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Further tweaking of indexscan cost estimates.

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This commit is contained in:
Tom Lane
2000-04-09 04:31:37 +00:00
parent 5db0ef84e6
commit 9c38a8d296
2 changed files with 18 additions and 6 deletions
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9
src/backend/optimizer/path/costsize.c
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@@ -42,7 +42,7 @@
* Portions Copyright (c) 1994, Regents of the University of California
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/optimizer/path/costsize.c,v 1.55 2000/03/30 00:53:29 tgl Exp $
* $Header: /cvsroot/pgsql/src/backend/optimizer/path/costsize.c,v 1.56 2000/04/09 04:31:36 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@@ -262,9 +262,12 @@ cost_index(Path *path, Query *root,
* effect. Would be nice to do better someday.
*/
tuples_fetched = ceil(indexSelectivity * baserel->tuples);
tuples_fetched = indexSelectivity * baserel->tuples;
/* Don't believe estimates less than 1... */
if (tuples_fetched < 1.0)
tuples_fetched = 1.0;
if (tuples_fetched > 0 && baserel->pages > 0)
if (baserel->pages > 0)
pages_fetched = ceil(baserel->pages *
log(tuples_fetched / baserel->pages + 1.0));
else