;
+
+	startchunk = sliceoffset / max_chunk_size;
+	endchunk = (sliceoffset + length - 1) / max_chunk_size;
+	numchunks = (endchunk - startchunk) + 1;
+
+	startoffset = sliceoffset % max_chunk_size;
+	endoffset = (sliceoffset + length - 1) % max_chunk_size;
+
 	/* Look for the valid index of toast relation */
 	validIndex = toast_open_indexes(toastrel,
 									AccessShareLock,
@@ -680,19 +684,19 @@ toast_fetch_datum_slice(struct varlena *attr, int32 sliceoffset, int32 length)
 				 RelationGetRelationName(toastrel));
 		if (residx < totalchunks - 1)
 		{
-			if (chunksize != TOAST_MAX_CHUNK_SIZE)
+			if (chunksize != max_chunk_size)
 				elog(ERROR, "unexpected chunk size %d (expected %d) in chunk %d of %d for toast value %u in %s when fetching slice",
-					 chunksize, (int) TOAST_MAX_CHUNK_SIZE,
+					 chunksize, max_chunk_size,
 					 residx, totalchunks,
 					 toast_pointer.va_valueid,
 					 RelationGetRelationName(toastrel));
 		}
 		else if (residx == totalchunks - 1)
 		{
-			if ((residx * TOAST_MAX_CHUNK_SIZE + chunksize) != attrsize)
+			if ((residx * max_chunk_size + chunksize) != attrsize)
 				elog(ERROR, "unexpected chunk size %d (expected %d) in final chunk %d for toast value %u in %s when fetching slice",
 					 chunksize,
-					 (int) (attrsize - residx * TOAST_MAX_CHUNK_SIZE),
+					 (int) (attrsize - residx * max_chunk_size),
 					 residx,
 					 toast_pointer.va_valueid,
 					 RelationGetRelationName(toastrel));
@@ -715,7 +719,7 @@ toast_fetch_datum_slice(struct varlena *attr, int32 sliceoffset, int32 length)
 			chcpyend = endoffset;
 
 		memcpy(VARDATA(result) +
-			   (residx * TOAST_MAX_CHUNK_SIZE - sliceoffset) + chcpystrt,
+			   (residx * max_chunk_size - sliceoffset) + chcpystrt,
 			   chunkdata + chcpystrt,
 			   (chcpyend - chcpystrt) + 1);
 
diff --git a/src/backend/access/common/toast_internals.c b/src/backend/access/common/toast_internals.c
index a971242490..beb303034d 100644
--- a/src/backend/access/common/toast_internals.c
+++ b/src/backend/access/common/toast_internals.c
@@ -15,9 +15,8 @@
 
 #include "access/detoast.h"
 #include "access/genam.h"
-#include "access/heapam.h"
-#include "access/heaptoast.h"
 #include "access/table.h"
+#include "access/tableam.h"
 #include "access/toast_internals.h"
 #include "access/xact.h"
 #include "catalog/catalog.h"
@@ -100,22 +99,21 @@ toast_compress_datum(Datum value)
  *	Save one single datum into the secondary relation and return
  *	a Datum reference for it.
  *
- * rel: the main relation we're working with (not the toast rel!)
+ * toastrel: the TOAST relation we're working with (not the main rel!)
+ * toastslot: a slot corresponding to 'toastrel'
+ * num_indexes, toastidxs, validIndex: as returned by toast_open_indexes
+ * toastoid: the toast OID that should be inserted into the new TOAST pointer
  * value: datum to be pushed to toast storage
  * oldexternal: if not NULL, toast pointer previously representing the datum
- * options: options to be passed to heap_insert() for toast rows
+ * options: options to be passed to table_tuple_insert() for toast rows
  * ----------
  */
 Datum
-toast_save_datum(Relation rel, Datum value,
-				 struct varlena *oldexternal, int options)
+toast_save_datum(Relation toastrel, TupleTableSlot *toastslot,
+				 int num_indexes, Relation *toastidxs, int validIndex,
+				 Oid toastoid, Datum value, struct varlena *oldexternal,
+				 int options, int max_chunk_size)
 {
-	Relation	toastrel;
-	Relation   *toastidxs;
-	HeapTuple	toasttup;
-	TupleDesc	toasttupDesc;
-	Datum		t_values[3];
-	bool		t_isnull[3];
 	CommandId	mycid = GetCurrentCommandId(true);
 	struct varlena *result;
 	struct varatt_external toast_pointer;
@@ -123,7 +121,7 @@ toast_save_datum(Relation rel, Datum value,
 	{
 		struct varlena hdr;
 		/* this is to make the union big enough for a chunk: */
-		char		data[TOAST_MAX_CHUNK_SIZE + VARHDRSZ];
+		char		data[BLCKSZ + VARHDRSZ];
 		/* ensure union is aligned well enough: */
 		int32		align_it;
 	}			chunk_data;
@@ -132,24 +130,9 @@ toast_save_datum(Relation rel, Datum value,
 	char	   *data_p;
 	int32		data_todo;
 	Pointer		dval = DatumGetPointer(value);
-	int			num_indexes;
-	int			validIndex;
 
 	Assert(!VARATT_IS_EXTERNAL(value));
-
-	/*
-	 * Open the toast relation and its indexes.  We can use the index to check
-	 * uniqueness of the OID we assign to the toasted item, even though it has
-	 * additional columns besides OID.
-	 */
-	toastrel = table_open(rel->rd_rel->reltoastrelid, RowExclusiveLock);
-	toasttupDesc = toastrel->rd_att;
-
-	/* Open all the toast indexes and look for the valid one */
-	validIndex = toast_open_indexes(toastrel,
-									RowExclusiveLock,
-									&toastidxs,
-									&num_indexes);
+	Assert(max_chunk_size <= BLCKSZ);
 
 	/*
 	 * Get the data pointer and length, and compute va_rawsize and va_extsize.
@@ -189,11 +172,11 @@ toast_save_datum(Relation rel, Datum value,
 	 *
 	 * Normally this is the actual OID of the target toast table, but during
 	 * table-rewriting operations such as CLUSTER, we have to insert the OID
-	 * of the table's real permanent toast table instead.  rd_toastoid is set
+	 * of the table's real permanent toast table instead.  toastoid is set
 	 * if we have to substitute such an OID.
 	 */
-	if (OidIsValid(rel->rd_toastoid))
-		toast_pointer.va_toastrelid = rel->rd_toastoid;
+	if (OidIsValid(toastoid))
+		toast_pointer.va_toastrelid = toastoid;
 	else
 		toast_pointer.va_toastrelid = RelationGetRelid(toastrel);
 
@@ -209,7 +192,7 @@ toast_save_datum(Relation rel, Datum value,
 	 * options have been changed), we have to pick a value ID that doesn't
 	 * conflict with either new or existing toast value OIDs.
 	 */
-	if (!OidIsValid(rel->rd_toastoid))
+	if (!OidIsValid(toastoid))
 	{
 		/* normal case: just choose an unused OID */
 		toast_pointer.va_valueid =
@@ -228,7 +211,7 @@ toast_save_datum(Relation rel, Datum value,
 			Assert(VARATT_IS_EXTERNAL_ONDISK(oldexternal));
 			/* Must copy to access aligned fields */
 			VARATT_EXTERNAL_GET_POINTER(old_toast_pointer, oldexternal);
-			if (old_toast_pointer.va_toastrelid == rel->rd_toastoid)
+			if (old_toast_pointer.va_toastrelid == toastoid)
 			{
 				/* This value came from the old toast table; reuse its OID */
 				toast_pointer.va_valueid = old_toast_pointer.va_valueid;
@@ -270,20 +253,11 @@ toast_save_datum(Relation rel, Datum value,
 					GetNewOidWithIndex(toastrel,
 									   RelationGetRelid(toastidxs[validIndex]),
 									   (AttrNumber) 1);
-			} while (toastid_valueid_exists(rel->rd_toastoid,
+			} while (toastid_valueid_exists(toastoid,
 											toast_pointer.va_valueid));
 		}
 	}
 
-	/*
-	 * Initialize constant parts of the tuple data
-	 */
-	t_values[0] = ObjectIdGetDatum(toast_pointer.va_valueid);
-	t_values[2] = PointerGetDatum(&chunk_data);
-	t_isnull[0] = false;
-	t_isnull[1] = false;
-	t_isnull[2] = false;
-
 	/*
 	 * Split up the item into chunks
 	 */
@@ -296,17 +270,22 @@ toast_save_datum(Relation rel, Datum value,
 		/*
 		 * Calculate the size of this chunk
 		 */
-		chunk_size = Min(TOAST_MAX_CHUNK_SIZE, data_todo);
+		chunk_size = Min(max_chunk_size, data_todo);
 
 		/*
 		 * Build a tuple and store it
 		 */
-		t_values[1] = Int32GetDatum(chunk_seq++);
+		toastslot->tts_values[0] = ObjectIdGetDatum(toast_pointer.va_valueid);
+		toastslot->tts_values[1] = Int32GetDatum(chunk_seq++);
 		SET_VARSIZE(&chunk_data, chunk_size + VARHDRSZ);
 		memcpy(VARDATA(&chunk_data), data_p, chunk_size);
-		toasttup = heap_form_tuple(toasttupDesc, t_values, t_isnull);
+		toastslot->tts_values[2] = PointerGetDatum(&chunk_data);
+		toastslot->tts_isnull[0] = false;
+		toastslot->tts_isnull[1] = false;
+		toastslot->tts_isnull[2] = false;
+		ExecStoreVirtualTuple(toastslot);
 
-		heap_insert(toastrel, toasttup, mycid, options, NULL);
+		table_tuple_insert(toastrel, toastslot, mycid, options, NULL);
 
 		/*
 		 * Create the index entry.  We cheat a little here by not using
@@ -323,8 +302,9 @@ toast_save_datum(Relation rel, Datum value,
 		{
 			/* Only index relations marked as ready can be updated */
 			if (toastidxs[i]->rd_index->indisready)
-				index_insert(toastidxs[i], t_values, t_isnull,
-							 &(toasttup->t_self),
+				index_insert(toastidxs[i], toastslot->tts_values,
+							 toastslot->tts_isnull,
+							 &(toastslot->tts_tid),
 							 toastrel,
 							 toastidxs[i]->rd_index->indisunique ?
 							 UNIQUE_CHECK_YES : UNIQUE_CHECK_NO,
@@ -332,9 +312,9 @@ toast_save_datum(Relation rel, Datum value,
 		}
 
 		/*
-		 * Free memory
+		 * Clear slot
 		 */
-		heap_freetuple(toasttup);
+		ExecClearTuple(toastslot);
 
 		/*
 		 * Move on to next chunk
@@ -343,12 +323,6 @@ toast_save_datum(Relation rel, Datum value,
 		data_p += chunk_size;
 	}
 
-	/*
-	 * Done - close toast relation and its indexes
-	 */
-	toast_close_indexes(toastidxs, num_indexes, RowExclusiveLock);
-	table_close(toastrel, RowExclusiveLock);
-
 	/*
 	 * Create the TOAST pointer value that we'll return
 	 */
@@ -366,35 +340,24 @@ toast_save_datum(Relation rel, Datum value,
  * ----------
  */
 void
-toast_delete_datum(Relation rel, Datum value, bool is_speculative)
+toast_delete_datum(Relation toastrel, int num_indexes, Relation *toastidxs,
+				   int validIndex, Datum value, bool is_speculative,
+				   uint32 specToken)
 {
 	struct varlena *attr = (struct varlena *) DatumGetPointer(value);
 	struct varatt_external toast_pointer;
-	Relation	toastrel;
-	Relation   *toastidxs;
 	ScanKeyData toastkey;
 	SysScanDesc toastscan;
-	HeapTuple	toasttup;
-	int			num_indexes;
-	int			validIndex;
+	TupleTableSlot *slot;
 	SnapshotData SnapshotToast;
 
-	if (!VARATT_IS_EXTERNAL_ONDISK(attr))
-		return;
+	Assert(VARATT_IS_EXTERNAL_ONDISK(attr));
 
 	/* Must copy to access aligned fields */
 	VARATT_EXTERNAL_GET_POINTER(toast_pointer, attr);
 
-	/*
-	 * Open the toast relation and its indexes
-	 */
-	toastrel = table_open(toast_pointer.va_toastrelid, RowExclusiveLock);
-
-	/* Fetch valid relation used for process */
-	validIndex = toast_open_indexes(toastrel,
-									RowExclusiveLock,
-									&toastidxs,
-									&num_indexes);
+	/* Check that caller gave us the correct TOAST relation. */
+	Assert(toast_pointer.va_toastrelid == RelationGetRelid(toastrel));
 
 	/*
 	 * Setup a scan key to find chunks with matching va_valueid
@@ -412,23 +375,19 @@ toast_delete_datum(Relation rel, Datum value, bool is_speculative)
 	init_toast_snapshot(&SnapshotToast);
 	toastscan = systable_beginscan_ordered(toastrel, toastidxs[validIndex],
 										   &SnapshotToast, 1, &toastkey);
-	while ((toasttup = systable_getnext_ordered(toastscan, ForwardScanDirection)) != NULL)
+	while ((slot = systable_getnextslot_ordered(toastscan, ForwardScanDirection)) != NULL)
 	{
 		/*
 		 * Have a chunk, delete it
 		 */
 		if (is_speculative)
-			heap_abort_speculative(toastrel, &toasttup->t_self);
+			table_tuple_complete_speculative(toastrel, slot, specToken, false);
 		else
-			simple_heap_delete(toastrel, &toasttup->t_self);
+			simple_table_tuple_delete(toastrel, &slot->tts_tid, &SnapshotToast);
 	}
 
-	/*
-	 * End scan and close relations
-	 */
+	/* End scan */
 	systable_endscan_ordered(toastscan);
-	toast_close_indexes(toastidxs, num_indexes, RowExclusiveLock);
-	table_close(toastrel, RowExclusiveLock);
 }
 
 /* ----------
diff --git a/src/backend/access/heap/heapam.c b/src/backend/access/heap/heapam.c
index 0128bb34ef..08bd087bc8 100644
--- a/src/backend/access/heap/heapam.c
+++ b/src/backend/access/heap/heapam.c
@@ -2809,7 +2809,7 @@ l1:
 		Assert(!HeapTupleHasExternal(&tp));
 	}
 	else if (HeapTupleHasExternal(&tp))
-		heap_toast_delete(relation, &tp, false);
+		heap_toast_delete(relation, &tp, false, 0);
 
 	/*
 	 * Mark tuple for invalidation from system caches at next command
@@ -5564,7 +5564,7 @@ heap_finish_speculative(Relation relation, ItemPointer tid)
  * confirmation records.
  */
 void
-heap_abort_speculative(Relation relation, ItemPointer tid)
+heap_abort_speculative(Relation relation, ItemPointer tid, uint32 specToken)
 {
 	TransactionId xid = GetCurrentTransactionId();
 	ItemId		lp;
@@ -5673,7 +5673,7 @@ heap_abort_speculative(Relation relation, ItemPointer tid)
 	if (HeapTupleHasExternal(&tp))
 	{
 		Assert(!IsToastRelation(relation));
-		heap_toast_delete(relation, &tp, true);
+		heap_toast_delete(relation, &tp, true, specToken);
 	}
 
 	/*
diff --git a/src/backend/access/heap/heapam_handler.c b/src/backend/access/heap/heapam_handler.c
index 2dd8821fac..97a7433092 100644
--- a/src/backend/access/heap/heapam_handler.c
+++ b/src/backend/access/heap/heapam_handler.c
@@ -28,6 +28,7 @@
 #include "access/rewriteheap.h"
 #include "access/tableam.h"
 #include "access/tsmapi.h"
+#include "access/heaptoast.h"
 #include "access/xact.h"
 #include "catalog/catalog.h"
 #include "catalog/index.h"
@@ -292,7 +293,7 @@ heapam_tuple_complete_speculative(Relation relation, TupleTableSlot *slot,
 	if (succeeded)
 		heap_finish_speculative(relation, &slot->tts_tid);
 	else
-		heap_abort_speculative(relation, &slot->tts_tid);
+		heap_abort_speculative(relation, &slot->tts_tid, specToken);
 
 	if (shouldFree)
 		pfree(tuple);
@@ -2041,6 +2042,15 @@ heapam_relation_needs_toast_table(Relation rel)
 	return (tuple_length > TOAST_TUPLE_THRESHOLD);
 }
 
+/*
+ * TOAST tables for heap relations are just heap relations.
+ */
+static Oid
+heapam_relation_toast_am(Relation rel)
+{
+	return rel->rd_rel->relam;
+}
+
 
 /* ------------------------------------------------------------------------
  * Planner related callbacks for the heap AM
@@ -2539,6 +2549,8 @@ static const TableAmRoutine heapam_methods = {
 
 	.relation_size = table_block_relation_size,
 	.relation_needs_toast_table = heapam_relation_needs_toast_table,
+	.relation_toast_am = heapam_relation_toast_am,
+	.toast_max_chunk_size = TOAST_MAX_CHUNK_SIZE,
 
 	.relation_estimate_size = heapam_estimate_rel_size,
 
diff --git a/src/backend/access/heap/heaptoast.c b/src/backend/access/heap/heaptoast.c
index dcfdee4467..cca916a39f 100644
--- a/src/backend/access/heap/heaptoast.c
+++ b/src/backend/access/heap/heaptoast.c
@@ -38,7 +38,8 @@
  * ----------
  */
 void
-heap_toast_delete(Relation rel, HeapTuple oldtup, bool is_speculative)
+heap_toast_delete(Relation rel, HeapTuple oldtup, bool is_speculative,
+				  uint32 specToken)
 {
 	TupleDesc	tupleDesc;
 	Datum		toast_values[MaxHeapAttributeNumber];
@@ -68,7 +69,8 @@ heap_toast_delete(Relation rel, HeapTuple oldtup, bool is_speculative)
 	heap_deform_tuple(oldtup, tupleDesc, toast_values, toast_isnull);
 
 	/* Do the real work. */
-	toast_delete_external(rel, toast_values, toast_isnull, is_speculative);
+	toast_delete_external(rel, toast_values, toast_isnull, is_speculative,
+						  specToken);
 }
 
 
@@ -151,6 +153,8 @@ heap_toast_insert_or_update(Relation rel, HeapTuple newtup, HeapTuple oldtup,
 		ttc.ttc_oldvalues = toast_oldvalues;
 		ttc.ttc_oldisnull = toast_oldisnull;
 	}
+	ttc.ttc_toastrel = NULL;
+	ttc.ttc_toastslot = NULL;
 	ttc.ttc_attr = toast_attr;
 	toast_tuple_init(&ttc);
 
@@ -207,7 +211,8 @@ heap_toast_insert_or_update(Relation rel, HeapTuple newtup, HeapTuple oldtup,
 		 */
 		if (toast_attr[biggest_attno].tai_size > maxDataLen &&
 			rel->rd_rel->reltoastrelid != InvalidOid)
-			toast_tuple_externalize(&ttc, biggest_attno, options);
+			toast_tuple_externalize(&ttc, biggest_attno, options,
+									TOAST_MAX_CHUNK_SIZE);
 	}
 
 	/*
@@ -224,7 +229,8 @@ heap_toast_insert_or_update(Relation rel, HeapTuple newtup, HeapTuple oldtup,
 		biggest_attno = toast_tuple_find_biggest_attribute(&ttc, false, false);
 		if (biggest_attno < 0)
 			break;
-		toast_tuple_externalize(&ttc, biggest_attno, options);
+		toast_tuple_externalize(&ttc, biggest_attno, options,
+								TOAST_MAX_CHUNK_SIZE);
 	}
 
 	/*
@@ -260,7 +266,8 @@ heap_toast_insert_or_update(Relation rel, HeapTuple newtup, HeapTuple oldtup,
 		if (biggest_attno < 0)
 			break;
 
-		toast_tuple_externalize(&ttc, biggest_attno, options);
+		toast_tuple_externalize(&ttc, biggest_attno, options,
+								TOAST_MAX_CHUNK_SIZE);
 	}
 
 	/*
@@ -323,7 +330,7 @@ heap_toast_insert_or_update(Relation rel, HeapTuple newtup, HeapTuple oldtup,
 	else
 		result_tuple = newtup;
 
-	toast_tuple_cleanup(&ttc);
+	toast_tuple_cleanup(&ttc, true);
 
 	return result_tuple;
 }
diff --git a/src/backend/access/index/genam.c b/src/backend/access/index/genam.c
index 2599b5d342..233ba24261 100644
--- a/src/backend/access/index/genam.c
+++ b/src/backend/access/index/genam.c
@@ -642,6 +642,26 @@ systable_getnext_ordered(SysScanDesc sysscan, ScanDirection direction)
 	return htup;
 }
 
+/*
+ * systable_getnextslot_ordered
+ *
+ * Return a slot containing the next tuple from an ordered catalog scan,
+ * or NULL if there are no more tuples.
+ */
+TupleTableSlot *
+systable_getnextslot_ordered(SysScanDesc sysscan, ScanDirection direction)
+{
+	Assert(sysscan->irel);
+	if (!index_getnext_slot(sysscan->iscan, direction, sysscan->slot))
+		return NULL;
+
+	/* See notes in systable_getnext */
+	if (sysscan->iscan->xs_recheck)
+		elog(ERROR, "system catalog scans with lossy index conditions are not implemented");
+
+	return sysscan->slot;
+}
+
 /*
  * systable_endscan_ordered --- close scan, release resources
  */
diff --git a/src/backend/access/table/toast_helper.c b/src/backend/access/table/toast_helper.c
index 7381be8669..dedc123e31 100644
--- a/src/backend/access/table/toast_helper.c
+++ b/src/backend/access/table/toast_helper.c
@@ -17,6 +17,7 @@
 #include "access/detoast.h"
 #include "access/table.h"
 #include "access/toast_helper.h"
+#include "access/tableam.h"
 #include "access/toast_internals.h"
 
 /*
@@ -247,26 +248,49 @@ toast_tuple_try_compression(ToastTupleContext *ttc, int attribute)
  * Move an attribute to external storage.
  */
 void
-toast_tuple_externalize(ToastTupleContext *ttc, int attribute, int options)
+toast_tuple_externalize(ToastTupleContext *ttc, int attribute, int options,
+						int max_chunk_size)
 {
 	Datum	   *value = &ttc->ttc_values[attribute];
 	Datum		old_value = *value;
 	ToastAttrInfo *attr = &ttc->ttc_attr[attribute];
 
-	attr->tai_colflags |= TOASTCOL_IGNORE;
-	*value = toast_save_datum(ttc->ttc_rel, old_value, attr->tai_oldexternal,
-							  options);
+	/* Initialize for TOAST table access, if not yet done. */
+	if (ttc->ttc_toastrel == NULL)
+	{
+		ttc->ttc_toastrel =
+			table_open(ttc->ttc_rel->rd_rel->reltoastrelid, RowExclusiveLock);
+		ttc->ttc_validtoastidx = toast_open_indexes(ttc->ttc_toastrel,
+													RowExclusiveLock,
+													&ttc->ttc_toastidxs,
+													&ttc->ttc_ntoastidxs);
+	}
+	if (ttc->ttc_toastslot == NULL)
+		ttc->ttc_toastslot = table_slot_create(ttc->ttc_toastrel, NULL);
+
+	/* Do the real work. */
+	*value = toast_save_datum(ttc->ttc_toastrel, ttc->ttc_toastslot,
+							  ttc->ttc_ntoastidxs, ttc->ttc_toastidxs,
+							  ttc->ttc_validtoastidx,
+							  ttc->ttc_rel->rd_toastoid,
+							  old_value, attr->tai_oldexternal,
+							  options, max_chunk_size);
+
+	/* Update bookkeeping information. */
 	if ((attr->tai_colflags & TOASTCOL_NEEDS_FREE) != 0)
 		pfree(DatumGetPointer(old_value));
-	attr->tai_colflags |= TOASTCOL_NEEDS_FREE;
+	attr->tai_colflags |= (TOASTCOL_NEEDS_FREE | TOASTCOL_IGNORE);
 	ttc->ttc_flags |= (TOAST_NEEDS_CHANGE | TOAST_NEEDS_FREE);
 }
 
 /*
  * Perform appropriate cleanup after one tuple has been subjected to TOAST.
+ *
+ * Pass cleanup_toastrel as true to destroy and clear ttc_toastrel and
+ * ttc_toastslot, or false if caller will do it.
  */
 void
-toast_tuple_cleanup(ToastTupleContext *ttc)
+toast_tuple_cleanup(ToastTupleContext *ttc, bool cleanup_toastrel)
 {
 	TupleDesc	tupleDesc = ttc->ttc_rel->rd_att;
 	int			numAttrs = tupleDesc->natts;
@@ -294,14 +318,46 @@ toast_tuple_cleanup(ToastTupleContext *ttc)
 	{
 		int			i;
 
+		/* Initialize for TOAST table access, if not yet done. */
+		if (ttc->ttc_toastrel == NULL)
+		{
+			ttc->ttc_toastrel =
+				table_open(ttc->ttc_rel->rd_rel->reltoastrelid,
+						   RowExclusiveLock);
+			ttc->ttc_validtoastidx = toast_open_indexes(ttc->ttc_toastrel,
+														RowExclusiveLock,
+														&ttc->ttc_toastidxs,
+														&ttc->ttc_ntoastidxs);
+		}
+
+		/* Delete those attributes which require it. */
 		for (i = 0; i < numAttrs; i++)
 		{
 			ToastAttrInfo *attr = &ttc->ttc_attr[i];
 
 			if ((attr->tai_colflags & TOASTCOL_NEEDS_DELETE_OLD) != 0)
-				toast_delete_datum(ttc->ttc_rel, ttc->ttc_oldvalues[i], false);
+				toast_delete_datum(ttc->ttc_toastrel, ttc->ttc_ntoastidxs,
+								   ttc->ttc_toastidxs, ttc->ttc_validtoastidx,
+								   ttc->ttc_oldvalues[i], false, 0);
 		}
 	}
+
+	/*
+	 * Close toast table and indexes and drop slot, if previously done and
+	 * if caller requests it.
+	 */
+	if (cleanup_toastrel && ttc->ttc_toastrel != NULL)
+	{
+		if (ttc->ttc_toastslot != NULL)
+		{
+			ExecDropSingleTupleTableSlot(ttc->ttc_toastslot);
+			ttc->ttc_toastslot = NULL;
+		}
+		toast_close_indexes(ttc->ttc_toastidxs, ttc->ttc_ntoastidxs,
+							RowExclusiveLock);
+		table_close(ttc->ttc_toastrel, RowExclusiveLock);
+		ttc->ttc_toastrel = NULL;
+	}
 }
 
 /*
@@ -310,22 +366,43 @@ toast_tuple_cleanup(ToastTupleContext *ttc)
  */
 void
 toast_delete_external(Relation rel, Datum *values, bool *isnull,
-					  bool is_speculative)
+					  bool is_speculative, uint32 specToken)
 {
 	TupleDesc	tupleDesc = rel->rd_att;
 	int			numAttrs = tupleDesc->natts;
 	int			i;
+	Relation    toastrel = NULL;
+	Relation   *toastidxs;
+	int         num_indexes;
+	int         validIndex;
 
 	for (i = 0; i < numAttrs; i++)
 	{
-		if (TupleDescAttr(tupleDesc, i)->attlen == -1)
-		{
-			Datum		value = values[i];
+		Datum	value;
+
+		if (isnull[i] || TupleDescAttr(tupleDesc, i)->attlen != -1)
+			continue;
+
+		value = values[i];
+		if (!VARATT_IS_EXTERNAL_ONDISK(PointerGetDatum(value)))
+			continue;
 
-			if (isnull[i])
-				continue;
-			else if (VARATT_IS_EXTERNAL_ONDISK(PointerGetDatum(value)))
-				toast_delete_datum(rel, value, is_speculative);
+		/* Initialize for TOAST table access, if not yet done. */
+		if (toastrel == NULL)
+		{
+			toastrel = table_open(rel->rd_rel->reltoastrelid,
+								  RowExclusiveLock);
+			validIndex = toast_open_indexes(toastrel, RowExclusiveLock,
+											&toastidxs, &num_indexes);
 		}
+
+		toast_delete_datum(toastrel, num_indexes, toastidxs, validIndex,
+						   value, is_speculative, specToken);
+	}
+
+	if (toastrel != NULL)
+	{
+		toast_close_indexes(toastidxs, num_indexes, RowExclusiveLock);
+		table_close(toastrel, RowExclusiveLock);
 	}
 }
diff --git a/src/backend/catalog/toasting.c b/src/backend/catalog/toasting.c
index de6282a667..f082463bf6 100644
--- a/src/backend/catalog/toasting.c
+++ b/src/backend/catalog/toasting.c
@@ -258,7 +258,7 @@ create_toast_table(Relation rel, Oid toastOid, Oid toastIndexOid,
 										   toast_typid,
 										   InvalidOid,
 										   rel->rd_rel->relowner,
-										   rel->rd_rel->relam,
+										   table_relation_toast_am(rel),
 										   tupdesc,
 										   NIL,
 										   RELKIND_TOASTVALUE,
diff --git a/src/include/access/genam.h b/src/include/access/genam.h
index a813b004be..128df5e916 100644
--- a/src/include/access/genam.h
+++ b/src/include/access/genam.h
@@ -21,8 +21,9 @@
 #include "utils/relcache.h"
 #include "utils/snapshot.h"
 
-/* We don't want this file to depend on execnodes.h. */
+/* We don't want this file to depend on execnodes.h or tuptable.h. */
 struct IndexInfo;
+struct TupleTableSlot;
 
 /*
  * Struct for statistics returned by ambuild
@@ -220,6 +221,8 @@ extern SysScanDesc systable_beginscan_ordered(Relation heapRelation,
 											  int nkeys, ScanKey key);
 extern HeapTuple systable_getnext_ordered(SysScanDesc sysscan,
 										  ScanDirection direction);
+extern struct TupleTableSlot *systable_getnextslot_ordered(SysScanDesc sysscan,
+														   ScanDirection direction);
 extern void systable_endscan_ordered(SysScanDesc sysscan);
 
 #endif							/* GENAM_H */
diff --git a/src/include/access/heapam.h b/src/include/access/heapam.h
index 858bcb6bc9..6ee0c6efa7 100644
--- a/src/include/access/heapam.h
+++ b/src/include/access/heapam.h
@@ -143,7 +143,8 @@ extern TM_Result heap_delete(Relation relation, ItemPointer tid,
 							 CommandId cid, Snapshot crosscheck, bool wait,
 							 struct TM_FailureData *tmfd, bool changingPart);
 extern void heap_finish_speculative(Relation relation, ItemPointer tid);
-extern void heap_abort_speculative(Relation relation, ItemPointer tid);
+extern void heap_abort_speculative(Relation relation, ItemPointer tid,
+					   uint32 specToken);
 extern TM_Result heap_update(Relation relation, ItemPointer otid,
 							 HeapTuple newtup,
 							 CommandId cid, Snapshot crosscheck, bool wait,
diff --git a/src/include/access/heaptoast.h b/src/include/access/heaptoast.h
index 488a2e4a7f..23f62dc4af 100644
--- a/src/include/access/heaptoast.h
+++ b/src/include/access/heaptoast.h
@@ -104,7 +104,7 @@ extern HeapTuple heap_toast_insert_or_update(Relation rel, HeapTuple newtup,
  * ----------
  */
 extern void heap_toast_delete(Relation rel, HeapTuple oldtup,
-							  bool is_speculative);
+							  bool is_speculative, uint32 specToken);
 
 /* ----------
  * toast_flatten_tuple -
diff --git a/src/include/access/tableam.h b/src/include/access/tableam.h
index 7f81703b78..521fd6232d 100644
--- a/src/include/access/tableam.h
+++ b/src/include/access/tableam.h
@@ -581,6 +581,27 @@ typedef struct TableAmRoutine
 	 */
 	bool		(*relation_needs_toast_table) (Relation rel);
 
+	/*
+	 * This callback should return the OID of the table AM that implements
+	 * TOAST tables for this AM.  If the relation_needs_toast_table callback
+	 * always returns false, this callback is not required.
+	 */
+	Oid		    (*relation_toast_am) (Relation rel);
+
+	/*
+	 * If this table AM can be used to implement a TOAST table, the following
+	 * field should be set to the maximum number of bytes that can be stored
+	 * in a single TOAST chunk.  It must not be set to a value greater than
+	 * BLCKSZ.  If this table AM is not used to implement a TOAST table, this
+	 * value is ignored.
+	 *
+	 * (Note that there is no requirement that the TOAST table be implemented
+	 * using the same AM as the table to which it is attached.  If this AM
+	 * has TOAST tables but uses some other AM to implement them, this value
+	 * is ignored; it is a property of the TOAST table, not the parent table.)
+	 */
+	int			toast_max_chunk_size;
+
 
 	/* ------------------------------------------------------------------------
 	 * Planner related functions.
@@ -1603,6 +1624,16 @@ table_relation_needs_toast_table(Relation rel)
 	return rel->rd_tableam->relation_needs_toast_table(rel);
 }
 
+/*
+ * Return the OID of the AM that should be used to implement the TOAST table
+ * for this relation.
+ */
+static inline Oid
+table_relation_toast_am(Relation rel)
+{
+	return rel->rd_tableam->relation_toast_am(rel);
+}
+
 
 /* ----------------------------------------------------------------------------
  * Planner related functionality
diff --git a/src/include/access/toast_helper.h b/src/include/access/toast_helper.h
index 7cefacb0ea..cfb4ae0385 100644
--- a/src/include/access/toast_helper.h
+++ b/src/include/access/toast_helper.h
@@ -14,6 +14,7 @@
 #ifndef TOAST_HELPER_H
 #define TOAST_HELPER_H
 
+#include "executor/tuptable.h"
 #include "utils/rel.h"
 
 /*
@@ -51,6 +52,17 @@ typedef struct
 	Datum	   *ttc_oldvalues;	/* values from previous tuple */
 	bool	   *ttc_oldisnull;	/* null flags from previous tuple */
 
+	/*
+	 * Before calling toast_tuple_init, the caller should either initialize
+	 * all of these fields or else set ttc_toastrel and ttc_toastslot to NULL.
+	 * In the latter case, all of the fields will be initialized as required.
+	 */
+	Relation	ttc_toastrel;	/* the toast table for the relation */
+	TupleTableSlot *ttc_toastslot;	/* a slot for the toast table */
+	int			ttc_ntoastidxs; /* # of toast indexes for toast table */
+	Relation   *ttc_toastidxs;	/* array of those toast indexes */
+	int			ttc_validtoastidx;	/* the valid toast index */
+
 	/*
 	 * Before calling toast_tuple_init, the caller should set tts_attr to
 	 * point to an array of ToastAttrInfo structures of a length equal to
@@ -106,10 +118,10 @@ extern int	toast_tuple_find_biggest_attribute(ToastTupleContext *ttc,
 											   bool check_main);
 extern void toast_tuple_try_compression(ToastTupleContext *ttc, int attribute);
 extern void toast_tuple_externalize(ToastTupleContext *ttc, int attribute,
-									int options);
-extern void toast_tuple_cleanup(ToastTupleContext *ttc);
+									int options, int max_chunk_size);
+extern void toast_tuple_cleanup(ToastTupleContext *ttc, bool cleanup_toastrel);
 
 extern void toast_delete_external(Relation rel, Datum *values, bool *isnull,
-								  bool is_speculative);
+								  bool is_speculative, uint32 specToken);
 
 #endif
diff --git a/src/include/access/toast_internals.h b/src/include/access/toast_internals.h
index 9bd1c97771..eb6137dfab 100644
--- a/src/include/access/toast_internals.h
+++ b/src/include/access/toast_internals.h
@@ -16,6 +16,8 @@
 #include "utils/relcache.h"
 #include "utils/snapshot.h"
 
+struct TupleTableSlot;
+
 /*
  *	The information at the start of the compressed toast data.
  */
@@ -40,9 +42,16 @@ typedef struct toast_compress_header
 extern Datum toast_compress_datum(Datum value);
 extern Oid	toast_get_valid_index(Oid toastoid, LOCKMODE lock);
 
-extern void toast_delete_datum(Relation rel, Datum value, bool is_speculative);
-extern Datum toast_save_datum(Relation rel, Datum value,
-							  struct varlena *oldexternal, int options);
+extern void toast_delete_datum(Relation toastrel, int num_indexes,
+							   Relation *toastidxs, int validIndex,
+							   Datum value, bool is_speculative,
+							   uint32 specToken);
+extern Datum toast_save_datum(Relation toastrel,
+							  struct TupleTableSlot *toastslot,
+							  int num_indexes, Relation *toastidxs,
+							  int validIndex, Oid toastoid,
+							  Datum value, struct varlena *oldexternal,
+							  int options, int max_chunk_size);
 
 extern int	toast_open_indexes(Relation toastrel,
 							   LOCKMODE lock,
-- 
2.17.2 (Apple Git-113)

From ebdb3fbf034eefa0ca8eb34d863d959f320f26cc Mon Sep 17 00:00:00 2001
From: Robert Haas <rhaas@postgresql.org>
Date: Fri, 8 Nov 2019 11:50:52 -0500
Subject: [PATCH 2/2] Move heap-specific detoasting logic into a separate
 function.

The new function, heap_fetch_toast_slice, is shared between
toast_fetch_datum_slice and toast_fetch_datum, and does all the
work of scanning the TOAST table, fetching chunks, and storing
them into the space allocated for the result varlena.

As an incidental side effect, this allows toast_fetch_datum_slice
to perform the scan with only a single scankey if all chunks are
being fetched, which might have some tiny performance benefit.
---
 src/backend/access/common/detoast.c | 244 ++++++++--------------------
 1 file changed, 71 insertions(+), 173 deletions(-)

diff --git a/src/backend/access/common/detoast.c b/src/backend/access/common/detoast.c
index ae7daa24de..0914efee3e 100644
--- a/src/backend/access/common/detoast.c
+++ b/src/backend/access/common/detoast.c
@@ -27,6 +27,9 @@ static struct varlena *toast_fetch_datum(struct varlena *attr);
 static struct varlena *toast_fetch_datum_slice(struct varlena *attr,
 											   int32 sliceoffset,
 											   int32 slicelength);
+static void heap_fetch_toast_slice(Relation toastrel, Oid valueid,
+								   int32 attrsize, int32 sliceoffset,
+								   int32 slicelength, struct varlena *result);
 static struct varlena *toast_decompress_datum(struct varlena *attr);
 static struct varlena *toast_decompress_datum_slice(struct varlena *attr, int32 slicelength);
 
@@ -325,19 +328,9 @@ static struct varlena *
 toast_fetch_datum(struct varlena *attr)
 {
 	Relation	toastrel;
-	Relation   *toastidxs;
-	ScanKeyData toastkey;
-	SysScanDesc toastscan;
-	HeapTuple	ttup;
-	TupleDesc	toasttupDesc;
 	struct varlena *result;
 	struct varatt_external toast_pointer;
 	int32		attrsize;
-	int32		nextidx;
-	int32		totalchunks;
-	int			num_indexes;
-	int			validIndex;
-	SnapshotData SnapshotToast;
 
 	if (!VARATT_IS_EXTERNAL_ONDISK(attr))
 		elog(ERROR, "toast_fetch_datum shouldn't be called for non-ondisk datums");
@@ -346,7 +339,6 @@ toast_fetch_datum(struct varlena *attr)
 	VARATT_EXTERNAL_GET_POINTER(toast_pointer, attr);
 
 	attrsize = toast_pointer.va_extsize;
-	totalchunks = ((attrsize - 1) / TOAST_MAX_CHUNK_SIZE) + 1;
 
 	result = (struct varlena *) palloc(attrsize + VARHDRSZ);
 
@@ -355,130 +347,19 @@ toast_fetch_datum(struct varlena *attr)
 	else
 		SET_VARSIZE(result, attrsize + VARHDRSZ);
 
+	if (attrsize == 0)
+		return result;		/* Probably shouldn't happen, but just in case. */
+
 	/*
 	 * Open the toast relation and its indexes
 	 */
 	toastrel = table_open(toast_pointer.va_toastrelid, AccessShareLock);
-	toasttupDesc = toastrel->rd_att;
-
-	/* Look for the valid index of the toast relation */
-	validIndex = toast_open_indexes(toastrel,
-									AccessShareLock,
-									&toastidxs,
-									&num_indexes);
-
-	/*
-	 * Setup a scan key to fetch from the index by va_valueid
-	 */
-	ScanKeyInit(&toastkey,
-				(AttrNumber) 1,
-				BTEqualStrategyNumber, F_OIDEQ,
-				ObjectIdGetDatum(toast_pointer.va_valueid));
-
-	/*
-	 * Read the chunks by index
-	 *
-	 * Note that because the index is actually on (valueid, chunkidx) we will
-	 * see the chunks in chunkidx order, even though we didn't explicitly ask
-	 * for it.
-	 */
-	nextidx = 0;
 
-	init_toast_snapshot(&SnapshotToast);
-	toastscan = systable_beginscan_ordered(toastrel, toastidxs[validIndex],
-										   &SnapshotToast, 1, &toastkey);
-	while ((ttup = systable_getnext_ordered(toastscan, ForwardScanDirection)) != NULL)
-	{
-		int32		residx;
-		Pointer		chunk;
-		bool		isnull;
-		char	   *chunkdata;
-		int32		chunksize;
-		int32		expected_size;
+	/* Fetch all chunks */
+	heap_fetch_toast_slice(toastrel, toast_pointer.va_valueid, attrsize, 0,
+						   attrsize, result);
 
-		/*
-		 * Have a chunk, extract the sequence number and the data
-		 */
-		residx = DatumGetInt32(fastgetattr(ttup, 2, toasttupDesc, &isnull));
-		Assert(!isnull);
-		chunk = DatumGetPointer(fastgetattr(ttup, 3, toasttupDesc, &isnull));
-		Assert(!isnull);
-		if (!VARATT_IS_EXTENDED(chunk))
-		{
-			chunksize = VARSIZE(chunk) - VARHDRSZ;
-			chunkdata = VARDATA(chunk);
-		}
-		else if (VARATT_IS_SHORT(chunk))
-		{
-			/* could happen due to heap_form_tuple doing its thing */
-			chunksize = VARSIZE_SHORT(chunk) - VARHDRSZ_SHORT;
-			chunkdata = VARDATA_SHORT(chunk);
-		}
-		else
-		{
-			/* should never happen */
-			elog(ERROR, "found toasted toast chunk for toast value %u in %s",
-				 toast_pointer.va_valueid,
-				 RelationGetRelationName(toastrel));
-			chunksize = 0;		/* keep compiler quiet */
-			chunkdata = NULL;
-		}
-
-		/*
-		 * Some checks on the data we've found
-		 */
-		if (residx != nextidx)
-			ereport(ERROR,
-					(errcode(ERRCODE_DATA_CORRUPTED),
-					 errmsg_internal("unexpected chunk number %d (expected %d) for toast value %u in %s",
-									 residx, nextidx,
-									 toast_pointer.va_valueid,
-									 RelationGetRelationName(toastrel))));
-		if (residx > totalchunks - 1)
-			ereport(ERROR,
-					(errcode(ERRCODE_DATA_CORRUPTED),
-					 errmsg_internal("unexpected chunk number %d (out of range %d..%d) for toast value %u in %s",
-									 residx,
-									 0, totalchunks - 1,
-									 toast_pointer.va_valueid,
-									 RelationGetRelationName(toastrel))));
-		expected_size = residx < totalchunks - 1 ? TOAST_MAX_CHUNK_SIZE
-			: attrsize % TOAST_MAX_CHUNK_SIZE;
-		if (chunksize != expected_size)
-			ereport(ERROR,
-					(errcode(ERRCODE_DATA_CORRUPTED),
-					 errmsg_internal("unexpected chunk size %d (expected %d) in chunk %d for toast value %u in %s",
-									 chunksize, expected_size,
-									 residx,
-									 toast_pointer.va_valueid,
-									 RelationGetRelationName(toastrel))));
-
-		/*
-		 * Copy the data into proper place in our result
-		 */
-		memcpy(VARDATA(result) + residx * TOAST_MAX_CHUNK_SIZE,
-			   chunkdata,
-			   chunksize);
-
-		nextidx++;
-	}
-
-	/*
-	 * Final checks that we successfully fetched the datum
-	 */
-	if (nextidx != totalchunks)
-		ereport(ERROR,
-				(errcode(ERRCODE_DATA_CORRUPTED),
-				 errmsg_internal("missing chunk number %d for toast value %u in %s",
-								 nextidx,
-								 toast_pointer.va_valueid,
-								 RelationGetRelationName(toastrel))));
-
-	/*
-	 * End scan and close relations
-	 */
-	systable_endscan_ordered(toastscan);
-	toast_close_indexes(toastidxs, num_indexes, AccessShareLock);
+	/* Close toast table */
 	table_close(toastrel, AccessShareLock);
 
 	return result;
@@ -500,22 +381,9 @@ toast_fetch_datum_slice(struct varlena *attr, int32 sliceoffset,
 						int32 slicelength)
 {
 	Relation	toastrel;
-	Relation   *toastidxs;
-	ScanKeyData toastkey[3];
-	int			nscankeys;
-	SysScanDesc toastscan;
-	HeapTuple	ttup;
-	TupleDesc	toasttupDesc;
 	struct varlena *result;
 	struct varatt_external toast_pointer;
 	int32		attrsize;
-	int32		nextidx;
-	int			startchunk;
-	int			endchunk;
-	int			totalchunks;
-	int			num_indexes;
-	int			validIndex;
-	SnapshotData SnapshotToast;
 
 	if (!VARATT_IS_EXTERNAL_ONDISK(attr))
 		elog(ERROR, "toast_fetch_datum_slice shouldn't be called for non-ondisk datums");
@@ -531,7 +399,6 @@ toast_fetch_datum_slice(struct varlena *attr, int32 sliceoffset,
 	Assert(!VARATT_EXTERNAL_IS_COMPRESSED(toast_pointer) || 0 == sliceoffset);
 
 	attrsize = toast_pointer.va_extsize;
-	totalchunks = ((attrsize - 1) / TOAST_MAX_CHUNK_SIZE) + 1;
 
 	if (sliceoffset >= attrsize)
 	{
@@ -560,15 +427,47 @@ toast_fetch_datum_slice(struct varlena *attr, int32 sliceoffset,
 	if (slicelength == 0)
 		return result;			/* Can save a lot of work at this point! */
 
-	startchunk = sliceoffset / TOAST_MAX_CHUNK_SIZE;
-	endchunk = (sliceoffset + slicelength - 1) / TOAST_MAX_CHUNK_SIZE;
-	Assert(endchunk <= totalchunks);
-
-	/*
-	 * Open the toast relation and its indexes
-	 */
+	/* Open the toast relation */
 	toastrel = table_open(toast_pointer.va_toastrelid, AccessShareLock);
-	toasttupDesc = toastrel->rd_att;
+
+	/* Fetch all chunks */
+	heap_fetch_toast_slice(toastrel, toast_pointer.va_valueid, attrsize,
+						   sliceoffset, slicelength, result);
+
+	/* Close toast table */
+	table_close(toastrel, AccessShareLock);
+
+	return result;
+}
+
+/*
+ * Fetch a TOAST slice from a heap table.
+ *
+ * toastrel is the relation from which chunks are to be fetched.
+ * valueid identifies the TOAST value from which chunks are being fetched.
+ * attrsize is the total size of the TOAST value.
+ * sliceoffset is the byte offset within the TOAST value from which to fetch.
+ * slicelength is the number of bytes to be fetched from the TOAST value.
+ * result is the varlena into which the results should be written.
+ */
+static void
+heap_fetch_toast_slice(Relation toastrel, Oid valueid, int32 attrsize,
+					   int32 sliceoffset, int32 slicelength,
+					   struct varlena *result)
+{
+	Relation   *toastidxs;
+	ScanKeyData toastkey[3];
+	TupleDesc	toasttupDesc = toastrel->rd_att;
+	int			nscankeys;
+	SysScanDesc toastscan;
+	HeapTuple	ttup;
+	int32		nextidx;
+	int32		totalchunks = ((attrsize - 1) / TOAST_MAX_CHUNK_SIZE) + 1;
+	int			startchunk;
+	int			endchunk;
+	int			num_indexes;
+	int			validIndex;
+	SnapshotData SnapshotToast;
 
 	/* Look for the valid index of toast relation */
 	validIndex = toast_open_indexes(toastrel,
@@ -576,6 +475,10 @@ toast_fetch_datum_slice(struct varlena *attr, int32 sliceoffset,
 									&toastidxs,
 									&num_indexes);
 
+	startchunk = sliceoffset / TOAST_MAX_CHUNK_SIZE;
+	endchunk = (sliceoffset + slicelength - 1) / TOAST_MAX_CHUNK_SIZE;
+	Assert(endchunk <= totalchunks);
+
 	/*
 	 * Setup a scan key to fetch from the index. This is either two keys or
 	 * three depending on the number of chunks.
@@ -583,12 +486,15 @@ toast_fetch_datum_slice(struct varlena *attr, int32 sliceoffset,
 	ScanKeyInit(&toastkey[0],
 				(AttrNumber) 1,
 				BTEqualStrategyNumber, F_OIDEQ,
-				ObjectIdGetDatum(toast_pointer.va_valueid));
+				ObjectIdGetDatum(valueid));
 
 	/*
-	 * Use equality condition for one chunk, a range condition otherwise:
+	 * No addition condition if fetching all chuns. Otherwise, use an
+	 * equality condition for one chunk, and a range condition otherwise.
 	 */
-	if (startchunk == endchunk)
+	if (startchunk == 0 && endchunk == totalchunks - 1)
+		nscankeys = 1;
+	else if (startchunk == endchunk)
 	{
 		ScanKeyInit(&toastkey[1],
 					(AttrNumber) 2,
@@ -609,15 +515,17 @@ toast_fetch_datum_slice(struct varlena *attr, int32 sliceoffset,
 		nscankeys = 3;
 	}
 
+	/* Prepare for scan */
+	init_toast_snapshot(&SnapshotToast);
+	toastscan = systable_beginscan_ordered(toastrel, toastidxs[validIndex],
+										   &SnapshotToast, nscankeys, toastkey);
+
 	/*
 	 * Read the chunks by index
 	 *
 	 * The index is on (valueid, chunkidx) so they will come in order
 	 */
-	init_toast_snapshot(&SnapshotToast);
 	nextidx = startchunk;
-	toastscan = systable_beginscan_ordered(toastrel, toastidxs[validIndex],
-										   &SnapshotToast, nscankeys, toastkey);
 	while ((ttup = systable_getnext_ordered(toastscan, ForwardScanDirection)) != NULL)
 	{
 		int32		residx;
@@ -651,8 +559,7 @@ toast_fetch_datum_slice(struct varlena *attr, int32 sliceoffset,
 		{
 			/* should never happen */
 			elog(ERROR, "found toasted toast chunk for toast value %u in %s",
-				 toast_pointer.va_valueid,
-				 RelationGetRelationName(toastrel));
+				 valueid, RelationGetRelationName(toastrel));
 			chunksize = 0;		/* keep compiler quiet */
 			chunkdata = NULL;
 		}
@@ -664,16 +571,14 @@ toast_fetch_datum_slice(struct varlena *attr, int32 sliceoffset,
 			ereport(ERROR,
 					(errcode(ERRCODE_DATA_CORRUPTED),
 					 errmsg_internal("unexpected chunk number %d (expected %d) for toast value %u in %s",
-									 residx, nextidx,
-									 toast_pointer.va_valueid,
+									 residx, nextidx, valueid,
 									 RelationGetRelationName(toastrel))));
 		if (residx > endchunk)
 			ereport(ERROR,
 					(errcode(ERRCODE_DATA_CORRUPTED),
 					 errmsg_internal("unexpected chunk number %d (out of range %d..%d) for toast value %u in %s",
 									 residx,
-									 startchunk, endchunk,
-									 toast_pointer.va_valueid,
+									 startchunk, endchunk, valueid,
 									 RelationGetRelationName(toastrel))));
 		expected_size = residx < totalchunks - 1 ? TOAST_MAX_CHUNK_SIZE
 			: attrsize % TOAST_MAX_CHUNK_SIZE;
@@ -682,8 +587,7 @@ toast_fetch_datum_slice(struct varlena *attr, int32 sliceoffset,
 					(errcode(ERRCODE_DATA_CORRUPTED),
 					 errmsg_internal("unexpected chunk size %d (expected %d) in chunk %d for toast value %u in %s",
 									 chunksize, expected_size,
-									 residx,
-									 toast_pointer.va_valueid,
+									 residx, valueid,
 									 RelationGetRelationName(toastrel))));
 
 		/*
@@ -711,18 +615,12 @@ toast_fetch_datum_slice(struct varlena *attr, int32 sliceoffset,
 		ereport(ERROR,
 				(errcode(ERRCODE_DATA_CORRUPTED),
 				 errmsg_internal("missing chunk number %d for toast value %u in %s",
-								 nextidx,
-								 toast_pointer.va_valueid,
+								 nextidx, valueid,
 								 RelationGetRelationName(toastrel))));
 
-	/*
-	 * End scan and close relations
-	 */
+	/* End scan and close indexes. */
 	systable_endscan_ordered(toastscan);
 	toast_close_indexes(toastidxs, num_indexes, AccessShareLock);
-	table_close(toastrel, AccessShareLock);
-
-	return result;
 }
 
 /* ----------
-- 
2.17.2 (Apple Git-113)

From d3cd945e2571aea730b7fc4285a1685e905375fc Mon Sep 17 00:00:00 2001
From: Robert Haas <rhaas@postgresql.org>
Date: Fri, 8 Nov 2019 10:24:34 -0500
Subject: [PATCH 1/2] Code cleanup for toast_fetch_datum and
 toast_fetch_datum_slice.

Rework some of the checks for bad TOAST chunks to be a bit simpler
and easier to understand. These checks verify that (1) we get all
and only the chunk numbers we expect to see and (2) each chunk has
the expected size. However, the existing code was a bit hard to
understand, at least for me; try to make it clearer.

As part of that, have toast_fetch_datum_slice check the relationship
between endchunk and totalchunks only with an Assert() rather than
checking every chunk number against both values. There's no need to
check that relationship in production builds because it's not a
function of whether on-disk corruption is present; it's just a
question of whether the code does the right math.

Also, have toast_fetch_datum_slice() use ereport(ERROR) rather than
elog(ERROR). Commit fd6ec93bf890314ac694dc8a7f3c45702ecc1bbd made
the two functions inconsistent with each other.

In toast_fetch_datum, rename two variables for better consistency with
toast_fetch_datum_slice. In toast_fetch_datum_slice, eliminate several
variables that are used only once, and rename length to slicelength
for clarity. In both functions, move some variables from the function
scope into the function's main loop.
---
 src/backend/access/common/detoast.c | 188 +++++++++++++---------------
 1 file changed, 86 insertions(+), 102 deletions(-)

diff --git a/src/backend/access/common/detoast.c b/src/backend/access/common/detoast.c
index f752ac7bbc..ae7daa24de 100644
--- a/src/backend/access/common/detoast.c
+++ b/src/backend/access/common/detoast.c
@@ -25,7 +25,8 @@
 
 static struct varlena *toast_fetch_datum(struct varlena *attr);
 static struct varlena *toast_fetch_datum_slice(struct varlena *attr,
-											   int32 sliceoffset, int32 length);
+											   int32 sliceoffset,
+											   int32 slicelength);
 static struct varlena *toast_decompress_datum(struct varlena *attr);
 static struct varlena *toast_decompress_datum_slice(struct varlena *attr, int32 slicelength);
 
@@ -331,14 +332,9 @@ toast_fetch_datum(struct varlena *attr)
 	TupleDesc	toasttupDesc;
 	struct varlena *result;
 	struct varatt_external toast_pointer;
-	int32		ressize;
-	int32		residx,
-				nextidx;
-	int32		numchunks;
-	Pointer		chunk;
-	bool		isnull;
-	char	   *chunkdata;
-	int32		chunksize;
+	int32		attrsize;
+	int32		nextidx;
+	int32		totalchunks;
 	int			num_indexes;
 	int			validIndex;
 	SnapshotData SnapshotToast;
@@ -349,15 +345,15 @@ toast_fetch_datum(struct varlena *attr)
 	/* Must copy to access aligned fields */
 	VARATT_EXTERNAL_GET_POINTER(toast_pointer, attr);
 
-	ressize = toast_pointer.va_extsize;
-	numchunks = ((ressize - 1) / TOAST_MAX_CHUNK_SIZE) + 1;
+	attrsize = toast_pointer.va_extsize;
+	totalchunks = ((attrsize - 1) / TOAST_MAX_CHUNK_SIZE) + 1;
 
-	result = (struct varlena *) palloc(ressize + VARHDRSZ);
+	result = (struct varlena *) palloc(attrsize + VARHDRSZ);
 
 	if (VARATT_EXTERNAL_IS_COMPRESSED(toast_pointer))
-		SET_VARSIZE_COMPRESSED(result, ressize + VARHDRSZ);
+		SET_VARSIZE_COMPRESSED(result, attrsize + VARHDRSZ);
 	else
-		SET_VARSIZE(result, ressize + VARHDRSZ);
+		SET_VARSIZE(result, attrsize + VARHDRSZ);
 
 	/*
 	 * Open the toast relation and its indexes
@@ -393,6 +389,13 @@ toast_fetch_datum(struct varlena *attr)
 										   &SnapshotToast, 1, &toastkey);
 	while ((ttup = systable_getnext_ordered(toastscan, ForwardScanDirection)) != NULL)
 	{
+		int32		residx;
+		Pointer		chunk;
+		bool		isnull;
+		char	   *chunkdata;
+		int32		chunksize;
+		int32		expected_size;
+
 		/*
 		 * Have a chunk, extract the sequence number and the data
 		 */
@@ -431,35 +434,22 @@ toast_fetch_datum(struct varlena *attr)
 									 residx, nextidx,
 									 toast_pointer.va_valueid,
 									 RelationGetRelationName(toastrel))));
-		if (residx < numchunks - 1)
-		{
-			if (chunksize != TOAST_MAX_CHUNK_SIZE)
-				ereport(ERROR,
-						(errcode(ERRCODE_DATA_CORRUPTED),
-						 errmsg_internal("unexpected chunk size %d (expected %d) in chunk %d of %d for toast value %u in %s",
-										 chunksize, (int) TOAST_MAX_CHUNK_SIZE,
-										 residx, numchunks,
-										 toast_pointer.va_valueid,
-										 RelationGetRelationName(toastrel))));
-		}
-		else if (residx == numchunks - 1)
-		{
-			if ((residx * TOAST_MAX_CHUNK_SIZE + chunksize) != ressize)
-				ereport(ERROR,
-						(errcode(ERRCODE_DATA_CORRUPTED),
-						 errmsg_internal("unexpected chunk size %d (expected %d) in final chunk %d for toast value %u in %s",
-										 chunksize,
-										 (int) (ressize - residx * TOAST_MAX_CHUNK_SIZE),
-										 residx,
-										 toast_pointer.va_valueid,
-										 RelationGetRelationName(toastrel))));
-		}
-		else
+		if (residx > totalchunks - 1)
 			ereport(ERROR,
 					(errcode(ERRCODE_DATA_CORRUPTED),
 					 errmsg_internal("unexpected chunk number %d (out of range %d..%d) for toast value %u in %s",
 									 residx,
-									 0, numchunks - 1,
+									 0, totalchunks - 1,
+									 toast_pointer.va_valueid,
+									 RelationGetRelationName(toastrel))));
+		expected_size = residx < totalchunks - 1 ? TOAST_MAX_CHUNK_SIZE
+			: attrsize % TOAST_MAX_CHUNK_SIZE;
+		if (chunksize != expected_size)
+			ereport(ERROR,
+					(errcode(ERRCODE_DATA_CORRUPTED),
+					 errmsg_internal("unexpected chunk size %d (expected %d) in chunk %d for toast value %u in %s",
+									 chunksize, expected_size,
+									 residx,
 									 toast_pointer.va_valueid,
 									 RelationGetRelationName(toastrel))));
 
@@ -476,7 +466,7 @@ toast_fetch_datum(struct varlena *attr)
 	/*
 	 * Final checks that we successfully fetched the datum
 	 */
-	if (nextidx != numchunks)
+	if (nextidx != totalchunks)
 		ereport(ERROR,
 				(errcode(ERRCODE_DATA_CORRUPTED),
 				 errmsg_internal("missing chunk number %d for toast value %u in %s",
@@ -506,7 +496,8 @@ toast_fetch_datum(struct varlena *attr)
  * ----------
  */
 static struct varlena *
-toast_fetch_datum_slice(struct varlena *attr, int32 sliceoffset, int32 length)
+toast_fetch_datum_slice(struct varlena *attr, int32 sliceoffset,
+						int32 slicelength)
 {
 	Relation	toastrel;
 	Relation   *toastidxs;
@@ -518,20 +509,10 @@ toast_fetch_datum_slice(struct varlena *attr, int32 sliceoffset, int32 length)
 	struct varlena *result;
 	struct varatt_external toast_pointer;
 	int32		attrsize;
-	int32		residx;
 	int32		nextidx;
-	int			numchunks;
 	int			startchunk;
 	int			endchunk;
-	int32		startoffset;
-	int32		endoffset;
 	int			totalchunks;
-	Pointer		chunk;
-	bool		isnull;
-	char	   *chunkdata;
-	int32		chunksize;
-	int32		chcpystrt;
-	int32		chcpyend;
 	int			num_indexes;
 	int			validIndex;
 	SnapshotData SnapshotToast;
@@ -555,7 +536,7 @@ toast_fetch_datum_slice(struct varlena *attr, int32 sliceoffset, int32 length)
 	if (sliceoffset >= attrsize)
 	{
 		sliceoffset = 0;
-		length = 0;
+		slicelength = 0;
 	}
 
 	/*
@@ -563,28 +544,25 @@ toast_fetch_datum_slice(struct varlena *attr, int32 sliceoffset, int32 length)
 	 * rawsize tracking amount of raw data, which is stored at the beginning
 	 * as an int32 value).
 	 */
-	if (VARATT_EXTERNAL_IS_COMPRESSED(toast_pointer) && length > 0)
-		length = length + sizeof(int32);
+	if (VARATT_EXTERNAL_IS_COMPRESSED(toast_pointer) && slicelength > 0)
+		slicelength = slicelength + sizeof(int32);
 
-	if (((sliceoffset + length) > attrsize) || length < 0)
-		length = attrsize - sliceoffset;
+	if (((sliceoffset + slicelength) > attrsize) || slicelength < 0)
+		slicelength = attrsize - sliceoffset;
 
-	result = (struct varlena *) palloc(length + VARHDRSZ);
+	result = (struct varlena *) palloc(slicelength + VARHDRSZ);
 
 	if (VARATT_EXTERNAL_IS_COMPRESSED(toast_pointer))
-		SET_VARSIZE_COMPRESSED(result, length + VARHDRSZ);
+		SET_VARSIZE_COMPRESSED(result, slicelength + VARHDRSZ);
 	else
-		SET_VARSIZE(result, length + VARHDRSZ);
+		SET_VARSIZE(result, slicelength + VARHDRSZ);
 
-	if (length == 0)
+	if (slicelength == 0)
 		return result;			/* Can save a lot of work at this point! */
 
 	startchunk = sliceoffset / TOAST_MAX_CHUNK_SIZE;
-	endchunk = (sliceoffset + length - 1) / TOAST_MAX_CHUNK_SIZE;
-	numchunks = (endchunk - startchunk) + 1;
-
-	startoffset = sliceoffset % TOAST_MAX_CHUNK_SIZE;
-	endoffset = (sliceoffset + length - 1) % TOAST_MAX_CHUNK_SIZE;
+	endchunk = (sliceoffset + slicelength - 1) / TOAST_MAX_CHUNK_SIZE;
+	Assert(endchunk <= totalchunks);
 
 	/*
 	 * Open the toast relation and its indexes
@@ -610,7 +588,7 @@ toast_fetch_datum_slice(struct varlena *attr, int32 sliceoffset, int32 length)
 	/*
 	 * Use equality condition for one chunk, a range condition otherwise:
 	 */
-	if (numchunks == 1)
+	if (startchunk == endchunk)
 	{
 		ScanKeyInit(&toastkey[1],
 					(AttrNumber) 2,
@@ -642,6 +620,15 @@ toast_fetch_datum_slice(struct varlena *attr, int32 sliceoffset, int32 length)
 										   &SnapshotToast, nscankeys, toastkey);
 	while ((ttup = systable_getnext_ordered(toastscan, ForwardScanDirection)) != NULL)
 	{
+		int32		residx;
+		Pointer		chunk;
+		bool		isnull;
+		char	   *chunkdata;
+		int32		chunksize;
+		int32		expected_size;
+		int32		chcpystrt;
+		int32		chcpyend;
+
 		/*
 		 * Have a chunk, extract the sequence number and the data
 		 */
@@ -673,36 +660,31 @@ toast_fetch_datum_slice(struct varlena *attr, int32 sliceoffset, int32 length)
 		/*
 		 * Some checks on the data we've found
 		 */
-		if ((residx != nextidx) || (residx > endchunk) || (residx < startchunk))
-			elog(ERROR, "unexpected chunk number %d (expected %d) for toast value %u in %s",
-				 residx, nextidx,
-				 toast_pointer.va_valueid,
-				 RelationGetRelationName(toastrel));
-		if (residx < totalchunks - 1)
-		{
-			if (chunksize != TOAST_MAX_CHUNK_SIZE)
-				elog(ERROR, "unexpected chunk size %d (expected %d) in chunk %d of %d for toast value %u in %s when fetching slice",
-					 chunksize, (int) TOAST_MAX_CHUNK_SIZE,
-					 residx, totalchunks,
-					 toast_pointer.va_valueid,
-					 RelationGetRelationName(toastrel));
-		}
-		else if (residx == totalchunks - 1)
-		{
-			if ((residx * TOAST_MAX_CHUNK_SIZE + chunksize) != attrsize)
-				elog(ERROR, "unexpected chunk size %d (expected %d) in final chunk %d for toast value %u in %s when fetching slice",
-					 chunksize,
-					 (int) (attrsize - residx * TOAST_MAX_CHUNK_SIZE),
-					 residx,
-					 toast_pointer.va_valueid,
-					 RelationGetRelationName(toastrel));
-		}
-		else
-			elog(ERROR, "unexpected chunk number %d (out of range %d..%d) for toast value %u in %s",
-				 residx,
-				 0, totalchunks - 1,
-				 toast_pointer.va_valueid,
-				 RelationGetRelationName(toastrel));
+		if (residx != nextidx)
+			ereport(ERROR,
+					(errcode(ERRCODE_DATA_CORRUPTED),
+					 errmsg_internal("unexpected chunk number %d (expected %d) for toast value %u in %s",
+									 residx, nextidx,
+									 toast_pointer.va_valueid,
+									 RelationGetRelationName(toastrel))));
+		if (residx > endchunk)
+			ereport(ERROR,
+					(errcode(ERRCODE_DATA_CORRUPTED),
+					 errmsg_internal("unexpected chunk number %d (out of range %d..%d) for toast value %u in %s",
+									 residx,
+									 startchunk, endchunk,
+									 toast_pointer.va_valueid,
+									 RelationGetRelationName(toastrel))));
+		expected_size = residx < totalchunks - 1 ? TOAST_MAX_CHUNK_SIZE
+			: attrsize % TOAST_MAX_CHUNK_SIZE;
+		if (chunksize != expected_size)
+			ereport(ERROR,
+					(errcode(ERRCODE_DATA_CORRUPTED),
+					 errmsg_internal("unexpected chunk size %d (expected %d) in chunk %d for toast value %u in %s",
+									 chunksize, expected_size,
+									 residx,
+									 toast_pointer.va_valueid,
+									 RelationGetRelationName(toastrel))));
 
 		/*
 		 * Copy the data into proper place in our result
@@ -710,9 +692,9 @@ toast_fetch_datum_slice(struct varlena *attr, int32 sliceoffset, int32 length)
 		chcpystrt = 0;
 		chcpyend = chunksize - 1;
 		if (residx == startchunk)
-			chcpystrt = startoffset;
+			chcpystrt = sliceoffset % TOAST_MAX_CHUNK_SIZE;
 		if (residx == endchunk)
-			chcpyend = endoffset;
+			chcpyend = (sliceoffset + slicelength - 1) % TOAST_MAX_CHUNK_SIZE;
 
 		memcpy(VARDATA(result) +
 			   (residx * TOAST_MAX_CHUNK_SIZE - sliceoffset) + chcpystrt,
@@ -726,10 +708,12 @@ toast_fetch_datum_slice(struct varlena *attr, int32 sliceoffset, int32 length)
 	 * Final checks that we successfully fetched the datum
 	 */
 	if (nextidx != (endchunk + 1))
-		elog(ERROR, "missing chunk number %d for toast value %u in %s",
-			 nextidx,
-			 toast_pointer.va_valueid,
-			 RelationGetRelationName(toastrel));
+		ereport(ERROR,
+				(errcode(ERRCODE_DATA_CORRUPTED),
+				 errmsg_internal("missing chunk number %d for toast value %u in %s",
+								 nextidx,
+								 toast_pointer.va_valueid,
+								 RelationGetRelationName(toastrel))));
 
 	/*
 	 * End scan and close relations
-- 
2.17.2 (Apple Git-113)

From 14034570a0c314f4c9d5de458b796bb0f4343006 Mon Sep 17 00:00:00 2001
From: Robert Haas <rhaas@postgresql.org>
Date: Fri, 22 Nov 2019 08:43:28 -0500
Subject: [PATCH v9 2/4] Code cleanup for toast_fetch_datum and
 toast_fetch_datum_slice.

Rework some of the checks for bad TOAST chunks to be a bit simpler
and easier to understand. These checks verify that (1) we get all
and only the chunk numbers we expect to see and (2) each chunk has
the expected size. However, the existing code was a bit hard to
understand, at least for me; try to make it clearer.

As part of that, have toast_fetch_datum_slice check the relationship
between endchunk and totalchunks only with an Assert() rather than
checking every chunk number against both values. There's no need to
check that relationship in production builds because it's not a
function of whether on-disk corruption is present; it's just a
question of whether the code does the right math.

Also, have toast_fetch_datum_slice() use ereport(ERROR) rather than
elog(ERROR). Commit fd6ec93bf890314ac694dc8a7f3c45702ecc1bbd made
the two functions inconsistent with each other.

Rename assorted variables for better clarity and consistency, and
move assorted variables from function scope to the function's main
loop. Remove a few variables that are used only once entirely.

Patch by me, reviewed by Peter Eisentraut.

Discussion: http://postgr.es/m/CA+TgmobBzxwFojJ0zV0Own3dr09y43hp+OzU2VW+nos4PMXWEg@mail.gmail.com
---
 src/backend/access/common/detoast.c | 220 +++++++++++++---------------
 1 file changed, 102 insertions(+), 118 deletions(-)

diff --git a/src/backend/access/common/detoast.c b/src/backend/access/common/detoast.c
index 8c89fc2a55..61d7e64c44 100644
--- a/src/backend/access/common/detoast.c
+++ b/src/backend/access/common/detoast.c
@@ -25,7 +25,8 @@
 
 static struct varlena *toast_fetch_datum(struct varlena *attr);
 static struct varlena *toast_fetch_datum_slice(struct varlena *attr,
-											   int32 sliceoffset, int32 length);
+											   int32 sliceoffset,
+											   int32 slicelength);
 static struct varlena *toast_decompress_datum(struct varlena *attr);
 static struct varlena *toast_decompress_datum_slice(struct varlena *attr, int32 slicelength);
 
@@ -331,14 +332,9 @@ toast_fetch_datum(struct varlena *attr)
 	TupleDesc	toasttupDesc;
 	struct varlena *result;
 	struct varatt_external toast_pointer;
-	int32		ressize;
-	int32		residx,
-				nextidx;
-	int32		numchunks;
-	Pointer		chunk;
-	bool		isnull;
-	char	   *chunkdata;
-	int32		chunksize;
+	int32		attrsize;
+	int32		expectedchunk;
+	int32		totalchunks;
 	int			num_indexes;
 	int			validIndex;
 	SnapshotData SnapshotToast;
@@ -349,15 +345,15 @@ toast_fetch_datum(struct varlena *attr)
 	/* Must copy to access aligned fields */
 	VARATT_EXTERNAL_GET_POINTER(toast_pointer, attr);
 
-	ressize = toast_pointer.va_extsize;
-	numchunks = ((ressize - 1) / TOAST_MAX_CHUNK_SIZE) + 1;
+	attrsize = toast_pointer.va_extsize;
+	totalchunks = ((attrsize - 1) / TOAST_MAX_CHUNK_SIZE) + 1;
 
-	result = (struct varlena *) palloc(ressize + VARHDRSZ);
+	result = (struct varlena *) palloc(attrsize + VARHDRSZ);
 
 	if (VARATT_EXTERNAL_IS_COMPRESSED(toast_pointer))
-		SET_VARSIZE_COMPRESSED(result, ressize + VARHDRSZ);
+		SET_VARSIZE_COMPRESSED(result, attrsize + VARHDRSZ);
 	else
-		SET_VARSIZE(result, ressize + VARHDRSZ);
+		SET_VARSIZE(result, attrsize + VARHDRSZ);
 
 	/*
 	 * Open the toast relation and its indexes
@@ -386,17 +382,24 @@ toast_fetch_datum(struct varlena *attr)
 	 * see the chunks in chunkidx order, even though we didn't explicitly ask
 	 * for it.
 	 */
-	nextidx = 0;
+	expectedchunk = 0;
 
 	init_toast_snapshot(&SnapshotToast);
 	toastscan = systable_beginscan_ordered(toastrel, toastidxs[validIndex],
 										   &SnapshotToast, 1, &toastkey);
 	while ((ttup = systable_getnext_ordered(toastscan, ForwardScanDirection)) != NULL)
 	{
+		int32		curchunk;
+		Pointer		chunk;
+		bool		isnull;
+		char	   *chunkdata;
+		int32		chunksize;
+		int32		expected_size;
+
 		/*
 		 * Have a chunk, extract the sequence number and the data
 		 */
-		residx = DatumGetInt32(fastgetattr(ttup, 2, toasttupDesc, &isnull));
+		curchunk = DatumGetInt32(fastgetattr(ttup, 2, toasttupDesc, &isnull));
 		Assert(!isnull);
 		chunk = DatumGetPointer(fastgetattr(ttup, 3, toasttupDesc, &isnull));
 		Assert(!isnull);
@@ -424,63 +427,50 @@ toast_fetch_datum(struct varlena *attr)
 		/*
 		 * Some checks on the data we've found
 		 */
-		if (residx != nextidx)
+		if (curchunk != expectedchunk)
 			ereport(ERROR,
 					(errcode(ERRCODE_DATA_CORRUPTED),
 					 errmsg_internal("unexpected chunk number %d (expected %d) for toast value %u in %s",
-									 residx, nextidx,
+									 curchunk, expectedchunk,
 									 toast_pointer.va_valueid,
 									 RelationGetRelationName(toastrel))));
-		if (residx < numchunks - 1)
-		{
-			if (chunksize != TOAST_MAX_CHUNK_SIZE)
-				ereport(ERROR,
-						(errcode(ERRCODE_DATA_CORRUPTED),
-						 errmsg_internal("unexpected chunk size %d (expected %d) in chunk %d of %d for toast value %u in %s",
-										 chunksize, (int) TOAST_MAX_CHUNK_SIZE,
-										 residx, numchunks,
-										 toast_pointer.va_valueid,
-										 RelationGetRelationName(toastrel))));
-		}
-		else if (residx == numchunks - 1)
-		{
-			if ((residx * TOAST_MAX_CHUNK_SIZE + chunksize) != ressize)
-				ereport(ERROR,
-						(errcode(ERRCODE_DATA_CORRUPTED),
-						 errmsg_internal("unexpected chunk size %d (expected %d) in final chunk %d for toast value %u in %s",
-										 chunksize,
-										 (int) (ressize - residx * TOAST_MAX_CHUNK_SIZE),
-										 residx,
-										 toast_pointer.va_valueid,
-										 RelationGetRelationName(toastrel))));
-		}
-		else
+		if (curchunk > totalchunks - 1)
 			ereport(ERROR,
 					(errcode(ERRCODE_DATA_CORRUPTED),
 					 errmsg_internal("unexpected chunk number %d (out of range %d..%d) for toast value %u in %s",
-									 residx,
-									 0, numchunks - 1,
+									 curchunk,
+									 0, totalchunks - 1,
+									 toast_pointer.va_valueid,
+									 RelationGetRelationName(toastrel))));
+		expected_size = curchunk < totalchunks - 1 ? TOAST_MAX_CHUNK_SIZE
+			: attrsize % TOAST_MAX_CHUNK_SIZE;
+		if (chunksize != expected_size)
+			ereport(ERROR,
+					(errcode(ERRCODE_DATA_CORRUPTED),
+					 errmsg_internal("unexpected chunk size %d (expected %d) in chunk %d of %d for toast value %u in %s",
+									 chunksize, expected_size,
+									 curchunk, totalchunks,
 									 toast_pointer.va_valueid,
 									 RelationGetRelationName(toastrel))));
 
 		/*
 		 * Copy the data into proper place in our result
 		 */
-		memcpy(VARDATA(result) + residx * TOAST_MAX_CHUNK_SIZE,
+		memcpy(VARDATA(result) + curchunk * TOAST_MAX_CHUNK_SIZE,
 			   chunkdata,
 			   chunksize);
 
-		nextidx++;
+		expectedchunk++;
 	}
 
 	/*
 	 * Final checks that we successfully fetched the datum
 	 */
-	if (nextidx != numchunks)
+	if (expectedchunk != totalchunks)
 		ereport(ERROR,
 				(errcode(ERRCODE_DATA_CORRUPTED),
 				 errmsg_internal("missing chunk number %d for toast value %u in %s",
-								 nextidx,
+								 expectedchunk,
 								 toast_pointer.va_valueid,
 								 RelationGetRelationName(toastrel))));
 
@@ -506,7 +496,8 @@ toast_fetch_datum(struct varlena *attr)
  * ----------
  */
 static struct varlena *
-toast_fetch_datum_slice(struct varlena *attr, int32 sliceoffset, int32 length)
+toast_fetch_datum_slice(struct varlena *attr, int32 sliceoffset,
+						int32 slicelength)
 {
 	Relation	toastrel;
 	Relation   *toastidxs;
@@ -518,20 +509,10 @@ toast_fetch_datum_slice(struct varlena *attr, int32 sliceoffset, int32 length)
 	struct varlena *result;
 	struct varatt_external toast_pointer;
 	int32		attrsize;
-	int32		residx;
-	int32		nextidx;
-	int			numchunks;
+	int32		expectedchunk;
 	int			startchunk;
 	int			endchunk;
-	int32		startoffset;
-	int32		endoffset;
 	int			totalchunks;
-	Pointer		chunk;
-	bool		isnull;
-	char	   *chunkdata;
-	int32		chunksize;
-	int32		chcpystrt;
-	int32		chcpyend;
 	int			num_indexes;
 	int			validIndex;
 	SnapshotData SnapshotToast;
@@ -555,7 +536,7 @@ toast_fetch_datum_slice(struct varlena *attr, int32 sliceoffset, int32 length)
 	if (sliceoffset >= attrsize)
 	{
 		sliceoffset = 0;
-		length = 0;
+		slicelength = 0;
 	}
 
 	/*
@@ -563,28 +544,25 @@ toast_fetch_datum_slice(struct varlena *attr, int32 sliceoffset, int32 length)
 	 * rawsize tracking amount of raw data, which is stored at the beginning
 	 * as an int32 value).
 	 */
-	if (VARATT_EXTERNAL_IS_COMPRESSED(toast_pointer) && length > 0)
-		length = length + sizeof(int32);
+	if (VARATT_EXTERNAL_IS_COMPRESSED(toast_pointer) && slicelength > 0)
+		slicelength = slicelength + sizeof(int32);
 
-	if (((sliceoffset + length) > attrsize) || length < 0)
-		length = attrsize - sliceoffset;
+	if (((sliceoffset + slicelength) > attrsize) || slicelength < 0)
+		slicelength = attrsize - sliceoffset;
 
-	result = (struct varlena *) palloc(length + VARHDRSZ);
+	result = (struct varlena *) palloc(slicelength + VARHDRSZ);
 
 	if (VARATT_EXTERNAL_IS_COMPRESSED(toast_pointer))
-		SET_VARSIZE_COMPRESSED(result, length + VARHDRSZ);
+		SET_VARSIZE_COMPRESSED(result, slicelength + VARHDRSZ);
 	else
-		SET_VARSIZE(result, length + VARHDRSZ);
+		SET_VARSIZE(result, slicelength + VARHDRSZ);
 
-	if (length == 0)
+	if (slicelength == 0)
 		return result;			/* Can save a lot of work at this point! */
 
 	startchunk = sliceoffset / TOAST_MAX_CHUNK_SIZE;
-	endchunk = (sliceoffset + length - 1) / TOAST_MAX_CHUNK_SIZE;
-	numchunks = (endchunk - startchunk) + 1;
-
-	startoffset = sliceoffset % TOAST_MAX_CHUNK_SIZE;
-	endoffset = (sliceoffset + length - 1) % TOAST_MAX_CHUNK_SIZE;
+	endchunk = (sliceoffset + slicelength - 1) / TOAST_MAX_CHUNK_SIZE;
+	Assert(endchunk < totalchunks);
 
 	/*
 	 * Open the toast relation and its indexes
@@ -610,7 +588,7 @@ toast_fetch_datum_slice(struct varlena *attr, int32 sliceoffset, int32 length)
 	/*
 	 * Use equality condition for one chunk, a range condition otherwise:
 	 */
-	if (numchunks == 1)
+	if (startchunk == endchunk)
 	{
 		ScanKeyInit(&toastkey[1],
 					(AttrNumber) 2,
@@ -637,15 +615,24 @@ toast_fetch_datum_slice(struct varlena *attr, int32 sliceoffset, int32 length)
 	 * The index is on (valueid, chunkidx) so they will come in order
 	 */
 	init_toast_snapshot(&SnapshotToast);
-	nextidx = startchunk;
+	expectedchunk = startchunk;
 	toastscan = systable_beginscan_ordered(toastrel, toastidxs[validIndex],
 										   &SnapshotToast, nscankeys, toastkey);
 	while ((ttup = systable_getnext_ordered(toastscan, ForwardScanDirection)) != NULL)
 	{
+		int32		curchunk;
+		Pointer		chunk;
+		bool		isnull;
+		char	   *chunkdata;
+		int32		chunksize;
+		int32		expected_size;
+		int32		chcpystrt;
+		int32		chcpyend;
+
 		/*
 		 * Have a chunk, extract the sequence number and the data
 		 */
-		residx = DatumGetInt32(fastgetattr(ttup, 2, toasttupDesc, &isnull));
+		curchunk = DatumGetInt32(fastgetattr(ttup, 2, toasttupDesc, &isnull));
 		Assert(!isnull);
 		chunk = DatumGetPointer(fastgetattr(ttup, 3, toasttupDesc, &isnull));
 		Assert(!isnull);
@@ -673,63 +660,60 @@ toast_fetch_datum_slice(struct varlena *attr, int32 sliceoffset, int32 length)
 		/*
 		 * Some checks on the data we've found
 		 */
-		if ((residx != nextidx) || (residx > endchunk) || (residx < startchunk))
-			elog(ERROR, "unexpected chunk number %d (expected %d) for toast value %u in %s",
-				 residx, nextidx,
-				 toast_pointer.va_valueid,
-				 RelationGetRelationName(toastrel));
-		if (residx < totalchunks - 1)
-		{
-			if (chunksize != TOAST_MAX_CHUNK_SIZE)
-				elog(ERROR, "unexpected chunk size %d (expected %d) in chunk %d of %d for toast value %u in %s when fetching slice",
-					 chunksize, (int) TOAST_MAX_CHUNK_SIZE,
-					 residx, totalchunks,
-					 toast_pointer.va_valueid,
-					 RelationGetRelationName(toastrel));
-		}
-		else if (residx == totalchunks - 1)
-		{
-			if ((residx * TOAST_MAX_CHUNK_SIZE + chunksize) != attrsize)
-				elog(ERROR, "unexpected chunk size %d (expected %d) in final chunk %d for toast value %u in %s when fetching slice",
-					 chunksize,
-					 (int) (attrsize - residx * TOAST_MAX_CHUNK_SIZE),
-					 residx,
-					 toast_pointer.va_valueid,
-					 RelationGetRelationName(toastrel));
-		}
-		else
-			elog(ERROR, "unexpected chunk number %d (out of range %d..%d) for toast value %u in %s",
-				 residx,
-				 0, totalchunks - 1,
-				 toast_pointer.va_valueid,
-				 RelationGetRelationName(toastrel));
+		if (curchunk != expectedchunk)
+			ereport(ERROR,
+					(errcode(ERRCODE_DATA_CORRUPTED),
+					 errmsg_internal("unexpected chunk number %d (expected %d) for toast value %u in %s",
+									 curchunk, expectedchunk,
+									 toast_pointer.va_valueid,
+									 RelationGetRelationName(toastrel))));
+		if (curchunk > endchunk)
+			ereport(ERROR,
+					(errcode(ERRCODE_DATA_CORRUPTED),
+					 errmsg_internal("unexpected chunk number %d (out of range %d..%d) for toast value %u in %s",
+									 curchunk,
+									 startchunk, endchunk,
+									 toast_pointer.va_valueid,
+									 RelationGetRelationName(toastrel))));
+		expected_size = curchunk < totalchunks - 1 ? TOAST_MAX_CHUNK_SIZE
+			: attrsize % TOAST_MAX_CHUNK_SIZE;
+		if (chunksize != expected_size)
+			ereport(ERROR,
+					(errcode(ERRCODE_DATA_CORRUPTED),
+					 errmsg_internal("unexpected chunk size %d (expected %d) in chunk %d of %d for toast value %u in %s",
+									 chunksize, expected_size,
+									 curchunk, totalchunks,
+									 toast_pointer.va_valueid,
+									 RelationGetRelationName(toastrel))));
 
 		/*
 		 * Copy the data into proper place in our result
 		 */
 		chcpystrt = 0;
 		chcpyend = chunksize - 1;
-		if (residx == startchunk)
-			chcpystrt = startoffset;
-		if (residx == endchunk)
-			chcpyend = endoffset;
+		if (curchunk == startchunk)
+			chcpystrt = sliceoffset % TOAST_MAX_CHUNK_SIZE;
+		if (curchunk == endchunk)
+			chcpyend = (sliceoffset + slicelength - 1) % TOAST_MAX_CHUNK_SIZE;
 
 		memcpy(VARDATA(result) +
-			   (residx * TOAST_MAX_CHUNK_SIZE - sliceoffset) + chcpystrt,
+			   (curchunk * TOAST_MAX_CHUNK_SIZE - sliceoffset) + chcpystrt,
 			   chunkdata + chcpystrt,
 			   (chcpyend - chcpystrt) + 1);
 
-		nextidx++;
+		expectedchunk++;
 	}
 
 	/*
 	 * Final checks that we successfully fetched the datum
 	 */
-	if (nextidx != (endchunk + 1))
-		elog(ERROR, "missing chunk number %d for toast value %u in %s",
-			 nextidx,
-			 toast_pointer.va_valueid,
-			 RelationGetRelationName(toastrel));
+	if (expectedchunk != (endchunk + 1))
+		ereport(ERROR,
+				(errcode(ERRCODE_DATA_CORRUPTED),
+				 errmsg_internal("missing chunk number %d for toast value %u in %s",
+								 expectedchunk,
+								 toast_pointer.va_valueid,
+								 RelationGetRelationName(toastrel))));
 
 	/*
 	 * End scan and close relations
-- 
2.17.2 (Apple Git-113)

From 2b03d85ec3d20f5e63ac4ce624c01368743811c1 Mon Sep 17 00:00:00 2001
From: Robert Haas <rhaas@postgresql.org>
Date: Fri, 8 Nov 2019 11:50:52 -0500
Subject: [PATCH v9 3/4] Move heap-specific detoasting logic into a separate
 function.

The new function, heap_fetch_toast_slice, is shared between
toast_fetch_datum_slice and toast_fetch_datum, and does all the
work of scanning the TOAST table, fetching chunks, and storing
them into the space allocated for the result varlena.

As an incidental side effect, this allows toast_fetch_datum_slice
to perform the scan with only a single scankey if all chunks are
being fetched, which might have some tiny performance benefit.

Discussion: http://postgr.es/m/CA+TgmobBzxwFojJ0zV0Own3dr09y43hp+OzU2VW+nos4PMXWEg@mail.gmail.com
---
 src/backend/access/common/detoast.c | 244 ++++++++--------------------
 1 file changed, 71 insertions(+), 173 deletions(-)

diff --git a/src/backend/access/common/detoast.c b/src/backend/access/common/detoast.c
index 61d7e64c44..04b195149f 100644
--- a/src/backend/access/common/detoast.c
+++ b/src/backend/access/common/detoast.c
@@ -27,6 +27,9 @@ static struct varlena *toast_fetch_datum(struct varlena *attr);
 static struct varlena *toast_fetch_datum_slice(struct varlena *attr,
 											   int32 sliceoffset,
 											   int32 slicelength);
+static void heap_fetch_toast_slice(Relation toastrel, Oid valueid,
+								   int32 attrsize, int32 sliceoffset,
+								   int32 slicelength, struct varlena *result);
 static struct varlena *toast_decompress_datum(struct varlena *attr);
 static struct varlena *toast_decompress_datum_slice(struct varlena *attr, int32 slicelength);
 
@@ -325,19 +328,9 @@ static struct varlena *
 toast_fetch_datum(struct varlena *attr)
 {
 	Relation	toastrel;
-	Relation   *toastidxs;
-	ScanKeyData toastkey;
-	SysScanDesc toastscan;
-	HeapTuple	ttup;
-	TupleDesc	toasttupDesc;
 	struct varlena *result;
 	struct varatt_external toast_pointer;
 	int32		attrsize;
-	int32		expectedchunk;
-	int32		totalchunks;
-	int			num_indexes;
-	int			validIndex;
-	SnapshotData SnapshotToast;
 
 	if (!VARATT_IS_EXTERNAL_ONDISK(attr))
 		elog(ERROR, "toast_fetch_datum shouldn't be called for non-ondisk datums");
@@ -346,7 +339,6 @@ toast_fetch_datum(struct varlena *attr)
 	VARATT_EXTERNAL_GET_POINTER(toast_pointer, attr);
 
 	attrsize = toast_pointer.va_extsize;
-	totalchunks = ((attrsize - 1) / TOAST_MAX_CHUNK_SIZE) + 1;
 
 	result = (struct varlena *) palloc(attrsize + VARHDRSZ);
 
@@ -355,130 +347,19 @@ toast_fetch_datum(struct varlena *attr)
 	else
 		SET_VARSIZE(result, attrsize + VARHDRSZ);
 
+	if (attrsize == 0)
+		return result;		/* Probably shouldn't happen, but just in case. */
+
 	/*
 	 * Open the toast relation and its indexes
 	 */
 	toastrel = table_open(toast_pointer.va_toastrelid, AccessShareLock);
-	toasttupDesc = toastrel->rd_att;
-
-	/* Look for the valid index of the toast relation */
-	validIndex = toast_open_indexes(toastrel,
-									AccessShareLock,
-									&toastidxs,
-									&num_indexes);
 
-	/*
-	 * Setup a scan key to fetch from the index by va_valueid
-	 */
-	ScanKeyInit(&toastkey,
-				(AttrNumber) 1,
-				BTEqualStrategyNumber, F_OIDEQ,
-				ObjectIdGetDatum(toast_pointer.va_valueid));
+	/* Fetch all chunks */
+	heap_fetch_toast_slice(toastrel, toast_pointer.va_valueid, attrsize, 0,
+						   attrsize, result);
 
-	/*
-	 * Read the chunks by index
-	 *
-	 * Note that because the index is actually on (valueid, chunkidx) we will
-	 * see the chunks in chunkidx order, even though we didn't explicitly ask
-	 * for it.
-	 */
-	expectedchunk = 0;
-
-	init_toast_snapshot(&SnapshotToast);
-	toastscan = systable_beginscan_ordered(toastrel, toastidxs[validIndex],
-										   &SnapshotToast, 1, &toastkey);
-	while ((ttup = systable_getnext_ordered(toastscan, ForwardScanDirection)) != NULL)
-	{
-		int32		curchunk;
-		Pointer		chunk;
-		bool		isnull;
-		char	   *chunkdata;
-		int32		chunksize;
-		int32		expected_size;
-
-		/*
-		 * Have a chunk, extract the sequence number and the data
-		 */
-		curchunk = DatumGetInt32(fastgetattr(ttup, 2, toasttupDesc, &isnull));
-		Assert(!isnull);
-		chunk = DatumGetPointer(fastgetattr(ttup, 3, toasttupDesc, &isnull));
-		Assert(!isnull);
-		if (!VARATT_IS_EXTENDED(chunk))
-		{
-			chunksize = VARSIZE(chunk) - VARHDRSZ;
-			chunkdata = VARDATA(chunk);
-		}
-		else if (VARATT_IS_SHORT(chunk))
-		{
-			/* could happen due to heap_form_tuple doing its thing */
-			chunksize = VARSIZE_SHORT(chunk) - VARHDRSZ_SHORT;
-			chunkdata = VARDATA_SHORT(chunk);
-		}
-		else
-		{
-			/* should never happen */
-			elog(ERROR, "found toasted toast chunk for toast value %u in %s",
-				 toast_pointer.va_valueid,
-				 RelationGetRelationName(toastrel));
-			chunksize = 0;		/* keep compiler quiet */
-			chunkdata = NULL;
-		}
-
-		/*
-		 * Some checks on the data we've found
-		 */
-		if (curchunk != expectedchunk)
-			ereport(ERROR,
-					(errcode(ERRCODE_DATA_CORRUPTED),
-					 errmsg_internal("unexpected chunk number %d (expected %d) for toast value %u in %s",
-									 curchunk, expectedchunk,
-									 toast_pointer.va_valueid,
-									 RelationGetRelationName(toastrel))));
-		if (curchunk > totalchunks - 1)
-			ereport(ERROR,
-					(errcode(ERRCODE_DATA_CORRUPTED),
-					 errmsg_internal("unexpected chunk number %d (out of range %d..%d) for toast value %u in %s",
-									 curchunk,
-									 0, totalchunks - 1,
-									 toast_pointer.va_valueid,
-									 RelationGetRelationName(toastrel))));
-		expected_size = curchunk < totalchunks - 1 ? TOAST_MAX_CHUNK_SIZE
-			: attrsize % TOAST_MAX_CHUNK_SIZE;
-		if (chunksize != expected_size)
-			ereport(ERROR,
-					(errcode(ERRCODE_DATA_CORRUPTED),
-					 errmsg_internal("unexpected chunk size %d (expected %d) in chunk %d of %d for toast value %u in %s",
-									 chunksize, expected_size,
-									 curchunk, totalchunks,
-									 toast_pointer.va_valueid,
-									 RelationGetRelationName(toastrel))));
-
-		/*
-		 * Copy the data into proper place in our result
-		 */
-		memcpy(VARDATA(result) + curchunk * TOAST_MAX_CHUNK_SIZE,
-			   chunkdata,
-			   chunksize);
-
-		expectedchunk++;
-	}
-
-	/*
-	 * Final checks that we successfully fetched the datum
-	 */
-	if (expectedchunk != totalchunks)
-		ereport(ERROR,
-				(errcode(ERRCODE_DATA_CORRUPTED),
-				 errmsg_internal("missing chunk number %d for toast value %u in %s",
-								 expectedchunk,
-								 toast_pointer.va_valueid,
-								 RelationGetRelationName(toastrel))));
-
-	/*
-	 * End scan and close relations
-	 */
-	systable_endscan_ordered(toastscan);
-	toast_close_indexes(toastidxs, num_indexes, AccessShareLock);
+	/* Close toast table */
 	table_close(toastrel, AccessShareLock);
 
 	return result;
@@ -500,22 +381,9 @@ toast_fetch_datum_slice(struct varlena *attr, int32 sliceoffset,
 						int32 slicelength)
 {
 	Relation	toastrel;
-	Relation   *toastidxs;
-	ScanKeyData toastkey[3];
-	int			nscankeys;
-	SysScanDesc toastscan;
-	HeapTuple	ttup;
-	TupleDesc	toasttupDesc;
 	struct varlena *result;
 	struct varatt_external toast_pointer;
 	int32		attrsize;
-	int32		expectedchunk;
-	int			startchunk;
-	int			endchunk;
-	int			totalchunks;
-	int			num_indexes;
-	int			validIndex;
-	SnapshotData SnapshotToast;
 
 	if (!VARATT_IS_EXTERNAL_ONDISK(attr))
 		elog(ERROR, "toast_fetch_datum_slice shouldn't be called for non-ondisk datums");
@@ -531,7 +399,6 @@ toast_fetch_datum_slice(struct varlena *attr, int32 sliceoffset,
 	Assert(!VARATT_EXTERNAL_IS_COMPRESSED(toast_pointer) || 0 == sliceoffset);
 
 	attrsize = toast_pointer.va_extsize;
-	totalchunks = ((attrsize - 1) / TOAST_MAX_CHUNK_SIZE) + 1;
 
 	if (sliceoffset >= attrsize)
 	{
@@ -560,15 +427,47 @@ toast_fetch_datum_slice(struct varlena *attr, int32 sliceoffset,
 	if (slicelength == 0)
 		return result;			/* Can save a lot of work at this point! */
 
-	startchunk = sliceoffset / TOAST_MAX_CHUNK_SIZE;
-	endchunk = (sliceoffset + slicelength - 1) / TOAST_MAX_CHUNK_SIZE;
-	Assert(endchunk < totalchunks);
-
-	/*
-	 * Open the toast relation and its indexes
-	 */
+	/* Open the toast relation */
 	toastrel = table_open(toast_pointer.va_toastrelid, AccessShareLock);
-	toasttupDesc = toastrel->rd_att;
+
+	/* Fetch all chunks */
+	heap_fetch_toast_slice(toastrel, toast_pointer.va_valueid, attrsize,
+						   sliceoffset, slicelength, result);
+
+	/* Close toast table */
+	table_close(toastrel, AccessShareLock);
+
+	return result;
+}
+
+/*
+ * Fetch a TOAST slice from a heap table.
+ *
+ * toastrel is the relation from which chunks are to be fetched.
+ * valueid identifies the TOAST value from which chunks are being fetched.
+ * attrsize is the total size of the TOAST value.
+ * sliceoffset is the byte offset within the TOAST value from which to fetch.
+ * slicelength is the number of bytes to be fetched from the TOAST value.
+ * result is the varlena into which the results should be written.
+ */
+static void
+heap_fetch_toast_slice(Relation toastrel, Oid valueid, int32 attrsize,
+					   int32 sliceoffset, int32 slicelength,
+					   struct varlena *result)
+{
+	Relation   *toastidxs;
+	ScanKeyData toastkey[3];
+	TupleDesc	toasttupDesc = toastrel->rd_att;
+	int			nscankeys;
+	SysScanDesc toastscan;
+	HeapTuple	ttup;
+	int32		expectedchunk;
+	int32		totalchunks = ((attrsize - 1) / TOAST_MAX_CHUNK_SIZE) + 1;
+	int			startchunk;
+	int			endchunk;
+	int			num_indexes;
+	int			validIndex;
+	SnapshotData SnapshotToast;
 
 	/* Look for the valid index of toast relation */
 	validIndex = toast_open_indexes(toastrel,
@@ -576,6 +475,10 @@ toast_fetch_datum_slice(struct varlena *attr, int32 sliceoffset,
 									&toastidxs,
 									&num_indexes);
 
+	startchunk = sliceoffset / TOAST_MAX_CHUNK_SIZE;
+	endchunk = (sliceoffset + slicelength - 1) / TOAST_MAX_CHUNK_SIZE;
+	Assert(endchunk <= totalchunks);
+
 	/*
 	 * Setup a scan key to fetch from the index. This is either two keys or
 	 * three depending on the number of chunks.
@@ -583,12 +486,15 @@ toast_fetch_datum_slice(struct varlena *attr, int32 sliceoffset,
 	ScanKeyInit(&toastkey[0],
 				(AttrNumber) 1,
 				BTEqualStrategyNumber, F_OIDEQ,
-				ObjectIdGetDatum(toast_pointer.va_valueid));
+				ObjectIdGetDatum(valueid));
 
 	/*
-	 * Use equality condition for one chunk, a range condition otherwise:
+	 * No addition condition if fetching all chuns. Otherwise, use an
+	 * equality condition for one chunk, and a range condition otherwise.
 	 */
-	if (startchunk == endchunk)
+	if (startchunk == 0 && endchunk == totalchunks - 1)
+		nscankeys = 1;
+	else if (startchunk == endchunk)
 	{
 		ScanKeyInit(&toastkey[1],
 					(AttrNumber) 2,
@@ -609,15 +515,17 @@ toast_fetch_datum_slice(struct varlena *attr, int32 sliceoffset,
 		nscankeys = 3;
 	}
 
+	/* Prepare for scan */
+	init_toast_snapshot(&SnapshotToast);
+	toastscan = systable_beginscan_ordered(toastrel, toastidxs[validIndex],
+										   &SnapshotToast, nscankeys, toastkey);
+
 	/*
 	 * Read the chunks by index
 	 *
 	 * The index is on (valueid, chunkidx) so they will come in order
 	 */
-	init_toast_snapshot(&SnapshotToast);
 	expectedchunk = startchunk;
-	toastscan = systable_beginscan_ordered(toastrel, toastidxs[validIndex],
-										   &SnapshotToast, nscankeys, toastkey);
 	while ((ttup = systable_getnext_ordered(toastscan, ForwardScanDirection)) != NULL)
 	{
 		int32		curchunk;
@@ -651,8 +559,7 @@ toast_fetch_datum_slice(struct varlena *attr, int32 sliceoffset,
 		{
 			/* should never happen */
 			elog(ERROR, "found toasted toast chunk for toast value %u in %s",
-				 toast_pointer.va_valueid,
-				 RelationGetRelationName(toastrel));
+				 valueid, RelationGetRelationName(toastrel));
 			chunksize = 0;		/* keep compiler quiet */
 			chunkdata = NULL;
 		}
@@ -664,16 +571,14 @@ toast_fetch_datum_slice(struct varlena *attr, int32 sliceoffset,
 			ereport(ERROR,
 					(errcode(ERRCODE_DATA_CORRUPTED),
 					 errmsg_internal("unexpected chunk number %d (expected %d) for toast value %u in %s",
-									 curchunk, expectedchunk,
-									 toast_pointer.va_valueid,
+									 curchunk, expectedchunk, valueid,
 									 RelationGetRelationName(toastrel))));
 		if (curchunk > endchunk)
 			ereport(ERROR,
 					(errcode(ERRCODE_DATA_CORRUPTED),
 					 errmsg_internal("unexpected chunk number %d (out of range %d..%d) for toast value %u in %s",
 									 curchunk,
-									 startchunk, endchunk,
-									 toast_pointer.va_valueid,
+									 startchunk, endchunk, valueid,
 									 RelationGetRelationName(toastrel))));
 		expected_size = curchunk < totalchunks - 1 ? TOAST_MAX_CHUNK_SIZE
 			: attrsize % TOAST_MAX_CHUNK_SIZE;
@@ -682,8 +587,7 @@ toast_fetch_datum_slice(struct varlena *attr, int32 sliceoffset,
 					(errcode(ERRCODE_DATA_CORRUPTED),
 					 errmsg_internal("unexpected chunk size %d (expected %d) in chunk %d of %d for toast value %u in %s",
 									 chunksize, expected_size,
-									 curchunk, totalchunks,
-									 toast_pointer.va_valueid,
+									 curchunk, totalchunks, valueid,
 									 RelationGetRelationName(toastrel))));
 
 		/*
@@ -711,18 +615,12 @@ toast_fetch_datum_slice(struct varlena *attr, int32 sliceoffset,
 		ereport(ERROR,
 				(errcode(ERRCODE_DATA_CORRUPTED),
 				 errmsg_internal("missing chunk number %d for toast value %u in %s",
-								 expectedchunk,
-								 toast_pointer.va_valueid,
+								 expectedchunk, valueid,
 								 RelationGetRelationName(toastrel))));
 
-	/*
-	 * End scan and close relations
-	 */
+	/* End scan and close indexes. */
 	systable_endscan_ordered(toastscan);
 	toast_close_indexes(toastidxs, num_indexes, AccessShareLock);
-	table_close(toastrel, AccessShareLock);
-
-	return result;
 }
 
 /* ----------
-- 
2.17.2 (Apple Git-113)

From f9e9c2e0e4a546eab8638643045e54a7da9147da Mon Sep 17 00:00:00 2001
From: Robert Haas <rhaas@postgresql.org>
Date: Fri, 22 Nov 2019 10:12:22 -0500
Subject: [PATCH v9 4/4] tableam: New callback relation_fetch_toast_slice.

Instead of always calling heap_fetch_toast_slice during detoasting,
invoke a table AM callback which, when the toast table is a heap
table, will be heap_fetch_toast_slice.

This makes it possible for a table AM other than heap to be used
as a TOAST table.
---
 src/backend/access/common/detoast.c      | 199 +----------------------
 src/backend/access/heap/heapam_handler.c |   1 +
 src/backend/access/heap/heaptoast.c      | 185 +++++++++++++++++++++
 src/include/access/heaptoast.h           |  10 ++
 src/include/access/tableam.h             |  46 ++++++
 5 files changed, 248 insertions(+), 193 deletions(-)

diff --git a/src/backend/access/common/detoast.c b/src/backend/access/common/detoast.c
index 04b195149f..3df0cf2512 100644
--- a/src/backend/access/common/detoast.c
+++ b/src/backend/access/common/detoast.c
@@ -14,22 +14,17 @@
 #include "postgres.h"
 
 #include "access/detoast.h"
-#include "access/genam.h"
-#include "access/heaptoast.h"
 #include "access/table.h"
+#include "access/tableam.h"
 #include "access/toast_internals.h"
 #include "common/pg_lzcompress.h"
 #include "utils/expandeddatum.h"
-#include "utils/fmgroids.h"
 #include "utils/rel.h"
 
 static struct varlena *toast_fetch_datum(struct varlena *attr);
 static struct varlena *toast_fetch_datum_slice(struct varlena *attr,
 											   int32 sliceoffset,
 											   int32 slicelength);
-static void heap_fetch_toast_slice(Relation toastrel, Oid valueid,
-								   int32 attrsize, int32 sliceoffset,
-								   int32 slicelength, struct varlena *result);
 static struct varlena *toast_decompress_datum(struct varlena *attr);
 static struct varlena *toast_decompress_datum_slice(struct varlena *attr, int32 slicelength);
 
@@ -356,8 +351,8 @@ toast_fetch_datum(struct varlena *attr)
 	toastrel = table_open(toast_pointer.va_toastrelid, AccessShareLock);
 
 	/* Fetch all chunks */
-	heap_fetch_toast_slice(toastrel, toast_pointer.va_valueid, attrsize, 0,
-						   attrsize, result);
+	table_relation_fetch_toast_slice(toastrel, toast_pointer.va_valueid,
+									 attrsize, 0, attrsize, result);
 
 	/* Close toast table */
 	table_close(toastrel, AccessShareLock);
@@ -431,8 +426,9 @@ toast_fetch_datum_slice(struct varlena *attr, int32 sliceoffset,
 	toastrel = table_open(toast_pointer.va_toastrelid, AccessShareLock);
 
 	/* Fetch all chunks */
-	heap_fetch_toast_slice(toastrel, toast_pointer.va_valueid, attrsize,
-						   sliceoffset, slicelength, result);
+	table_relation_fetch_toast_slice(toastrel, toast_pointer.va_valueid,
+									 attrsize, sliceoffset, slicelength,
+									 result);
 
 	/* Close toast table */
 	table_close(toastrel, AccessShareLock);
@@ -440,189 +436,6 @@ toast_fetch_datum_slice(struct varlena *attr, int32 sliceoffset,
 	return result;
 }
 
-/*
- * Fetch a TOAST slice from a heap table.
- *
- * toastrel is the relation from which chunks are to be fetched.
- * valueid identifies the TOAST value from which chunks are being fetched.
- * attrsize is the total size of the TOAST value.
- * sliceoffset is the byte offset within the TOAST value from which to fetch.
- * slicelength is the number of bytes to be fetched from the TOAST value.
- * result is the varlena into which the results should be written.
- */
-static void
-heap_fetch_toast_slice(Relation toastrel, Oid valueid, int32 attrsize,
-					   int32 sliceoffset, int32 slicelength,
-					   struct varlena *result)
-{
-	Relation   *toastidxs;
-	ScanKeyData toastkey[3];
-	TupleDesc	toasttupDesc = toastrel->rd_att;
-	int			nscankeys;
-	SysScanDesc toastscan;
-	HeapTuple	ttup;
-	int32		expectedchunk;
-	int32		totalchunks = ((attrsize - 1) / TOAST_MAX_CHUNK_SIZE) + 1;
-	int			startchunk;
-	int			endchunk;
-	int			num_indexes;
-	int			validIndex;
-	SnapshotData SnapshotToast;
-
-	/* Look for the valid index of toast relation */
-	validIndex = toast_open_indexes(toastrel,
-									AccessShareLock,
-									&toastidxs,
-									&num_indexes);
-
-	startchunk = sliceoffset / TOAST_MAX_CHUNK_SIZE;
-	endchunk = (sliceoffset + slicelength - 1) / TOAST_MAX_CHUNK_SIZE;
-	Assert(endchunk <= totalchunks);
-
-	/*
-	 * Setup a scan key to fetch from the index. This is either two keys or
-	 * three depending on the number of chunks.
-	 */
-	ScanKeyInit(&toastkey[0],
-				(AttrNumber) 1,
-				BTEqualStrategyNumber, F_OIDEQ,
-				ObjectIdGetDatum(valueid));
-
-	/*
-	 * No addition condition if fetching all chuns. Otherwise, use an
-	 * equality condition for one chunk, and a range condition otherwise.
-	 */
-	if (startchunk == 0 && endchunk == totalchunks - 1)
-		nscankeys = 1;
-	else if (startchunk == endchunk)
-	{
-		ScanKeyInit(&toastkey[1],
-					(AttrNumber) 2,
-					BTEqualStrategyNumber, F_INT4EQ,
-					Int32GetDatum(startchunk));
-		nscankeys = 2;
-	}
-	else
-	{
-		ScanKeyInit(&toastkey[1],
-					(AttrNumber) 2,
-					BTGreaterEqualStrategyNumber, F_INT4GE,
-					Int32GetDatum(startchunk));
-		ScanKeyInit(&toastkey[2],
-					(AttrNumber) 2,
-					BTLessEqualStrategyNumber, F_INT4LE,
-					Int32GetDatum(endchunk));
-		nscankeys = 3;
-	}
-
-	/* Prepare for scan */
-	init_toast_snapshot(&SnapshotToast);
-	toastscan = systable_beginscan_ordered(toastrel, toastidxs[validIndex],
-										   &SnapshotToast, nscankeys, toastkey);
-
-	/*
-	 * Read the chunks by index
-	 *
-	 * The index is on (valueid, chunkidx) so they will come in order
-	 */
-	expectedchunk = startchunk;
-	while ((ttup = systable_getnext_ordered(toastscan, ForwardScanDirection)) != NULL)
-	{
-		int32		curchunk;
-		Pointer		chunk;
-		bool		isnull;
-		char	   *chunkdata;
-		int32		chunksize;
-		int32		expected_size;
-		int32		chcpystrt;
-		int32		chcpyend;
-
-		/*
-		 * Have a chunk, extract the sequence number and the data
-		 */
-		curchunk = DatumGetInt32(fastgetattr(ttup, 2, toasttupDesc, &isnull));
-		Assert(!isnull);
-		chunk = DatumGetPointer(fastgetattr(ttup, 3, toasttupDesc, &isnull));
-		Assert(!isnull);
-		if (!VARATT_IS_EXTENDED(chunk))
-		{
-			chunksize = VARSIZE(chunk) - VARHDRSZ;
-			chunkdata = VARDATA(chunk);
-		}
-		else if (VARATT_IS_SHORT(chunk))
-		{
-			/* could happen due to heap_form_tuple doing its thing */
-			chunksize = VARSIZE_SHORT(chunk) - VARHDRSZ_SHORT;
-			chunkdata = VARDATA_SHORT(chunk);
-		}
-		else
-		{
-			/* should never happen */
-			elog(ERROR, "found toasted toast chunk for toast value %u in %s",
-				 valueid, RelationGetRelationName(toastrel));
-			chunksize = 0;		/* keep compiler quiet */
-			chunkdata = NULL;
-		}
-
-		/*
-		 * Some checks on the data we've found
-		 */
-		if (curchunk != expectedchunk)
-			ereport(ERROR,
-					(errcode(ERRCODE_DATA_CORRUPTED),
-					 errmsg_internal("unexpected chunk number %d (expected %d) for toast value %u in %s",
-									 curchunk, expectedchunk, valueid,
-									 RelationGetRelationName(toastrel))));
-		if (curchunk > endchunk)
-			ereport(ERROR,
-					(errcode(ERRCODE_DATA_CORRUPTED),
-					 errmsg_internal("unexpected chunk number %d (out of range %d..%d) for toast value %u in %s",
-									 curchunk,
-									 startchunk, endchunk, valueid,
-									 RelationGetRelationName(toastrel))));
-		expected_size = curchunk < totalchunks - 1 ? TOAST_MAX_CHUNK_SIZE
-			: attrsize % TOAST_MAX_CHUNK_SIZE;
-		if (chunksize != expected_size)
-			ereport(ERROR,
-					(errcode(ERRCODE_DATA_CORRUPTED),
-					 errmsg_internal("unexpected chunk size %d (expected %d) in chunk %d of %d for toast value %u in %s",
-									 chunksize, expected_size,
-									 curchunk, totalchunks, valueid,
-									 RelationGetRelationName(toastrel))));
-
-		/*
-		 * Copy the data into proper place in our result
-		 */
-		chcpystrt = 0;
-		chcpyend = chunksize - 1;
-		if (curchunk == startchunk)
-			chcpystrt = sliceoffset % TOAST_MAX_CHUNK_SIZE;
-		if (curchunk == endchunk)
-			chcpyend = (sliceoffset + slicelength - 1) % TOAST_MAX_CHUNK_SIZE;
-
-		memcpy(VARDATA(result) +
-			   (curchunk * TOAST_MAX_CHUNK_SIZE - sliceoffset) + chcpystrt,
-			   chunkdata + chcpystrt,
-			   (chcpyend - chcpystrt) + 1);
-
-		expectedchunk++;
-	}
-
-	/*
-	 * Final checks that we successfully fetched the datum
-	 */
-	if (expectedchunk != (endchunk + 1))
-		ereport(ERROR,
-				(errcode(ERRCODE_DATA_CORRUPTED),
-				 errmsg_internal("missing chunk number %d for toast value %u in %s",
-								 expectedchunk, valueid,
-								 RelationGetRelationName(toastrel))));
-
-	/* End scan and close indexes. */
-	systable_endscan_ordered(toastscan);
-	toast_close_indexes(toastidxs, num_indexes, AccessShareLock);
-}
-
 /* ----------
  * toast_decompress_datum -
  *
diff --git a/src/backend/access/heap/heapam_handler.c b/src/backend/access/heap/heapam_handler.c
index 1d053e74e6..b443c6c1d5 100644
--- a/src/backend/access/heap/heapam_handler.c
+++ b/src/backend/access/heap/heapam_handler.c
@@ -2545,6 +2545,7 @@ static const TableAmRoutine heapam_methods = {
 	.relation_size = table_block_relation_size,
 	.relation_needs_toast_table = heapam_relation_needs_toast_table,
 	.relation_toast_am = heapam_relation_toast_am,
+	.relation_fetch_toast_slice = heap_fetch_toast_slice,
 
 	.relation_estimate_size = heapam_estimate_rel_size,
 
diff --git a/src/backend/access/heap/heaptoast.c b/src/backend/access/heap/heaptoast.c
index dcfdee4467..2ee639081a 100644
--- a/src/backend/access/heap/heaptoast.c
+++ b/src/backend/access/heap/heaptoast.c
@@ -25,10 +25,12 @@
 #include "postgres.h"
 
 #include "access/detoast.h"
+#include "access/genam.h"
 #include "access/heapam.h"
 #include "access/heaptoast.h"
 #include "access/toast_helper.h"
 #include "access/toast_internals.h"
+#include "utils/fmgroids.h"
 
 
 /* ----------
@@ -604,3 +606,186 @@ toast_build_flattened_tuple(TupleDesc tupleDesc,
 
 	return new_tuple;
 }
+
+/*
+ * Fetch a TOAST slice from a heap table.
+ *
+ * toastrel is the relation from which chunks are to be fetched.
+ * valueid identifies the TOAST value from which chunks are being fetched.
+ * attrsize is the total size of the TOAST value.
+ * sliceoffset is the byte offset within the TOAST value from which to fetch.
+ * slicelength is the number of bytes to be fetched from the TOAST value.
+ * result is the varlena into which the results should be written.
+ */
+void
+heap_fetch_toast_slice(Relation toastrel, Oid valueid, int32 attrsize,
+					   int32 sliceoffset, int32 slicelength,
+					   struct varlena *result)
+{
+	Relation   *toastidxs;
+	ScanKeyData toastkey[3];
+	TupleDesc	toasttupDesc = toastrel->rd_att;
+	int			nscankeys;
+	SysScanDesc toastscan;
+	HeapTuple	ttup;
+	int32		expectedchunk;
+	int32		totalchunks = ((attrsize - 1) / TOAST_MAX_CHUNK_SIZE) + 1;
+	int			startchunk;
+	int			endchunk;
+	int			num_indexes;
+	int			validIndex;
+	SnapshotData SnapshotToast;
+
+	/* Look for the valid index of toast relation */
+	validIndex = toast_open_indexes(toastrel,
+									AccessShareLock,
+									&toastidxs,
+									&num_indexes);
+
+	startchunk = sliceoffset / TOAST_MAX_CHUNK_SIZE;
+	endchunk = (sliceoffset + slicelength - 1) / TOAST_MAX_CHUNK_SIZE;
+	Assert(endchunk <= totalchunks);
+
+	/*
+	 * Setup a scan key to fetch from the index. This is either two keys or
+	 * three depending on the number of chunks.
+	 */
+	ScanKeyInit(&toastkey[0],
+				(AttrNumber) 1,
+				BTEqualStrategyNumber, F_OIDEQ,
+				ObjectIdGetDatum(valueid));
+
+	/*
+	 * No addition condition if fetching all chuns. Otherwise, use an
+	 * equality condition for one chunk, and a range condition otherwise.
+	 */
+	if (startchunk == 0 && endchunk == totalchunks - 1)
+		nscankeys = 1;
+	else if (startchunk == endchunk)
+	{
+		ScanKeyInit(&toastkey[1],
+					(AttrNumber) 2,
+					BTEqualStrategyNumber, F_INT4EQ,
+					Int32GetDatum(startchunk));
+		nscankeys = 2;
+	}
+	else
+	{
+		ScanKeyInit(&toastkey[1],
+					(AttrNumber) 2,
+					BTGreaterEqualStrategyNumber, F_INT4GE,
+					Int32GetDatum(startchunk));
+		ScanKeyInit(&toastkey[2],
+					(AttrNumber) 2,
+					BTLessEqualStrategyNumber, F_INT4LE,
+					Int32GetDatum(endchunk));
+		nscankeys = 3;
+	}
+
+	/* Prepare for scan */
+	init_toast_snapshot(&SnapshotToast);
+	toastscan = systable_beginscan_ordered(toastrel, toastidxs[validIndex],
+										   &SnapshotToast, nscankeys, toastkey);
+
+	/*
+	 * Read the chunks by index
+	 *
+	 * The index is on (valueid, chunkidx) so they will come in order
+	 */
+	expectedchunk = startchunk;
+	while ((ttup = systable_getnext_ordered(toastscan, ForwardScanDirection)) != NULL)
+	{
+		int32		curchunk;
+		Pointer		chunk;
+		bool		isnull;
+		char	   *chunkdata;
+		int32		chunksize;
+		int32		expected_size;
+		int32		chcpystrt;
+		int32		chcpyend;
+
+		/*
+		 * Have a chunk, extract the sequence number and the data
+		 */
+		curchunk = DatumGetInt32(fastgetattr(ttup, 2, toasttupDesc, &isnull));
+		Assert(!isnull);
+		chunk = DatumGetPointer(fastgetattr(ttup, 3, toasttupDesc, &isnull));
+		Assert(!isnull);
+		if (!VARATT_IS_EXTENDED(chunk))
+		{
+			chunksize = VARSIZE(chunk) - VARHDRSZ;
+			chunkdata = VARDATA(chunk);
+		}
+		else if (VARATT_IS_SHORT(chunk))
+		{
+			/* could happen due to heap_form_tuple doing its thing */
+			chunksize = VARSIZE_SHORT(chunk) - VARHDRSZ_SHORT;
+			chunkdata = VARDATA_SHORT(chunk);
+		}
+		else
+		{
+			/* should never happen */
+			elog(ERROR, "found toasted toast chunk for toast value %u in %s",
+				 valueid, RelationGetRelationName(toastrel));
+			chunksize = 0;		/* keep compiler quiet */
+			chunkdata = NULL;
+		}
+
+		/*
+		 * Some checks on the data we've found
+		 */
+		if (curchunk != expectedchunk)
+			ereport(ERROR,
+					(errcode(ERRCODE_DATA_CORRUPTED),
+					 errmsg_internal("unexpected chunk number %d (expected %d) for toast value %u in %s",
+									 curchunk, expectedchunk, valueid,
+									 RelationGetRelationName(toastrel))));
+		if (curchunk > endchunk)
+			ereport(ERROR,
+					(errcode(ERRCODE_DATA_CORRUPTED),
+					 errmsg_internal("unexpected chunk number %d (out of range %d..%d) for toast value %u in %s",
+									 curchunk,
+									 startchunk, endchunk, valueid,
+									 RelationGetRelationName(toastrel))));
+		expected_size = curchunk < totalchunks - 1 ? TOAST_MAX_CHUNK_SIZE
+			: attrsize % TOAST_MAX_CHUNK_SIZE;
+		if (chunksize != expected_size)
+			ereport(ERROR,
+					(errcode(ERRCODE_DATA_CORRUPTED),
+					 errmsg_internal("unexpected chunk size %d (expected %d) in chunk %d of %d for toast value %u in %s",
+									 chunksize, expected_size,
+									 curchunk, totalchunks, valueid,
+									 RelationGetRelationName(toastrel))));
+
+		/*
+		 * Copy the data into proper place in our result
+		 */
+		chcpystrt = 0;
+		chcpyend = chunksize - 1;
+		if (curchunk == startchunk)
+			chcpystrt = sliceoffset % TOAST_MAX_CHUNK_SIZE;
+		if (curchunk == endchunk)
+			chcpyend = (sliceoffset + slicelength - 1) % TOAST_MAX_CHUNK_SIZE;
+
+		memcpy(VARDATA(result) +
+			   (curchunk * TOAST_MAX_CHUNK_SIZE - sliceoffset) + chcpystrt,
+			   chunkdata + chcpystrt,
+			   (chcpyend - chcpystrt) + 1);
+
+		expectedchunk++;
+	}
+
+	/*
+	 * Final checks that we successfully fetched the datum
+	 */
+	if (expectedchunk != (endchunk + 1))
+		ereport(ERROR,
+				(errcode(ERRCODE_DATA_CORRUPTED),
+				 errmsg_internal("missing chunk number %d for toast value %u in %s",
+								 expectedchunk, valueid,
+								 RelationGetRelationName(toastrel))));
+
+	/* End scan and close indexes. */
+	systable_endscan_ordered(toastscan);
+	toast_close_indexes(toastidxs, num_indexes, AccessShareLock);
+}
diff --git a/src/include/access/heaptoast.h b/src/include/access/heaptoast.h
index 488a2e4a7f..0bf6b23c8f 100644
--- a/src/include/access/heaptoast.h
+++ b/src/include/access/heaptoast.h
@@ -136,4 +136,14 @@ extern HeapTuple toast_build_flattened_tuple(TupleDesc tupleDesc,
 											 Datum *values,
 											 bool *isnull);
 
+/* ----------
+ * heap_fetch_toast_slice
+ *
+ *	Fetch a slice from a toast value stored in a heap table.
+ * ----------
+ */
+extern void heap_fetch_toast_slice(Relation toastrel, Oid valueid,
+								   int32 attrsize, int32 sliceoffset,
+								   int32 slicelength, struct varlena *result);
+
 #endif							/* HEAPTOAST_H */
diff --git a/src/include/access/tableam.h b/src/include/access/tableam.h
index 7ac9bb6d65..b784aaf5a9 100644
--- a/src/include/access/tableam.h
+++ b/src/include/access/tableam.h
@@ -588,6 +588,17 @@ typedef struct TableAmRoutine
 	 */
 	Oid		    (*relation_toast_am) (Relation rel);
 
+	/*
+	 * This callback is invoked when detoasting a value stored in a toast
+	 * table implemented by this AM.  See table_relation_fetch_toast_slice()
+	 * for more details.
+	 */
+	void		(*relation_fetch_toast_slice) (Relation toastrel, Oid valueid,
+											   int32 attrsize,
+											   int32 sliceoffset,
+											   int32 slicelength,
+											   struct varlena *result);
+
 
 	/* ------------------------------------------------------------------------
 	 * Planner related functions.
@@ -1620,6 +1631,41 @@ table_relation_toast_am(Relation rel)
 	return rel->rd_tableam->relation_toast_am(rel);
 }
 
+/*
+ * Fetch all or part of a TOAST value from a TOAST table.
+ *
+ * If this AM is never used to implement a TOAST table, then this callback
+ * is not needed. But, if toasted values are ever stored in a table of this
+ * type, then you will need this callback.
+ *
+ * toastrel is the relation in which the toasted value is stored.
+ *
+ * valueid identifes which toast value is to be fetched. For the heap,
+ * this corresponds to the values stored in the chunk_id column.
+ *
+ * attrsize is the total size of the toast value to be fetched.
+ *
+ * sliceoffset is the offset within the toast value of the first byte that
+ * should be fetched.
+ *
+ * slicelength is the number of bytes from the toast value that should be
+ * fetched.
+ *
+ * result is caller-allocated space into which the fetched bytes should be
+ * stored.
+ */
+static inline void
+table_relation_fetch_toast_slice(Relation toastrel, Oid valueid,
+								 int32 attrsize, int32 sliceoffset,
+								 int32 slicelength, struct varlena *result)
+{
+	return toastrel->rd_tableam->relation_fetch_toast_slice(toastrel, valueid,
+															attrsize,
+															sliceoffset,
+															slicelength,
+															result);
+}
+
 
 /* ----------------------------------------------------------------------------
  * Planner related functionality
-- 
2.17.2 (Apple Git-113)

From 1e92076fe0b73423b572db9dfd34b6e4d2a13deb Mon Sep 17 00:00:00 2001
From: Robert Haas <rhaas@postgresql.org>
Date: Fri, 22 Nov 2019 09:23:34 -0500
Subject: [PATCH v9 1/4] tableam: Allow choice of toast AM.

Previously, the toast table had to be implemented by the same AM that
was used for the main table, which was bad, because the detoasting
code won't work with anything but heap. This commit doesn't fix the
latter problem, though I plan to do that in a later commit, but it
does let you choose what AM you'd like to use, so that a table AM
can at least choose heap and get something that works.

Patch by me, reviewed by Andres Freund.

Discussion: http://postgr.es/m/CA+TgmoZv-=2iWM4jcw5ZhJeL18HF96+W1yJeYrnGMYdkFFnEpQ@mail.gmail.com
---
 src/backend/access/heap/heapam_handler.c | 10 ++++++++++
 src/backend/catalog/toasting.c           |  2 +-
 src/include/access/tableam.h             | 17 +++++++++++++++++
 3 files changed, 28 insertions(+), 1 deletion(-)

diff --git a/src/backend/access/heap/heapam_handler.c b/src/backend/access/heap/heapam_handler.c
index 92073fec54..1d053e74e6 100644
--- a/src/backend/access/heap/heapam_handler.c
+++ b/src/backend/access/heap/heapam_handler.c
@@ -2037,6 +2037,15 @@ heapam_relation_needs_toast_table(Relation rel)
 	return (tuple_length > TOAST_TUPLE_THRESHOLD);
 }
 
+/*
+ * TOAST tables for heap relations are just heap relations.
+ */
+static Oid
+heapam_relation_toast_am(Relation rel)
+{
+	return rel->rd_rel->relam;
+}
+
 
 /* ------------------------------------------------------------------------
  * Planner related callbacks for the heap AM
@@ -2535,6 +2544,7 @@ static const TableAmRoutine heapam_methods = {
 
 	.relation_size = table_block_relation_size,
 	.relation_needs_toast_table = heapam_relation_needs_toast_table,
+	.relation_toast_am = heapam_relation_toast_am,
 
 	.relation_estimate_size = heapam_estimate_rel_size,
 
diff --git a/src/backend/catalog/toasting.c b/src/backend/catalog/toasting.c
index de6282a667..f082463bf6 100644
--- a/src/backend/catalog/toasting.c
+++ b/src/backend/catalog/toasting.c
@@ -258,7 +258,7 @@ create_toast_table(Relation rel, Oid toastOid, Oid toastIndexOid,
 										   toast_typid,
 										   InvalidOid,
 										   rel->rd_rel->relowner,
-										   rel->rd_rel->relam,
+										   table_relation_toast_am(rel),
 										   tupdesc,
 										   NIL,
 										   RELKIND_TOASTVALUE,
diff --git a/src/include/access/tableam.h b/src/include/access/tableam.h
index 64022917e2..7ac9bb6d65 100644
--- a/src/include/access/tableam.h
+++ b/src/include/access/tableam.h
@@ -581,6 +581,13 @@ typedef struct TableAmRoutine
 	 */
 	bool		(*relation_needs_toast_table) (Relation rel);
 
+	/*
+	 * This callback should return the OID of the table AM that implements
+	 * TOAST tables for this AM.  If the relation_needs_toast_table callback
+	 * always returns false, this callback is not required.
+	 */
+	Oid		    (*relation_toast_am) (Relation rel);
+
 
 	/* ------------------------------------------------------------------------
 	 * Planner related functions.
@@ -1603,6 +1610,16 @@ table_relation_needs_toast_table(Relation rel)
 	return rel->rd_tableam->relation_needs_toast_table(rel);
 }
 
+/*
+ * Return the OID of the AM that should be used to implement the TOAST table
+ * for this relation.
+ */
+static inline Oid
+table_relation_toast_am(Relation rel)
+{
+	return rel->rd_tableam->relation_toast_am(rel);
+}
+
 
 /* ----------------------------------------------------------------------------
  * Planner related functionality
-- 
2.17.2 (Apple Git-113)

From 41c08290d25eebc5e2aad9e6211db4bc7a9053b4 Mon Sep 17 00:00:00 2001
From: Robert Haas <rhaas@postgresql.org>
Date: Fri, 22 Nov 2019 10:12:22 -0500
Subject: [PATCH v10 3/3] tableam: New callback relation_fetch_toast_slice.

Instead of always calling heap_fetch_toast_slice during detoasting,
invoke a table AM callback which, when the toast table is a heap
table, will be heap_fetch_toast_slice.

This makes it possible for a table AM other than heap to be used
as a TOAST table.
---
 src/backend/access/common/detoast.c      | 199 +----------------------
 src/backend/access/heap/heapam_handler.c |   1 +
 src/backend/access/heap/heaptoast.c      | 185 +++++++++++++++++++++
 src/include/access/heaptoast.h           |  10 ++
 src/include/access/tableam.h             |  46 ++++++
 5 files changed, 248 insertions(+), 193 deletions(-)

diff --git a/src/backend/access/common/detoast.c b/src/backend/access/common/detoast.c
index c1e6eabe89..3df0cf2512 100644
--- a/src/backend/access/common/detoast.c
+++ b/src/backend/access/common/detoast.c
@@ -14,22 +14,17 @@
 #include "postgres.h"
 
 #include "access/detoast.h"
-#include "access/genam.h"
-#include "access/heaptoast.h"
 #include "access/table.h"
+#include "access/tableam.h"
 #include "access/toast_internals.h"
 #include "common/pg_lzcompress.h"
 #include "utils/expandeddatum.h"
-#include "utils/fmgroids.h"
 #include "utils/rel.h"
 
 static struct varlena *toast_fetch_datum(struct varlena *attr);
 static struct varlena *toast_fetch_datum_slice(struct varlena *attr,
 											   int32 sliceoffset,
 											   int32 slicelength);
-static void heap_fetch_toast_slice(Relation toastrel, Oid valueid,
-								   int32 attrsize, int32 sliceoffset,
-								   int32 slicelength, struct varlena *result);
 static struct varlena *toast_decompress_datum(struct varlena *attr);
 static struct varlena *toast_decompress_datum_slice(struct varlena *attr, int32 slicelength);
 
@@ -356,8 +351,8 @@ toast_fetch_datum(struct varlena *attr)
 	toastrel = table_open(toast_pointer.va_toastrelid, AccessShareLock);
 
 	/* Fetch all chunks */
-	heap_fetch_toast_slice(toastrel, toast_pointer.va_valueid, attrsize, 0,
-						   attrsize, result);
+	table_relation_fetch_toast_slice(toastrel, toast_pointer.va_valueid,
+									 attrsize, 0, attrsize, result);
 
 	/* Close toast table */
 	table_close(toastrel, AccessShareLock);
@@ -431,8 +426,9 @@ toast_fetch_datum_slice(struct varlena *attr, int32 sliceoffset,
 	toastrel = table_open(toast_pointer.va_toastrelid, AccessShareLock);
 
 	/* Fetch all chunks */
-	heap_fetch_toast_slice(toastrel, toast_pointer.va_valueid, attrsize,
-						   sliceoffset, slicelength, result);
+	table_relation_fetch_toast_slice(toastrel, toast_pointer.va_valueid,
+									 attrsize, sliceoffset, slicelength,
+									 result);
 
 	/* Close toast table */
 	table_close(toastrel, AccessShareLock);
@@ -440,189 +436,6 @@ toast_fetch_datum_slice(struct varlena *attr, int32 sliceoffset,
 	return result;
 }
 
-/*
- * Fetch a TOAST slice from a heap table.
- *
- * toastrel is the relation from which chunks are to be fetched.
- * valueid identifies the TOAST value from which chunks are being fetched.
- * attrsize is the total size of the TOAST value.
- * sliceoffset is the byte offset within the TOAST value from which to fetch.
- * slicelength is the number of bytes to be fetched from the TOAST value.
- * result is the varlena into which the results should be written.
- */
-static void
-heap_fetch_toast_slice(Relation toastrel, Oid valueid, int32 attrsize,
-					   int32 sliceoffset, int32 slicelength,
-					   struct varlena *result)
-{
-	Relation   *toastidxs;
-	ScanKeyData toastkey[3];
-	TupleDesc	toasttupDesc = toastrel->rd_att;
-	int			nscankeys;
-	SysScanDesc toastscan;
-	HeapTuple	ttup;
-	int32		expectedchunk;
-	int32		totalchunks = ((attrsize - 1) / TOAST_MAX_CHUNK_SIZE) + 1;
-	int			startchunk;
-	int			endchunk;
-	int			num_indexes;
-	int			validIndex;
-	SnapshotData SnapshotToast;
-
-	/* Look for the valid index of toast relation */
-	validIndex = toast_open_indexes(toastrel,
-									AccessShareLock,
-									&toastidxs,
-									&num_indexes);
-
-	startchunk = sliceoffset / TOAST_MAX_CHUNK_SIZE;
-	endchunk = (sliceoffset + slicelength - 1) / TOAST_MAX_CHUNK_SIZE;
-	Assert(endchunk <= totalchunks);
-
-	/*
-	 * Setup a scan key to fetch from the index. This is either two keys or
-	 * three depending on the number of chunks.
-	 */
-	ScanKeyInit(&toastkey[0],
-				(AttrNumber) 1,
-				BTEqualStrategyNumber, F_OIDEQ,
-				ObjectIdGetDatum(valueid));
-
-	/*
-	 * No addition condition if fetching all chuns. Otherwise, use an
-	 * equality condition for one chunk, and a range condition otherwise.
-	 */
-	if (startchunk == 0 && endchunk == totalchunks - 1)
-		nscankeys = 1;
-	else if (startchunk == endchunk)
-	{
-		ScanKeyInit(&toastkey[1],
-					(AttrNumber) 2,
-					BTEqualStrategyNumber, F_INT4EQ,
-					Int32GetDatum(startchunk));
-		nscankeys = 2;
-	}
-	else
-	{
-		ScanKeyInit(&toastkey[1],
-					(AttrNumber) 2,
-					BTGreaterEqualStrategyNumber, F_INT4GE,
-					Int32GetDatum(startchunk));
-		ScanKeyInit(&toastkey[2],
-					(AttrNumber) 2,
-					BTLessEqualStrategyNumber, F_INT4LE,
-					Int32GetDatum(endchunk));
-		nscankeys = 3;
-	}
-
-	/* Prepare for scan */
-	init_toast_snapshot(&SnapshotToast);
-	toastscan = systable_beginscan_ordered(toastrel, toastidxs[validIndex],
-										   &SnapshotToast, nscankeys, toastkey);
-
-	/*
-	 * Read the chunks by index
-	 *
-	 * The index is on (valueid, chunkidx) so they will come in order
-	 */
-	expectedchunk = startchunk;
-	while ((ttup = systable_getnext_ordered(toastscan, ForwardScanDirection)) != NULL)
-	{
-		int32		curchunk;
-		Pointer		chunk;
-		bool		isnull;
-		char	   *chunkdata;
-		int32		chunksize;
-		int32		expected_size;
-		int32		chcpystrt;
-		int32		chcpyend;
-
-		/*
-		 * Have a chunk, extract the sequence number and the data
-		 */
-		curchunk = DatumGetInt32(fastgetattr(ttup, 2, toasttupDesc, &isnull));
-		Assert(!isnull);
-		chunk = DatumGetPointer(fastgetattr(ttup, 3, toasttupDesc, &isnull));
-		Assert(!isnull);
-		if (!VARATT_IS_EXTENDED(chunk))
-		{
-			chunksize = VARSIZE(chunk) - VARHDRSZ;
-			chunkdata = VARDATA(chunk);
-		}
-		else if (VARATT_IS_SHORT(chunk))
-		{
-			/* could happen due to heap_form_tuple doing its thing */
-			chunksize = VARSIZE_SHORT(chunk) - VARHDRSZ_SHORT;
-			chunkdata = VARDATA_SHORT(chunk);
-		}
-		else
-		{
-			/* should never happen */
-			elog(ERROR, "found toasted toast chunk for toast value %u in %s",
-				 valueid, RelationGetRelationName(toastrel));
-			chunksize = 0;		/* keep compiler quiet */
-			chunkdata = NULL;
-		}
-
-		/*
-		 * Some checks on the data we've found
-		 */
-		if (curchunk != expectedchunk)
-			ereport(ERROR,
-					(errcode(ERRCODE_DATA_CORRUPTED),
-					 errmsg_internal("unexpected chunk number %d (expected %d) for toast value %u in %s",
-									 curchunk, expectedchunk, valueid,
-									 RelationGetRelationName(toastrel))));
-		if (curchunk > endchunk)
-			ereport(ERROR,
-					(errcode(ERRCODE_DATA_CORRUPTED),
-					 errmsg_internal("unexpected chunk number %d (out of range %d..%d) for toast value %u in %s",
-									 curchunk,
-									 startchunk, endchunk, valueid,
-									 RelationGetRelationName(toastrel))));
-		expected_size = curchunk < totalchunks - 1 ? TOAST_MAX_CHUNK_SIZE
-			: attrsize - ((totalchunks - 1) * TOAST_MAX_CHUNK_SIZE);
-		if (chunksize != expected_size)
-			ereport(ERROR,
-					(errcode(ERRCODE_DATA_CORRUPTED),
-					 errmsg_internal("unexpected chunk size %d (expected %d) in chunk %d of %d for toast value %u in %s",
-									 chunksize, expected_size,
-									 curchunk, totalchunks, valueid,
-									 RelationGetRelationName(toastrel))));
-
-		/*
-		 * Copy the data into proper place in our result
-		 */
-		chcpystrt = 0;
-		chcpyend = chunksize - 1;
-		if (curchunk == startchunk)
-			chcpystrt = sliceoffset % TOAST_MAX_CHUNK_SIZE;
-		if (curchunk == endchunk)
-			chcpyend = (sliceoffset + slicelength - 1) % TOAST_MAX_CHUNK_SIZE;
-
-		memcpy(VARDATA(result) +
-			   (curchunk * TOAST_MAX_CHUNK_SIZE - sliceoffset) + chcpystrt,
-			   chunkdata + chcpystrt,
-			   (chcpyend - chcpystrt) + 1);
-
-		expectedchunk++;
-	}
-
-	/*
-	 * Final checks that we successfully fetched the datum
-	 */
-	if (expectedchunk != (endchunk + 1))
-		ereport(ERROR,
-				(errcode(ERRCODE_DATA_CORRUPTED),
-				 errmsg_internal("missing chunk number %d for toast value %u in %s",
-								 expectedchunk, valueid,
-								 RelationGetRelationName(toastrel))));
-
-	/* End scan and close indexes. */
-	systable_endscan_ordered(toastscan);
-	toast_close_indexes(toastidxs, num_indexes, AccessShareLock);
-}
-
 /* ----------
  * toast_decompress_datum -
  *
diff --git a/src/backend/access/heap/heapam_handler.c b/src/backend/access/heap/heapam_handler.c
index 1d053e74e6..b443c6c1d5 100644
--- a/src/backend/access/heap/heapam_handler.c
+++ b/src/backend/access/heap/heapam_handler.c
@@ -2545,6 +2545,7 @@ static const TableAmRoutine heapam_methods = {
 	.relation_size = table_block_relation_size,
 	.relation_needs_toast_table = heapam_relation_needs_toast_table,
 	.relation_toast_am = heapam_relation_toast_am,
+	.relation_fetch_toast_slice = heap_fetch_toast_slice,
 
 	.relation_estimate_size = heapam_estimate_rel_size,
 
diff --git a/src/backend/access/heap/heaptoast.c b/src/backend/access/heap/heaptoast.c
index dcfdee4467..410920c1a7 100644
--- a/src/backend/access/heap/heaptoast.c
+++ b/src/backend/access/heap/heaptoast.c
@@ -25,10 +25,12 @@
 #include "postgres.h"
 
 #include "access/detoast.h"
+#include "access/genam.h"
 #include "access/heapam.h"
 #include "access/heaptoast.h"
 #include "access/toast_helper.h"
 #include "access/toast_internals.h"
+#include "utils/fmgroids.h"
 
 
 /* ----------
@@ -604,3 +606,186 @@ toast_build_flattened_tuple(TupleDesc tupleDesc,
 
 	return new_tuple;
 }
+
+/*
+ * Fetch a TOAST slice from a heap table.
+ *
+ * toastrel is the relation from which chunks are to be fetched.
+ * valueid identifies the TOAST value from which chunks are being fetched.
+ * attrsize is the total size of the TOAST value.
+ * sliceoffset is the byte offset within the TOAST value from which to fetch.
+ * slicelength is the number of bytes to be fetched from the TOAST value.
+ * result is the varlena into which the results should be written.
+ */
+void
+heap_fetch_toast_slice(Relation toastrel, Oid valueid, int32 attrsize,
+					   int32 sliceoffset, int32 slicelength,
+					   struct varlena *result)
+{
+	Relation   *toastidxs;
+	ScanKeyData toastkey[3];
+	TupleDesc	toasttupDesc = toastrel->rd_att;
+	int			nscankeys;
+	SysScanDesc toastscan;
+	HeapTuple	ttup;
+	int32		expectedchunk;
+	int32		totalchunks = ((attrsize - 1) / TOAST_MAX_CHUNK_SIZE) + 1;
+	int			startchunk;
+	int			endchunk;
+	int			num_indexes;
+	int			validIndex;
+	SnapshotData SnapshotToast;
+
+	/* Look for the valid index of toast relation */
+	validIndex = toast_open_indexes(toastrel,
+									AccessShareLock,
+									&toastidxs,
+									&num_indexes);
+
+	startchunk = sliceoffset / TOAST_MAX_CHUNK_SIZE;
+	endchunk = (sliceoffset + slicelength - 1) / TOAST_MAX_CHUNK_SIZE;
+	Assert(endchunk <= totalchunks);
+
+	/*
+	 * Setup a scan key to fetch from the index. This is either two keys or
+	 * three depending on the number of chunks.
+	 */
+	ScanKeyInit(&toastkey[0],
+				(AttrNumber) 1,
+				BTEqualStrategyNumber, F_OIDEQ,
+				ObjectIdGetDatum(valueid));
+
+	/*
+	 * No addition condition if fetching all chuns. Otherwise, use an
+	 * equality condition for one chunk, and a range condition otherwise.
+	 */
+	if (startchunk == 0 && endchunk == totalchunks - 1)
+		nscankeys = 1;
+	else if (startchunk == endchunk)
+	{
+		ScanKeyInit(&toastkey[1],
+					(AttrNumber) 2,
+					BTEqualStrategyNumber, F_INT4EQ,
+					Int32GetDatum(startchunk));
+		nscankeys = 2;
+	}
+	else
+	{
+		ScanKeyInit(&toastkey[1],
+					(AttrNumber) 2,
+					BTGreaterEqualStrategyNumber, F_INT4GE,
+					Int32GetDatum(startchunk));
+		ScanKeyInit(&toastkey[2],
+					(AttrNumber) 2,
+					BTLessEqualStrategyNumber, F_INT4LE,
+					Int32GetDatum(endchunk));
+		nscankeys = 3;
+	}
+
+	/* Prepare for scan */
+	init_toast_snapshot(&SnapshotToast);
+	toastscan = systable_beginscan_ordered(toastrel, toastidxs[validIndex],
+										   &SnapshotToast, nscankeys, toastkey);
+
+	/*
+	 * Read the chunks by index
+	 *
+	 * The index is on (valueid, chunkidx) so they will come in order
+	 */
+	expectedchunk = startchunk;
+	while ((ttup = systable_getnext_ordered(toastscan, ForwardScanDirection)) != NULL)
+	{
+		int32		curchunk;
+		Pointer		chunk;
+		bool		isnull;
+		char	   *chunkdata;
+		int32		chunksize;
+		int32		expected_size;
+		int32		chcpystrt;
+		int32		chcpyend;
+
+		/*
+		 * Have a chunk, extract the sequence number and the data
+		 */
+		curchunk = DatumGetInt32(fastgetattr(ttup, 2, toasttupDesc, &isnull));
+		Assert(!isnull);
+		chunk = DatumGetPointer(fastgetattr(ttup, 3, toasttupDesc, &isnull));
+		Assert(!isnull);
+		if (!VARATT_IS_EXTENDED(chunk))
+		{
+			chunksize = VARSIZE(chunk) - VARHDRSZ;
+			chunkdata = VARDATA(chunk);
+		}
+		else if (VARATT_IS_SHORT(chunk))
+		{
+			/* could happen due to heap_form_tuple doing its thing */
+			chunksize = VARSIZE_SHORT(chunk) - VARHDRSZ_SHORT;
+			chunkdata = VARDATA_SHORT(chunk);
+		}
+		else
+		{
+			/* should never happen */
+			elog(ERROR, "found toasted toast chunk for toast value %u in %s",
+				 valueid, RelationGetRelationName(toastrel));
+			chunksize = 0;		/* keep compiler quiet */
+			chunkdata = NULL;
+		}
+
+		/*
+		 * Some checks on the data we've found
+		 */
+		if (curchunk != expectedchunk)
+			ereport(ERROR,
+					(errcode(ERRCODE_DATA_CORRUPTED),
+					 errmsg_internal("unexpected chunk number %d (expected %d) for toast value %u in %s",
+									 curchunk, expectedchunk, valueid,
+									 RelationGetRelationName(toastrel))));
+		if (curchunk > endchunk)
+			ereport(ERROR,
+					(errcode(ERRCODE_DATA_CORRUPTED),
+					 errmsg_internal("unexpected chunk number %d (out of range %d..%d) for toast value %u in %s",
+									 curchunk,
+									 startchunk, endchunk, valueid,
+									 RelationGetRelationName(toastrel))));
+		expected_size = curchunk < totalchunks - 1 ? TOAST_MAX_CHUNK_SIZE
+			: attrsize - ((totalchunks - 1) * TOAST_MAX_CHUNK_SIZE);
+		if (chunksize != expected_size)
+			ereport(ERROR,
+					(errcode(ERRCODE_DATA_CORRUPTED),
+					 errmsg_internal("unexpected chunk size %d (expected %d) in chunk %d of %d for toast value %u in %s",
+									 chunksize, expected_size,
+									 curchunk, totalchunks, valueid,
+									 RelationGetRelationName(toastrel))));
+
+		/*
+		 * Copy the data into proper place in our result
+		 */
+		chcpystrt = 0;
+		chcpyend = chunksize - 1;
+		if (curchunk == startchunk)
+			chcpystrt = sliceoffset % TOAST_MAX_CHUNK_SIZE;
+		if (curchunk == endchunk)
+			chcpyend = (sliceoffset + slicelength - 1) % TOAST_MAX_CHUNK_SIZE;
+
+		memcpy(VARDATA(result) +
+			   (curchunk * TOAST_MAX_CHUNK_SIZE - sliceoffset) + chcpystrt,
+			   chunkdata + chcpystrt,
+			   (chcpyend - chcpystrt) + 1);
+
+		expectedchunk++;
+	}
+
+	/*
+	 * Final checks that we successfully fetched the datum
+	 */
+	if (expectedchunk != (endchunk + 1))
+		ereport(ERROR,
+				(errcode(ERRCODE_DATA_CORRUPTED),
+				 errmsg_internal("missing chunk number %d for toast value %u in %s",
+								 expectedchunk, valueid,
+								 RelationGetRelationName(toastrel))));
+
+	/* End scan and close indexes. */
+	systable_endscan_ordered(toastscan);
+	toast_close_indexes(toastidxs, num_indexes, AccessShareLock);
+}
diff --git a/src/include/access/heaptoast.h b/src/include/access/heaptoast.h
index 488a2e4a7f..0bf6b23c8f 100644
--- a/src/include/access/heaptoast.h
+++ b/src/include/access/heaptoast.h
@@ -136,4 +136,14 @@ extern HeapTuple toast_build_flattened_tuple(TupleDesc tupleDesc,
 											 Datum *values,
 											 bool *isnull);
 
+/* ----------
+ * heap_fetch_toast_slice
+ *
+ *	Fetch a slice from a toast value stored in a heap table.
+ * ----------
+ */
+extern void heap_fetch_toast_slice(Relation toastrel, Oid valueid,
+								   int32 attrsize, int32 sliceoffset,
+								   int32 slicelength, struct varlena *result);
+
 #endif							/* HEAPTOAST_H */
diff --git a/src/include/access/tableam.h b/src/include/access/tableam.h
index 7ac9bb6d65..b784aaf5a9 100644
--- a/src/include/access/tableam.h
+++ b/src/include/access/tableam.h
@@ -588,6 +588,17 @@ typedef struct TableAmRoutine
 	 */
 	Oid		    (*relation_toast_am) (Relation rel);
 
+	/*
+	 * This callback is invoked when detoasting a value stored in a toast
+	 * table implemented by this AM.  See table_relation_fetch_toast_slice()
+	 * for more details.
+	 */
+	void		(*relation_fetch_toast_slice) (Relation toastrel, Oid valueid,
+											   int32 attrsize,
+											   int32 sliceoffset,
+											   int32 slicelength,
+											   struct varlena *result);
+
 
 	/* ------------------------------------------------------------------------
 	 * Planner related functions.
@@ -1620,6 +1631,41 @@ table_relation_toast_am(Relation rel)
 	return rel->rd_tableam->relation_toast_am(rel);
 }
 
+/*
+ * Fetch all or part of a TOAST value from a TOAST table.
+ *
+ * If this AM is never used to implement a TOAST table, then this callback
+ * is not needed. But, if toasted values are ever stored in a table of this
+ * type, then you will need this callback.
+ *
+ * toastrel is the relation in which the toasted value is stored.
+ *
+ * valueid identifes which toast value is to be fetched. For the heap,
+ * this corresponds to the values stored in the chunk_id column.
+ *
+ * attrsize is the total size of the toast value to be fetched.
+ *
+ * sliceoffset is the offset within the toast value of the first byte that
+ * should be fetched.
+ *
+ * slicelength is the number of bytes from the toast value that should be
+ * fetched.
+ *
+ * result is caller-allocated space into which the fetched bytes should be
+ * stored.
+ */
+static inline void
+table_relation_fetch_toast_slice(Relation toastrel, Oid valueid,
+								 int32 attrsize, int32 sliceoffset,
+								 int32 slicelength, struct varlena *result)
+{
+	return toastrel->rd_tableam->relation_fetch_toast_slice(toastrel, valueid,
+															attrsize,
+															sliceoffset,
+															slicelength,
+															result);
+}
+
 
 /* ----------------------------------------------------------------------------
  * Planner related functionality
-- 
2.17.2 (Apple Git-113)

From 97618036ff22138aefb3ba4e94c02ef8f1fdcdde Mon Sep 17 00:00:00 2001
From: Robert Haas <rhaas@postgresql.org>
Date: Fri, 22 Nov 2019 09:23:34 -0500
Subject: [PATCH v10 1/3] tableam: Allow choice of toast AM.

Previously, the toast table had to be implemented by the same AM that
was used for the main table, which was bad, because the detoasting
code won't work with anything but heap. This commit doesn't fix the
latter problem, though I plan to do that in a later commit, but it
does let you choose what AM you'd like to use, so that a table AM
can at least choose heap and get something that works.

Patch by me, reviewed by Andres Freund.

Discussion: http://postgr.es/m/CA+TgmoZv-=2iWM4jcw5ZhJeL18HF96+W1yJeYrnGMYdkFFnEpQ@mail.gmail.com
---
 src/backend/access/heap/heapam_handler.c | 10 ++++++++++
 src/backend/catalog/toasting.c           |  2 +-
 src/include/access/tableam.h             | 17 +++++++++++++++++
 3 files changed, 28 insertions(+), 1 deletion(-)

diff --git a/src/backend/access/heap/heapam_handler.c b/src/backend/access/heap/heapam_handler.c
index 92073fec54..1d053e74e6 100644
--- a/src/backend/access/heap/heapam_handler.c
+++ b/src/backend/access/heap/heapam_handler.c
@@ -2037,6 +2037,15 @@ heapam_relation_needs_toast_table(Relation rel)
 	return (tuple_length > TOAST_TUPLE_THRESHOLD);
 }
 
+/*
+ * TOAST tables for heap relations are just heap relations.
+ */
+static Oid
+heapam_relation_toast_am(Relation rel)
+{
+	return rel->rd_rel->relam;
+}
+
 
 /* ------------------------------------------------------------------------
  * Planner related callbacks for the heap AM
@@ -2535,6 +2544,7 @@ static const TableAmRoutine heapam_methods = {
 
 	.relation_size = table_block_relation_size,
 	.relation_needs_toast_table = heapam_relation_needs_toast_table,
+	.relation_toast_am = heapam_relation_toast_am,
 
 	.relation_estimate_size = heapam_estimate_rel_size,
 
diff --git a/src/backend/catalog/toasting.c b/src/backend/catalog/toasting.c
index de6282a667..f082463bf6 100644
--- a/src/backend/catalog/toasting.c
+++ b/src/backend/catalog/toasting.c
@@ -258,7 +258,7 @@ create_toast_table(Relation rel, Oid toastOid, Oid toastIndexOid,
 										   toast_typid,
 										   InvalidOid,
 										   rel->rd_rel->relowner,
-										   rel->rd_rel->relam,
+										   table_relation_toast_am(rel),
 										   tupdesc,
 										   NIL,
 										   RELKIND_TOASTVALUE,
diff --git a/src/include/access/tableam.h b/src/include/access/tableam.h
index 64022917e2..7ac9bb6d65 100644
--- a/src/include/access/tableam.h
+++ b/src/include/access/tableam.h
@@ -581,6 +581,13 @@ typedef struct TableAmRoutine
 	 */
 	bool		(*relation_needs_toast_table) (Relation rel);
 
+	/*
+	 * This callback should return the OID of the table AM that implements
+	 * TOAST tables for this AM.  If the relation_needs_toast_table callback
+	 * always returns false, this callback is not required.
+	 */
+	Oid		    (*relation_toast_am) (Relation rel);
+
 
 	/* ------------------------------------------------------------------------
 	 * Planner related functions.
@@ -1603,6 +1610,16 @@ table_relation_needs_toast_table(Relation rel)
 	return rel->rd_tableam->relation_needs_toast_table(rel);
 }
 
+/*
+ * Return the OID of the AM that should be used to implement the TOAST table
+ * for this relation.
+ */
+static inline Oid
+table_relation_toast_am(Relation rel)
+{
+	return rel->rd_tableam->relation_toast_am(rel);
+}
+
 
 /* ----------------------------------------------------------------------------
  * Planner related functionality
-- 
2.17.2 (Apple Git-113)

From 064308827edc8dd98e222226dcad2a0cf15b679c Mon Sep 17 00:00:00 2001
From: Robert Haas <rhaas@postgresql.org>
Date: Fri, 8 Nov 2019 11:50:52 -0500
Subject: [PATCH v10 2/3] Move heap-specific detoasting logic into a separate
 function.

The new function, heap_fetch_toast_slice, is shared between
toast_fetch_datum_slice and toast_fetch_datum, and does all the
work of scanning the TOAST table, fetching chunks, and storing
them into the space allocated for the result varlena.

As an incidental side effect, this allows toast_fetch_datum_slice
to perform the scan with only a single scankey if all chunks are
being fetched, which might have some tiny performance benefit.

Discussion: http://postgr.es/m/CA+TgmobBzxwFojJ0zV0Own3dr09y43hp+OzU2VW+nos4PMXWEg@mail.gmail.com
---
 src/backend/access/common/detoast.c | 244 ++++++++--------------------
 1 file changed, 71 insertions(+), 173 deletions(-)

diff --git a/src/backend/access/common/detoast.c b/src/backend/access/common/detoast.c
index 6341107e88..c1e6eabe89 100644
--- a/src/backend/access/common/detoast.c
+++ b/src/backend/access/common/detoast.c
@@ -27,6 +27,9 @@ static struct varlena *toast_fetch_datum(struct varlena *attr);
 static struct varlena *toast_fetch_datum_slice(struct varlena *attr,
 											   int32 sliceoffset,
 											   int32 slicelength);
+static void heap_fetch_toast_slice(Relation toastrel, Oid valueid,
+								   int32 attrsize, int32 sliceoffset,
+								   int32 slicelength, struct varlena *result);
 static struct varlena *toast_decompress_datum(struct varlena *attr);
 static struct varlena *toast_decompress_datum_slice(struct varlena *attr, int32 slicelength);
 
@@ -325,19 +328,9 @@ static struct varlena *
 toast_fetch_datum(struct varlena *attr)
 {
 	Relation	toastrel;
-	Relation   *toastidxs;
-	ScanKeyData toastkey;
-	SysScanDesc toastscan;
-	HeapTuple	ttup;
-	TupleDesc	toasttupDesc;
 	struct varlena *result;
 	struct varatt_external toast_pointer;
 	int32		attrsize;
-	int32		expectedchunk;
-	int32		totalchunks;
-	int			num_indexes;
-	int			validIndex;
-	SnapshotData SnapshotToast;
 
 	if (!VARATT_IS_EXTERNAL_ONDISK(attr))
 		elog(ERROR, "toast_fetch_datum shouldn't be called for non-ondisk datums");
@@ -346,7 +339,6 @@ toast_fetch_datum(struct varlena *attr)
 	VARATT_EXTERNAL_GET_POINTER(toast_pointer, attr);
 
 	attrsize = toast_pointer.va_extsize;
-	totalchunks = ((attrsize - 1) / TOAST_MAX_CHUNK_SIZE) + 1;
 
 	result = (struct varlena *) palloc(attrsize + VARHDRSZ);
 
@@ -355,130 +347,19 @@ toast_fetch_datum(struct varlena *attr)
 	else
 		SET_VARSIZE(result, attrsize + VARHDRSZ);
 
+	if (attrsize == 0)
+		return result;		/* Probably shouldn't happen, but just in case. */
+
 	/*
 	 * Open the toast relation and its indexes
 	 */
 	toastrel = table_open(toast_pointer.va_toastrelid, AccessShareLock);
-	toasttupDesc = toastrel->rd_att;
-
-	/* Look for the valid index of the toast relation */
-	validIndex = toast_open_indexes(toastrel,
-									AccessShareLock,
-									&toastidxs,
-									&num_indexes);
 
-	/*
-	 * Setup a scan key to fetch from the index by va_valueid
-	 */
-	ScanKeyInit(&toastkey,
-				(AttrNumber) 1,
-				BTEqualStrategyNumber, F_OIDEQ,
-				ObjectIdGetDatum(toast_pointer.va_valueid));
+	/* Fetch all chunks */
+	heap_fetch_toast_slice(toastrel, toast_pointer.va_valueid, attrsize, 0,
+						   attrsize, result);
 
-	/*
-	 * Read the chunks by index
-	 *
-	 * Note that because the index is actually on (valueid, chunkidx) we will
-	 * see the chunks in chunkidx order, even though we didn't explicitly ask
-	 * for it.
-	 */
-	expectedchunk = 0;
-
-	init_toast_snapshot(&SnapshotToast);
-	toastscan = systable_beginscan_ordered(toastrel, toastidxs[validIndex],
-										   &SnapshotToast, 1, &toastkey);
-	while ((ttup = systable_getnext_ordered(toastscan, ForwardScanDirection)) != NULL)
-	{
-		int32		curchunk;
-		Pointer		chunk;
-		bool		isnull;
-		char	   *chunkdata;
-		int32		chunksize;
-		int32		expected_size;
-
-		/*
-		 * Have a chunk, extract the sequence number and the data
-		 */
-		curchunk = DatumGetInt32(fastgetattr(ttup, 2, toasttupDesc, &isnull));
-		Assert(!isnull);
-		chunk = DatumGetPointer(fastgetattr(ttup, 3, toasttupDesc, &isnull));
-		Assert(!isnull);
-		if (!VARATT_IS_EXTENDED(chunk))
-		{
-			chunksize = VARSIZE(chunk) - VARHDRSZ;
-			chunkdata = VARDATA(chunk);
-		}
-		else if (VARATT_IS_SHORT(chunk))
-		{
-			/* could happen due to heap_form_tuple doing its thing */
-			chunksize = VARSIZE_SHORT(chunk) - VARHDRSZ_SHORT;
-			chunkdata = VARDATA_SHORT(chunk);
-		}
-		else
-		{
-			/* should never happen */
-			elog(ERROR, "found toasted toast chunk for toast value %u in %s",
-				 toast_pointer.va_valueid,
-				 RelationGetRelationName(toastrel));
-			chunksize = 0;		/* keep compiler quiet */
-			chunkdata = NULL;
-		}
-
-		/*
-		 * Some checks on the data we've found
-		 */
-		if (curchunk != expectedchunk)
-			ereport(ERROR,
-					(errcode(ERRCODE_DATA_CORRUPTED),
-					 errmsg_internal("unexpected chunk number %d (expected %d) for toast value %u in %s",
-									 curchunk, expectedchunk,
-									 toast_pointer.va_valueid,
-									 RelationGetRelationName(toastrel))));
-		if (curchunk > totalchunks - 1)
-			ereport(ERROR,
-					(errcode(ERRCODE_DATA_CORRUPTED),
-					 errmsg_internal("unexpected chunk number %d (out of range %d..%d) for toast value %u in %s",
-									 curchunk,
-									 0, totalchunks - 1,
-									 toast_pointer.va_valueid,
-									 RelationGetRelationName(toastrel))));
-		expected_size = curchunk < totalchunks - 1 ? TOAST_MAX_CHUNK_SIZE
-			: attrsize - ((totalchunks - 1) * TOAST_MAX_CHUNK_SIZE);
-		if (chunksize != expected_size)
-			ereport(ERROR,
-					(errcode(ERRCODE_DATA_CORRUPTED),
-					 errmsg_internal("unexpected chunk size %d (expected %d) in chunk %d of %d for toast value %u in %s",
-									 chunksize, expected_size,
-									 curchunk, totalchunks,
-									 toast_pointer.va_valueid,
-									 RelationGetRelationName(toastrel))));
-
-		/*
-		 * Copy the data into proper place in our result
-		 */
-		memcpy(VARDATA(result) + curchunk * TOAST_MAX_CHUNK_SIZE,
-			   chunkdata,
-			   chunksize);
-
-		expectedchunk++;
-	}
-
-	/*
-	 * Final checks that we successfully fetched the datum
-	 */
-	if (expectedchunk != totalchunks)
-		ereport(ERROR,
-				(errcode(ERRCODE_DATA_CORRUPTED),
-				 errmsg_internal("missing chunk number %d for toast value %u in %s",
-								 expectedchunk,
-								 toast_pointer.va_valueid,
-								 RelationGetRelationName(toastrel))));
-
-	/*
-	 * End scan and close relations
-	 */
-	systable_endscan_ordered(toastscan);
-	toast_close_indexes(toastidxs, num_indexes, AccessShareLock);
+	/* Close toast table */
 	table_close(toastrel, AccessShareLock);
 
 	return result;
@@ -500,22 +381,9 @@ toast_fetch_datum_slice(struct varlena *attr, int32 sliceoffset,
 						int32 slicelength)
 {
 	Relation	toastrel;
-	Relation   *toastidxs;
-	ScanKeyData toastkey[3];
-	int			nscankeys;
-	SysScanDesc toastscan;
-	HeapTuple	ttup;
-	TupleDesc	toasttupDesc;
 	struct varlena *result;
 	struct varatt_external toast_pointer;
 	int32		attrsize;
-	int32		expectedchunk;
-	int			startchunk;
-	int			endchunk;
-	int			totalchunks;
-	int			num_indexes;
-	int			validIndex;
-	SnapshotData SnapshotToast;
 
 	if (!VARATT_IS_EXTERNAL_ONDISK(attr))
 		elog(ERROR, "toast_fetch_datum_slice shouldn't be called for non-ondisk datums");
@@ -531,7 +399,6 @@ toast_fetch_datum_slice(struct varlena *attr, int32 sliceoffset,
 	Assert(!VARATT_EXTERNAL_IS_COMPRESSED(toast_pointer) || 0 == sliceoffset);
 
 	attrsize = toast_pointer.va_extsize;
-	totalchunks = ((attrsize - 1) / TOAST_MAX_CHUNK_SIZE) + 1;
 
 	if (sliceoffset >= attrsize)
 	{
@@ -560,15 +427,47 @@ toast_fetch_datum_slice(struct varlena *attr, int32 sliceoffset,
 	if (slicelength == 0)
 		return result;			/* Can save a lot of work at this point! */
 
-	startchunk = sliceoffset / TOAST_MAX_CHUNK_SIZE;
-	endchunk = (sliceoffset + slicelength - 1) / TOAST_MAX_CHUNK_SIZE;
-	Assert(endchunk < totalchunks);
-
-	/*
-	 * Open the toast relation and its indexes
-	 */
+	/* Open the toast relation */
 	toastrel = table_open(toast_pointer.va_toastrelid, AccessShareLock);
-	toasttupDesc = toastrel->rd_att;
+
+	/* Fetch all chunks */
+	heap_fetch_toast_slice(toastrel, toast_pointer.va_valueid, attrsize,
+						   sliceoffset, slicelength, result);
+
+	/* Close toast table */
+	table_close(toastrel, AccessShareLock);
+
+	return result;
+}
+
+/*
+ * Fetch a TOAST slice from a heap table.
+ *
+ * toastrel is the relation from which chunks are to be fetched.
+ * valueid identifies the TOAST value from which chunks are being fetched.
+ * attrsize is the total size of the TOAST value.
+ * sliceoffset is the byte offset within the TOAST value from which to fetch.
+ * slicelength is the number of bytes to be fetched from the TOAST value.
+ * result is the varlena into which the results should be written.
+ */
+static void
+heap_fetch_toast_slice(Relation toastrel, Oid valueid, int32 attrsize,
+					   int32 sliceoffset, int32 slicelength,
+					   struct varlena *result)
+{
+	Relation   *toastidxs;
+	ScanKeyData toastkey[3];
+	TupleDesc	toasttupDesc = toastrel->rd_att;
+	int			nscankeys;
+	SysScanDesc toastscan;
+	HeapTuple	ttup;
+	int32		expectedchunk;
+	int32		totalchunks = ((attrsize - 1) / TOAST_MAX_CHUNK_SIZE) + 1;
+	int			startchunk;
+	int			endchunk;
+	int			num_indexes;
+	int			validIndex;
+	SnapshotData SnapshotToast;
 
 	/* Look for the valid index of toast relation */
 	validIndex = toast_open_indexes(toastrel,
@@ -576,6 +475,10 @@ toast_fetch_datum_slice(struct varlena *attr, int32 sliceoffset,
 									&toastidxs,
 									&num_indexes);
 
+	startchunk = sliceoffset / TOAST_MAX_CHUNK_SIZE;
+	endchunk = (sliceoffset + slicelength - 1) / TOAST_MAX_CHUNK_SIZE;
+	Assert(endchunk <= totalchunks);
+
 	/*
 	 * Setup a scan key to fetch from the index. This is either two keys or
 	 * three depending on the number of chunks.
@@ -583,12 +486,15 @@ toast_fetch_datum_slice(struct varlena *attr, int32 sliceoffset,
 	ScanKeyInit(&toastkey[0],
 				(AttrNumber) 1,
 				BTEqualStrategyNumber, F_OIDEQ,
-				ObjectIdGetDatum(toast_pointer.va_valueid));
+				ObjectIdGetDatum(valueid));
 
 	/*
-	 * Use equality condition for one chunk, a range condition otherwise:
+	 * No addition condition if fetching all chuns. Otherwise, use an
+	 * equality condition for one chunk, and a range condition otherwise.
 	 */
-	if (startchunk == endchunk)
+	if (startchunk == 0 && endchunk == totalchunks - 1)
+		nscankeys = 1;
+	else if (startchunk == endchunk)
 	{
 		ScanKeyInit(&toastkey[1],
 					(AttrNumber) 2,
@@ -609,15 +515,17 @@ toast_fetch_datum_slice(struct varlena *attr, int32 sliceoffset,
 		nscankeys = 3;
 	}
 
+	/* Prepare for scan */
+	init_toast_snapshot(&SnapshotToast);
+	toastscan = systable_beginscan_ordered(toastrel, toastidxs[validIndex],
+										   &SnapshotToast, nscankeys, toastkey);
+
 	/*
 	 * Read the chunks by index
 	 *
 	 * The index is on (valueid, chunkidx) so they will come in order
 	 */
-	init_toast_snapshot(&SnapshotToast);
 	expectedchunk = startchunk;
-	toastscan = systable_beginscan_ordered(toastrel, toastidxs[validIndex],
-										   &SnapshotToast, nscankeys, toastkey);
 	while ((ttup = systable_getnext_ordered(toastscan, ForwardScanDirection)) != NULL)
 	{
 		int32		curchunk;
@@ -651,8 +559,7 @@ toast_fetch_datum_slice(struct varlena *attr, int32 sliceoffset,
 		{
 			/* should never happen */
 			elog(ERROR, "found toasted toast chunk for toast value %u in %s",
-				 toast_pointer.va_valueid,
-				 RelationGetRelationName(toastrel));
+				 valueid, RelationGetRelationName(toastrel));
 			chunksize = 0;		/* keep compiler quiet */
 			chunkdata = NULL;
 		}
@@ -664,16 +571,14 @@ toast_fetch_datum_slice(struct varlena *attr, int32 sliceoffset,
 			ereport(ERROR,
 					(errcode(ERRCODE_DATA_CORRUPTED),
 					 errmsg_internal("unexpected chunk number %d (expected %d) for toast value %u in %s",
-									 curchunk, expectedchunk,
-									 toast_pointer.va_valueid,
+									 curchunk, expectedchunk, valueid,
 									 RelationGetRelationName(toastrel))));
 		if (curchunk > endchunk)
 			ereport(ERROR,
 					(errcode(ERRCODE_DATA_CORRUPTED),
 					 errmsg_internal("unexpected chunk number %d (out of range %d..%d) for toast value %u in %s",
 									 curchunk,
-									 startchunk, endchunk,
-									 toast_pointer.va_valueid,
+									 startchunk, endchunk, valueid,
 									 RelationGetRelationName(toastrel))));
 		expected_size = curchunk < totalchunks - 1 ? TOAST_MAX_CHUNK_SIZE
 			: attrsize - ((totalchunks - 1) * TOAST_MAX_CHUNK_SIZE);
@@ -682,8 +587,7 @@ toast_fetch_datum_slice(struct varlena *attr, int32 sliceoffset,
 					(errcode(ERRCODE_DATA_CORRUPTED),
 					 errmsg_internal("unexpected chunk size %d (expected %d) in chunk %d of %d for toast value %u in %s",
 									 chunksize, expected_size,
-									 curchunk, totalchunks,
-									 toast_pointer.va_valueid,
+									 curchunk, totalchunks, valueid,
 									 RelationGetRelationName(toastrel))));
 
 		/*
@@ -711,18 +615,12 @@ toast_fetch_datum_slice(struct varlena *attr, int32 sliceoffset,
 		ereport(ERROR,
 				(errcode(ERRCODE_DATA_CORRUPTED),
 				 errmsg_internal("missing chunk number %d for toast value %u in %s",
-								 expectedchunk,
-								 toast_pointer.va_valueid,
+								 expectedchunk, valueid,
 								 RelationGetRelationName(toastrel))));
 
-	/*
-	 * End scan and close relations
-	 */
+	/* End scan and close indexes. */
 	systable_endscan_ordered(toastscan);
 	toast_close_indexes(toastidxs, num_indexes, AccessShareLock);
-	table_close(toastrel, AccessShareLock);
-
-	return result;
 }
 
 /* ----------
-- 
2.17.2 (Apple Git-113)

From a594dcc09614c26ffd7c149349aba97afb845cc9 Mon Sep 17 00:00:00 2001
From: Robert Haas <rhaas@postgresql.org>
Date: Wed, 18 Dec 2019 11:22:51 -0500
Subject: [PATCH v11 2/2] tableam: New callback relation_fetch_toast_slice.

Instead of always calling heap_fetch_toast_slice during detoasting,
invoke a table AM callback which, when the toast table is a heap
table, will be heap_fetch_toast_slice.

This makes it possible for a table AM other than heap to be used
as a TOAST table.

Patch by me, reviewed by Andres Freund and Peter Eisentraut.

Discussion: http://postgr.es/m/CA+TgmoZv-=2iWM4jcw5ZhJeL18HF96+W1yJeYrnGMYdkFFnEpQ@mail.gmail.com
---
 src/backend/access/common/detoast.c      | 199 +----------------------
 src/backend/access/heap/heapam_handler.c |   1 +
 src/backend/access/heap/heaptoast.c      | 185 +++++++++++++++++++++
 src/include/access/heaptoast.h           |  10 ++
 src/include/access/tableam.h             |  46 ++++++
 5 files changed, 248 insertions(+), 193 deletions(-)

diff --git a/src/backend/access/common/detoast.c b/src/backend/access/common/detoast.c
index 78fcc876da..3df0cf2512 100644
--- a/src/backend/access/common/detoast.c
+++ b/src/backend/access/common/detoast.c
@@ -14,22 +14,17 @@
 #include "postgres.h"
 
 #include "access/detoast.h"
-#include "access/genam.h"
-#include "access/heaptoast.h"
 #include "access/table.h"
+#include "access/tableam.h"
 #include "access/toast_internals.h"
 #include "common/pg_lzcompress.h"
 #include "utils/expandeddatum.h"
-#include "utils/fmgroids.h"
 #include "utils/rel.h"
 
 static struct varlena *toast_fetch_datum(struct varlena *attr);
 static struct varlena *toast_fetch_datum_slice(struct varlena *attr,
 											   int32 sliceoffset,
 											   int32 slicelength);
-static void heap_fetch_toast_slice(Relation toastrel, Oid valueid,
-								   int32 attrsize, int32 sliceoffset,
-								   int32 slicelength, struct varlena *result);
 static struct varlena *toast_decompress_datum(struct varlena *attr);
 static struct varlena *toast_decompress_datum_slice(struct varlena *attr, int32 slicelength);
 
@@ -356,8 +351,8 @@ toast_fetch_datum(struct varlena *attr)
 	toastrel = table_open(toast_pointer.va_toastrelid, AccessShareLock);
 
 	/* Fetch all chunks */
-	heap_fetch_toast_slice(toastrel, toast_pointer.va_valueid, attrsize, 0,
-						   attrsize, result);
+	table_relation_fetch_toast_slice(toastrel, toast_pointer.va_valueid,
+									 attrsize, 0, attrsize, result);
 
 	/* Close toast table */
 	table_close(toastrel, AccessShareLock);
@@ -431,8 +426,9 @@ toast_fetch_datum_slice(struct varlena *attr, int32 sliceoffset,
 	toastrel = table_open(toast_pointer.va_toastrelid, AccessShareLock);
 
 	/* Fetch all chunks */
-	heap_fetch_toast_slice(toastrel, toast_pointer.va_valueid, attrsize,
-						   sliceoffset, slicelength, result);
+	table_relation_fetch_toast_slice(toastrel, toast_pointer.va_valueid,
+									 attrsize, sliceoffset, slicelength,
+									 result);
 
 	/* Close toast table */
 	table_close(toastrel, AccessShareLock);
@@ -440,189 +436,6 @@ toast_fetch_datum_slice(struct varlena *attr, int32 sliceoffset,
 	return result;
 }
 
-/*
- * Fetch a TOAST slice from a heap table.
- *
- * toastrel is the relation from which chunks are to be fetched.
- * valueid identifies the TOAST value from which chunks are being fetched.
- * attrsize is the total size of the TOAST value.
- * sliceoffset is the byte offset within the TOAST value from which to fetch.
- * slicelength is the number of bytes to be fetched from the TOAST value.
- * result is the varlena into which the results should be written.
- */
-static void
-heap_fetch_toast_slice(Relation toastrel, Oid valueid, int32 attrsize,
-					   int32 sliceoffset, int32 slicelength,
-					   struct varlena *result)
-{
-	Relation   *toastidxs;
-	ScanKeyData toastkey[3];
-	TupleDesc	toasttupDesc = toastrel->rd_att;
-	int			nscankeys;
-	SysScanDesc toastscan;
-	HeapTuple	ttup;
-	int32		expectedchunk;
-	int32		totalchunks = ((attrsize - 1) / TOAST_MAX_CHUNK_SIZE) + 1;
-	int			startchunk;
-	int			endchunk;
-	int			num_indexes;
-	int			validIndex;
-	SnapshotData SnapshotToast;
-
-	/* Look for the valid index of toast relation */
-	validIndex = toast_open_indexes(toastrel,
-									AccessShareLock,
-									&toastidxs,
-									&num_indexes);
-
-	startchunk = sliceoffset / TOAST_MAX_CHUNK_SIZE;
-	endchunk = (sliceoffset + slicelength - 1) / TOAST_MAX_CHUNK_SIZE;
-	Assert(endchunk <= totalchunks);
-
-	/*
-	 * Setup a scan key to fetch from the index. This is either two keys or
-	 * three depending on the number of chunks.
-	 */
-	ScanKeyInit(&toastkey[0],
-				(AttrNumber) 1,
-				BTEqualStrategyNumber, F_OIDEQ,
-				ObjectIdGetDatum(valueid));
-
-	/*
-	 * No additional condition if fetching all chunks. Otherwise, use an
-	 * equality condition for one chunk, and a range condition otherwise.
-	 */
-	if (startchunk == 0 && endchunk == totalchunks - 1)
-		nscankeys = 1;
-	else if (startchunk == endchunk)
-	{
-		ScanKeyInit(&toastkey[1],
-					(AttrNumber) 2,
-					BTEqualStrategyNumber, F_INT4EQ,
-					Int32GetDatum(startchunk));
-		nscankeys = 2;
-	}
-	else
-	{
-		ScanKeyInit(&toastkey[1],
-					(AttrNumber) 2,
-					BTGreaterEqualStrategyNumber, F_INT4GE,
-					Int32GetDatum(startchunk));
-		ScanKeyInit(&toastkey[2],
-					(AttrNumber) 2,
-					BTLessEqualStrategyNumber, F_INT4LE,
-					Int32GetDatum(endchunk));
-		nscankeys = 3;
-	}
-
-	/* Prepare for scan */
-	init_toast_snapshot(&SnapshotToast);
-	toastscan = systable_beginscan_ordered(toastrel, toastidxs[validIndex],
-										   &SnapshotToast, nscankeys, toastkey);
-
-	/*
-	 * Read the chunks by index
-	 *
-	 * The index is on (valueid, chunkidx) so they will come in order
-	 */
-	expectedchunk = startchunk;
-	while ((ttup = systable_getnext_ordered(toastscan, ForwardScanDirection)) != NULL)
-	{
-		int32		curchunk;
-		Pointer		chunk;
-		bool		isnull;
-		char	   *chunkdata;
-		int32		chunksize;
-		int32		expected_size;
-		int32		chcpystrt;
-		int32		chcpyend;
-
-		/*
-		 * Have a chunk, extract the sequence number and the data
-		 */
-		curchunk = DatumGetInt32(fastgetattr(ttup, 2, toasttupDesc, &isnull));
-		Assert(!isnull);
-		chunk = DatumGetPointer(fastgetattr(ttup, 3, toasttupDesc, &isnull));
-		Assert(!isnull);
-		if (!VARATT_IS_EXTENDED(chunk))
-		{
-			chunksize = VARSIZE(chunk) - VARHDRSZ;
-			chunkdata = VARDATA(chunk);
-		}
-		else if (VARATT_IS_SHORT(chunk))
-		{
-			/* could happen due to heap_form_tuple doing its thing */
-			chunksize = VARSIZE_SHORT(chunk) - VARHDRSZ_SHORT;
-			chunkdata = VARDATA_SHORT(chunk);
-		}
-		else
-		{
-			/* should never happen */
-			elog(ERROR, "found toasted toast chunk for toast value %u in %s",
-				 valueid, RelationGetRelationName(toastrel));
-			chunksize = 0;		/* keep compiler quiet */
-			chunkdata = NULL;
-		}
-
-		/*
-		 * Some checks on the data we've found
-		 */
-		if (curchunk != expectedchunk)
-			ereport(ERROR,
-					(errcode(ERRCODE_DATA_CORRUPTED),
-					 errmsg_internal("unexpected chunk number %d (expected %d) for toast value %u in %s",
-									 curchunk, expectedchunk, valueid,
-									 RelationGetRelationName(toastrel))));
-		if (curchunk > endchunk)
-			ereport(ERROR,
-					(errcode(ERRCODE_DATA_CORRUPTED),
-					 errmsg_internal("unexpected chunk number %d (out of range %d..%d) for toast value %u in %s",
-									 curchunk,
-									 startchunk, endchunk, valueid,
-									 RelationGetRelationName(toastrel))));
-		expected_size = curchunk < totalchunks - 1 ? TOAST_MAX_CHUNK_SIZE
-			: attrsize - ((totalchunks - 1) * TOAST_MAX_CHUNK_SIZE);
-		if (chunksize != expected_size)
-			ereport(ERROR,
-					(errcode(ERRCODE_DATA_CORRUPTED),
-					 errmsg_internal("unexpected chunk size %d (expected %d) in chunk %d of %d for toast value %u in %s",
-									 chunksize, expected_size,
-									 curchunk, totalchunks, valueid,
-									 RelationGetRelationName(toastrel))));
-
-		/*
-		 * Copy the data into proper place in our result
-		 */
-		chcpystrt = 0;
-		chcpyend = chunksize - 1;
-		if (curchunk == startchunk)
-			chcpystrt = sliceoffset % TOAST_MAX_CHUNK_SIZE;
-		if (curchunk == endchunk)
-			chcpyend = (sliceoffset + slicelength - 1) % TOAST_MAX_CHUNK_SIZE;
-
-		memcpy(VARDATA(result) +
-			   (curchunk * TOAST_MAX_CHUNK_SIZE - sliceoffset) + chcpystrt,
-			   chunkdata + chcpystrt,
-			   (chcpyend - chcpystrt) + 1);
-
-		expectedchunk++;
-	}
-
-	/*
-	 * Final checks that we successfully fetched the datum
-	 */
-	if (expectedchunk != (endchunk + 1))
-		ereport(ERROR,
-				(errcode(ERRCODE_DATA_CORRUPTED),
-				 errmsg_internal("missing chunk number %d for toast value %u in %s",
-								 expectedchunk, valueid,
-								 RelationGetRelationName(toastrel))));
-
-	/* End scan and close indexes. */
-	systable_endscan_ordered(toastscan);
-	toast_close_indexes(toastidxs, num_indexes, AccessShareLock);
-}
-
 /* ----------
  * toast_decompress_datum -
  *
diff --git a/src/backend/access/heap/heapam_handler.c b/src/backend/access/heap/heapam_handler.c
index 1d053e74e6..b443c6c1d5 100644
--- a/src/backend/access/heap/heapam_handler.c
+++ b/src/backend/access/heap/heapam_handler.c
@@ -2545,6 +2545,7 @@ static const TableAmRoutine heapam_methods = {
 	.relation_size = table_block_relation_size,
 	.relation_needs_toast_table = heapam_relation_needs_toast_table,
 	.relation_toast_am = heapam_relation_toast_am,
+	.relation_fetch_toast_slice = heap_fetch_toast_slice,
 
 	.relation_estimate_size = heapam_estimate_rel_size,
 
diff --git a/src/backend/access/heap/heaptoast.c b/src/backend/access/heap/heaptoast.c
index dcfdee4467..3382425281 100644
--- a/src/backend/access/heap/heaptoast.c
+++ b/src/backend/access/heap/heaptoast.c
@@ -25,10 +25,12 @@
 #include "postgres.h"
 
 #include "access/detoast.h"
+#include "access/genam.h"
 #include "access/heapam.h"
 #include "access/heaptoast.h"
 #include "access/toast_helper.h"
 #include "access/toast_internals.h"
+#include "utils/fmgroids.h"
 
 
 /* ----------
@@ -604,3 +606,186 @@ toast_build_flattened_tuple(TupleDesc tupleDesc,
 
 	return new_tuple;
 }
+
+/*
+ * Fetch a TOAST slice from a heap table.
+ *
+ * toastrel is the relation from which chunks are to be fetched.
+ * valueid identifies the TOAST value from which chunks are being fetched.
+ * attrsize is the total size of the TOAST value.
+ * sliceoffset is the byte offset within the TOAST value from which to fetch.
+ * slicelength is the number of bytes to be fetched from the TOAST value.
+ * result is the varlena into which the results should be written.
+ */
+void
+heap_fetch_toast_slice(Relation toastrel, Oid valueid, int32 attrsize,
+					   int32 sliceoffset, int32 slicelength,
+					   struct varlena *result)
+{
+	Relation   *toastidxs;
+	ScanKeyData toastkey[3];
+	TupleDesc	toasttupDesc = toastrel->rd_att;
+	int			nscankeys;
+	SysScanDesc toastscan;
+	HeapTuple	ttup;
+	int32		expectedchunk;
+	int32		totalchunks = ((attrsize - 1) / TOAST_MAX_CHUNK_SIZE) + 1;
+	int			startchunk;
+	int			endchunk;
+	int			num_indexes;
+	int			validIndex;
+	SnapshotData SnapshotToast;
+
+	/* Look for the valid index of toast relation */
+	validIndex = toast_open_indexes(toastrel,
+									AccessShareLock,
+									&toastidxs,
+									&num_indexes);
+
+	startchunk = sliceoffset / TOAST_MAX_CHUNK_SIZE;
+	endchunk = (sliceoffset + slicelength - 1) / TOAST_MAX_CHUNK_SIZE;
+	Assert(endchunk <= totalchunks);
+
+	/*
+	 * Setup a scan key to fetch from the index. This is either two keys or
+	 * three depending on the number of chunks.
+	 */
+	ScanKeyInit(&toastkey[0],
+				(AttrNumber) 1,
+				BTEqualStrategyNumber, F_OIDEQ,
+				ObjectIdGetDatum(valueid));
+
+	/*
+	 * No additional condition if fetching all chunks. Otherwise, use an
+	 * equality condition for one chunk, and a range condition otherwise.
+	 */
+	if (startchunk == 0 && endchunk == totalchunks - 1)
+		nscankeys = 1;
+	else if (startchunk == endchunk)
+	{
+		ScanKeyInit(&toastkey[1],
+					(AttrNumber) 2,
+					BTEqualStrategyNumber, F_INT4EQ,
+					Int32GetDatum(startchunk));
+		nscankeys = 2;
+	}
+	else
+	{
+		ScanKeyInit(&toastkey[1],
+					(AttrNumber) 2,
+					BTGreaterEqualStrategyNumber, F_INT4GE,
+					Int32GetDatum(startchunk));
+		ScanKeyInit(&toastkey[2],
+					(AttrNumber) 2,
+					BTLessEqualStrategyNumber, F_INT4LE,
+					Int32GetDatum(endchunk));
+		nscankeys = 3;
+	}
+
+	/* Prepare for scan */
+	init_toast_snapshot(&SnapshotToast);
+	toastscan = systable_beginscan_ordered(toastrel, toastidxs[validIndex],
+										   &SnapshotToast, nscankeys, toastkey);
+
+	/*
+	 * Read the chunks by index
+	 *
+	 * The index is on (valueid, chunkidx) so they will come in order
+	 */
+	expectedchunk = startchunk;
+	while ((ttup = systable_getnext_ordered(toastscan, ForwardScanDirection)) != NULL)
+	{
+		int32		curchunk;
+		Pointer		chunk;
+		bool		isnull;
+		char	   *chunkdata;
+		int32		chunksize;
+		int32		expected_size;
+		int32		chcpystrt;
+		int32		chcpyend;
+
+		/*
+		 * Have a chunk, extract the sequence number and the data
+		 */
+		curchunk = DatumGetInt32(fastgetattr(ttup, 2, toasttupDesc, &isnull));
+		Assert(!isnull);
+		chunk = DatumGetPointer(fastgetattr(ttup, 3, toasttupDesc, &isnull));
+		Assert(!isnull);
+		if (!VARATT_IS_EXTENDED(chunk))
+		{
+			chunksize = VARSIZE(chunk) - VARHDRSZ;
+			chunkdata = VARDATA(chunk);
+		}
+		else if (VARATT_IS_SHORT(chunk))
+		{
+			/* could happen due to heap_form_tuple doing its thing */
+			chunksize = VARSIZE_SHORT(chunk) - VARHDRSZ_SHORT;
+			chunkdata = VARDATA_SHORT(chunk);
+		}
+		else
+		{
+			/* should never happen */
+			elog(ERROR, "found toasted toast chunk for toast value %u in %s",
+				 valueid, RelationGetRelationName(toastrel));
+			chunksize = 0;		/* keep compiler quiet */
+			chunkdata = NULL;
+		}
+
+		/*
+		 * Some checks on the data we've found
+		 */
+		if (curchunk != expectedchunk)
+			ereport(ERROR,
+					(errcode(ERRCODE_DATA_CORRUPTED),
+					 errmsg_internal("unexpected chunk number %d (expected %d) for toast value %u in %s",
+									 curchunk, expectedchunk, valueid,
+									 RelationGetRelationName(toastrel))));
+		if (curchunk > endchunk)
+			ereport(ERROR,
+					(errcode(ERRCODE_DATA_CORRUPTED),
+					 errmsg_internal("unexpected chunk number %d (out of range %d..%d) for toast value %u in %s",
+									 curchunk,
+									 startchunk, endchunk, valueid,
+									 RelationGetRelationName(toastrel))));
+		expected_size = curchunk < totalchunks - 1 ? TOAST_MAX_CHUNK_SIZE
+			: attrsize - ((totalchunks - 1) * TOAST_MAX_CHUNK_SIZE);
+		if (chunksize != expected_size)
+			ereport(ERROR,
+					(errcode(ERRCODE_DATA_CORRUPTED),
+					 errmsg_internal("unexpected chunk size %d (expected %d) in chunk %d of %d for toast value %u in %s",
+									 chunksize, expected_size,
+									 curchunk, totalchunks, valueid,
+									 RelationGetRelationName(toastrel))));
+
+		/*
+		 * Copy the data into proper place in our result
+		 */
+		chcpystrt = 0;
+		chcpyend = chunksize - 1;
+		if (curchunk == startchunk)
+			chcpystrt = sliceoffset % TOAST_MAX_CHUNK_SIZE;
+		if (curchunk == endchunk)
+			chcpyend = (sliceoffset + slicelength - 1) % TOAST_MAX_CHUNK_SIZE;
+
+		memcpy(VARDATA(result) +
+			   (curchunk * TOAST_MAX_CHUNK_SIZE - sliceoffset) + chcpystrt,
+			   chunkdata + chcpystrt,
+			   (chcpyend - chcpystrt) + 1);
+
+		expectedchunk++;
+	}
+
+	/*
+	 * Final checks that we successfully fetched the datum
+	 */
+	if (expectedchunk != (endchunk + 1))
+		ereport(ERROR,
+				(errcode(ERRCODE_DATA_CORRUPTED),
+				 errmsg_internal("missing chunk number %d for toast value %u in %s",
+								 expectedchunk, valueid,
+								 RelationGetRelationName(toastrel))));
+
+	/* End scan and close indexes. */
+	systable_endscan_ordered(toastscan);
+	toast_close_indexes(toastidxs, num_indexes, AccessShareLock);
+}
diff --git a/src/include/access/heaptoast.h b/src/include/access/heaptoast.h
index 488a2e4a7f..0bf6b23c8f 100644
--- a/src/include/access/heaptoast.h
+++ b/src/include/access/heaptoast.h
@@ -136,4 +136,14 @@ extern HeapTuple toast_build_flattened_tuple(TupleDesc tupleDesc,
 											 Datum *values,
 											 bool *isnull);
 
+/* ----------
+ * heap_fetch_toast_slice
+ *
+ *	Fetch a slice from a toast value stored in a heap table.
+ * ----------
+ */
+extern void heap_fetch_toast_slice(Relation toastrel, Oid valueid,
+								   int32 attrsize, int32 sliceoffset,
+								   int32 slicelength, struct varlena *result);
+
 #endif							/* HEAPTOAST_H */
diff --git a/src/include/access/tableam.h b/src/include/access/tableam.h
index 7ac9bb6d65..b784aaf5a9 100644
--- a/src/include/access/tableam.h
+++ b/src/include/access/tableam.h
@@ -588,6 +588,17 @@ typedef struct TableAmRoutine
 	 */
 	Oid		    (*relation_toast_am) (Relation rel);
 
+	/*
+	 * This callback is invoked when detoasting a value stored in a toast
+	 * table implemented by this AM.  See table_relation_fetch_toast_slice()
+	 * for more details.
+	 */
+	void		(*relation_fetch_toast_slice) (Relation toastrel, Oid valueid,
+											   int32 attrsize,
+											   int32 sliceoffset,
+											   int32 slicelength,
+											   struct varlena *result);
+
 
 	/* ------------------------------------------------------------------------
 	 * Planner related functions.
@@ -1620,6 +1631,41 @@ table_relation_toast_am(Relation rel)
 	return rel->rd_tableam->relation_toast_am(rel);
 }
 
+/*
+ * Fetch all or part of a TOAST value from a TOAST table.
+ *
+ * If this AM is never used to implement a TOAST table, then this callback
+ * is not needed. But, if toasted values are ever stored in a table of this
+ * type, then you will need this callback.
+ *
+ * toastrel is the relation in which the toasted value is stored.
+ *
+ * valueid identifes which toast value is to be fetched. For the heap,
+ * this corresponds to the values stored in the chunk_id column.
+ *
+ * attrsize is the total size of the toast value to be fetched.
+ *
+ * sliceoffset is the offset within the toast value of the first byte that
+ * should be fetched.
+ *
+ * slicelength is the number of bytes from the toast value that should be
+ * fetched.
+ *
+ * result is caller-allocated space into which the fetched bytes should be
+ * stored.
+ */
+static inline void
+table_relation_fetch_toast_slice(Relation toastrel, Oid valueid,
+								 int32 attrsize, int32 sliceoffset,
+								 int32 slicelength, struct varlena *result)
+{
+	return toastrel->rd_tableam->relation_fetch_toast_slice(toastrel, valueid,
+															attrsize,
+															sliceoffset,
+															slicelength,
+															result);
+}
+
 
 /* ----------------------------------------------------------------------------
  * Planner related functionality
-- 
2.17.2 (Apple Git-113)

From 7889fa4ca1713a0b075255f0ea1a9fb17c591cce Mon Sep 17 00:00:00 2001
From: Robert Haas <rhaas@postgresql.org>
Date: Wed, 18 Dec 2019 11:22:46 -0500
Subject: [PATCH v11 1/2] tableam: Allow choice of toast AM.

Previously, the toast table had to be implemented by the same AM that
was used for the main table, which was bad, because the detoasting
code won't work with anything but heap. This commit doesn't fix the
latter problem, though I plan to do that in a later commit, but it
does let you choose what AM you'd like to use, so that a table AM
can at least choose heap and get something that works.

Patch by me, reviewed by Andres Freund.

Discussion: http://postgr.es/m/CA+TgmoZv-=2iWM4jcw5ZhJeL18HF96+W1yJeYrnGMYdkFFnEpQ@mail.gmail.com
---
 src/backend/access/heap/heapam_handler.c | 10 ++++++++++
 src/backend/catalog/toasting.c           |  2 +-
 src/include/access/tableam.h             | 17 +++++++++++++++++
 3 files changed, 28 insertions(+), 1 deletion(-)

diff --git a/src/backend/access/heap/heapam_handler.c b/src/backend/access/heap/heapam_handler.c
index 92073fec54..1d053e74e6 100644
--- a/src/backend/access/heap/heapam_handler.c
+++ b/src/backend/access/heap/heapam_handler.c
@@ -2037,6 +2037,15 @@ heapam_relation_needs_toast_table(Relation rel)
 	return (tuple_length > TOAST_TUPLE_THRESHOLD);
 }
 
+/*
+ * TOAST tables for heap relations are just heap relations.
+ */
+static Oid
+heapam_relation_toast_am(Relation rel)
+{
+	return rel->rd_rel->relam;
+}
+
 
 /* ------------------------------------------------------------------------
  * Planner related callbacks for the heap AM
@@ -2535,6 +2544,7 @@ static const TableAmRoutine heapam_methods = {
 
 	.relation_size = table_block_relation_size,
 	.relation_needs_toast_table = heapam_relation_needs_toast_table,
+	.relation_toast_am = heapam_relation_toast_am,
 
 	.relation_estimate_size = heapam_estimate_rel_size,
 
diff --git a/src/backend/catalog/toasting.c b/src/backend/catalog/toasting.c
index de6282a667..f082463bf6 100644
--- a/src/backend/catalog/toasting.c
+++ b/src/backend/catalog/toasting.c
@@ -258,7 +258,7 @@ create_toast_table(Relation rel, Oid toastOid, Oid toastIndexOid,
 										   toast_typid,
 										   InvalidOid,
 										   rel->rd_rel->relowner,
-										   rel->rd_rel->relam,
+										   table_relation_toast_am(rel),
 										   tupdesc,
 										   NIL,
 										   RELKIND_TOASTVALUE,
diff --git a/src/include/access/tableam.h b/src/include/access/tableam.h
index 64022917e2..7ac9bb6d65 100644
--- a/src/include/access/tableam.h
+++ b/src/include/access/tableam.h
@@ -581,6 +581,13 @@ typedef struct TableAmRoutine
 	 */
 	bool		(*relation_needs_toast_table) (Relation rel);
 
+	/*
+	 * This callback should return the OID of the table AM that implements
+	 * TOAST tables for this AM.  If the relation_needs_toast_table callback
+	 * always returns false, this callback is not required.
+	 */
+	Oid		    (*relation_toast_am) (Relation rel);
+
 
 	/* ------------------------------------------------------------------------
 	 * Planner related functions.
@@ -1603,6 +1610,16 @@ table_relation_needs_toast_table(Relation rel)
 	return rel->rd_tableam->relation_needs_toast_table(rel);
 }
 
+/*
+ * Return the OID of the AM that should be used to implement the TOAST table
+ * for this relation.
+ */
+static inline Oid
+table_relation_toast_am(Relation rel)
+{
+	return rel->rd_tableam->relation_toast_am(rel);
+}
+
 
 /* ----------------------------------------------------------------------------
  * Planner related functionality
-- 
2.17.2 (Apple Git-113)