From c1c9537f045ba7293416711347c7113fa8ec33f9 Mon Sep 17 00:00:00 2001 From: Melanie Plageman Date: Fri, 5 Apr 2024 02:50:42 -0400 Subject: [PATCH v15 12/13] Move BitmapHeapScan initialization to helper Author: Melanie Plageman Discussion: https://postgr.es/m/CAAKRu_ZwCwWFeL_H3ia26bP2e7HiKLWt0ZmGXPVwPO6uXq0vaA%40mail.gmail.com --- src/backend/executor/nodeBitmapHeapscan.c | 170 ++++++++++++---------- 1 file changed, 92 insertions(+), 78 deletions(-) diff --git a/src/backend/executor/nodeBitmapHeapscan.c b/src/backend/executor/nodeBitmapHeapscan.c index d22a433f06..aaeece6697 100644 --- a/src/backend/executor/nodeBitmapHeapscan.c +++ b/src/backend/executor/nodeBitmapHeapscan.c @@ -109,6 +109,94 @@ bhs_end_iterate(BitmapHeapIterator *iterator) } + /* + * If we haven't yet performed the underlying index scan, do it, and begin + * the iteration over the bitmap. + * + * For prefetching, we use *two* iterators, one for the pages we are actually + * scanning and another that runs ahead of the first for prefetching. + * node->prefetch_pages tracks exactly how many pages ahead the prefetch + * iterator is. Also, node->prefetch_target tracks the desired prefetch + * distance, which starts small and increases up to the + * scan->prefetch_maximum. This is to avoid doing a lot of prefetching in a + * scan that stops after a few tuples because of a LIMIT. + */ +static void +BitmapHeapInitialize(BitmapHeapScanState *node) +{ + Relation rel = node->ss.ss_currentRelation; + bool pf_maximum = 0; + bool init_shared_state = false; + uint32 extra_flags = 0; + + Assert(!node->initialized); + + /* + * The leader will immediately come out of the function, but others will + * be blocked until leader populates the TBM and wakes them up. + */ + init_shared_state = node->pstate ? + BitmapShouldInitializeSharedState(node->pstate) : false; + + /* + * Maximum number of prefetches for the tablespace if configured, + * otherwise the current value of the effective_io_concurrency GUC. + */ +#ifdef USE_PREFETCH + pf_maximum = get_tablespace_io_concurrency(rel->rd_rel->reltablespace); +#endif + + if (!node->pstate || init_shared_state) + { + node->tbm = (TIDBitmap *) MultiExecProcNode(outerPlanState(node)); + + if (!node->tbm || !IsA(node->tbm, TIDBitmap)) + elog(ERROR, "unrecognized result from subplan"); + + if (init_shared_state) + { + /* + * Prepare to iterate over the TBM. This will return the + * dsa_pointer of the iterator state which will be used by + * multiple processes to iterate jointly. + */ + node->pstate->tbmiterator = tbm_prepare_shared_iterate(node->tbm); + +#ifdef USE_PREFETCH + if (pf_maximum > 0) + { + node->pstate->prefetch_iterator = + tbm_prepare_shared_iterate(node->tbm); + } +#endif + /* We have initialized the shared state so wake up others. */ + BitmapDoneInitializingSharedState(node->pstate); + } + } + + /* + * We can potentially skip fetching heap pages if we do not need any + * columns of the table, either for checking non-indexable quals or for + * returning data. This test is a bit simplistic, as it checks the + * stronger condition that there's no qual or return tlist at all. But in + * most cases it's probably not worth working harder than that. + */ + if (node->ss.ps.plan->qual != NIL || node->ss.ps.plan->targetlist != NIL) + extra_flags |= SO_NEED_TUPLE; + + node->ss.ss_currentScanDesc = table_beginscan_bm(node->ss.ss_currentScanDesc, + rel, + node->ss.ps.state->es_snapshot, + extra_flags, + pf_maximum, + node->tbm, + node->pstate, + node->ss.ps.state->es_query_dsa); + + node->initialized = true; +} + + /* ---------------------------------------------------------------- * BitmapHeapNext * @@ -124,88 +212,14 @@ BitmapHeapNext(BitmapHeapScanState *node) /* * If we haven't yet performed the underlying index scan, do it, and begin - * the iteration over the bitmap. - * - * For prefetching, we use *two* iterators, one for the pages we are - * actually scanning and another that runs ahead of the first for - * prefetching. node->prefetch_pages tracks exactly how many pages ahead - * the prefetch iterator is. Also, node->prefetch_target tracks the - * desired prefetch distance, which starts small and increases up to the - * scan->prefetch_maximum. This is to avoid doing a lot of prefetching in - * a scan that stops after a few tuples because of a LIMIT. + * the iteration over the bitmap. This happens on rescan as well. */ if (!node->initialized) { - Relation rel = node->ss.ss_currentRelation; - bool pf_maximum = 0; - bool init_shared_state = false; - uint32 extra_flags = 0; - - /* - * The leader will immediately come out of the function, but others - * will be blocked until leader populates the TBM and wakes them up. - */ - init_shared_state = node->pstate ? - BitmapShouldInitializeSharedState(node->pstate) : false; - - /* - * Maximum number of prefetches for the tablespace if configured, - * otherwise the current value of the effective_io_concurrency GUC. - */ -#ifdef USE_PREFETCH - pf_maximum = get_tablespace_io_concurrency(rel->rd_rel->reltablespace); -#endif - - if (!node->pstate || init_shared_state) - { - node->tbm = (TIDBitmap *) MultiExecProcNode(outerPlanState(node)); - - if (!node->tbm || !IsA(node->tbm, TIDBitmap)) - elog(ERROR, "unrecognized result from subplan"); - - if (init_shared_state) - { - /* - * Prepare to iterate over the TBM. This will return the - * dsa_pointer of the iterator state which will be used by - * multiple processes to iterate jointly. - */ - node->pstate->tbmiterator = tbm_prepare_shared_iterate(node->tbm); - -#ifdef USE_PREFETCH - if (pf_maximum > 0) - { - node->pstate->prefetch_iterator = - tbm_prepare_shared_iterate(node->tbm); - } -#endif - /* We have initialized the shared state so wake up others. */ - BitmapDoneInitializingSharedState(node->pstate); - } - } - - /* - * We can potentially skip fetching heap pages if we do not need any - * columns of the table, either for checking non-indexable quals or - * for returning data. This test is a bit simplistic, as it checks - * the stronger condition that there's no qual or return tlist at all. - * But in most cases it's probably not worth working harder than that. - */ - if (node->ss.ps.plan->qual != NIL || node->ss.ps.plan->targetlist != NIL) - extra_flags |= SO_NEED_TUPLE; - - scan = table_beginscan_bm(node->ss.ss_currentScanDesc, - rel, - node->ss.ps.state->es_snapshot, - extra_flags, - pf_maximum, - node->tbm, - node->pstate, - node->ss.ps.state->es_query_dsa); - - node->ss.ss_currentScanDesc = scan; - node->initialized = true; + BitmapHeapInitialize(node); + /* We may have a new scan descriptor */ + scan = node->ss.ss_currentScanDesc; goto new_page; } -- 2.40.1