From 7b400e9ccd7d8d83358bd503b7209c8ed1ec7ea3 Mon Sep 17 00:00:00 2001 From: Melanie Plageman Date: Mon, 2 Mar 2026 16:31:33 -0500 Subject: [PATCH v45 3/5] Pass down information on table modification to scan node Pass down information to sequential scan, index [only] scan, bitmap table scan, sample scan, and TID range scan nodes on whether or not the query modifies the relation being scanned. A later commit will use this information to update the VM during on-access pruning only if the relation is not modified by the query. Author: Melanie Plageman Reviewed-by: Andres Freund Reviewed-by: Andrey Borodin Reviewed-by: Chao Li Discussion: https://postgr.es/m/4379FDA3-9446-4E2C-9C15-32EFE8D4F31B%40yandex-team.ru --- src/backend/executor/execUtils.c | 8 ++++++++ src/backend/executor/nodeBitmapHeapscan.c | 5 ++++- src/backend/executor/nodeIndexonlyscan.c | 11 ++++++++--- src/backend/executor/nodeIndexscan.c | 16 ++++++++++++---- src/backend/executor/nodeSamplescan.c | 5 ++++- src/backend/executor/nodeSeqscan.c | 14 +++++++++++--- src/backend/executor/nodeTidrangescan.c | 15 ++++++++++++--- src/include/access/tableam.h | 3 +++ src/include/executor/executor.h | 2 ++ 9 files changed, 64 insertions(+), 15 deletions(-) diff --git a/src/backend/executor/execUtils.c b/src/backend/executor/execUtils.c index 9886ab06b69..d2ffe28e010 100644 --- a/src/backend/executor/execUtils.c +++ b/src/backend/executor/execUtils.c @@ -736,6 +736,14 @@ ExecRelationIsTargetRelation(EState *estate, Index scanrelid) return list_member_int(estate->es_plannedstmt->resultRelations, scanrelid); } +/* Return true if the scan node's relation is not modified by the query */ +bool +ScanRelIsReadOnly(ScanState *ss) +{ + return !bms_is_member(((Scan *) ss->ps.plan)->scanrelid, + ss->ps.state->es_plannedstmt->modifiedRelids); +} + /* ---------------------------------------------------------------- * ExecOpenScanRelation * diff --git a/src/backend/executor/nodeBitmapHeapscan.c b/src/backend/executor/nodeBitmapHeapscan.c index 7e2c1b7467b..dba6c31d188 100644 --- a/src/backend/executor/nodeBitmapHeapscan.c +++ b/src/backend/executor/nodeBitmapHeapscan.c @@ -144,9 +144,12 @@ BitmapTableScanSetup(BitmapHeapScanState *node) */ if (!node->ss.ss_currentScanDesc) { + uint32 flags = ScanRelIsReadOnly(&node->ss) ? + SO_HINT_REL_READ_ONLY : 0; + node->ss.ss_currentScanDesc = table_beginscan_bm(node->ss.ss_currentRelation, - 0, + flags, node->ss.ps.state->es_snapshot, 0, NULL); diff --git a/src/backend/executor/nodeIndexonlyscan.c b/src/backend/executor/nodeIndexonlyscan.c index 5cacb4b215a..88491249a9a 100644 --- a/src/backend/executor/nodeIndexonlyscan.c +++ b/src/backend/executor/nodeIndexonlyscan.c @@ -85,6 +85,9 @@ IndexOnlyNext(IndexOnlyScanState *node) if (scandesc == NULL) { + uint32 flags = ScanRelIsReadOnly(&node->ss) ? + SO_HINT_REL_READ_ONLY : 0; + /* * We reach here if the index only scan is not parallel, or if we're * serially executing an index only scan that was planned to be @@ -92,7 +95,7 @@ IndexOnlyNext(IndexOnlyScanState *node) */ scandesc = index_beginscan(node->ss.ss_currentRelation, node->ioss_RelationDesc, - 0, /* flags */ + flags, estate->es_snapshot, node->ioss_Instrument, node->ioss_NumScanKeys, @@ -792,7 +795,8 @@ ExecIndexOnlyScanInitializeDSM(IndexOnlyScanState *node, node->ioss_ScanDesc = index_beginscan_parallel(node->ss.ss_currentRelation, node->ioss_RelationDesc, - 0, /* flags */ + ScanRelIsReadOnly(&node->ss) ? + SO_HINT_REL_READ_ONLY : 0, node->ioss_Instrument, node->ioss_NumScanKeys, node->ioss_NumOrderByKeys, @@ -859,7 +863,8 @@ ExecIndexOnlyScanInitializeWorker(IndexOnlyScanState *node, node->ioss_ScanDesc = index_beginscan_parallel(node->ss.ss_currentRelation, node->ioss_RelationDesc, - 0, /* flags */ + ScanRelIsReadOnly(&node->ss) ? + SO_HINT_REL_READ_ONLY : 0, node->ioss_Instrument, node->ioss_NumScanKeys, node->ioss_NumOrderByKeys, diff --git a/src/backend/executor/nodeIndexscan.c b/src/backend/executor/nodeIndexscan.c index aaef31dbbad..16ec455a964 100644 --- a/src/backend/executor/nodeIndexscan.c +++ b/src/backend/executor/nodeIndexscan.c @@ -104,13 +104,16 @@ IndexNext(IndexScanState *node) if (scandesc == NULL) { + uint32 flags = ScanRelIsReadOnly(&node->ss) ? + SO_HINT_REL_READ_ONLY : 0; + /* * We reach here if the index scan is not parallel, or if we're * serially executing an index scan that was planned to be parallel. */ scandesc = index_beginscan(node->ss.ss_currentRelation, node->iss_RelationDesc, - 0, /* flags */ + flags, estate->es_snapshot, node->iss_Instrument, node->iss_NumScanKeys, @@ -201,13 +204,16 @@ IndexNextWithReorder(IndexScanState *node) if (scandesc == NULL) { + uint32 flags = ScanRelIsReadOnly(&node->ss) ? + SO_HINT_REL_READ_ONLY : 0; + /* * We reach here if the index scan is not parallel, or if we're * serially executing an index scan that was planned to be parallel. */ scandesc = index_beginscan(node->ss.ss_currentRelation, node->iss_RelationDesc, - 0, /* flags */ + flags, estate->es_snapshot, node->iss_Instrument, node->iss_NumScanKeys, @@ -1729,7 +1735,8 @@ ExecIndexScanInitializeDSM(IndexScanState *node, node->iss_ScanDesc = index_beginscan_parallel(node->ss.ss_currentRelation, node->iss_RelationDesc, - 0, /* flags */ + ScanRelIsReadOnly(&node->ss) ? + SO_HINT_REL_READ_ONLY : 0, node->iss_Instrument, node->iss_NumScanKeys, node->iss_NumOrderByKeys, @@ -1794,7 +1801,8 @@ ExecIndexScanInitializeWorker(IndexScanState *node, node->iss_ScanDesc = index_beginscan_parallel(node->ss.ss_currentRelation, node->iss_RelationDesc, - 0, /* flags */ + ScanRelIsReadOnly(&node->ss) ? + SO_HINT_REL_READ_ONLY : 0, node->iss_Instrument, node->iss_NumScanKeys, node->iss_NumOrderByKeys, diff --git a/src/backend/executor/nodeSamplescan.c b/src/backend/executor/nodeSamplescan.c index cf4dd6a16b4..b6a02072da5 100644 --- a/src/backend/executor/nodeSamplescan.c +++ b/src/backend/executor/nodeSamplescan.c @@ -292,9 +292,12 @@ tablesample_init(SampleScanState *scanstate) /* Now we can create or reset the HeapScanDesc */ if (scanstate->ss.ss_currentScanDesc == NULL) { + uint32 flags = ScanRelIsReadOnly(&scanstate->ss) ? + SO_HINT_REL_READ_ONLY : 0; + scanstate->ss.ss_currentScanDesc = table_beginscan_sampling(scanstate->ss.ss_currentRelation, - 0, + flags, scanstate->ss.ps.state->es_snapshot, 0, NULL, scanstate->use_bulkread, diff --git a/src/backend/executor/nodeSeqscan.c b/src/backend/executor/nodeSeqscan.c index 376e877e87c..2d0993a83f4 100644 --- a/src/backend/executor/nodeSeqscan.c +++ b/src/backend/executor/nodeSeqscan.c @@ -65,12 +65,15 @@ SeqNext(SeqScanState *node) if (scandesc == NULL) { + uint32 flags = ScanRelIsReadOnly(&node->ss) ? + SO_HINT_REL_READ_ONLY : 0; + /* * We reach here if the scan is not parallel, or if we're serially * executing a scan that was planned to be parallel. */ scandesc = table_beginscan(node->ss.ss_currentRelation, - 0, estate->es_snapshot, + flags, estate->es_snapshot, 0, NULL); node->ss.ss_currentScanDesc = scandesc; } @@ -368,14 +371,17 @@ ExecSeqScanInitializeDSM(SeqScanState *node, { EState *estate = node->ss.ps.state; ParallelTableScanDesc pscan; + uint32 flags = ScanRelIsReadOnly(&node->ss) ? + SO_HINT_REL_READ_ONLY : 0; pscan = shm_toc_allocate(pcxt->toc, node->pscan_len); table_parallelscan_initialize(node->ss.ss_currentRelation, pscan, estate->es_snapshot); shm_toc_insert(pcxt->toc, node->ss.ps.plan->plan_node_id, pscan); + node->ss.ss_currentScanDesc = - table_beginscan_parallel(node->ss.ss_currentRelation, 0, pscan); + table_beginscan_parallel(node->ss.ss_currentRelation, flags, pscan); } /* ---------------------------------------------------------------- @@ -405,8 +411,10 @@ ExecSeqScanInitializeWorker(SeqScanState *node, ParallelWorkerContext *pwcxt) { ParallelTableScanDesc pscan; + uint32 flags = ScanRelIsReadOnly(&node->ss) ? + SO_HINT_REL_READ_ONLY : 0; pscan = shm_toc_lookup(pwcxt->toc, node->ss.ps.plan->plan_node_id, false); node->ss.ss_currentScanDesc = - table_beginscan_parallel(node->ss.ss_currentRelation, 0, pscan); + table_beginscan_parallel(node->ss.ss_currentRelation, flags, pscan); } diff --git a/src/backend/executor/nodeTidrangescan.c b/src/backend/executor/nodeTidrangescan.c index bacd7aa5bc4..05ed5364238 100644 --- a/src/backend/executor/nodeTidrangescan.c +++ b/src/backend/executor/nodeTidrangescan.c @@ -242,8 +242,11 @@ TidRangeNext(TidRangeScanState *node) if (scandesc == NULL) { + uint32 flags = ScanRelIsReadOnly(&node->ss) ? + SO_HINT_REL_READ_ONLY : 0; + scandesc = table_beginscan_tidrange(node->ss.ss_currentRelation, - 0, + flags, estate->es_snapshot, &node->trss_mintid, &node->trss_maxtid); @@ -453,15 +456,18 @@ ExecTidRangeScanInitializeDSM(TidRangeScanState *node, ParallelContext *pcxt) { EState *estate = node->ss.ps.state; ParallelTableScanDesc pscan; + uint32 flags = ScanRelIsReadOnly(&node->ss) ? + SO_HINT_REL_READ_ONLY : 0; pscan = shm_toc_allocate(pcxt->toc, node->trss_pscanlen); table_parallelscan_initialize(node->ss.ss_currentRelation, pscan, estate->es_snapshot); shm_toc_insert(pcxt->toc, node->ss.ps.plan->plan_node_id, pscan); + node->ss.ss_currentScanDesc = table_beginscan_parallel_tidrange(node->ss.ss_currentRelation, - 0, pscan); + flags, pscan); } /* ---------------------------------------------------------------- @@ -491,9 +497,12 @@ ExecTidRangeScanInitializeWorker(TidRangeScanState *node, ParallelWorkerContext *pwcxt) { ParallelTableScanDesc pscan; + uint32 flags = ScanRelIsReadOnly(&node->ss) ? + SO_HINT_REL_READ_ONLY : 0; pscan = shm_toc_lookup(pwcxt->toc, node->ss.ps.plan->plan_node_id, false); + node->ss.ss_currentScanDesc = table_beginscan_parallel_tidrange(node->ss.ss_currentRelation, - 0, pscan); + flags, pscan); } diff --git a/src/include/access/tableam.h b/src/include/access/tableam.h index e1f90f2b6a7..a8fd8f0d45c 100644 --- a/src/include/access/tableam.h +++ b/src/include/access/tableam.h @@ -63,6 +63,9 @@ typedef enum ScanOptions /* unregister snapshot at scan end? */ SO_TEMP_SNAPSHOT = 1 << 9, + + /* set if the query doesn't modify the relation */ + SO_HINT_REL_READ_ONLY = 1 << 10, } ScanOptions; /* diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 07f4b1f7490..7979a17e4ec 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -690,6 +690,8 @@ extern void ExecCreateScanSlotFromOuterPlan(EState *estate, extern bool ExecRelationIsTargetRelation(EState *estate, Index scanrelid); +extern bool ScanRelIsReadOnly(ScanState *ss); + extern Relation ExecOpenScanRelation(EState *estate, Index scanrelid, int eflags); extern void ExecInitRangeTable(EState *estate, List *rangeTable, List *permInfos, -- 2.43.0