Commit9c38a8d

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Further tweaking of indexscan cost estimates.

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+18

-6

lines changed

+18

-6

lines changed

Lines changed: 6 additions & 3 deletions

Original file line number	Diff line number	Diff line change
`@@ -42,7 +42,7 @@`
`42`	`42`	`* Portions Copyright (c) 1994, Regents of the University of California`
`43`	`43`	`*`
`44`	`44`	`* IDENTIFICATION`
`45`		`- * $Header: /cvsroot/pgsql/src/backend/optimizer/path/costsize.c,v 1.55 2000/03/30 00:53:29 tgl Exp $`
	`45`	`+ * $Header: /cvsroot/pgsql/src/backend/optimizer/path/costsize.c,v 1.56 2000/04/09 04:31:36 tgl Exp $`
`46`	`46`	`*`
`47`	`47`	`*-------------------------------------------------------------------------`
`48`	`48`	`*/`
`@@ -262,9 +262,12 @@ cost_index(Path path, Query root,`
`262`	`262`	`* effect. Would be nice to do better someday.`
`263`	`263`	`*/`
`264`	`264`
`265`		`-tuples_fetched=ceil(indexSelectivity*baserel->tuples);`
	`265`	`+tuples_fetched=indexSelectivity*baserel->tuples;`
	`266`	`+/* Don't believe estimates less than 1... */`
	`267`	`+if (tuples_fetched<1.0)`
	`268`	`+tuples_fetched=1.0;`
`266`	`269`
`267`		`-if (tuples_fetched>0&&baserel->pages>0)`
	`270`	`+if (baserel->pages>0)`
`268`	`271`	`pages_fetched=ceil(baserel->pages*`
`269`	`272`	`log(tuples_fetched /baserel->pages+1.0));`
`270`	`273`	`else`

Lines changed: 12 additions & 3 deletions

Original file line number	Diff line number	Diff line change
`@@ -15,7 +15,7 @@`
`15`	`15`	`*`
`16`	`16`	`*`
`17`	`17`	`* IDENTIFICATION`
`18`		`- * $Header: /cvsroot/pgsql/src/backend/utils/adt/selfuncs.c,v 1.62 2000/03/30 00:53:30 tgl Exp $`
	`18`	`+ * $Header: /cvsroot/pgsql/src/backend/utils/adt/selfuncs.c,v 1.63 2000/04/09 04:31:37 tgl Exp $`
`19`	`19`	`*`
`20`	`20`	`*-------------------------------------------------------------------------`
`21`	`21`	`*/`
`@@ -902,10 +902,19 @@ genericcostestimate(Query root, RelOptInfo rel,`
`902`	`902`	`lfirsti(rel->relids));`
`903`	`903`
`904`	`904`	`/* Estimate the number of index tuples that will be visited */`
`905`		`-numIndexTuples=ceil(indexSelectivityindex->tuples);`
	`905`	`+numIndexTuples=indexSelectivityindex->tuples;`
`906`	`906`
`907`	`907`	`/* Estimate the number of index pages that will be retrieved */`
`908`		`-numIndexPages=ceil(indexSelectivityindex->pages);`
	`908`	`+numIndexPages=indexSelectivityindex->pages;`
	`909`	`+`
	`910`	`+/*`
	`911`	`+ * Always estimate at least one tuple and page are touched,`
	`912`	`+ * even when indexSelectivity estimate is tiny.`
	`913`	`+ */`
	`914`	`+if (numIndexTuples<1.0)`
	`915`	`+numIndexTuples=1.0;`
	`916`	`+if (numIndexPages<1.0)`
	`917`	`+numIndexPages=1.0;`
`909`	`918`
`910`	`919`	`/*`
`911`	`920`	`* Compute the index access cost.`

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