Backpatch b61d161c14

From 82daf888eb6834400be482affe38c1f23851826b Mon Sep 17 00:00:00 2001
From: Justin Pryzby <pryzbyj@telsasoft.com>
Date: Mon, 22 Jun 2020 18:22:58 -0500
Subject: [PATCH 1/4] Rename from "errcbarg"..

..the name of which Alvaro didn't like.  I renamed this, but it was
accidentally re-introduced while trading patches with Amit.

We should *also* rename VACUUM_ERRCB* to ERRINFO, but I didn't do that here.
---
 src/backend/access/heap/vacuumlazy.c | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/src/backend/access/heap/vacuumlazy.c b/src/backend/access/heap/vacuumlazy.c
index 3bef0e124b..a6a5d906c0 100644
--- a/src/backend/access/heap/vacuumlazy.c
+++ b/src/backend/access/heap/vacuumlazy.c
@@ -2459,7 +2459,7 @@ lazy_cleanup_index(Relation indrel,
 	IndexVacuumInfo ivinfo;
 	const char *msg;
 	PGRUsage	ru0;
-	LVRelStats	olderrcbarg;
+	LVRelStats	olderrinfo;
 
 	pg_rusage_init(&ru0);
 
@@ -2473,7 +2473,7 @@ lazy_cleanup_index(Relation indrel,
 	ivinfo.strategy = vac_strategy;
 
 	/* Update error traceback information */
-	olderrcbarg = *vacrelstats;
+	olderrinfo = *vacrelstats;
 	update_vacuum_error_info(vacrelstats,
 							 VACUUM_ERRCB_PHASE_INDEX_CLEANUP,
 							 InvalidBlockNumber,
@@ -2483,9 +2483,9 @@ lazy_cleanup_index(Relation indrel,
 
 	/* Revert back to the old phase information for error traceback */
 	update_vacuum_error_info(vacrelstats,
-							 olderrcbarg.phase,
-							 olderrcbarg.blkno,
-							 olderrcbarg.indname);
+							 olderrinfo.phase,
+							 olderrinfo.blkno,
+							 olderrinfo.indname);
 	if (!(*stats))
 		return;
 
-- 
2.17.0

From 308faea3626e8c270eb75659bec3f7e15125a73a Mon Sep 17 00:00:00 2001
From: Justin Pryzby <pryzbyj@telsasoft.com>
Date: Mon, 22 Jun 2020 18:51:35 -0500
Subject: [PATCH 2/4] Add assert and document why indname is safe

---
 src/backend/access/heap/vacuumlazy.c | 19 ++++++++++++++++---
 1 file changed, 16 insertions(+), 3 deletions(-)

diff --git a/src/backend/access/heap/vacuumlazy.c b/src/backend/access/heap/vacuumlazy.c
index a6a5d906c0..40173480b8 100644
--- a/src/backend/access/heap/vacuumlazy.c
+++ b/src/backend/access/heap/vacuumlazy.c
@@ -3606,10 +3606,23 @@ update_vacuum_error_info(LVRelStats *errinfo, int phase, BlockNumber blkno,
 	errinfo->blkno = blkno;
 	errinfo->phase = phase;
 
-	/* Free index name from any previous phase */
 	if (errinfo->indname)
+	{
+		/*
+		 * indname is only ever saved during lazy_vacuum_index(), which
+		 * during which the phase information is not not further
+		 * manipulated, until it's restored before returning from
+		 * lazy_vacuum_index().
+		 */
+		Assert(indname == NULL);
+
 		pfree(errinfo->indname);
+		errinfo->indname = NULL;
+	}
 
-	/* For index phases, save the name of the current index for the callback */
-	errinfo->indname = indname ? pstrdup(indname) : NULL;
+	if (indname)
+	{
+		/* For index phases, save the name of the current index for the callback */
+		errinfo->indname = pstrdup(indname);
+	}
 }
-- 
2.17.0

From 87ff6cc66510233b1b86a250e8ac48e52b7d54c2 Mon Sep 17 00:00:00 2001
From: Justin Pryzby <pryzbyj@telsasoft.com>
Date: Mon, 22 Jun 2020 16:36:14 -0500
Subject: [PATCH 3/4] Move error information into a separate struct..

..to avoid copying large LVRelStats struct.

Andres things this is a problem but Tom thinks it's a micro-optimization.

See: b61d161c146328ae6ba9ed937862d66e5c8b035a

This also moves relname and relnamespace (see ef75140fe).

Discussion: https://www.postgresql.org/message-id/20200622200939.jkuniq3vtiumeszj%40alap3.anarazel.de
---
 src/backend/access/heap/vacuumlazy.c | 116 ++++++++++++++-------------
 1 file changed, 62 insertions(+), 54 deletions(-)

diff --git a/src/backend/access/heap/vacuumlazy.c b/src/backend/access/heap/vacuumlazy.c
index 40173480b8..6bd2867660 100644
--- a/src/backend/access/heap/vacuumlazy.c
+++ b/src/backend/access/heap/vacuumlazy.c
@@ -288,10 +288,17 @@ typedef struct LVParallelState
 	int			nindexes_parallel_condcleanup;
 } LVParallelState;
 
-typedef struct LVRelStats
+typedef struct
 {
 	char	   *relnamespace;
 	char	   *relname;
+	char	   *indname;
+	BlockNumber blkno;			/* used only for heap operations */
+	VacErrPhase phase;
+} LVSavedPosition;
+
+typedef struct LVRelStats
+{
 	/* useindex = true means two-pass strategy; false means one-pass */
 	bool		useindex;
 	/* Overall statistics about rel */
@@ -313,10 +320,7 @@ typedef struct LVRelStats
 	TransactionId latestRemovedXid;
 	bool		lock_waiter_detected;
 
-	/* Used for error callback */
-	char	   *indname;
-	BlockNumber blkno;			/* used only for heap operations */
-	VacErrPhase phase;
+	LVSavedPosition errinfo; /* Used for error callback */
 } LVRelStats;
 
 /* A few variables that don't seem worth passing around as parameters */
@@ -388,7 +392,7 @@ static void end_parallel_vacuum(Relation *Irel, IndexBulkDeleteResult **stats,
 static LVSharedIndStats *get_indstats(LVShared *lvshared, int n);
 static bool skip_parallel_vacuum_index(Relation indrel, LVShared *lvshared);
 static void vacuum_error_callback(void *arg);
-static void update_vacuum_error_info(LVRelStats *errinfo, int phase,
+static void update_vacuum_error_info(LVSavedPosition *errinfo, int phase,
 									 BlockNumber blkno, char *indname);
 
 
@@ -475,10 +479,10 @@ heap_vacuum_rel(Relation onerel, VacuumParams *params,
 
 	vacrelstats = (LVRelStats *) palloc0(sizeof(LVRelStats));
 
-	vacrelstats->relnamespace = get_namespace_name(RelationGetNamespace(onerel));
-	vacrelstats->relname = pstrdup(RelationGetRelationName(onerel));
-	vacrelstats->indname = NULL;
-	vacrelstats->phase = VACUUM_ERRCB_PHASE_UNKNOWN;
+	vacrelstats->errinfo.relnamespace = get_namespace_name(RelationGetNamespace(onerel));
+	vacrelstats->errinfo.relname = pstrdup(RelationGetRelationName(onerel));
+	vacrelstats->errinfo.indname = NULL;
+	vacrelstats->errinfo.phase = VACUUM_ERRCB_PHASE_UNKNOWN;
 	vacrelstats->old_rel_pages = onerel->rd_rel->relpages;
 	vacrelstats->old_live_tuples = onerel->rd_rel->reltuples;
 	vacrelstats->num_index_scans = 0;
@@ -502,7 +506,7 @@ heap_vacuum_rel(Relation onerel, VacuumParams *params,
 	 * information is restored at the end of those phases.
 	 */
 	errcallback.callback = vacuum_error_callback;
-	errcallback.arg = vacrelstats;
+	errcallback.arg = &vacrelstats->errinfo;
 	errcallback.previous = error_context_stack;
 	error_context_stack = &errcallback;
 
@@ -538,7 +542,8 @@ heap_vacuum_rel(Relation onerel, VacuumParams *params,
 		 * which we add context information to errors, so we don't need to
 		 * revert to the previous phase.
 		 */
-		update_vacuum_error_info(vacrelstats, VACUUM_ERRCB_PHASE_TRUNCATE,
+		update_vacuum_error_info(&vacrelstats->errinfo,
+								 VACUUM_ERRCB_PHASE_TRUNCATE,
 								 vacrelstats->nonempty_pages, NULL);
 		lazy_truncate_heap(onerel, vacrelstats);
 	}
@@ -650,8 +655,8 @@ heap_vacuum_rel(Relation onerel, VacuumParams *params,
 			}
 			appendStringInfo(&buf, msgfmt,
 							 get_database_name(MyDatabaseId),
-							 vacrelstats->relnamespace,
-							 vacrelstats->relname,
+							 vacrelstats->errinfo.relnamespace,
+							 vacrelstats->errinfo.relname,
 							 vacrelstats->num_index_scans);
 			appendStringInfo(&buf, _("pages: %u removed, %u remain, %u skipped due to pins, %u skipped frozen\n"),
 							 vacrelstats->pages_removed,
@@ -786,13 +791,13 @@ lazy_scan_heap(Relation onerel, VacuumParams *params, LVRelStats *vacrelstats,
 	if (aggressive)
 		ereport(elevel,
 				(errmsg("aggressively vacuuming \"%s.%s\"",
-						vacrelstats->relnamespace,
-						vacrelstats->relname)));
+						vacrelstats->errinfo.relnamespace,
+						vacrelstats->errinfo.relname)));
 	else
 		ereport(elevel,
 				(errmsg("vacuuming \"%s.%s\"",
-						vacrelstats->relnamespace,
-						vacrelstats->relname)));
+						vacrelstats->errinfo.relnamespace,
+						vacrelstats->errinfo.relname)));
 
 	empty_pages = vacuumed_pages = 0;
 	next_fsm_block_to_vacuum = (BlockNumber) 0;
@@ -828,7 +833,7 @@ lazy_scan_heap(Relation onerel, VacuumParams *params, LVRelStats *vacrelstats,
 			if (params->nworkers > 0)
 				ereport(WARNING,
 						(errmsg("disabling parallel option of vacuum on \"%s\" --- cannot vacuum temporary tables in parallel",
-								vacrelstats->relname)));
+								vacrelstats->errinfo.relname)));
 		}
 		else
 			lps = begin_parallel_vacuum(RelationGetRelid(onerel), Irel,
@@ -948,7 +953,8 @@ lazy_scan_heap(Relation onerel, VacuumParams *params, LVRelStats *vacrelstats,
 
 		pgstat_progress_update_param(PROGRESS_VACUUM_HEAP_BLKS_SCANNED, blkno);
 
-		update_vacuum_error_info(vacrelstats, VACUUM_ERRCB_PHASE_SCAN_HEAP,
+		update_vacuum_error_info(&vacrelstats->errinfo,
+								 VACUUM_ERRCB_PHASE_SCAN_HEAP,
 								 blkno, NULL);
 
 		if (blkno == next_unskippable_block)
@@ -1582,7 +1588,7 @@ lazy_scan_heap(Relation onerel, VacuumParams *params, LVRelStats *vacrelstats,
 				 && VM_ALL_VISIBLE(onerel, blkno, &vmbuffer))
 		{
 			elog(WARNING, "page is not marked all-visible but visibility map bit is set in relation \"%s\" page %u",
-				 vacrelstats->relname, blkno);
+				 vacrelstats->errinfo.relname, blkno);
 			visibilitymap_clear(onerel, blkno, vmbuffer,
 								VISIBILITYMAP_VALID_BITS);
 		}
@@ -1603,7 +1609,7 @@ lazy_scan_heap(Relation onerel, VacuumParams *params, LVRelStats *vacrelstats,
 		else if (PageIsAllVisible(page) && has_dead_tuples)
 		{
 			elog(WARNING, "page containing dead tuples is marked as all-visible in relation \"%s\" page %u",
-				 vacrelstats->relname, blkno);
+				 vacrelstats->errinfo.relname, blkno);
 			PageClearAllVisible(page);
 			MarkBufferDirty(buf);
 			visibilitymap_clear(onerel, blkno, vmbuffer,
@@ -1713,7 +1719,7 @@ lazy_scan_heap(Relation onerel, VacuumParams *params, LVRelStats *vacrelstats,
 	if (vacuumed_pages)
 		ereport(elevel,
 				(errmsg("\"%s\": removed %.0f row versions in %u pages",
-						vacrelstats->relname,
+						vacrelstats->errinfo.relname,
 						tups_vacuumed, vacuumed_pages)));
 
 	/*
@@ -1742,7 +1748,7 @@ lazy_scan_heap(Relation onerel, VacuumParams *params, LVRelStats *vacrelstats,
 
 	ereport(elevel,
 			(errmsg("\"%s\": found %.0f removable, %.0f nonremovable row versions in %u out of %u pages",
-					vacrelstats->relname,
+					vacrelstats->errinfo.relname,
 					tups_vacuumed, num_tuples,
 					vacrelstats->scanned_pages, nblocks),
 			 errdetail_internal("%s", buf.data)));
@@ -1820,15 +1826,16 @@ lazy_vacuum_heap(Relation onerel, LVRelStats *vacrelstats)
 	int			npages;
 	PGRUsage	ru0;
 	Buffer		vmbuffer = InvalidBuffer;
-	LVRelStats	olderrinfo;
+	LVSavedPosition	olderrinfo;
 
 	/* Report that we are now vacuuming the heap */
 	pgstat_progress_update_param(PROGRESS_VACUUM_PHASE,
 								 PROGRESS_VACUUM_PHASE_VACUUM_HEAP);
 
 	/* Update error traceback information */
-	olderrinfo = *vacrelstats;
-	update_vacuum_error_info(vacrelstats, VACUUM_ERRCB_PHASE_VACUUM_HEAP,
+	olderrinfo = vacrelstats->errinfo;
+	update_vacuum_error_info(&vacrelstats->errinfo,
+							 VACUUM_ERRCB_PHASE_VACUUM_HEAP,
 							 InvalidBlockNumber, NULL);
 
 	pg_rusage_init(&ru0);
@@ -1845,7 +1852,7 @@ lazy_vacuum_heap(Relation onerel, LVRelStats *vacrelstats)
 		vacuum_delay_point();
 
 		tblk = ItemPointerGetBlockNumber(&vacrelstats->dead_tuples->itemptrs[tupindex]);
-		vacrelstats->blkno = tblk;
+		vacrelstats->errinfo.blkno = tblk;
 		buf = ReadBufferExtended(onerel, MAIN_FORKNUM, tblk, RBM_NORMAL,
 								 vac_strategy);
 		if (!ConditionalLockBufferForCleanup(buf))
@@ -1874,12 +1881,12 @@ lazy_vacuum_heap(Relation onerel, LVRelStats *vacrelstats)
 
 	ereport(elevel,
 			(errmsg("\"%s\": removed %d row versions in %d pages",
-					vacrelstats->relname,
+					vacrelstats->errinfo.relname,
 					tupindex, npages),
 			 errdetail_internal("%s", pg_rusage_show(&ru0))));
 
 	/* Revert to the previous phase information for error traceback */
-	update_vacuum_error_info(vacrelstats,
+	update_vacuum_error_info(&vacrelstats->errinfo,
 							 olderrinfo.phase,
 							 olderrinfo.blkno,
 							 olderrinfo.indname);
@@ -1905,13 +1912,14 @@ lazy_vacuum_page(Relation onerel, BlockNumber blkno, Buffer buffer,
 	int			uncnt = 0;
 	TransactionId visibility_cutoff_xid;
 	bool		all_frozen;
-	LVRelStats	olderrinfo;
+	LVSavedPosition	olderrinfo;
 
 	pgstat_progress_update_param(PROGRESS_VACUUM_HEAP_BLKS_VACUUMED, blkno);
 
 	/* Update error traceback information */
-	olderrinfo = *vacrelstats;
-	update_vacuum_error_info(vacrelstats, VACUUM_ERRCB_PHASE_VACUUM_HEAP,
+	olderrinfo = vacrelstats->errinfo;
+	update_vacuum_error_info(&vacrelstats->errinfo,
+							 VACUUM_ERRCB_PHASE_VACUUM_HEAP,
 							 blkno, NULL);
 
 	START_CRIT_SECTION();
@@ -1991,7 +1999,7 @@ lazy_vacuum_page(Relation onerel, BlockNumber blkno, Buffer buffer,
 	}
 
 	/* Revert to the previous phase information for error traceback */
-	update_vacuum_error_info(vacrelstats,
+	update_vacuum_error_info(&vacrelstats->errinfo,
 							 olderrinfo.phase,
 							 olderrinfo.blkno,
 							 olderrinfo.indname);
@@ -2404,7 +2412,7 @@ lazy_vacuum_index(Relation indrel, IndexBulkDeleteResult **stats,
 	IndexVacuumInfo ivinfo;
 	const char *msg;
 	PGRUsage	ru0;
-	LVRelStats	olderrinfo;
+	LVSavedPosition	olderrinfo;
 
 	pg_rusage_init(&ru0);
 
@@ -2417,8 +2425,8 @@ lazy_vacuum_index(Relation indrel, IndexBulkDeleteResult **stats,
 	ivinfo.strategy = vac_strategy;
 
 	/* Update error traceback information */
-	olderrinfo = *vacrelstats;
-	update_vacuum_error_info(vacrelstats,
+	olderrinfo = vacrelstats->errinfo;
+	update_vacuum_error_info(&vacrelstats->errinfo,
 							 VACUUM_ERRCB_PHASE_VACUUM_INDEX,
 							 InvalidBlockNumber,
 							 RelationGetRelationName(indrel));
@@ -2434,12 +2442,12 @@ lazy_vacuum_index(Relation indrel, IndexBulkDeleteResult **stats,
 
 	ereport(elevel,
 			(errmsg(msg,
-					vacrelstats->indname,
+					vacrelstats->errinfo.indname,
 					dead_tuples->num_tuples),
 			 errdetail_internal("%s", pg_rusage_show(&ru0))));
 
 	/* Revert to the previous phase information for error traceback */
-	update_vacuum_error_info(vacrelstats,
+	update_vacuum_error_info(&vacrelstats->errinfo,
 							 olderrinfo.phase,
 							 olderrinfo.blkno,
 							 olderrinfo.indname);
@@ -2459,7 +2467,7 @@ lazy_cleanup_index(Relation indrel,
 	IndexVacuumInfo ivinfo;
 	const char *msg;
 	PGRUsage	ru0;
-	LVRelStats	olderrinfo;
+	LVSavedPosition	olderrinfo;
 
 	pg_rusage_init(&ru0);
 
@@ -2473,8 +2481,8 @@ lazy_cleanup_index(Relation indrel,
 	ivinfo.strategy = vac_strategy;
 
 	/* Update error traceback information */
-	olderrinfo = *vacrelstats;
-	update_vacuum_error_info(vacrelstats,
+	olderrinfo = vacrelstats->errinfo;
+	update_vacuum_error_info(&vacrelstats->errinfo,
 							 VACUUM_ERRCB_PHASE_INDEX_CLEANUP,
 							 InvalidBlockNumber,
 							 RelationGetRelationName(indrel));
@@ -2482,7 +2490,7 @@ lazy_cleanup_index(Relation indrel,
 	*stats = index_vacuum_cleanup(&ivinfo, *stats);
 
 	/* Revert back to the old phase information for error traceback */
-	update_vacuum_error_info(vacrelstats,
+	update_vacuum_error_info(&vacrelstats->errinfo,
 							 olderrinfo.phase,
 							 olderrinfo.blkno,
 							 olderrinfo.indname);
@@ -2597,7 +2605,7 @@ lazy_truncate_heap(Relation onerel, LVRelStats *vacrelstats)
 				vacrelstats->lock_waiter_detected = true;
 				ereport(elevel,
 						(errmsg("\"%s\": stopping truncate due to conflicting lock request",
-								vacrelstats->relname)));
+								vacrelstats->errinfo.relname)));
 				return;
 			}
 
@@ -2630,7 +2638,7 @@ lazy_truncate_heap(Relation onerel, LVRelStats *vacrelstats)
 		 * were vacuuming.
 		 */
 		new_rel_pages = count_nondeletable_pages(onerel, vacrelstats);
-		vacrelstats->blkno = new_rel_pages;
+		vacrelstats->errinfo.blkno = new_rel_pages;
 
 		if (new_rel_pages >= old_rel_pages)
 		{
@@ -2663,7 +2671,7 @@ lazy_truncate_heap(Relation onerel, LVRelStats *vacrelstats)
 
 		ereport(elevel,
 				(errmsg("\"%s\": truncated %u to %u pages",
-						vacrelstats->relname,
+						vacrelstats->errinfo.relname,
 						old_rel_pages, new_rel_pages),
 				 errdetail_internal("%s",
 									pg_rusage_show(&ru0))));
@@ -2728,7 +2736,7 @@ count_nondeletable_pages(Relation onerel, LVRelStats *vacrelstats)
 				{
 					ereport(elevel,
 							(errmsg("\"%s\": suspending truncate due to conflicting lock request",
-									vacrelstats->relname)));
+									vacrelstats->errinfo.relname)));
 
 					vacrelstats->lock_waiter_detected = true;
 					return blkno;
@@ -3521,14 +3529,14 @@ parallel_vacuum_main(dsm_segment *seg, shm_toc *toc)
 	 * Initialize vacrelstats for use as error callback arg by parallel
 	 * worker.
 	 */
-	vacrelstats.relnamespace = get_namespace_name(RelationGetNamespace(onerel));
-	vacrelstats.relname = pstrdup(RelationGetRelationName(onerel));
-	vacrelstats.indname = NULL;
-	vacrelstats.phase = VACUUM_ERRCB_PHASE_UNKNOWN; /* Not yet processing */
+	vacrelstats.errinfo.relnamespace = get_namespace_name(RelationGetNamespace(onerel));
+	vacrelstats.errinfo.relname = pstrdup(RelationGetRelationName(onerel));
+	vacrelstats.errinfo.indname = NULL;
+	vacrelstats.errinfo.phase = VACUUM_ERRCB_PHASE_UNKNOWN; /* Not yet processing */
 
 	/* Setup error traceback support for ereport() */
 	errcallback.callback = vacuum_error_callback;
-	errcallback.arg = &vacrelstats;
+	errcallback.arg = &vacrelstats.errinfo;
 	errcallback.previous = error_context_stack;
 	error_context_stack = &errcallback;
 
@@ -3559,7 +3567,7 @@ parallel_vacuum_main(dsm_segment *seg, shm_toc *toc)
 static void
 vacuum_error_callback(void *arg)
 {
-	LVRelStats *errinfo = arg;
+	LVSavedPosition *errinfo = arg;
 
 	switch (errinfo->phase)
 	{
@@ -3600,7 +3608,7 @@ vacuum_error_callback(void *arg)
 
 /* Update vacuum error callback for the current phase, block, and index. */
 static void
-update_vacuum_error_info(LVRelStats *errinfo, int phase, BlockNumber blkno,
+update_vacuum_error_info(LVSavedPosition *errinfo, int phase, BlockNumber blkno,
 						 char *indname)
 {
 	errinfo->blkno = blkno;
-- 
2.17.0

From 2b98df134ed4b84ed22cb7b749dc43fa43e2f370 Mon Sep 17 00:00:00 2001
From: Justin Pryzby <pryzbyj@telsasoft.com>
Date: Mon, 22 Jun 2020 17:13:39 -0500
Subject: [PATCH 4/4] Update functions to pass only errinfo struct..

..this is a more complete change, and probably a good idea since parallel
workers have an partially-populated LVRelStats, and it's better to avoid the
idea that it's usable (dead_tuples in particular is a bogus pointer).
---
 src/backend/access/heap/vacuumlazy.c | 58 ++++++++++++++--------------
 1 file changed, 29 insertions(+), 29 deletions(-)

diff --git a/src/backend/access/heap/vacuumlazy.c b/src/backend/access/heap/vacuumlazy.c
index 6bd2867660..db3bd86338 100644
--- a/src/backend/access/heap/vacuumlazy.c
+++ b/src/backend/access/heap/vacuumlazy.c
@@ -344,10 +344,10 @@ static void lazy_vacuum_all_indexes(Relation onerel, Relation *Irel,
 									LVRelStats *vacrelstats, LVParallelState *lps,
 									int nindexes);
 static void lazy_vacuum_index(Relation indrel, IndexBulkDeleteResult **stats,
-							  LVDeadTuples *dead_tuples, double reltuples, LVRelStats *vacrelstats);
+							  LVDeadTuples *dead_tuples, double reltuples, LVSavedPosition *errinfo);
 static void lazy_cleanup_index(Relation indrel,
 							   IndexBulkDeleteResult **stats,
-							   double reltuples, bool estimated_count, LVRelStats *vacrelstats);
+							   double reltuples, bool estimated_count, LVSavedPosition *errinfo);
 static int	lazy_vacuum_page(Relation onerel, BlockNumber blkno, Buffer buffer,
 							 int tupindex, LVRelStats *vacrelstats, Buffer *vmbuffer);
 static bool should_attempt_truncation(VacuumParams *params,
@@ -367,13 +367,13 @@ static void lazy_parallel_vacuum_indexes(Relation *Irel, IndexBulkDeleteResult *
 										 int nindexes);
 static void parallel_vacuum_index(Relation *Irel, IndexBulkDeleteResult **stats,
 								  LVShared *lvshared, LVDeadTuples *dead_tuples,
-								  int nindexes, LVRelStats *vacrelstats);
+								  int nindexes, LVSavedPosition *errinfo);
 static void vacuum_indexes_leader(Relation *Irel, IndexBulkDeleteResult **stats,
 								  LVRelStats *vacrelstats, LVParallelState *lps,
 								  int nindexes);
 static void vacuum_one_index(Relation indrel, IndexBulkDeleteResult **stats,
 							 LVShared *lvshared, LVSharedIndStats *shared_indstats,
-							 LVDeadTuples *dead_tuples, LVRelStats *vacrelstats);
+							 LVDeadTuples *dead_tuples, LVSavedPosition *errinfo);
 static void lazy_cleanup_all_indexes(Relation *Irel, IndexBulkDeleteResult **stats,
 									 LVRelStats *vacrelstats, LVParallelState *lps,
 									 int nindexes);
@@ -1798,7 +1798,7 @@ lazy_vacuum_all_indexes(Relation onerel, Relation *Irel,
 
 		for (idx = 0; idx < nindexes; idx++)
 			lazy_vacuum_index(Irel[idx], &stats[idx], vacrelstats->dead_tuples,
-							  vacrelstats->old_live_tuples, vacrelstats);
+							  vacrelstats->old_live_tuples, &vacrelstats->errinfo);
 	}
 
 	/* Increase and report the number of index scans */
@@ -2163,7 +2163,7 @@ lazy_parallel_vacuum_indexes(Relation *Irel, IndexBulkDeleteResult **stats,
 	 * indexes in the case where no workers are launched.
 	 */
 	parallel_vacuum_index(Irel, stats, lps->lvshared,
-						  vacrelstats->dead_tuples, nindexes, vacrelstats);
+						  vacrelstats->dead_tuples, nindexes, &vacrelstats->errinfo);
 
 	/*
 	 * Next, accumulate buffer and WAL usage.  (This must wait for the workers
@@ -2198,7 +2198,7 @@ lazy_parallel_vacuum_indexes(Relation *Irel, IndexBulkDeleteResult **stats,
 static void
 parallel_vacuum_index(Relation *Irel, IndexBulkDeleteResult **stats,
 					  LVShared *lvshared, LVDeadTuples *dead_tuples,
-					  int nindexes, LVRelStats *vacrelstats)
+					  int nindexes, LVSavedPosition	*errinfo)
 {
 	/*
 	 * Increment the active worker count if we are able to launch any worker.
@@ -2232,7 +2232,7 @@ parallel_vacuum_index(Relation *Irel, IndexBulkDeleteResult **stats,
 
 		/* Do vacuum or cleanup of the index */
 		vacuum_one_index(Irel[idx], &(stats[idx]), lvshared, shared_indstats,
-						 dead_tuples, vacrelstats);
+						 dead_tuples, errinfo);
 	}
 
 	/*
@@ -2273,7 +2273,7 @@ vacuum_indexes_leader(Relation *Irel, IndexBulkDeleteResult **stats,
 			skip_parallel_vacuum_index(Irel[i], lps->lvshared))
 			vacuum_one_index(Irel[i], &(stats[i]), lps->lvshared,
 							 shared_indstats, vacrelstats->dead_tuples,
-							 vacrelstats);
+							 &vacrelstats->errinfo);
 	}
 
 	/*
@@ -2293,7 +2293,7 @@ vacuum_indexes_leader(Relation *Irel, IndexBulkDeleteResult **stats,
 static void
 vacuum_one_index(Relation indrel, IndexBulkDeleteResult **stats,
 				 LVShared *lvshared, LVSharedIndStats *shared_indstats,
-				 LVDeadTuples *dead_tuples, LVRelStats *vacrelstats)
+				 LVDeadTuples *dead_tuples, LVSavedPosition *errinfo)
 {
 	IndexBulkDeleteResult *bulkdelete_res = NULL;
 
@@ -2313,10 +2313,10 @@ vacuum_one_index(Relation indrel, IndexBulkDeleteResult **stats,
 	/* Do vacuum or cleanup of the index */
 	if (lvshared->for_cleanup)
 		lazy_cleanup_index(indrel, stats, lvshared->reltuples,
-						   lvshared->estimated_count, vacrelstats);
+						   lvshared->estimated_count, errinfo);
 	else
 		lazy_vacuum_index(indrel, stats, dead_tuples,
-						  lvshared->reltuples, vacrelstats);
+						  lvshared->reltuples, errinfo);
 
 	/*
 	 * Copy the index bulk-deletion result returned from ambulkdelete and
@@ -2392,7 +2392,7 @@ lazy_cleanup_all_indexes(Relation *Irel, IndexBulkDeleteResult **stats,
 			lazy_cleanup_index(Irel[idx], &stats[idx],
 							   vacrelstats->new_rel_tuples,
 							   vacrelstats->tupcount_pages < vacrelstats->rel_pages,
-							   vacrelstats);
+							   &vacrelstats->errinfo);
 	}
 }
 
@@ -2407,7 +2407,7 @@ lazy_cleanup_all_indexes(Relation *Irel, IndexBulkDeleteResult **stats,
  */
 static void
 lazy_vacuum_index(Relation indrel, IndexBulkDeleteResult **stats,
-				  LVDeadTuples *dead_tuples, double reltuples, LVRelStats *vacrelstats)
+				  LVDeadTuples *dead_tuples, double reltuples, LVSavedPosition *errinfo)
 {
 	IndexVacuumInfo ivinfo;
 	const char *msg;
@@ -2425,8 +2425,8 @@ lazy_vacuum_index(Relation indrel, IndexBulkDeleteResult **stats,
 	ivinfo.strategy = vac_strategy;
 
 	/* Update error traceback information */
-	olderrinfo = vacrelstats->errinfo;
-	update_vacuum_error_info(&vacrelstats->errinfo,
+	olderrinfo = *errinfo;
+	update_vacuum_error_info(errinfo,
 							 VACUUM_ERRCB_PHASE_VACUUM_INDEX,
 							 InvalidBlockNumber,
 							 RelationGetRelationName(indrel));
@@ -2442,12 +2442,12 @@ lazy_vacuum_index(Relation indrel, IndexBulkDeleteResult **stats,
 
 	ereport(elevel,
 			(errmsg(msg,
-					vacrelstats->errinfo.indname,
+					errinfo->indname,
 					dead_tuples->num_tuples),
 			 errdetail_internal("%s", pg_rusage_show(&ru0))));
 
 	/* Revert to the previous phase information for error traceback */
-	update_vacuum_error_info(&vacrelstats->errinfo,
+	update_vacuum_error_info(errinfo,
 							 olderrinfo.phase,
 							 olderrinfo.blkno,
 							 olderrinfo.indname);
@@ -2462,7 +2462,7 @@ lazy_vacuum_index(Relation indrel, IndexBulkDeleteResult **stats,
 static void
 lazy_cleanup_index(Relation indrel,
 				   IndexBulkDeleteResult **stats,
-				   double reltuples, bool estimated_count, LVRelStats *vacrelstats)
+				   double reltuples, bool estimated_count, LVSavedPosition *errinfo)
 {
 	IndexVacuumInfo ivinfo;
 	const char *msg;
@@ -2481,8 +2481,8 @@ lazy_cleanup_index(Relation indrel,
 	ivinfo.strategy = vac_strategy;
 
 	/* Update error traceback information */
-	olderrinfo = vacrelstats->errinfo;
-	update_vacuum_error_info(&vacrelstats->errinfo,
+	olderrinfo = *errinfo;
+	update_vacuum_error_info(errinfo,
 							 VACUUM_ERRCB_PHASE_INDEX_CLEANUP,
 							 InvalidBlockNumber,
 							 RelationGetRelationName(indrel));
@@ -2490,7 +2490,7 @@ lazy_cleanup_index(Relation indrel,
 	*stats = index_vacuum_cleanup(&ivinfo, *stats);
 
 	/* Revert back to the old phase information for error traceback */
-	update_vacuum_error_info(&vacrelstats->errinfo,
+	update_vacuum_error_info(errinfo,
 							 olderrinfo.phase,
 							 olderrinfo.blkno,
 							 olderrinfo.indname);
@@ -3474,7 +3474,7 @@ parallel_vacuum_main(dsm_segment *seg, shm_toc *toc)
 	int			nindexes;
 	char	   *sharedquery;
 	IndexBulkDeleteResult **stats;
-	LVRelStats	vacrelstats;
+	LVSavedPosition errinfo;
 	ErrorContextCallback errcallback;
 
 	lvshared = (LVShared *) shm_toc_lookup(toc, PARALLEL_VACUUM_KEY_SHARED,
@@ -3529,14 +3529,14 @@ parallel_vacuum_main(dsm_segment *seg, shm_toc *toc)
 	 * Initialize vacrelstats for use as error callback arg by parallel
 	 * worker.
 	 */
-	vacrelstats.errinfo.relnamespace = get_namespace_name(RelationGetNamespace(onerel));
-	vacrelstats.errinfo.relname = pstrdup(RelationGetRelationName(onerel));
-	vacrelstats.errinfo.indname = NULL;
-	vacrelstats.errinfo.phase = VACUUM_ERRCB_PHASE_UNKNOWN; /* Not yet processing */
+	errinfo.relnamespace = get_namespace_name(RelationGetNamespace(onerel));
+	errinfo.relname = pstrdup(RelationGetRelationName(onerel));
+	errinfo.indname = NULL;
+	errinfo.phase = VACUUM_ERRCB_PHASE_UNKNOWN; /* Not yet processing */
 
 	/* Setup error traceback support for ereport() */
 	errcallback.callback = vacuum_error_callback;
-	errcallback.arg = &vacrelstats.errinfo;
+	errcallback.arg = &errinfo;
 	errcallback.previous = error_context_stack;
 	error_context_stack = &errcallback;
 
@@ -3545,7 +3545,7 @@ parallel_vacuum_main(dsm_segment *seg, shm_toc *toc)
 
 	/* Process indexes to perform vacuum/cleanup */
 	parallel_vacuum_index(indrels, stats, lvshared, dead_tuples, nindexes,
-						  &vacrelstats);
+						  &errinfo);
 
 	/* Report buffer/WAL usage during parallel execution */
 	buffer_usage = shm_toc_lookup(toc, PARALLEL_VACUUM_KEY_BUFFER_USAGE, false);
-- 
2.17.0

From bbfdff2483730d45c663b75de4700e50f09ab4d3 Mon Sep 17 00:00:00 2001
From: Justin Pryzby <pryzbyj@telsasoft.com>
Date: Mon, 22 Jun 2020 18:22:58 -0500
Subject: [PATCH v2 1/5] Rename from "errcbarg"..

..the name of which Alvaro didn't like.  I renamed this, but it was
accidentally re-introduced while trading patches with Amit.

We should *also* rename VACUUM_ERRCB* to VACUUM_ERRINFO, but I didn't do that here.
---
 src/backend/access/heap/vacuumlazy.c | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/src/backend/access/heap/vacuumlazy.c b/src/backend/access/heap/vacuumlazy.c
index 3bef0e124b..a6a5d906c0 100644
--- a/src/backend/access/heap/vacuumlazy.c
+++ b/src/backend/access/heap/vacuumlazy.c
@@ -2459,7 +2459,7 @@ lazy_cleanup_index(Relation indrel,
 	IndexVacuumInfo ivinfo;
 	const char *msg;
 	PGRUsage	ru0;
-	LVRelStats	olderrcbarg;
+	LVRelStats	olderrinfo;
 
 	pg_rusage_init(&ru0);
 
@@ -2473,7 +2473,7 @@ lazy_cleanup_index(Relation indrel,
 	ivinfo.strategy = vac_strategy;
 
 	/* Update error traceback information */
-	olderrcbarg = *vacrelstats;
+	olderrinfo = *vacrelstats;
 	update_vacuum_error_info(vacrelstats,
 							 VACUUM_ERRCB_PHASE_INDEX_CLEANUP,
 							 InvalidBlockNumber,
@@ -2483,9 +2483,9 @@ lazy_cleanup_index(Relation indrel,
 
 	/* Revert back to the old phase information for error traceback */
 	update_vacuum_error_info(vacrelstats,
-							 olderrcbarg.phase,
-							 olderrcbarg.blkno,
-							 olderrcbarg.indname);
+							 olderrinfo.phase,
+							 olderrinfo.blkno,
+							 olderrinfo.indname);
 	if (!(*stats))
 		return;
 
-- 
2.17.0

From afd4916d190d7da48b535432f8edea65615d7fe8 Mon Sep 17 00:00:00 2001
From: Justin Pryzby <pryzbyj@telsasoft.com>
Date: Mon, 22 Jun 2020 18:51:35 -0500
Subject: [PATCH v2 2/5] Specially save the index name in
 lazy_{vacuum,cleanup}_index..

..at expense of symmetry, move handling of index outside of
update_vacuum_error_info, since it's more clear this way that use of indname is
limited and safe.
---
 src/backend/access/heap/vacuumlazy.c | 49 ++++++++++++----------------
 1 file changed, 20 insertions(+), 29 deletions(-)

diff --git a/src/backend/access/heap/vacuumlazy.c b/src/backend/access/heap/vacuumlazy.c
index a6a5d906c0..43a3c093fd 100644
--- a/src/backend/access/heap/vacuumlazy.c
+++ b/src/backend/access/heap/vacuumlazy.c
@@ -389,7 +389,7 @@ static LVSharedIndStats *get_indstats(LVShared *lvshared, int n);
 static bool skip_parallel_vacuum_index(Relation indrel, LVShared *lvshared);
 static void vacuum_error_callback(void *arg);
 static void update_vacuum_error_info(LVRelStats *errinfo, int phase,
-									 BlockNumber blkno, char *indname);
+									 BlockNumber blkno);
 
 
 /*
@@ -477,7 +477,6 @@ heap_vacuum_rel(Relation onerel, VacuumParams *params,
 
 	vacrelstats->relnamespace = get_namespace_name(RelationGetNamespace(onerel));
 	vacrelstats->relname = pstrdup(RelationGetRelationName(onerel));
-	vacrelstats->indname = NULL;
 	vacrelstats->phase = VACUUM_ERRCB_PHASE_UNKNOWN;
 	vacrelstats->old_rel_pages = onerel->rd_rel->relpages;
 	vacrelstats->old_live_tuples = onerel->rd_rel->reltuples;
@@ -539,7 +538,7 @@ heap_vacuum_rel(Relation onerel, VacuumParams *params,
 		 * revert to the previous phase.
 		 */
 		update_vacuum_error_info(vacrelstats, VACUUM_ERRCB_PHASE_TRUNCATE,
-								 vacrelstats->nonempty_pages, NULL);
+								 vacrelstats->nonempty_pages);
 		lazy_truncate_heap(onerel, vacrelstats);
 	}
 
@@ -949,7 +948,7 @@ lazy_scan_heap(Relation onerel, VacuumParams *params, LVRelStats *vacrelstats,
 		pgstat_progress_update_param(PROGRESS_VACUUM_HEAP_BLKS_SCANNED, blkno);
 
 		update_vacuum_error_info(vacrelstats, VACUUM_ERRCB_PHASE_SCAN_HEAP,
-								 blkno, NULL);
+								 blkno);
 
 		if (blkno == next_unskippable_block)
 		{
@@ -1829,7 +1828,7 @@ lazy_vacuum_heap(Relation onerel, LVRelStats *vacrelstats)
 	/* Update error traceback information */
 	olderrinfo = *vacrelstats;
 	update_vacuum_error_info(vacrelstats, VACUUM_ERRCB_PHASE_VACUUM_HEAP,
-							 InvalidBlockNumber, NULL);
+							 InvalidBlockNumber);
 
 	pg_rusage_init(&ru0);
 	npages = 0;
@@ -1881,8 +1880,7 @@ lazy_vacuum_heap(Relation onerel, LVRelStats *vacrelstats)
 	/* Revert to the previous phase information for error traceback */
 	update_vacuum_error_info(vacrelstats,
 							 olderrinfo.phase,
-							 olderrinfo.blkno,
-							 olderrinfo.indname);
+							 olderrinfo.blkno);
 }
 
 /*
@@ -1912,7 +1910,7 @@ lazy_vacuum_page(Relation onerel, BlockNumber blkno, Buffer buffer,
 	/* Update error traceback information */
 	olderrinfo = *vacrelstats;
 	update_vacuum_error_info(vacrelstats, VACUUM_ERRCB_PHASE_VACUUM_HEAP,
-							 blkno, NULL);
+							 blkno);
 
 	START_CRIT_SECTION();
 
@@ -1993,8 +1991,7 @@ lazy_vacuum_page(Relation onerel, BlockNumber blkno, Buffer buffer,
 	/* Revert to the previous phase information for error traceback */
 	update_vacuum_error_info(vacrelstats,
 							 olderrinfo.phase,
-							 olderrinfo.blkno,
-							 olderrinfo.indname);
+							 olderrinfo.blkno);
 	return tupindex;
 }
 
@@ -2418,10 +2415,11 @@ lazy_vacuum_index(Relation indrel, IndexBulkDeleteResult **stats,
 
 	/* Update error traceback information */
 	olderrinfo = *vacrelstats;
+	/* The index name is also saved during this phase */
+	vacrelstats->indname = pstrdup(RelationGetRelationName(indrel));
 	update_vacuum_error_info(vacrelstats,
 							 VACUUM_ERRCB_PHASE_VACUUM_INDEX,
-							 InvalidBlockNumber,
-							 RelationGetRelationName(indrel));
+							 InvalidBlockNumber);
 
 	/* Do bulk deletion */
 	*stats = index_bulk_delete(&ivinfo, *stats,
@@ -2441,8 +2439,8 @@ lazy_vacuum_index(Relation indrel, IndexBulkDeleteResult **stats,
 	/* Revert to the previous phase information for error traceback */
 	update_vacuum_error_info(vacrelstats,
 							 olderrinfo.phase,
-							 olderrinfo.blkno,
-							 olderrinfo.indname);
+							 olderrinfo.blkno);
+	pfree(vacrelstats->indname);
 }
 
 /*
@@ -2474,18 +2472,20 @@ lazy_cleanup_index(Relation indrel,
 
 	/* Update error traceback information */
 	olderrinfo = *vacrelstats;
+	/* The index name is also saved during this phase */
+	vacrelstats->indname = pstrdup(RelationGetRelationName(indrel));
 	update_vacuum_error_info(vacrelstats,
 							 VACUUM_ERRCB_PHASE_INDEX_CLEANUP,
-							 InvalidBlockNumber,
-							 RelationGetRelationName(indrel));
+							 InvalidBlockNumber);
 
 	*stats = index_vacuum_cleanup(&ivinfo, *stats);
 
 	/* Revert back to the old phase information for error traceback */
 	update_vacuum_error_info(vacrelstats,
 							 olderrinfo.phase,
-							 olderrinfo.blkno,
-							 olderrinfo.indname);
+							 olderrinfo.blkno);
+	pfree(vacrelstats->indname);
+
 	if (!(*stats))
 		return;
 
@@ -3523,7 +3523,6 @@ parallel_vacuum_main(dsm_segment *seg, shm_toc *toc)
 	 */
 	vacrelstats.relnamespace = get_namespace_name(RelationGetNamespace(onerel));
 	vacrelstats.relname = pstrdup(RelationGetRelationName(onerel));
-	vacrelstats.indname = NULL;
 	vacrelstats.phase = VACUUM_ERRCB_PHASE_UNKNOWN; /* Not yet processing */
 
 	/* Setup error traceback support for ereport() */
@@ -3598,18 +3597,10 @@ vacuum_error_callback(void *arg)
 	}
 }
 
-/* Update vacuum error callback for the current phase, block, and index. */
+/* Update vacuum error callback for the current phase and block. */
 static void
-update_vacuum_error_info(LVRelStats *errinfo, int phase, BlockNumber blkno,
-						 char *indname)
+update_vacuum_error_info(LVRelStats *errinfo, int phase, BlockNumber blkno)
 {
 	errinfo->blkno = blkno;
 	errinfo->phase = phase;
-
-	/* Free index name from any previous phase */
-	if (errinfo->indname)
-		pfree(errinfo->indname);
-
-	/* For index phases, save the name of the current index for the callback */
-	errinfo->indname = indname ? pstrdup(indname) : NULL;
 }
-- 
2.17.0

From f57302143cea857b29b4f19f30bad0e28209c50d Mon Sep 17 00:00:00 2001
From: Justin Pryzby <pryzbyj@telsasoft.com>
Date: Tue, 23 Jun 2020 08:35:29 -0500
Subject: [PATCH v2 3/5] Save phase/blkno in local variables, for consistency
 with indname

---
 src/backend/access/heap/vacuumlazy.c | 32 +++++++++++-----------------
 1 file changed, 12 insertions(+), 20 deletions(-)

diff --git a/src/backend/access/heap/vacuumlazy.c b/src/backend/access/heap/vacuumlazy.c
index 43a3c093fd..2393269565 100644
--- a/src/backend/access/heap/vacuumlazy.c
+++ b/src/backend/access/heap/vacuumlazy.c
@@ -1819,14 +1819,14 @@ lazy_vacuum_heap(Relation onerel, LVRelStats *vacrelstats)
 	int			npages;
 	PGRUsage	ru0;
 	Buffer		vmbuffer = InvalidBuffer;
-	LVRelStats	olderrinfo;
+	int			oldphase = vacrelstats->phase,
+				oldblkno = vacrelstats->blkno;
 
 	/* Report that we are now vacuuming the heap */
 	pgstat_progress_update_param(PROGRESS_VACUUM_PHASE,
 								 PROGRESS_VACUUM_PHASE_VACUUM_HEAP);
 
 	/* Update error traceback information */
-	olderrinfo = *vacrelstats;
 	update_vacuum_error_info(vacrelstats, VACUUM_ERRCB_PHASE_VACUUM_HEAP,
 							 InvalidBlockNumber);
 
@@ -1878,9 +1878,7 @@ lazy_vacuum_heap(Relation onerel, LVRelStats *vacrelstats)
 			 errdetail_internal("%s", pg_rusage_show(&ru0))));
 
 	/* Revert to the previous phase information for error traceback */
-	update_vacuum_error_info(vacrelstats,
-							 olderrinfo.phase,
-							 olderrinfo.blkno);
+	update_vacuum_error_info(vacrelstats, oldphase, oldblkno);
 }
 
 /*
@@ -1903,12 +1901,12 @@ lazy_vacuum_page(Relation onerel, BlockNumber blkno, Buffer buffer,
 	int			uncnt = 0;
 	TransactionId visibility_cutoff_xid;
 	bool		all_frozen;
-	LVRelStats	olderrinfo;
+	int			oldphase = vacrelstats->phase,
+				oldblkno = vacrelstats->blkno;
 
 	pgstat_progress_update_param(PROGRESS_VACUUM_HEAP_BLKS_VACUUMED, blkno);
 
 	/* Update error traceback information */
-	olderrinfo = *vacrelstats;
 	update_vacuum_error_info(vacrelstats, VACUUM_ERRCB_PHASE_VACUUM_HEAP,
 							 blkno);
 
@@ -1989,9 +1987,7 @@ lazy_vacuum_page(Relation onerel, BlockNumber blkno, Buffer buffer,
 	}
 
 	/* Revert to the previous phase information for error traceback */
-	update_vacuum_error_info(vacrelstats,
-							 olderrinfo.phase,
-							 olderrinfo.blkno);
+	update_vacuum_error_info(vacrelstats, oldphase, oldblkno);
 	return tupindex;
 }
 
@@ -2401,7 +2397,8 @@ lazy_vacuum_index(Relation indrel, IndexBulkDeleteResult **stats,
 	IndexVacuumInfo ivinfo;
 	const char *msg;
 	PGRUsage	ru0;
-	LVRelStats	olderrinfo;
+	int			oldphase = vacrelstats->phase,
+				oldblkno = vacrelstats->blkno;
 
 	pg_rusage_init(&ru0);
 
@@ -2414,7 +2411,6 @@ lazy_vacuum_index(Relation indrel, IndexBulkDeleteResult **stats,
 	ivinfo.strategy = vac_strategy;
 
 	/* Update error traceback information */
-	olderrinfo = *vacrelstats;
 	/* The index name is also saved during this phase */
 	vacrelstats->indname = pstrdup(RelationGetRelationName(indrel));
 	update_vacuum_error_info(vacrelstats,
@@ -2437,9 +2433,7 @@ lazy_vacuum_index(Relation indrel, IndexBulkDeleteResult **stats,
 			 errdetail_internal("%s", pg_rusage_show(&ru0))));
 
 	/* Revert to the previous phase information for error traceback */
-	update_vacuum_error_info(vacrelstats,
-							 olderrinfo.phase,
-							 olderrinfo.blkno);
+	update_vacuum_error_info(vacrelstats, oldphase, oldblkno);
 	pfree(vacrelstats->indname);
 }
 
@@ -2457,7 +2451,8 @@ lazy_cleanup_index(Relation indrel,
 	IndexVacuumInfo ivinfo;
 	const char *msg;
 	PGRUsage	ru0;
-	LVRelStats	olderrinfo;
+	int			oldphase = vacrelstats->phase,
+				oldblkno = vacrelstats->blkno;
 
 	pg_rusage_init(&ru0);
 
@@ -2471,7 +2466,6 @@ lazy_cleanup_index(Relation indrel,
 	ivinfo.strategy = vac_strategy;
 
 	/* Update error traceback information */
-	olderrinfo = *vacrelstats;
 	/* The index name is also saved during this phase */
 	vacrelstats->indname = pstrdup(RelationGetRelationName(indrel));
 	update_vacuum_error_info(vacrelstats,
@@ -2481,9 +2475,7 @@ lazy_cleanup_index(Relation indrel,
 	*stats = index_vacuum_cleanup(&ivinfo, *stats);
 
 	/* Revert back to the old phase information for error traceback */
-	update_vacuum_error_info(vacrelstats,
-							 olderrinfo.phase,
-							 olderrinfo.blkno);
+	update_vacuum_error_info(vacrelstats, oldphase, oldblkno);
 	pfree(vacrelstats->indname);
 
 	if (!(*stats))
-- 
2.17.0

From 78d378fd22f74828981692e5e253214bccef4311 Mon Sep 17 00:00:00 2001
From: Justin Pryzby <pryzbyj@telsasoft.com>
Date: Mon, 22 Jun 2020 16:36:14 -0500
Subject: [PATCH v2 4/5] Move error information into a separate struct..

..to avoid copying large LVRelStats struct.

Andres things this is a problem but Tom thinks it's a micro-optimization.

See: b61d161c146328ae6ba9ed937862d66e5c8b035a

This also moves relname and relnamespace (see ef75140fe).

Discussion: https://www.postgresql.org/message-id/20200622200939.jkuniq3vtiumeszj%40alap3.anarazel.de
---
 src/backend/access/heap/vacuumlazy.c | 128 +++++++++++++++------------
 1 file changed, 72 insertions(+), 56 deletions(-)

diff --git a/src/backend/access/heap/vacuumlazy.c b/src/backend/access/heap/vacuumlazy.c
index 2393269565..9eb4bc66ae 100644
--- a/src/backend/access/heap/vacuumlazy.c
+++ b/src/backend/access/heap/vacuumlazy.c
@@ -288,10 +288,17 @@ typedef struct LVParallelState
 	int			nindexes_parallel_condcleanup;
 } LVParallelState;
 
-typedef struct LVRelStats
+typedef struct
 {
 	char	   *relnamespace;
 	char	   *relname;
+	char	   *indname;
+	BlockNumber blkno;			/* used only for heap operations */
+	VacErrPhase phase;
+} LVSavedPosition;
+
+typedef struct LVRelStats
+{
 	/* useindex = true means two-pass strategy; false means one-pass */
 	bool		useindex;
 	/* Overall statistics about rel */
@@ -313,10 +320,7 @@ typedef struct LVRelStats
 	TransactionId latestRemovedXid;
 	bool		lock_waiter_detected;
 
-	/* Used for error callback */
-	char	   *indname;
-	BlockNumber blkno;			/* used only for heap operations */
-	VacErrPhase phase;
+	LVSavedPosition errinfo; /* Used for error callback */
 } LVRelStats;
 
 /* A few variables that don't seem worth passing around as parameters */
@@ -388,7 +392,7 @@ static void end_parallel_vacuum(Relation *Irel, IndexBulkDeleteResult **stats,
 static LVSharedIndStats *get_indstats(LVShared *lvshared, int n);
 static bool skip_parallel_vacuum_index(Relation indrel, LVShared *lvshared);
 static void vacuum_error_callback(void *arg);
-static void update_vacuum_error_info(LVRelStats *errinfo, int phase,
+static void update_vacuum_error_info(LVSavedPosition *errinfo, int phase,
 									 BlockNumber blkno);
 
 
@@ -475,9 +479,9 @@ heap_vacuum_rel(Relation onerel, VacuumParams *params,
 
 	vacrelstats = (LVRelStats *) palloc0(sizeof(LVRelStats));
 
-	vacrelstats->relnamespace = get_namespace_name(RelationGetNamespace(onerel));
-	vacrelstats->relname = pstrdup(RelationGetRelationName(onerel));
-	vacrelstats->phase = VACUUM_ERRCB_PHASE_UNKNOWN;
+	vacrelstats->errinfo.relnamespace = get_namespace_name(RelationGetNamespace(onerel));
+	vacrelstats->errinfo.relname = pstrdup(RelationGetRelationName(onerel));
+	vacrelstats->errinfo.phase = VACUUM_ERRCB_PHASE_UNKNOWN;
 	vacrelstats->old_rel_pages = onerel->rd_rel->relpages;
 	vacrelstats->old_live_tuples = onerel->rd_rel->reltuples;
 	vacrelstats->num_index_scans = 0;
@@ -501,7 +505,7 @@ heap_vacuum_rel(Relation onerel, VacuumParams *params,
 	 * information is restored at the end of those phases.
 	 */
 	errcallback.callback = vacuum_error_callback;
-	errcallback.arg = vacrelstats;
+	errcallback.arg = &vacrelstats->errinfo;
 	errcallback.previous = error_context_stack;
 	error_context_stack = &errcallback;
 
@@ -537,7 +541,8 @@ heap_vacuum_rel(Relation onerel, VacuumParams *params,
 		 * which we add context information to errors, so we don't need to
 		 * revert to the previous phase.
 		 */
-		update_vacuum_error_info(vacrelstats, VACUUM_ERRCB_PHASE_TRUNCATE,
+		update_vacuum_error_info(&vacrelstats->errinfo,
+								 VACUUM_ERRCB_PHASE_TRUNCATE,
 								 vacrelstats->nonempty_pages);
 		lazy_truncate_heap(onerel, vacrelstats);
 	}
@@ -649,8 +654,8 @@ heap_vacuum_rel(Relation onerel, VacuumParams *params,
 			}
 			appendStringInfo(&buf, msgfmt,
 							 get_database_name(MyDatabaseId),
-							 vacrelstats->relnamespace,
-							 vacrelstats->relname,
+							 vacrelstats->errinfo.relnamespace,
+							 vacrelstats->errinfo.relname,
 							 vacrelstats->num_index_scans);
 			appendStringInfo(&buf, _("pages: %u removed, %u remain, %u skipped due to pins, %u skipped frozen\n"),
 							 vacrelstats->pages_removed,
@@ -785,13 +790,13 @@ lazy_scan_heap(Relation onerel, VacuumParams *params, LVRelStats *vacrelstats,
 	if (aggressive)
 		ereport(elevel,
 				(errmsg("aggressively vacuuming \"%s.%s\"",
-						vacrelstats->relnamespace,
-						vacrelstats->relname)));
+						vacrelstats->errinfo.relnamespace,
+						vacrelstats->errinfo.relname)));
 	else
 		ereport(elevel,
 				(errmsg("vacuuming \"%s.%s\"",
-						vacrelstats->relnamespace,
-						vacrelstats->relname)));
+						vacrelstats->errinfo.relnamespace,
+						vacrelstats->errinfo.relname)));
 
 	empty_pages = vacuumed_pages = 0;
 	next_fsm_block_to_vacuum = (BlockNumber) 0;
@@ -827,7 +832,7 @@ lazy_scan_heap(Relation onerel, VacuumParams *params, LVRelStats *vacrelstats,
 			if (params->nworkers > 0)
 				ereport(WARNING,
 						(errmsg("disabling parallel option of vacuum on \"%s\" --- cannot vacuum temporary tables in parallel",
-								vacrelstats->relname)));
+								vacrelstats->errinfo.relname)));
 		}
 		else
 			lps = begin_parallel_vacuum(RelationGetRelid(onerel), Irel,
@@ -947,7 +952,8 @@ lazy_scan_heap(Relation onerel, VacuumParams *params, LVRelStats *vacrelstats,
 
 		pgstat_progress_update_param(PROGRESS_VACUUM_HEAP_BLKS_SCANNED, blkno);
 
-		update_vacuum_error_info(vacrelstats, VACUUM_ERRCB_PHASE_SCAN_HEAP,
+		update_vacuum_error_info(&vacrelstats->errinfo,
+								 VACUUM_ERRCB_PHASE_SCAN_HEAP,
 								 blkno);
 
 		if (blkno == next_unskippable_block)
@@ -1581,7 +1587,7 @@ lazy_scan_heap(Relation onerel, VacuumParams *params, LVRelStats *vacrelstats,
 				 && VM_ALL_VISIBLE(onerel, blkno, &vmbuffer))
 		{
 			elog(WARNING, "page is not marked all-visible but visibility map bit is set in relation \"%s\" page %u",
-				 vacrelstats->relname, blkno);
+				 vacrelstats->errinfo.relname, blkno);
 			visibilitymap_clear(onerel, blkno, vmbuffer,
 								VISIBILITYMAP_VALID_BITS);
 		}
@@ -1602,7 +1608,7 @@ lazy_scan_heap(Relation onerel, VacuumParams *params, LVRelStats *vacrelstats,
 		else if (PageIsAllVisible(page) && has_dead_tuples)
 		{
 			elog(WARNING, "page containing dead tuples is marked as all-visible in relation \"%s\" page %u",
-				 vacrelstats->relname, blkno);
+				 vacrelstats->errinfo.relname, blkno);
 			PageClearAllVisible(page);
 			MarkBufferDirty(buf);
 			visibilitymap_clear(onerel, blkno, vmbuffer,
@@ -1712,7 +1718,7 @@ lazy_scan_heap(Relation onerel, VacuumParams *params, LVRelStats *vacrelstats,
 	if (vacuumed_pages)
 		ereport(elevel,
 				(errmsg("\"%s\": removed %.0f row versions in %u pages",
-						vacrelstats->relname,
+						vacrelstats->errinfo.relname,
 						tups_vacuumed, vacuumed_pages)));
 
 	/*
@@ -1741,7 +1747,7 @@ lazy_scan_heap(Relation onerel, VacuumParams *params, LVRelStats *vacrelstats,
 
 	ereport(elevel,
 			(errmsg("\"%s\": found %.0f removable, %.0f nonremovable row versions in %u out of %u pages",
-					vacrelstats->relname,
+					vacrelstats->errinfo.relname,
 					tups_vacuumed, num_tuples,
 					vacrelstats->scanned_pages, nblocks),
 			 errdetail_internal("%s", buf.data)));
@@ -1819,15 +1825,16 @@ lazy_vacuum_heap(Relation onerel, LVRelStats *vacrelstats)
 	int			npages;
 	PGRUsage	ru0;
 	Buffer		vmbuffer = InvalidBuffer;
-	int			oldphase = vacrelstats->phase,
-				oldblkno = vacrelstats->blkno;
+	LVSavedPosition	olderrinfo;
 
 	/* Report that we are now vacuuming the heap */
 	pgstat_progress_update_param(PROGRESS_VACUUM_PHASE,
 								 PROGRESS_VACUUM_PHASE_VACUUM_HEAP);
 
 	/* Update error traceback information */
-	update_vacuum_error_info(vacrelstats, VACUUM_ERRCB_PHASE_VACUUM_HEAP,
+	olderrinfo = vacrelstats->errinfo;
+	update_vacuum_error_info(&vacrelstats->errinfo,
+							 VACUUM_ERRCB_PHASE_VACUUM_HEAP,
 							 InvalidBlockNumber);
 
 	pg_rusage_init(&ru0);
@@ -1844,7 +1851,7 @@ lazy_vacuum_heap(Relation onerel, LVRelStats *vacrelstats)
 		vacuum_delay_point();
 
 		tblk = ItemPointerGetBlockNumber(&vacrelstats->dead_tuples->itemptrs[tupindex]);
-		vacrelstats->blkno = tblk;
+		vacrelstats->errinfo.blkno = tblk;
 		buf = ReadBufferExtended(onerel, MAIN_FORKNUM, tblk, RBM_NORMAL,
 								 vac_strategy);
 		if (!ConditionalLockBufferForCleanup(buf))
@@ -1873,12 +1880,14 @@ lazy_vacuum_heap(Relation onerel, LVRelStats *vacrelstats)
 
 	ereport(elevel,
 			(errmsg("\"%s\": removed %d row versions in %d pages",
-					vacrelstats->relname,
+					vacrelstats->errinfo.relname,
 					tupindex, npages),
 			 errdetail_internal("%s", pg_rusage_show(&ru0))));
 
 	/* Revert to the previous phase information for error traceback */
-	update_vacuum_error_info(vacrelstats, oldphase, oldblkno);
+	update_vacuum_error_info(&vacrelstats->errinfo,
+							 olderrinfo.phase,
+							 olderrinfo.blkno);
 }
 
 /*
@@ -1901,13 +1910,14 @@ lazy_vacuum_page(Relation onerel, BlockNumber blkno, Buffer buffer,
 	int			uncnt = 0;
 	TransactionId visibility_cutoff_xid;
 	bool		all_frozen;
-	int			oldphase = vacrelstats->phase,
-				oldblkno = vacrelstats->blkno;
+	LVSavedPosition	olderrinfo;
 
 	pgstat_progress_update_param(PROGRESS_VACUUM_HEAP_BLKS_VACUUMED, blkno);
 
 	/* Update error traceback information */
-	update_vacuum_error_info(vacrelstats, VACUUM_ERRCB_PHASE_VACUUM_HEAP,
+	olderrinfo = vacrelstats->errinfo;
+	update_vacuum_error_info(&vacrelstats->errinfo,
+							 VACUUM_ERRCB_PHASE_VACUUM_HEAP,
 							 blkno);
 
 	START_CRIT_SECTION();
@@ -1987,7 +1997,9 @@ lazy_vacuum_page(Relation onerel, BlockNumber blkno, Buffer buffer,
 	}
 
 	/* Revert to the previous phase information for error traceback */
-	update_vacuum_error_info(vacrelstats, oldphase, oldblkno);
+	update_vacuum_error_info(&vacrelstats->errinfo,
+							 olderrinfo.phase,
+							 olderrinfo.blkno);
 	return tupindex;
 }
 
@@ -2397,8 +2409,7 @@ lazy_vacuum_index(Relation indrel, IndexBulkDeleteResult **stats,
 	IndexVacuumInfo ivinfo;
 	const char *msg;
 	PGRUsage	ru0;
-	int			oldphase = vacrelstats->phase,
-				oldblkno = vacrelstats->blkno;
+	LVSavedPosition	olderrinfo;
 
 	pg_rusage_init(&ru0);
 
@@ -2411,9 +2422,10 @@ lazy_vacuum_index(Relation indrel, IndexBulkDeleteResult **stats,
 	ivinfo.strategy = vac_strategy;
 
 	/* Update error traceback information */
+	olderrinfo = vacrelstats->errinfo;
 	/* The index name is also saved during this phase */
-	vacrelstats->indname = pstrdup(RelationGetRelationName(indrel));
-	update_vacuum_error_info(vacrelstats,
+	vacrelstats->errinfo.indname = pstrdup(RelationGetRelationName(indrel));
+	update_vacuum_error_info(&vacrelstats->errinfo,
 							 VACUUM_ERRCB_PHASE_VACUUM_INDEX,
 							 InvalidBlockNumber);
 
@@ -2428,13 +2440,15 @@ lazy_vacuum_index(Relation indrel, IndexBulkDeleteResult **stats,
 
 	ereport(elevel,
 			(errmsg(msg,
-					vacrelstats->indname,
+					vacrelstats->errinfo.indname,
 					dead_tuples->num_tuples),
 			 errdetail_internal("%s", pg_rusage_show(&ru0))));
 
 	/* Revert to the previous phase information for error traceback */
-	update_vacuum_error_info(vacrelstats, oldphase, oldblkno);
-	pfree(vacrelstats->indname);
+	update_vacuum_error_info(&vacrelstats->errinfo,
+							 olderrinfo.phase,
+							 olderrinfo.blkno);
+	pfree(vacrelstats->errinfo.indname);
 }
 
 /*
@@ -2451,8 +2465,7 @@ lazy_cleanup_index(Relation indrel,
 	IndexVacuumInfo ivinfo;
 	const char *msg;
 	PGRUsage	ru0;
-	int			oldphase = vacrelstats->phase,
-				oldblkno = vacrelstats->blkno;
+	LVSavedPosition	olderrinfo;
 
 	pg_rusage_init(&ru0);
 
@@ -2466,17 +2479,20 @@ lazy_cleanup_index(Relation indrel,
 	ivinfo.strategy = vac_strategy;
 
 	/* Update error traceback information */
+	olderrinfo = vacrelstats->errinfo;
 	/* The index name is also saved during this phase */
-	vacrelstats->indname = pstrdup(RelationGetRelationName(indrel));
-	update_vacuum_error_info(vacrelstats,
+	vacrelstats->errinfo.indname = pstrdup(RelationGetRelationName(indrel));
+	update_vacuum_error_info(&vacrelstats->errinfo,
 							 VACUUM_ERRCB_PHASE_INDEX_CLEANUP,
 							 InvalidBlockNumber);
 
 	*stats = index_vacuum_cleanup(&ivinfo, *stats);
 
 	/* Revert back to the old phase information for error traceback */
-	update_vacuum_error_info(vacrelstats, oldphase, oldblkno);
-	pfree(vacrelstats->indname);
+	update_vacuum_error_info(&vacrelstats->errinfo,
+							 olderrinfo.phase,
+							 olderrinfo.blkno);
+	pfree(vacrelstats->errinfo.indname);
 
 	if (!(*stats))
 		return;
@@ -2589,7 +2605,7 @@ lazy_truncate_heap(Relation onerel, LVRelStats *vacrelstats)
 				vacrelstats->lock_waiter_detected = true;
 				ereport(elevel,
 						(errmsg("\"%s\": stopping truncate due to conflicting lock request",
-								vacrelstats->relname)));
+								vacrelstats->errinfo.relname)));
 				return;
 			}
 
@@ -2622,7 +2638,7 @@ lazy_truncate_heap(Relation onerel, LVRelStats *vacrelstats)
 		 * were vacuuming.
 		 */
 		new_rel_pages = count_nondeletable_pages(onerel, vacrelstats);
-		vacrelstats->blkno = new_rel_pages;
+		vacrelstats->errinfo.blkno = new_rel_pages;
 
 		if (new_rel_pages >= old_rel_pages)
 		{
@@ -2655,7 +2671,7 @@ lazy_truncate_heap(Relation onerel, LVRelStats *vacrelstats)
 
 		ereport(elevel,
 				(errmsg("\"%s\": truncated %u to %u pages",
-						vacrelstats->relname,
+						vacrelstats->errinfo.relname,
 						old_rel_pages, new_rel_pages),
 				 errdetail_internal("%s",
 									pg_rusage_show(&ru0))));
@@ -2720,7 +2736,7 @@ count_nondeletable_pages(Relation onerel, LVRelStats *vacrelstats)
 				{
 					ereport(elevel,
 							(errmsg("\"%s\": suspending truncate due to conflicting lock request",
-									vacrelstats->relname)));
+									vacrelstats->errinfo.relname)));
 
 					vacrelstats->lock_waiter_detected = true;
 					return blkno;
@@ -3513,13 +3529,13 @@ parallel_vacuum_main(dsm_segment *seg, shm_toc *toc)
 	 * Initialize vacrelstats for use as error callback arg by parallel
 	 * worker.
 	 */
-	vacrelstats.relnamespace = get_namespace_name(RelationGetNamespace(onerel));
-	vacrelstats.relname = pstrdup(RelationGetRelationName(onerel));
-	vacrelstats.phase = VACUUM_ERRCB_PHASE_UNKNOWN; /* Not yet processing */
+	vacrelstats.errinfo.relnamespace = get_namespace_name(RelationGetNamespace(onerel));
+	vacrelstats.errinfo.relname = pstrdup(RelationGetRelationName(onerel));
+	vacrelstats.errinfo.phase = VACUUM_ERRCB_PHASE_UNKNOWN; /* Not yet processing */
 
 	/* Setup error traceback support for ereport() */
 	errcallback.callback = vacuum_error_callback;
-	errcallback.arg = &vacrelstats;
+	errcallback.arg = &vacrelstats.errinfo;
 	errcallback.previous = error_context_stack;
 	error_context_stack = &errcallback;
 
@@ -3550,7 +3566,7 @@ parallel_vacuum_main(dsm_segment *seg, shm_toc *toc)
 static void
 vacuum_error_callback(void *arg)
 {
-	LVRelStats *errinfo = arg;
+	LVSavedPosition *errinfo = arg;
 
 	switch (errinfo->phase)
 	{
@@ -3591,7 +3607,7 @@ vacuum_error_callback(void *arg)
 
 /* Update vacuum error callback for the current phase and block. */
 static void
-update_vacuum_error_info(LVRelStats *errinfo, int phase, BlockNumber blkno)
+update_vacuum_error_info(LVSavedPosition *errinfo, int phase, BlockNumber blkno)
 {
 	errinfo->blkno = blkno;
 	errinfo->phase = phase;
-- 
2.17.0

From 5e15b14c39fcbf9fce1599d0583f1aa568986e43 Mon Sep 17 00:00:00 2001
From: Justin Pryzby <pryzbyj@telsasoft.com>
Date: Mon, 22 Jun 2020 17:13:39 -0500
Subject: [PATCH v2 5/5] Update functions to pass only errinfo struct..

..this is a more complete change, and probably a good idea since parallel
workers have an partially-populated LVRelStats, and it's better to avoid the
idea that it's usable (dead_tuples in particular is a bogus pointer).
---
 src/backend/access/heap/vacuumlazy.c | 64 ++++++++++++++--------------
 1 file changed, 32 insertions(+), 32 deletions(-)

diff --git a/src/backend/access/heap/vacuumlazy.c b/src/backend/access/heap/vacuumlazy.c
index 9eb4bc66ae..d239ad4d62 100644
--- a/src/backend/access/heap/vacuumlazy.c
+++ b/src/backend/access/heap/vacuumlazy.c
@@ -344,10 +344,10 @@ static void lazy_vacuum_all_indexes(Relation onerel, Relation *Irel,
 									LVRelStats *vacrelstats, LVParallelState *lps,
 									int nindexes);
 static void lazy_vacuum_index(Relation indrel, IndexBulkDeleteResult **stats,
-							  LVDeadTuples *dead_tuples, double reltuples, LVRelStats *vacrelstats);
+							  LVDeadTuples *dead_tuples, double reltuples, LVSavedPosition *errinfo);
 static void lazy_cleanup_index(Relation indrel,
 							   IndexBulkDeleteResult **stats,
-							   double reltuples, bool estimated_count, LVRelStats *vacrelstats);
+							   double reltuples, bool estimated_count, LVSavedPosition *errinfo);
 static int	lazy_vacuum_page(Relation onerel, BlockNumber blkno, Buffer buffer,
 							 int tupindex, LVRelStats *vacrelstats, Buffer *vmbuffer);
 static bool should_attempt_truncation(VacuumParams *params,
@@ -367,13 +367,13 @@ static void lazy_parallel_vacuum_indexes(Relation *Irel, IndexBulkDeleteResult *
 										 int nindexes);
 static void parallel_vacuum_index(Relation *Irel, IndexBulkDeleteResult **stats,
 								  LVShared *lvshared, LVDeadTuples *dead_tuples,
-								  int nindexes, LVRelStats *vacrelstats);
+								  int nindexes, LVSavedPosition *errinfo);
 static void vacuum_indexes_leader(Relation *Irel, IndexBulkDeleteResult **stats,
 								  LVRelStats *vacrelstats, LVParallelState *lps,
 								  int nindexes);
 static void vacuum_one_index(Relation indrel, IndexBulkDeleteResult **stats,
 							 LVShared *lvshared, LVSharedIndStats *shared_indstats,
-							 LVDeadTuples *dead_tuples, LVRelStats *vacrelstats);
+							 LVDeadTuples *dead_tuples, LVSavedPosition *errinfo);
 static void lazy_cleanup_all_indexes(Relation *Irel, IndexBulkDeleteResult **stats,
 									 LVRelStats *vacrelstats, LVParallelState *lps,
 									 int nindexes);
@@ -1797,7 +1797,7 @@ lazy_vacuum_all_indexes(Relation onerel, Relation *Irel,
 
 		for (idx = 0; idx < nindexes; idx++)
 			lazy_vacuum_index(Irel[idx], &stats[idx], vacrelstats->dead_tuples,
-							  vacrelstats->old_live_tuples, vacrelstats);
+							  vacrelstats->old_live_tuples, &vacrelstats->errinfo);
 	}
 
 	/* Increase and report the number of index scans */
@@ -2160,7 +2160,7 @@ lazy_parallel_vacuum_indexes(Relation *Irel, IndexBulkDeleteResult **stats,
 	 * indexes in the case where no workers are launched.
 	 */
 	parallel_vacuum_index(Irel, stats, lps->lvshared,
-						  vacrelstats->dead_tuples, nindexes, vacrelstats);
+						  vacrelstats->dead_tuples, nindexes, &vacrelstats->errinfo);
 
 	/*
 	 * Next, accumulate buffer and WAL usage.  (This must wait for the workers
@@ -2195,7 +2195,7 @@ lazy_parallel_vacuum_indexes(Relation *Irel, IndexBulkDeleteResult **stats,
 static void
 parallel_vacuum_index(Relation *Irel, IndexBulkDeleteResult **stats,
 					  LVShared *lvshared, LVDeadTuples *dead_tuples,
-					  int nindexes, LVRelStats *vacrelstats)
+					  int nindexes, LVSavedPosition	*errinfo)
 {
 	/*
 	 * Increment the active worker count if we are able to launch any worker.
@@ -2229,7 +2229,7 @@ parallel_vacuum_index(Relation *Irel, IndexBulkDeleteResult **stats,
 
 		/* Do vacuum or cleanup of the index */
 		vacuum_one_index(Irel[idx], &(stats[idx]), lvshared, shared_indstats,
-						 dead_tuples, vacrelstats);
+						 dead_tuples, errinfo);
 	}
 
 	/*
@@ -2270,7 +2270,7 @@ vacuum_indexes_leader(Relation *Irel, IndexBulkDeleteResult **stats,
 			skip_parallel_vacuum_index(Irel[i], lps->lvshared))
 			vacuum_one_index(Irel[i], &(stats[i]), lps->lvshared,
 							 shared_indstats, vacrelstats->dead_tuples,
-							 vacrelstats);
+							 &vacrelstats->errinfo);
 	}
 
 	/*
@@ -2290,7 +2290,7 @@ vacuum_indexes_leader(Relation *Irel, IndexBulkDeleteResult **stats,
 static void
 vacuum_one_index(Relation indrel, IndexBulkDeleteResult **stats,
 				 LVShared *lvshared, LVSharedIndStats *shared_indstats,
-				 LVDeadTuples *dead_tuples, LVRelStats *vacrelstats)
+				 LVDeadTuples *dead_tuples, LVSavedPosition *errinfo)
 {
 	IndexBulkDeleteResult *bulkdelete_res = NULL;
 
@@ -2310,10 +2310,10 @@ vacuum_one_index(Relation indrel, IndexBulkDeleteResult **stats,
 	/* Do vacuum or cleanup of the index */
 	if (lvshared->for_cleanup)
 		lazy_cleanup_index(indrel, stats, lvshared->reltuples,
-						   lvshared->estimated_count, vacrelstats);
+						   lvshared->estimated_count, errinfo);
 	else
 		lazy_vacuum_index(indrel, stats, dead_tuples,
-						  lvshared->reltuples, vacrelstats);
+						  lvshared->reltuples, errinfo);
 
 	/*
 	 * Copy the index bulk-deletion result returned from ambulkdelete and
@@ -2389,7 +2389,7 @@ lazy_cleanup_all_indexes(Relation *Irel, IndexBulkDeleteResult **stats,
 			lazy_cleanup_index(Irel[idx], &stats[idx],
 							   vacrelstats->new_rel_tuples,
 							   vacrelstats->tupcount_pages < vacrelstats->rel_pages,
-							   vacrelstats);
+							   &vacrelstats->errinfo);
 	}
 }
 
@@ -2404,7 +2404,7 @@ lazy_cleanup_all_indexes(Relation *Irel, IndexBulkDeleteResult **stats,
  */
 static void
 lazy_vacuum_index(Relation indrel, IndexBulkDeleteResult **stats,
-				  LVDeadTuples *dead_tuples, double reltuples, LVRelStats *vacrelstats)
+				  LVDeadTuples *dead_tuples, double reltuples, LVSavedPosition *errinfo)
 {
 	IndexVacuumInfo ivinfo;
 	const char *msg;
@@ -2422,10 +2422,10 @@ lazy_vacuum_index(Relation indrel, IndexBulkDeleteResult **stats,
 	ivinfo.strategy = vac_strategy;
 
 	/* Update error traceback information */
-	olderrinfo = vacrelstats->errinfo;
+	olderrinfo = *errinfo;
 	/* The index name is also saved during this phase */
-	vacrelstats->errinfo.indname = pstrdup(RelationGetRelationName(indrel));
-	update_vacuum_error_info(&vacrelstats->errinfo,
+	errinfo->indname = pstrdup(RelationGetRelationName(indrel));
+	update_vacuum_error_info(errinfo,
 							 VACUUM_ERRCB_PHASE_VACUUM_INDEX,
 							 InvalidBlockNumber);
 
@@ -2440,15 +2440,15 @@ lazy_vacuum_index(Relation indrel, IndexBulkDeleteResult **stats,
 
 	ereport(elevel,
 			(errmsg(msg,
-					vacrelstats->errinfo.indname,
+					errinfo->indname,
 					dead_tuples->num_tuples),
 			 errdetail_internal("%s", pg_rusage_show(&ru0))));
 
 	/* Revert to the previous phase information for error traceback */
-	update_vacuum_error_info(&vacrelstats->errinfo,
+	update_vacuum_error_info(errinfo,
 							 olderrinfo.phase,
 							 olderrinfo.blkno);
-	pfree(vacrelstats->errinfo.indname);
+	pfree(errinfo->indname);
 }
 
 /*
@@ -2460,7 +2460,7 @@ lazy_vacuum_index(Relation indrel, IndexBulkDeleteResult **stats,
 static void
 lazy_cleanup_index(Relation indrel,
 				   IndexBulkDeleteResult **stats,
-				   double reltuples, bool estimated_count, LVRelStats *vacrelstats)
+				   double reltuples, bool estimated_count, LVSavedPosition *errinfo)
 {
 	IndexVacuumInfo ivinfo;
 	const char *msg;
@@ -2479,20 +2479,20 @@ lazy_cleanup_index(Relation indrel,
 	ivinfo.strategy = vac_strategy;
 
 	/* Update error traceback information */
-	olderrinfo = vacrelstats->errinfo;
+	olderrinfo = *errinfo;
 	/* The index name is also saved during this phase */
-	vacrelstats->errinfo.indname = pstrdup(RelationGetRelationName(indrel));
-	update_vacuum_error_info(&vacrelstats->errinfo,
+	errinfo->indname = pstrdup(RelationGetRelationName(indrel));
+	update_vacuum_error_info(errinfo,
 							 VACUUM_ERRCB_PHASE_INDEX_CLEANUP,
 							 InvalidBlockNumber);
 
 	*stats = index_vacuum_cleanup(&ivinfo, *stats);
 
 	/* Revert back to the old phase information for error traceback */
-	update_vacuum_error_info(&vacrelstats->errinfo,
+	update_vacuum_error_info(errinfo,
 							 olderrinfo.phase,
 							 olderrinfo.blkno);
-	pfree(vacrelstats->errinfo.indname);
+	pfree(errinfo->indname);
 
 	if (!(*stats))
 		return;
@@ -3474,7 +3474,7 @@ parallel_vacuum_main(dsm_segment *seg, shm_toc *toc)
 	int			nindexes;
 	char	   *sharedquery;
 	IndexBulkDeleteResult **stats;
-	LVRelStats	vacrelstats;
+	LVSavedPosition errinfo;
 	ErrorContextCallback errcallback;
 
 	lvshared = (LVShared *) shm_toc_lookup(toc, PARALLEL_VACUUM_KEY_SHARED,
@@ -3529,13 +3529,13 @@ parallel_vacuum_main(dsm_segment *seg, shm_toc *toc)
 	 * Initialize vacrelstats for use as error callback arg by parallel
 	 * worker.
 	 */
-	vacrelstats.errinfo.relnamespace = get_namespace_name(RelationGetNamespace(onerel));
-	vacrelstats.errinfo.relname = pstrdup(RelationGetRelationName(onerel));
-	vacrelstats.errinfo.phase = VACUUM_ERRCB_PHASE_UNKNOWN; /* Not yet processing */
+	errinfo.relnamespace = get_namespace_name(RelationGetNamespace(onerel));
+	errinfo.relname = pstrdup(RelationGetRelationName(onerel));
+	errinfo.phase = VACUUM_ERRCB_PHASE_UNKNOWN; /* Not yet processing */
 
 	/* Setup error traceback support for ereport() */
 	errcallback.callback = vacuum_error_callback;
-	errcallback.arg = &vacrelstats.errinfo;
+	errcallback.arg = &errinfo;
 	errcallback.previous = error_context_stack;
 	error_context_stack = &errcallback;
 
@@ -3544,7 +3544,7 @@ parallel_vacuum_main(dsm_segment *seg, shm_toc *toc)
 
 	/* Process indexes to perform vacuum/cleanup */
 	parallel_vacuum_index(indrels, stats, lvshared, dead_tuples, nindexes,
-						  &vacrelstats);
+						  &errinfo);
 
 	/* Report buffer/WAL usage during parallel execution */
 	buffer_usage = shm_toc_lookup(toc, PARALLEL_VACUUM_KEY_BUFFER_USAGE, false);
-- 
2.17.0

diff --git i/src/backend/access/heap/vacuumlazy.c w/src/backend/access/heap/vacuumlazy.c
index 3bef0e124ba..afd6128233b 100644
--- i/src/backend/access/heap/vacuumlazy.c
+++ w/src/backend/access/heap/vacuumlazy.c
@@ -319,6 +319,12 @@ typedef struct LVRelStats
 	VacErrPhase phase;
 } LVRelStats;
 
+typedef struct LVSavedPos
+{
+	BlockNumber blkno;
+	VacErrPhase phase;
+} LVSavedPos;
+
 /* A few variables that don't seem worth passing around as parameters */
 static int	elevel = -1;
 
@@ -388,9 +394,9 @@ static void end_parallel_vacuum(Relation *Irel, IndexBulkDeleteResult **stats,
 static LVSharedIndStats *get_indstats(LVShared *lvshared, int n);
 static bool skip_parallel_vacuum_index(Relation indrel, LVShared *lvshared);
 static void vacuum_error_callback(void *arg);
-static void update_vacuum_error_info(LVRelStats *errinfo, int phase,
-									 BlockNumber blkno, char *indname);
-
+static void update_vacuum_error_info(LVRelStats *errinfo, LVSavedPos *oldpos,
+										   int phase, BlockNumber blkno, char *indname);
+static void restore_vacuum_error_info(LVRelStats *errinfo, const LVSavedPos *oldpos);
 
 /*
  *	heap_vacuum_rel() -- perform VACUUM for one heap relation
@@ -538,7 +544,8 @@ heap_vacuum_rel(Relation onerel, VacuumParams *params,
 		 * which we add context information to errors, so we don't need to
 		 * revert to the previous phase.
 		 */
-		update_vacuum_error_info(vacrelstats, VACUUM_ERRCB_PHASE_TRUNCATE,
+		update_vacuum_error_info(vacrelstats, NULL,
+								 VACUUM_ERRCB_PHASE_TRUNCATE,
 								 vacrelstats->nonempty_pages, NULL);
 		lazy_truncate_heap(onerel, vacrelstats);
 	}
@@ -948,8 +955,8 @@ lazy_scan_heap(Relation onerel, VacuumParams *params, LVRelStats *vacrelstats,
 
 		pgstat_progress_update_param(PROGRESS_VACUUM_HEAP_BLKS_SCANNED, blkno);
 
-		update_vacuum_error_info(vacrelstats, VACUUM_ERRCB_PHASE_SCAN_HEAP,
-								 blkno, NULL);
+		update_vacuum_error_info(vacrelstats, NULL,
+								 VACUUM_ERRCB_PHASE_SCAN_HEAP, blkno, NULL);
 
 		if (blkno == next_unskippable_block)
 		{
@@ -1820,15 +1827,14 @@ lazy_vacuum_heap(Relation onerel, LVRelStats *vacrelstats)
 	int			npages;
 	PGRUsage	ru0;
 	Buffer		vmbuffer = InvalidBuffer;
-	LVRelStats	olderrinfo;
+	LVSavedPos	oldpos;
 
 	/* Report that we are now vacuuming the heap */
 	pgstat_progress_update_param(PROGRESS_VACUUM_PHASE,
 								 PROGRESS_VACUUM_PHASE_VACUUM_HEAP);
 
 	/* Update error traceback information */
-	olderrinfo = *vacrelstats;
-	update_vacuum_error_info(vacrelstats, VACUUM_ERRCB_PHASE_VACUUM_HEAP,
+	update_vacuum_error_info(vacrelstats, &oldpos, VACUUM_ERRCB_PHASE_VACUUM_HEAP,
 							 InvalidBlockNumber, NULL);
 
 	pg_rusage_init(&ru0);
@@ -1879,10 +1885,7 @@ lazy_vacuum_heap(Relation onerel, LVRelStats *vacrelstats)
 			 errdetail_internal("%s", pg_rusage_show(&ru0))));
 
 	/* Revert to the previous phase information for error traceback */
-	update_vacuum_error_info(vacrelstats,
-							 olderrinfo.phase,
-							 olderrinfo.blkno,
-							 olderrinfo.indname);
+	restore_vacuum_error_info(vacrelstats, &oldpos);
 }
 
 /*
@@ -1905,14 +1908,13 @@ lazy_vacuum_page(Relation onerel, BlockNumber blkno, Buffer buffer,
 	int			uncnt = 0;
 	TransactionId visibility_cutoff_xid;
 	bool		all_frozen;
-	LVRelStats	olderrinfo;
+	LVSavedPos	oldpos;
 
 	pgstat_progress_update_param(PROGRESS_VACUUM_HEAP_BLKS_VACUUMED, blkno);
 
 	/* Update error traceback information */
-	olderrinfo = *vacrelstats;
-	update_vacuum_error_info(vacrelstats, VACUUM_ERRCB_PHASE_VACUUM_HEAP,
-							 blkno, NULL);
+	update_vacuum_error_info(vacrelstats, &oldpos,
+							 VACUUM_ERRCB_PHASE_VACUUM_HEAP, blkno, NULL);
 
 	START_CRIT_SECTION();
 
@@ -1991,10 +1993,7 @@ lazy_vacuum_page(Relation onerel, BlockNumber blkno, Buffer buffer,
 	}
 
 	/* Revert to the previous phase information for error traceback */
-	update_vacuum_error_info(vacrelstats,
-							 olderrinfo.phase,
-							 olderrinfo.blkno,
-							 olderrinfo.indname);
+	restore_vacuum_error_info(vacrelstats, &oldpos);
 	return tupindex;
 }
 
@@ -2404,7 +2403,7 @@ lazy_vacuum_index(Relation indrel, IndexBulkDeleteResult **stats,
 	IndexVacuumInfo ivinfo;
 	const char *msg;
 	PGRUsage	ru0;
-	LVRelStats	olderrinfo;
+	LVSavedPos	oldpos;
 
 	pg_rusage_init(&ru0);
 
@@ -2417,8 +2416,7 @@ lazy_vacuum_index(Relation indrel, IndexBulkDeleteResult **stats,
 	ivinfo.strategy = vac_strategy;
 
 	/* Update error traceback information */
-	olderrinfo = *vacrelstats;
-	update_vacuum_error_info(vacrelstats,
+	update_vacuum_error_info(vacrelstats, &oldpos,
 							 VACUUM_ERRCB_PHASE_VACUUM_INDEX,
 							 InvalidBlockNumber,
 							 RelationGetRelationName(indrel));
@@ -2439,10 +2437,7 @@ lazy_vacuum_index(Relation indrel, IndexBulkDeleteResult **stats,
 			 errdetail_internal("%s", pg_rusage_show(&ru0))));
 
 	/* Revert to the previous phase information for error traceback */
-	update_vacuum_error_info(vacrelstats,
-							 olderrinfo.phase,
-							 olderrinfo.blkno,
-							 olderrinfo.indname);
+	restore_vacuum_error_info(vacrelstats, &oldpos);
 }
 
 /*
@@ -2459,7 +2454,7 @@ lazy_cleanup_index(Relation indrel,
 	IndexVacuumInfo ivinfo;
 	const char *msg;
 	PGRUsage	ru0;
-	LVRelStats	olderrcbarg;
+	LVSavedPos	oldpos;
 
 	pg_rusage_init(&ru0);
 
@@ -2473,8 +2468,7 @@ lazy_cleanup_index(Relation indrel,
 	ivinfo.strategy = vac_strategy;
 
 	/* Update error traceback information */
-	olderrcbarg = *vacrelstats;
-	update_vacuum_error_info(vacrelstats,
+	update_vacuum_error_info(vacrelstats, &oldpos,
 							 VACUUM_ERRCB_PHASE_INDEX_CLEANUP,
 							 InvalidBlockNumber,
 							 RelationGetRelationName(indrel));
@@ -2482,10 +2476,8 @@ lazy_cleanup_index(Relation indrel,
 	*stats = index_vacuum_cleanup(&ivinfo, *stats);
 
 	/* Revert back to the old phase information for error traceback */
-	update_vacuum_error_info(vacrelstats,
-							 olderrcbarg.phase,
-							 olderrcbarg.blkno,
-							 olderrcbarg.indname);
+	restore_vacuum_error_info(vacrelstats, &oldpos);
+
 	if (!(*stats))
 		return;
 
@@ -3600,9 +3592,15 @@ vacuum_error_callback(void *arg)
 
 /* Update vacuum error callback for the current phase, block, and index. */
 static void
-update_vacuum_error_info(LVRelStats *errinfo, int phase, BlockNumber blkno,
-						 char *indname)
+update_vacuum_error_info(LVRelStats *errinfo, LVSavedPos *oldpos,
+						 int phase, BlockNumber blkno, char *indname)
 {
+	if (oldpos)
+	{
+		oldpos->blkno = errinfo->blkno;
+		oldpos->phase = errinfo->phase;
+	}
+
 	errinfo->blkno = blkno;
 	errinfo->phase = phase;
 
@@ -3613,3 +3611,17 @@ update_vacuum_error_info(LVRelStats *errinfo, int phase, BlockNumber blkno,
 	/* For index phases, save the name of the current index for the callback */
 	errinfo->indname = indname ? pstrdup(indname) : NULL;
 }
+
+static void
+restore_vacuum_error_info(LVRelStats *errinfo, const LVSavedPos *oldpos)
+{
+	errinfo->blkno = oldpos->blkno;
+	errinfo->phase = oldpos->phase;
+
+	/* FIXME: Imo pretty ugly that we don't restore the name properly */
+	if (errinfo->indname)
+	{
+		pfree(errinfo->indname);
+		errinfo->indname = NULL;
+	}
+}

diff --git a/src/backend/access/heap/vacuumlazy.c b/src/backend/access/heap/vacuumlazy.c
index 3bef0e1..58bc3df 100644
--- a/src/backend/access/heap/vacuumlazy.c
+++ b/src/backend/access/heap/vacuumlazy.c
@@ -389,7 +389,7 @@ static LVSharedIndStats *get_indstats(LVShared *lvshared, int n);
 static bool skip_parallel_vacuum_index(Relation indrel, LVShared *lvshared);
 static void vacuum_error_callback(void *arg);
 static void update_vacuum_error_info(LVRelStats *errinfo, int phase,
-									 BlockNumber blkno, char *indname);
+									 BlockNumber blkno);
 
 
 /*
@@ -539,7 +539,7 @@ heap_vacuum_rel(Relation onerel, VacuumParams *params,
 		 * revert to the previous phase.
 		 */
 		update_vacuum_error_info(vacrelstats, VACUUM_ERRCB_PHASE_TRUNCATE,
-								 vacrelstats->nonempty_pages, NULL);
+								 vacrelstats->nonempty_pages);
 		lazy_truncate_heap(onerel, vacrelstats);
 	}
 
@@ -949,7 +949,7 @@ lazy_scan_heap(Relation onerel, VacuumParams *params, LVRelStats *vacrelstats,
 		pgstat_progress_update_param(PROGRESS_VACUUM_HEAP_BLKS_SCANNED, blkno);
 
 		update_vacuum_error_info(vacrelstats, VACUUM_ERRCB_PHASE_SCAN_HEAP,
-								 blkno, NULL);
+								 blkno);
 
 		if (blkno == next_unskippable_block)
 		{
@@ -1829,7 +1829,7 @@ lazy_vacuum_heap(Relation onerel, LVRelStats *vacrelstats)
 	/* Update error traceback information */
 	olderrinfo = *vacrelstats;
 	update_vacuum_error_info(vacrelstats, VACUUM_ERRCB_PHASE_VACUUM_HEAP,
-							 InvalidBlockNumber, NULL);
+							 InvalidBlockNumber);
 
 	pg_rusage_init(&ru0);
 	npages = 0;
@@ -1881,8 +1881,7 @@ lazy_vacuum_heap(Relation onerel, LVRelStats *vacrelstats)
 	/* Revert to the previous phase information for error traceback */
 	update_vacuum_error_info(vacrelstats,
 							 olderrinfo.phase,
-							 olderrinfo.blkno,
-							 olderrinfo.indname);
+							 olderrinfo.blkno);
 }
 
 /*
@@ -1912,7 +1911,7 @@ lazy_vacuum_page(Relation onerel, BlockNumber blkno, Buffer buffer,
 	/* Update error traceback information */
 	olderrinfo = *vacrelstats;
 	update_vacuum_error_info(vacrelstats, VACUUM_ERRCB_PHASE_VACUUM_HEAP,
-							 blkno, NULL);
+							 blkno);
 
 	START_CRIT_SECTION();
 
@@ -1993,8 +1992,7 @@ lazy_vacuum_page(Relation onerel, BlockNumber blkno, Buffer buffer,
 	/* Revert to the previous phase information for error traceback */
 	update_vacuum_error_info(vacrelstats,
 							 olderrinfo.phase,
-							 olderrinfo.blkno,
-							 olderrinfo.indname);
+							 olderrinfo.blkno);
 	return tupindex;
 }
 
@@ -2418,10 +2416,16 @@ lazy_vacuum_index(Relation indrel, IndexBulkDeleteResult **stats,
 
 	/* Update error traceback information */
 	olderrinfo = *vacrelstats;
+
+	/*
+	 * The index name is saved only during this phase and restored immediately
+	 * after this phase.  See vacuum_error_callback.
+	 */
+	Assert(vacrelstats->indname == NULL);
+	vacrelstats->indname = pstrdup(RelationGetRelationName(indrel));
 	update_vacuum_error_info(vacrelstats,
 							 VACUUM_ERRCB_PHASE_VACUUM_INDEX,
-							 InvalidBlockNumber,
-							 RelationGetRelationName(indrel));
+							 InvalidBlockNumber);
 
 	/* Do bulk deletion */
 	*stats = index_bulk_delete(&ivinfo, *stats,
@@ -2441,8 +2445,9 @@ lazy_vacuum_index(Relation indrel, IndexBulkDeleteResult **stats,
 	/* Revert to the previous phase information for error traceback */
 	update_vacuum_error_info(vacrelstats,
 							 olderrinfo.phase,
-							 olderrinfo.blkno,
-							 olderrinfo.indname);
+							 olderrinfo.blkno);
+	pfree(vacrelstats->indname);
+	vacrelstats->indname = NULL;
 }
 
 /*
@@ -2474,18 +2479,26 @@ lazy_cleanup_index(Relation indrel,
 
 	/* Update error traceback information */
 	olderrcbarg = *vacrelstats;
+
+	/*
+	 * The index name is saved only during this phase and restored immediately
+	 * after this phase.  See vacuum_error_callback.
+	 */
+	Assert(vacrelstats->indname == NULL);
+	vacrelstats->indname = pstrdup(RelationGetRelationName(indrel));
 	update_vacuum_error_info(vacrelstats,
 							 VACUUM_ERRCB_PHASE_INDEX_CLEANUP,
-							 InvalidBlockNumber,
-							 RelationGetRelationName(indrel));
+							 InvalidBlockNumber);
 
 	*stats = index_vacuum_cleanup(&ivinfo, *stats);
 
 	/* Revert back to the old phase information for error traceback */
 	update_vacuum_error_info(vacrelstats,
 							 olderrcbarg.phase,
-							 olderrcbarg.blkno,
-							 olderrcbarg.indname);
+							 olderrcbarg.blkno);
+	pfree(vacrelstats->indname);
+	vacrelstats->indname = NULL;
+
 	if (!(*stats))
 		return;
 
@@ -3598,18 +3611,10 @@ vacuum_error_callback(void *arg)
 	}
 }
 
-/* Update vacuum error callback for the current phase, block, and index. */
+/* Update vacuum error callback for the current phase and block. */
 static void
-update_vacuum_error_info(LVRelStats *errinfo, int phase, BlockNumber blkno,
-						 char *indname)
+update_vacuum_error_info(LVRelStats *errinfo, int phase, BlockNumber blkno)
 {
 	errinfo->blkno = blkno;
 	errinfo->phase = phase;
-
-	/* Free index name from any previous phase */
-	if (errinfo->indname)
-		pfree(errinfo->indname);
-
-	/* For index phases, save the name of the current index for the callback */
-	errinfo->indname = indname ? pstrdup(indname) : NULL;
 }

diff --git a/src/backend/access/heap/vacuumlazy.c b/src/backend/access/heap/vacuumlazy.c
index 58bc3df..39a0fdb 100644
--- a/src/backend/access/heap/vacuumlazy.c
+++ b/src/backend/access/heap/vacuumlazy.c
@@ -319,6 +319,13 @@ typedef struct LVRelStats
 	VacErrPhase phase;
 } LVRelStats;
 
+/* Struct for saving and restoring vacuum error information. */
+typedef struct LVSavedErrInfo
+{
+	BlockNumber blkno;
+	VacErrPhase phase;
+} LVSavedErrInfo;
+
 /* A few variables that don't seem worth passing around as parameters */
 static int	elevel = -1;
 
@@ -388,8 +395,9 @@ static void end_parallel_vacuum(Relation *Irel, IndexBulkDeleteResult **stats,
 static LVSharedIndStats *get_indstats(LVShared *lvshared, int n);
 static bool skip_parallel_vacuum_index(Relation indrel, LVShared *lvshared);
 static void vacuum_error_callback(void *arg);
-static void update_vacuum_error_info(LVRelStats *errinfo, int phase,
-									 BlockNumber blkno);
+static void update_vacuum_error_info(LVRelStats *errinfo, LVSavedErrInfo *oldpos,
+									 int phase, BlockNumber blkno);
+static void restore_vacuum_error_info(LVRelStats *errinfo, const LVSavedErrInfo *oldpos);
 
 
 /*
@@ -538,7 +546,7 @@ heap_vacuum_rel(Relation onerel, VacuumParams *params,
 		 * which we add context information to errors, so we don't need to
 		 * revert to the previous phase.
 		 */
-		update_vacuum_error_info(vacrelstats, VACUUM_ERRCB_PHASE_TRUNCATE,
+		update_vacuum_error_info(vacrelstats, NULL, VACUUM_ERRCB_PHASE_TRUNCATE,
 								 vacrelstats->nonempty_pages);
 		lazy_truncate_heap(onerel, vacrelstats);
 	}
@@ -948,7 +956,7 @@ lazy_scan_heap(Relation onerel, VacuumParams *params, LVRelStats *vacrelstats,
 
 		pgstat_progress_update_param(PROGRESS_VACUUM_HEAP_BLKS_SCANNED, blkno);
 
-		update_vacuum_error_info(vacrelstats, VACUUM_ERRCB_PHASE_SCAN_HEAP,
+		update_vacuum_error_info(vacrelstats, NULL, VACUUM_ERRCB_PHASE_SCAN_HEAP,
 								 blkno);
 
 		if (blkno == next_unskippable_block)
@@ -1820,15 +1828,14 @@ lazy_vacuum_heap(Relation onerel, LVRelStats *vacrelstats)
 	int			npages;
 	PGRUsage	ru0;
 	Buffer		vmbuffer = InvalidBuffer;
-	LVRelStats	olderrinfo;
+	LVSavedErrInfo oldpos;
 
 	/* Report that we are now vacuuming the heap */
 	pgstat_progress_update_param(PROGRESS_VACUUM_PHASE,
 								 PROGRESS_VACUUM_PHASE_VACUUM_HEAP);
 
 	/* Update error traceback information */
-	olderrinfo = *vacrelstats;
-	update_vacuum_error_info(vacrelstats, VACUUM_ERRCB_PHASE_VACUUM_HEAP,
+	update_vacuum_error_info(vacrelstats, &oldpos, VACUUM_ERRCB_PHASE_VACUUM_HEAP,
 							 InvalidBlockNumber);
 
 	pg_rusage_init(&ru0);
@@ -1879,9 +1886,7 @@ lazy_vacuum_heap(Relation onerel, LVRelStats *vacrelstats)
 			 errdetail_internal("%s", pg_rusage_show(&ru0))));
 
 	/* Revert to the previous phase information for error traceback */
-	update_vacuum_error_info(vacrelstats,
-							 olderrinfo.phase,
-							 olderrinfo.blkno);
+	restore_vacuum_error_info(vacrelstats, &oldpos);
 }
 
 /*
@@ -1904,13 +1909,12 @@ lazy_vacuum_page(Relation onerel, BlockNumber blkno, Buffer buffer,
 	int			uncnt = 0;
 	TransactionId visibility_cutoff_xid;
 	bool		all_frozen;
-	LVRelStats	olderrinfo;
+	LVSavedErrInfo oldpos;
 
 	pgstat_progress_update_param(PROGRESS_VACUUM_HEAP_BLKS_VACUUMED, blkno);
 
 	/* Update error traceback information */
-	olderrinfo = *vacrelstats;
-	update_vacuum_error_info(vacrelstats, VACUUM_ERRCB_PHASE_VACUUM_HEAP,
+	update_vacuum_error_info(vacrelstats, &oldpos, VACUUM_ERRCB_PHASE_VACUUM_HEAP,
 							 blkno);
 
 	START_CRIT_SECTION();
@@ -1990,9 +1994,7 @@ lazy_vacuum_page(Relation onerel, BlockNumber blkno, Buffer buffer,
 	}
 
 	/* Revert to the previous phase information for error traceback */
-	update_vacuum_error_info(vacrelstats,
-							 olderrinfo.phase,
-							 olderrinfo.blkno);
+	restore_vacuum_error_info(vacrelstats, &oldpos);
 	return tupindex;
 }
 
@@ -2402,7 +2404,7 @@ lazy_vacuum_index(Relation indrel, IndexBulkDeleteResult **stats,
 	IndexVacuumInfo ivinfo;
 	const char *msg;
 	PGRUsage	ru0;
-	LVRelStats	olderrinfo;
+	LVSavedErrInfo oldpos;
 
 	pg_rusage_init(&ru0);
 
@@ -2414,16 +2416,15 @@ lazy_vacuum_index(Relation indrel, IndexBulkDeleteResult **stats,
 	ivinfo.num_heap_tuples = reltuples;
 	ivinfo.strategy = vac_strategy;
 
-	/* Update error traceback information */
-	olderrinfo = *vacrelstats;
-
 	/*
+	 * Update error traceback information.
+	 *
 	 * The index name is saved only during this phase and restored immediately
 	 * after this phase.  See vacuum_error_callback.
 	 */
 	Assert(vacrelstats->indname == NULL);
 	vacrelstats->indname = pstrdup(RelationGetRelationName(indrel));
-	update_vacuum_error_info(vacrelstats,
+	update_vacuum_error_info(vacrelstats, &oldpos,
 							 VACUUM_ERRCB_PHASE_VACUUM_INDEX,
 							 InvalidBlockNumber);
 
@@ -2443,9 +2444,7 @@ lazy_vacuum_index(Relation indrel, IndexBulkDeleteResult **stats,
 			 errdetail_internal("%s", pg_rusage_show(&ru0))));
 
 	/* Revert to the previous phase information for error traceback */
-	update_vacuum_error_info(vacrelstats,
-							 olderrinfo.phase,
-							 olderrinfo.blkno);
+	restore_vacuum_error_info(vacrelstats, &oldpos);
 	pfree(vacrelstats->indname);
 	vacrelstats->indname = NULL;
 }
@@ -2464,7 +2463,7 @@ lazy_cleanup_index(Relation indrel,
 	IndexVacuumInfo ivinfo;
 	const char *msg;
 	PGRUsage	ru0;
-	LVRelStats	olderrcbarg;
+	LVSavedErrInfo oldpos;
 
 	pg_rusage_init(&ru0);
 
@@ -2477,25 +2476,22 @@ lazy_cleanup_index(Relation indrel,
 	ivinfo.num_heap_tuples = reltuples;
 	ivinfo.strategy = vac_strategy;
 
-	/* Update error traceback information */
-	olderrcbarg = *vacrelstats;
-
 	/*
+	 * Update error traceback information.
+	 *
 	 * The index name is saved only during this phase and restored immediately
 	 * after this phase.  See vacuum_error_callback.
 	 */
 	Assert(vacrelstats->indname == NULL);
 	vacrelstats->indname = pstrdup(RelationGetRelationName(indrel));
-	update_vacuum_error_info(vacrelstats,
+	update_vacuum_error_info(vacrelstats, &oldpos,
 							 VACUUM_ERRCB_PHASE_INDEX_CLEANUP,
 							 InvalidBlockNumber);
 
 	*stats = index_vacuum_cleanup(&ivinfo, *stats);
 
 	/* Revert back to the old phase information for error traceback */
-	update_vacuum_error_info(vacrelstats,
-							 olderrcbarg.phase,
-							 olderrcbarg.blkno);
+	restore_vacuum_error_info(vacrelstats, &oldpos);
 	pfree(vacrelstats->indname);
 	vacrelstats->indname = NULL;
 
@@ -3611,10 +3607,30 @@ vacuum_error_callback(void *arg)
 	}
 }
 
-/* Update vacuum error callback for the current phase and block. */
+/*
+ * Updates the information required for vacuum error callback.  This also saves
+ * the current information which can be later restored via restore_vacuum_error_info.
+ */
 static void
-update_vacuum_error_info(LVRelStats *errinfo, int phase, BlockNumber blkno)
+update_vacuum_error_info(LVRelStats *errinfo, LVSavedErrInfo *oldpos, int phase,
+						 BlockNumber blkno)
 {
+	if (oldpos)
+	{
+		oldpos->blkno = errinfo->blkno;
+		oldpos->phase = errinfo->phase;
+	}
+
 	errinfo->blkno = blkno;
 	errinfo->phase = phase;
 }
+
+/*
+ * Restores the vacuum information saved via a prior call to update_vacuum_error_info.
+ */
+static void
+restore_vacuum_error_info(LVRelStats *errinfo, const LVSavedErrInfo *oldpos)
+{
+	errinfo->blkno = oldpos->blkno;
+	errinfo->phase = oldpos->phase;
+}
diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list
index c65a552..7eaaad1 100644
--- a/src/tools/pgindent/typedefs.list
+++ b/src/tools/pgindent/typedefs.list
@@ -1250,6 +1250,7 @@ LUID
 LVDeadTuples
 LVParallelState
 LVRelStats
+LVSavedErrInfo
 LVShared
 LVSharedIndStats
 LWLock

From 89d883387fadb318c3b93b6208acc34cae69111a Mon Sep 17 00:00:00 2001
From: Amit Kapila <akapila@postgresql.org>
Date: Fri, 26 Jun 2020 09:01:38 +0530
Subject: [PATCH] Improve vacuum error context handling.

Use separate functions to save and restore error context information as
that made code easier to understand.  Also, make it clear that the index
information required for error context is sane.

Author: Andres Freund, Justin Pryzby, Amit Kapila
Backpatch-through: 13, where it was introduced
Discussion: https://postgr.es/m/CAA4eK1LWo+v1OWu=Sky27GTGSCuOmr7iaURNbc5xz6jO+SaPeA@mail.gmail.com
---
 src/backend/access/heap/vacuumlazy.c | 123 ++++++++++++++++++++---------------
 src/tools/pgindent/typedefs.list     |   1 +
 2 files changed, 73 insertions(+), 51 deletions(-)

diff --git a/src/backend/access/heap/vacuumlazy.c b/src/backend/access/heap/vacuumlazy.c
index 3bef0e1..68effca 100644
--- a/src/backend/access/heap/vacuumlazy.c
+++ b/src/backend/access/heap/vacuumlazy.c
@@ -319,6 +319,13 @@ typedef struct LVRelStats
 	VacErrPhase phase;
 } LVRelStats;
 
+/* Struct for saving and restoring vacuum error information. */
+typedef struct LVSavedErrInfo
+{
+	BlockNumber blkno;
+	VacErrPhase phase;
+} LVSavedErrInfo;
+
 /* A few variables that don't seem worth passing around as parameters */
 static int	elevel = -1;
 
@@ -388,8 +395,9 @@ static void end_parallel_vacuum(Relation *Irel, IndexBulkDeleteResult **stats,
 static LVSharedIndStats *get_indstats(LVShared *lvshared, int n);
 static bool skip_parallel_vacuum_index(Relation indrel, LVShared *lvshared);
 static void vacuum_error_callback(void *arg);
-static void update_vacuum_error_info(LVRelStats *errinfo, int phase,
-									 BlockNumber blkno, char *indname);
+static void update_vacuum_error_info(LVRelStats *errinfo, LVSavedErrInfo *saved_err_info,
+									 int phase, BlockNumber blkno);
+static void restore_vacuum_error_info(LVRelStats *errinfo, const LVSavedErrInfo *saved_err_info);
 
 
 /*
@@ -538,8 +546,8 @@ heap_vacuum_rel(Relation onerel, VacuumParams *params,
 		 * which we add context information to errors, so we don't need to
 		 * revert to the previous phase.
 		 */
-		update_vacuum_error_info(vacrelstats, VACUUM_ERRCB_PHASE_TRUNCATE,
-								 vacrelstats->nonempty_pages, NULL);
+		update_vacuum_error_info(vacrelstats, NULL, VACUUM_ERRCB_PHASE_TRUNCATE,
+								 vacrelstats->nonempty_pages);
 		lazy_truncate_heap(onerel, vacrelstats);
 	}
 
@@ -948,8 +956,8 @@ lazy_scan_heap(Relation onerel, VacuumParams *params, LVRelStats *vacrelstats,
 
 		pgstat_progress_update_param(PROGRESS_VACUUM_HEAP_BLKS_SCANNED, blkno);
 
-		update_vacuum_error_info(vacrelstats, VACUUM_ERRCB_PHASE_SCAN_HEAP,
-								 blkno, NULL);
+		update_vacuum_error_info(vacrelstats, NULL, VACUUM_ERRCB_PHASE_SCAN_HEAP,
+								 blkno);
 
 		if (blkno == next_unskippable_block)
 		{
@@ -1820,16 +1828,15 @@ lazy_vacuum_heap(Relation onerel, LVRelStats *vacrelstats)
 	int			npages;
 	PGRUsage	ru0;
 	Buffer		vmbuffer = InvalidBuffer;
-	LVRelStats	olderrinfo;
+	LVSavedErrInfo saved_err_info;
 
 	/* Report that we are now vacuuming the heap */
 	pgstat_progress_update_param(PROGRESS_VACUUM_PHASE,
 								 PROGRESS_VACUUM_PHASE_VACUUM_HEAP);
 
 	/* Update error traceback information */
-	olderrinfo = *vacrelstats;
-	update_vacuum_error_info(vacrelstats, VACUUM_ERRCB_PHASE_VACUUM_HEAP,
-							 InvalidBlockNumber, NULL);
+	update_vacuum_error_info(vacrelstats, &saved_err_info, VACUUM_ERRCB_PHASE_VACUUM_HEAP,
+							 InvalidBlockNumber);
 
 	pg_rusage_init(&ru0);
 	npages = 0;
@@ -1879,10 +1886,7 @@ lazy_vacuum_heap(Relation onerel, LVRelStats *vacrelstats)
 			 errdetail_internal("%s", pg_rusage_show(&ru0))));
 
 	/* Revert to the previous phase information for error traceback */
-	update_vacuum_error_info(vacrelstats,
-							 olderrinfo.phase,
-							 olderrinfo.blkno,
-							 olderrinfo.indname);
+	restore_vacuum_error_info(vacrelstats, &saved_err_info);
 }
 
 /*
@@ -1905,14 +1909,13 @@ lazy_vacuum_page(Relation onerel, BlockNumber blkno, Buffer buffer,
 	int			uncnt = 0;
 	TransactionId visibility_cutoff_xid;
 	bool		all_frozen;
-	LVRelStats	olderrinfo;
+	LVSavedErrInfo saved_err_info;
 
 	pgstat_progress_update_param(PROGRESS_VACUUM_HEAP_BLKS_VACUUMED, blkno);
 
 	/* Update error traceback information */
-	olderrinfo = *vacrelstats;
-	update_vacuum_error_info(vacrelstats, VACUUM_ERRCB_PHASE_VACUUM_HEAP,
-							 blkno, NULL);
+	update_vacuum_error_info(vacrelstats, &saved_err_info, VACUUM_ERRCB_PHASE_VACUUM_HEAP,
+							 blkno);
 
 	START_CRIT_SECTION();
 
@@ -1991,10 +1994,7 @@ lazy_vacuum_page(Relation onerel, BlockNumber blkno, Buffer buffer,
 	}
 
 	/* Revert to the previous phase information for error traceback */
-	update_vacuum_error_info(vacrelstats,
-							 olderrinfo.phase,
-							 olderrinfo.blkno,
-							 olderrinfo.indname);
+	restore_vacuum_error_info(vacrelstats, &saved_err_info);
 	return tupindex;
 }
 
@@ -2404,7 +2404,7 @@ lazy_vacuum_index(Relation indrel, IndexBulkDeleteResult **stats,
 	IndexVacuumInfo ivinfo;
 	const char *msg;
 	PGRUsage	ru0;
-	LVRelStats	olderrinfo;
+	LVSavedErrInfo saved_err_info;
 
 	pg_rusage_init(&ru0);
 
@@ -2416,12 +2416,17 @@ lazy_vacuum_index(Relation indrel, IndexBulkDeleteResult **stats,
 	ivinfo.num_heap_tuples = reltuples;
 	ivinfo.strategy = vac_strategy;
 
-	/* Update error traceback information */
-	olderrinfo = *vacrelstats;
-	update_vacuum_error_info(vacrelstats,
+	/*
+	 * Update error traceback information.
+	 *
+	 * The index name is saved during this phase and restored immediately
+	 * after this phase.  See vacuum_error_callback.
+	 */
+	Assert(vacrelstats->indname == NULL);
+	vacrelstats->indname = pstrdup(RelationGetRelationName(indrel));
+	update_vacuum_error_info(vacrelstats, &saved_err_info,
 							 VACUUM_ERRCB_PHASE_VACUUM_INDEX,
-							 InvalidBlockNumber,
-							 RelationGetRelationName(indrel));
+							 InvalidBlockNumber);
 
 	/* Do bulk deletion */
 	*stats = index_bulk_delete(&ivinfo, *stats,
@@ -2439,10 +2444,9 @@ lazy_vacuum_index(Relation indrel, IndexBulkDeleteResult **stats,
 			 errdetail_internal("%s", pg_rusage_show(&ru0))));
 
 	/* Revert to the previous phase information for error traceback */
-	update_vacuum_error_info(vacrelstats,
-							 olderrinfo.phase,
-							 olderrinfo.blkno,
-							 olderrinfo.indname);
+	restore_vacuum_error_info(vacrelstats, &saved_err_info);
+	pfree(vacrelstats->indname);
+	vacrelstats->indname = NULL;
 }
 
 /*
@@ -2459,7 +2463,7 @@ lazy_cleanup_index(Relation indrel,
 	IndexVacuumInfo ivinfo;
 	const char *msg;
 	PGRUsage	ru0;
-	LVRelStats	olderrcbarg;
+	LVSavedErrInfo saved_err_info;
 
 	pg_rusage_init(&ru0);
 
@@ -2472,20 +2476,25 @@ lazy_cleanup_index(Relation indrel,
 	ivinfo.num_heap_tuples = reltuples;
 	ivinfo.strategy = vac_strategy;
 
-	/* Update error traceback information */
-	olderrcbarg = *vacrelstats;
-	update_vacuum_error_info(vacrelstats,
+	/*
+	 * Update error traceback information.
+	 *
+	 * The index name is saved during this phase and restored immediately
+	 * after this phase.  See vacuum_error_callback.
+	 */
+	Assert(vacrelstats->indname == NULL);
+	vacrelstats->indname = pstrdup(RelationGetRelationName(indrel));
+	update_vacuum_error_info(vacrelstats, &saved_err_info,
 							 VACUUM_ERRCB_PHASE_INDEX_CLEANUP,
-							 InvalidBlockNumber,
-							 RelationGetRelationName(indrel));
+							 InvalidBlockNumber);
 
 	*stats = index_vacuum_cleanup(&ivinfo, *stats);
 
 	/* Revert back to the old phase information for error traceback */
-	update_vacuum_error_info(vacrelstats,
-							 olderrcbarg.phase,
-							 olderrcbarg.blkno,
-							 olderrcbarg.indname);
+	restore_vacuum_error_info(vacrelstats, &saved_err_info);
+	pfree(vacrelstats->indname);
+	vacrelstats->indname = NULL;
+
 	if (!(*stats))
 		return;
 
@@ -3598,18 +3607,30 @@ vacuum_error_callback(void *arg)
 	}
 }
 
-/* Update vacuum error callback for the current phase, block, and index. */
+/*
+ * Updates the information required for vacuum error callback.  This also saves
+ * the current information which can be later restored via restore_vacuum_error_info.
+ */
 static void
-update_vacuum_error_info(LVRelStats *errinfo, int phase, BlockNumber blkno,
-						 char *indname)
+update_vacuum_error_info(LVRelStats *errinfo, LVSavedErrInfo *saved_err_info, int phase,
+						 BlockNumber blkno)
 {
+	if (saved_err_info)
+	{
+		saved_err_info->blkno = errinfo->blkno;
+		saved_err_info->phase = errinfo->phase;
+	}
+
 	errinfo->blkno = blkno;
 	errinfo->phase = phase;
+}
 
-	/* Free index name from any previous phase */
-	if (errinfo->indname)
-		pfree(errinfo->indname);
-
-	/* For index phases, save the name of the current index for the callback */
-	errinfo->indname = indname ? pstrdup(indname) : NULL;
+/*
+ * Restores the vacuum information saved via a prior call to update_vacuum_error_info.
+ */
+static void
+restore_vacuum_error_info(LVRelStats *errinfo, const LVSavedErrInfo *saved_err_info)
+{
+	errinfo->blkno = saved_err_info->blkno;
+	errinfo->phase = saved_err_info->phase;
 }
diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list
index c65a552..7eaaad1 100644
--- a/src/tools/pgindent/typedefs.list
+++ b/src/tools/pgindent/typedefs.list
@@ -1250,6 +1250,7 @@ LUID
 LVDeadTuples
 LVParallelState
 LVRelStats
+LVSavedErrInfo
 LVShared
 LVSharedIndStats
 LWLock
-- 
1.8.3.1