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help / color / mirror / Atom feedFrom: Melanie Plageman <[email protected]>
Subject: [PATCH v18 01/10] BitmapHeapScan: begin scan after bitmap creation
Date: Mon, 12 Feb 2024 18:50:29 -0500
It makes more sense for BitmapHeapScan to scan the index, build the
bitmap, and only then begin the scan on the underlying table.
This is mostly a cosmetic change for now, but later commits will need
to pass parameters to table_beginscan_bm() that are unavailable in
ExecInitBitmapHeapScan().
Author: Melanie Plageman
Reviewed-by: Tomas Vondra, Andres Freund, Heikki Linnakangas
Discussion: https://postgr.es/m/CAAKRu_ZwCwWFeL_H3ia26bP2e7HiKLWt0ZmGXPVwPO6uXq0vaA%40mail.gmail.com
---
src/backend/executor/nodeBitmapHeapscan.c | 27 +++++++++++++++++------
1 file changed, 20 insertions(+), 7 deletions(-)
diff --git a/src/backend/executor/nodeBitmapHeapscan.c b/src/backend/executor/nodeBitmapHeapscan.c
index cee7f45aabe..c8c466e3c5c 100644
--- a/src/backend/executor/nodeBitmapHeapscan.c
+++ b/src/backend/executor/nodeBitmapHeapscan.c
@@ -178,6 +178,21 @@ BitmapHeapNext(BitmapHeapScanState *node)
}
#endif /* USE_PREFETCH */
}
+
+ /*
+ * If this is the first scan of the underlying table, create the table
+ * scan descriptor and begin the scan.
+ */
+ if (!scan)
+ {
+ scan = table_beginscan_bm(node->ss.ss_currentRelation,
+ node->ss.ps.state->es_snapshot,
+ 0,
+ NULL);
+
+ node->ss.ss_currentScanDesc = scan;
+ }
+
node->initialized = true;
}
@@ -601,7 +616,8 @@ ExecReScanBitmapHeapScan(BitmapHeapScanState *node)
PlanState *outerPlan = outerPlanState(node);
/* rescan to release any page pin */
- table_rescan(node->ss.ss_currentScanDesc, NULL);
+ if (node->ss.ss_currentScanDesc)
+ table_rescan(node->ss.ss_currentScanDesc, NULL);
/* release bitmaps and buffers if any */
if (node->tbmiterator)
@@ -678,7 +694,9 @@ ExecEndBitmapHeapScan(BitmapHeapScanState *node)
/*
* close heap scan
*/
- table_endscan(scanDesc);
+ if (scanDesc)
+ table_endscan(scanDesc);
+
}
/* ----------------------------------------------------------------
@@ -783,11 +801,6 @@ ExecInitBitmapHeapScan(BitmapHeapScan *node, EState *estate, int eflags)
scanstate->ss.ss_currentRelation = currentRelation;
- scanstate->ss.ss_currentScanDesc = table_beginscan_bm(currentRelation,
- estate->es_snapshot,
- 0,
- NULL);
-
/*
* all done.
*/
--
2.40.1
--zmcd37za4qx3kv73
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
filename="v18-0002-BitmapHeapScan-postpone-setting-can_skip_fetch.patch"
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