From e55985d3be4aed47c703674c735c124ff0b3c03c Mon Sep 17 00:00:00 2001 From: Tom Lane Date: Thu, 30 Mar 2000 00:53:30 +0000 Subject: Tweak indexscan cost estimation: round estimated # of tuples visited up to next integer. Previously, if selectivity was small, we could compute very tiny scan cost on the basis of estimating that only 0.001 tuple would be fetched, which is silly. This naturally led to some rather silly plans... --- src/backend/optimizer/path/costsize.c | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-) (limited to 'src/backend/optimizer/path/costsize.c') diff --git a/src/backend/optimizer/path/costsize.c b/src/backend/optimizer/path/costsize.c index 4270032d278..37b4dfc42e7 100644 --- a/src/backend/optimizer/path/costsize.c +++ b/src/backend/optimizer/path/costsize.c @@ -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 1.54 2000/03/22 22:08:33 tgl Exp $ + * $Header: /cvsroot/pgsql/src/backend/optimizer/path/costsize.c,v 1.55 2000/03/30 00:53:29 tgl Exp $ * *------------------------------------------------------------------------- */ @@ -262,11 +262,11 @@ cost_index(Path *path, Query *root, * effect. Would be nice to do better someday. */ - tuples_fetched = indexSelectivity * baserel->tuples; + tuples_fetched = ceil(indexSelectivity * baserel->tuples); if (tuples_fetched > 0 && baserel->pages > 0) - pages_fetched = baserel->pages * - log(tuples_fetched / baserel->pages + 1.0); + pages_fetched = ceil(baserel->pages * + log(tuples_fetched / baserel->pages + 1.0)); else pages_fetched = tuples_fetched; @@ -594,7 +594,7 @@ cost_hashjoin(Path *path, * conservatively as the inner disbursion times the inner tuple count. */ run_cost += cpu_operator_cost * outer_path->parent->rows * - (inner_path->parent->rows * innerdisbursion); + ceil(inner_path->parent->rows * innerdisbursion); /* * Estimate the number of tuples that get through the hashing filter -- cgit v1.2.3