diff options
| author | Tom Lane <tgl@sss.pgh.pa.us> | 2000-04-09 04:31:37 +0000 |
|---|---|---|
| committer | Tom Lane <tgl@sss.pgh.pa.us> | 2000-04-09 04:31:37 +0000 |
| commit | 9c38a8d29684e9b9822ff7ca7f84c22ecab9cf1e (patch) | |
| tree | 327e21cf137ba71211081342429002a4d279f997 /src/backend/utils/adt/selfuncs.c | |
| parent | 5db0ef84e6642bd9daedc4023107edbbb4c6aecf (diff) | |
| download | postgresql-9c38a8d29684e9b9822ff7ca7f84c22ecab9cf1e.tar.gz postgresql-9c38a8d29684e9b9822ff7ca7f84c22ecab9cf1e.zip | |
Further tweaking of indexscan cost estimates.
Diffstat (limited to 'src/backend/utils/adt/selfuncs.c')
| -rw-r--r-- | src/backend/utils/adt/selfuncs.c | 15 |
1 files changed, 12 insertions, 3 deletions
diff --git a/src/backend/utils/adt/selfuncs.c b/src/backend/utils/adt/selfuncs.c index 0cd408ed78f..7e03b10d431 100644 --- a/src/backend/utils/adt/selfuncs.c +++ b/src/backend/utils/adt/selfuncs.c @@ -15,7 +15,7 @@ * * * IDENTIFICATION - * $Header: /cvsroot/pgsql/src/backend/utils/adt/selfuncs.c,v 1.62 2000/03/30 00:53:30 tgl Exp $ + * $Header: /cvsroot/pgsql/src/backend/utils/adt/selfuncs.c,v 1.63 2000/04/09 04:31:37 tgl Exp $ * *------------------------------------------------------------------------- */ @@ -902,10 +902,19 @@ genericcostestimate(Query *root, RelOptInfo *rel, lfirsti(rel->relids)); /* Estimate the number of index tuples that will be visited */ - numIndexTuples = ceil(*indexSelectivity * index->tuples); + numIndexTuples = *indexSelectivity * index->tuples; /* Estimate the number of index pages that will be retrieved */ - numIndexPages = ceil(*indexSelectivity * index->pages); + numIndexPages = *indexSelectivity * index->pages; + + /* + * Always estimate at least one tuple and page are touched, + * even when indexSelectivity estimate is tiny. + */ + if (numIndexTuples < 1.0) + numIndexTuples = 1.0; + if (numIndexPages < 1.0) + numIndexPages = 1.0; /* * Compute the index access cost. |