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Minor performance improvement: avoid unnecessary creation/unioning of

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bitmaps for multiple indexscans.  Instead just let each indexscan add
TIDs directly into the BitmapOr node's result bitmap.
This commit is contained in:
Tom Lane
2005-04-20 15:48:36 +00:00
parent de4fbfadc5
commit 9d64632144
4 changed files with 65 additions and 17 deletions
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21
src/backend/executor/nodeBitmapIndexscan.c
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@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/executor/nodeBitmapIndexscan.c,v 1.1 2005/04/19 22:35:12 tgl Exp $
* $PostgreSQL: pgsql/src/backend/executor/nodeBitmapIndexscan.c,v 1.2 2005/04/20 15:48:36 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -63,9 +63,21 @@ MultiExecBitmapIndexScan(BitmapIndexScanState *node)
scandesc = node->biss_ScanDesc;
/*
* Prepare result bitmap
* Prepare the result bitmap. Normally we just create a new one to pass
* back; however, our parent node is allowed to store a pre-made one
* into node->biss_result, in which case we just OR our tuple IDs into
* the existing bitmap. (This saves needing explicit UNION steps.)
*/
tbm = tbm_create(work_mem * 1024L);
if (node->biss_result)
{
tbm = node->biss_result;
node->biss_result = NULL; /* reset for next time */
}
else
{
/* XXX should we use less than work_mem for this? */
tbm = tbm_create(work_mem * 1024L);
}
/*
* Get TIDs from index and insert into bitmap
@ -271,6 +283,9 @@ ExecInitBitmapIndexScan(BitmapIndexScan *node, EState *estate)
indexstate->ss.ps.plan = (Plan *) node;
indexstate->ss.ps.state = estate;
/* normally we don't make the result bitmap till runtime */
indexstate->biss_result = NULL;
/*
* Miscellaneous initialization
*