commit 3726b6ffdba5461dcbf82cce5de13760a2642468
Author: Konstantin Knizhnik <k.knizhnik@postgrespro.ru>
Date:   Fri Jan 15 12:57:46 2021 +0300

    Increase IOS vm cache.

diff --git a/src/backend/access/heap/visibilitymap.c b/src/backend/access/heap/visibilitymap.c
index e198df65d82..98e249b0c2a 100644
--- a/src/backend/access/heap/visibilitymap.c
+++ b/src/backend/access/heap/visibilitymap.c
@@ -99,24 +99,6 @@
 
 /*#define TRACE_VISIBILITYMAP */
 
-/*
- * Size of the bitmap on each visibility map page, in bytes. There's no
- * extra headers, so the whole page minus the standard page header is
- * used for the bitmap.
- */
-#define MAPSIZE (BLCKSZ - MAXALIGN(SizeOfPageHeaderData))
-
-/* Number of heap blocks we can represent in one byte */
-#define HEAPBLOCKS_PER_BYTE (BITS_PER_BYTE / BITS_PER_HEAPBLOCK)
-
-/* Number of heap blocks we can represent in one visibility map page. */
-#define HEAPBLOCKS_PER_PAGE (MAPSIZE * HEAPBLOCKS_PER_BYTE)
-
-/* Mapping from heap block number to the right bit in the visibility map */
-#define HEAPBLK_TO_MAPBLOCK(x) ((x) / HEAPBLOCKS_PER_PAGE)
-#define HEAPBLK_TO_MAPBYTE(x) (((x) % HEAPBLOCKS_PER_PAGE) / HEAPBLOCKS_PER_BYTE)
-#define HEAPBLK_TO_OFFSET(x) (((x) % HEAPBLOCKS_PER_BYTE) * BITS_PER_HEAPBLOCK)
-
 /* Masks for counting subsets of bits in the visibility map. */
 #define VISIBLE_MASK64	UINT64CONST(0x5555555555555555) /* The lower bit of each
 														 * bit pair */
diff --git a/src/backend/executor/nodeIndexonlyscan.c b/src/backend/executor/nodeIndexonlyscan.c
index 0754e28a9aa..47c6e8929a3 100644
--- a/src/backend/executor/nodeIndexonlyscan.c
+++ b/src/backend/executor/nodeIndexonlyscan.c
@@ -101,7 +101,9 @@ IndexOnlyNext(IndexOnlyScanState *node)
 
 		/* Set it up for index-only scan */
 		node->ioss_ScanDesc->xs_want_itup = true;
-		node->ioss_VMBuffer = InvalidBuffer;
+
+		for (int i = 0; i < VMBUF_SIZE; i++)
+			node->ioss_VMBuffer[i] = InvalidBuffer;
 
 		/*
 		 * If no run-time keys to calculate or they are ready, go ahead and
@@ -121,6 +123,7 @@ IndexOnlyNext(IndexOnlyScanState *node)
 	while ((tid = index_getnext_tid(scandesc, direction)) != NULL)
 	{
 		bool		tuple_from_heap = false;
+		Buffer		*vm_buf;
 
 		CHECK_FOR_INTERRUPTS();
 
@@ -158,9 +161,11 @@ IndexOnlyNext(IndexOnlyScanState *node)
 		 * It's worth going through this complexity to avoid needing to lock
 		 * the VM buffer, which could cause significant contention.
 		 */
+		vm_buf = &node->ioss_VMBuffer[HEAPBLK_TO_MAPBLOCK(
+				ItemPointerGetBlockNumber(tid)) % VMBUF_SIZE];
 		if (!VM_ALL_VISIBLE(scandesc->heapRelation,
 							ItemPointerGetBlockNumber(tid),
-							&node->ioss_VMBuffer))
+							vm_buf))
 		{
 			/*
 			 * Rats, we have to visit the heap to check visibility.
@@ -377,11 +382,14 @@ ExecEndIndexOnlyScan(IndexOnlyScanState *node)
 	indexRelationDesc = node->ioss_RelationDesc;
 	indexScanDesc = node->ioss_ScanDesc;
 
-	/* Release VM buffer pin, if any. */
-	if (node->ioss_VMBuffer != InvalidBuffer)
+	/* Release VM buffer pins, if any. */
+	for (int i = 0; i < VMBUF_SIZE; i++)
 	{
-		ReleaseBuffer(node->ioss_VMBuffer);
-		node->ioss_VMBuffer = InvalidBuffer;
+		if (node->ioss_VMBuffer[i] != InvalidBuffer)
+		{
+			ReleaseBuffer(node->ioss_VMBuffer[i]);
+			node->ioss_VMBuffer[i] = InvalidBuffer;
+		}
 	}
 
 	/*
@@ -680,7 +688,8 @@ ExecIndexOnlyScanInitializeDSM(IndexOnlyScanState *node,
 								 node->ioss_NumOrderByKeys,
 								 piscan);
 	node->ioss_ScanDesc->xs_want_itup = true;
-	node->ioss_VMBuffer = InvalidBuffer;
+	for (int i = 0; i < VMBUF_SIZE; i++)
+		node->ioss_VMBuffer[i] = InvalidBuffer;
 
 	/*
 	 * If no run-time keys to calculate or they are ready, go ahead and pass
diff --git a/src/include/access/visibilitymap.h b/src/include/access/visibilitymap.h
index 57362c36876..0c9bda8de17 100644
--- a/src/include/access/visibilitymap.h
+++ b/src/include/access/visibilitymap.h
@@ -28,6 +28,24 @@
 #define VISIBILITYMAP_VALID_BITS	0x03	/* OR of all valid visibilitymap
 											 * flags bits */
 
+/*
+ * Size of the bitmap on each visibility map page, in bytes. There's no
+ * extra headers, so the whole page minus the standard page header is
+ * used for the bitmap.
+ */
+#define MAPSIZE (BLCKSZ - MAXALIGN(SizeOfPageHeaderData))
+
+/* Number of heap blocks we can represent in one byte */
+#define HEAPBLOCKS_PER_BYTE (BITS_PER_BYTE / BITS_PER_HEAPBLOCK)
+
+/* Number of heap blocks we can represent in one visibility map page. */
+#define HEAPBLOCKS_PER_PAGE (MAPSIZE * HEAPBLOCKS_PER_BYTE)
+
+/* Mapping from heap block number to the right bit in the visibility map */
+#define HEAPBLK_TO_MAPBLOCK(x) ((x) / HEAPBLOCKS_PER_PAGE)
+#define HEAPBLK_TO_MAPBYTE(x) (((x) % HEAPBLOCKS_PER_PAGE) / HEAPBLOCKS_PER_BYTE)
+#define HEAPBLK_TO_OFFSET(x) (((x) % HEAPBLOCKS_PER_BYTE) * BITS_PER_HEAPBLOCK)
+
 /* Macros for visibilitymap test */
 #define VM_ALL_VISIBLE(r, b, v) \
 	((visibilitymap_get_status((r), (b), (v)) & VISIBILITYMAP_ALL_VISIBLE) != 0)
diff --git a/src/include/nodes/execnodes.h b/src/include/nodes/execnodes.h
index e31ad6204e6..15290be11c6 100644
--- a/src/include/nodes/execnodes.h
+++ b/src/include/nodes/execnodes.h
@@ -1439,6 +1439,8 @@ typedef struct IndexScanState
 	Size		iss_PscanLen;
 } IndexScanState;
 
+#define VMBUF_SIZE 64
+
 /* ----------------
  *	 IndexOnlyScanState information
  *
@@ -1473,7 +1475,7 @@ typedef struct IndexOnlyScanState
 	Relation	ioss_RelationDesc;
 	struct IndexScanDescData *ioss_ScanDesc;
 	TupleTableSlot *ioss_TableSlot;
-	Buffer		ioss_VMBuffer;
+	Buffer		ioss_VMBuffer[VMBUF_SIZE];
 	Size		ioss_PscanLen;
 } IndexOnlyScanState;