v21-0005-BitmapHeapScan-initialize-some-prefetch-state-el.patch

From 3f5829e150ec3dbbccee6e5ecc378db6025694c3 Mon Sep 17 00:00:00 2001
From: Melanie Plageman <melanieplageman@gmail.com>
Date: Sat, 6 Apr 2024 12:51:11 -0400
Subject: [PATCH v21 05/20] BitmapHeapScan initialize some prefetch state
 elsewhere

The prefetch_target and prefetch_pages members can be initialized in the
scan and rescan functions. This makes it more straightforward to use the
unified TBMIterator API for BitmapHeapScan.

Author: Melanie Plageman
Discussion: https://postgr.es/m/CAAKRu_ZwCwWFeL_H3ia26bP2e7HiKLWt0ZmGXPVwPO6uXq0vaA%40mail.gmail.com
---
 src/backend/executor/nodeBitmapHeapscan.c | 13 +++++++------
 1 file changed, 7 insertions(+), 6 deletions(-)

diff --git a/src/backend/executor/nodeBitmapHeapscan.c b/src/backend/executor/nodeBitmapHeapscan.c
index f6e066a0cb3..b885bfeabd3 100644
--- a/src/backend/executor/nodeBitmapHeapscan.c
+++ b/src/backend/executor/nodeBitmapHeapscan.c
@@ -111,11 +111,7 @@ BitmapHeapNext(BitmapHeapScanState *node)
 
 #ifdef USE_PREFETCH
 			if (node->prefetch_maximum > 0)
-			{
 				node->prefetch_iterator = tbm_begin_serial_iterate(tbm);
-				node->prefetch_pages = 0;
-				node->prefetch_target = -1;
-			}
 #endif							/* USE_PREFETCH */
 		}
 		else
@@ -591,6 +587,9 @@ ExecReScanBitmapHeapScan(BitmapHeapScanState *node)
 	node->recheck = true;
 	node->blockno = InvalidBlockNumber;
 	node->pfblockno = InvalidBlockNumber;
+	/* Only used for serial BHS */
+	node->prefetch_pages = 0;
+	node->prefetch_target = -1;
 
 	ExecScanReScan(&node->ss);
 
@@ -676,7 +675,7 @@ ExecInitBitmapHeapScan(BitmapHeapScan *node, EState *estate, int eflags)
 	scanstate->lossy_pages = 0;
 	scanstate->prefetch_iterator = NULL;
 	scanstate->prefetch_pages = 0;
-	scanstate->prefetch_target = 0;
+	scanstate->prefetch_target = -1;
 	scanstate->initialized = false;
 	scanstate->shared_prefetch_iterator = NULL;
 	scanstate->pstate = NULL;
@@ -812,7 +811,7 @@ ExecBitmapHeapInitializeDSM(BitmapHeapScanState *node,
 	/* Initialize the mutex */
 	SpinLockInit(&pstate->mutex);
 	pstate->prefetch_pages = 0;
-	pstate->prefetch_target = 0;
+	pstate->prefetch_target = -1;
 	pstate->state = BM_INITIAL;
 
 	ConditionVariableInit(&pstate->cv);
@@ -839,6 +838,8 @@ ExecBitmapHeapReInitializeDSM(BitmapHeapScanState *node,
 		return;
 
 	pstate->state = BM_INITIAL;
+	pstate->prefetch_pages = 0;
+	pstate->prefetch_target = -1;
 
 	if (DsaPointerIsValid(pstate->tbmiterator))
 		tbm_free_shared_area(dsa, pstate->tbmiterator);
-- 
2.34.1