From e65a9baa52c99c93a9a9a281aebacd38b8299721 Mon Sep 17 00:00:00 2001 From: Melanie Plageman Date: Mon, 12 Feb 2024 18:50:29 -0500 Subject: [PATCH v17 1/9] BitmapHeapScan: begin scan after bitmap creation 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