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BitmapHeapScan: postpone setting can_skip_fetch

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Set BitmapHeapScanState->can_skip_fetch in BitmapHeapNext() instead of
in ExecInitBitmapHeapScan(). This is a preliminary step to pushing the
skip fetch optimization into heap AM code.

Author: Melanie Plageman
Reviewed-by: Tomas Vondra, Andres Freund, Heikki Linnakangas
Discussion: https://postgr.es/m/CAAKRu_ZwCwWFeL_H3ia26bP2e7HiKLWt0ZmGXPVwPO6uXq0vaA%40mail.gmail.com
This commit is contained in:
Tomas Vondra 2024-04-06 23:56:46 +02:00
parent 74eaf66f98
commit fe1431e39c
1 changed files with 11 additions and 10 deletions
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21
src/backend/executor/nodeBitmapHeapscan.c
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@ -105,6 +105,16 @@ BitmapHeapNext(BitmapHeapScanState *node)
*/ */
if (!node->initialized) if (!node->initialized)
{ {
/*
* 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.
*/
node->can_skip_fetch = (node->ss.ps.plan->qual == NIL &&
node->ss.ps.plan->targetlist == NIL);
if (!pstate) if (!pstate)
{ {
tbm = (TIDBitmap *) MultiExecProcNode(outerPlanState(node)); tbm = (TIDBitmap *) MultiExecProcNode(outerPlanState(node));
@ -743,16 +753,7 @@ ExecInitBitmapHeapScan(BitmapHeapScan *node, EState *estate, int eflags)
scanstate->shared_tbmiterator = NULL; scanstate->shared_tbmiterator = NULL;
scanstate->shared_prefetch_iterator = NULL; scanstate->shared_prefetch_iterator = NULL;
scanstate->pstate = NULL; scanstate->pstate = NULL;
scanstate->can_skip_fetch = false;
/*
* 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.
*/
scanstate->can_skip_fetch = (node->scan.plan.qual == NIL &&
node->scan.plan.targetlist == NIL);
/* /*
* Miscellaneous initialization * Miscellaneous initialization