diff options
| author | Tom Lane | 2007-05-22 01:40:42 +0000 |
|---|---|---|
| committer | Tom Lane | 2007-05-22 01:40:42 +0000 |
| commit | 107cbb2b9011e7179427aa67b35a97b49d572f6c (patch) | |
| tree | 95709ca1fac67db588e3093d61bc647a4b4ce4b2 /src/include/optimizer | |
| parent | 06df9a69e83396da87083bf5810855547b3ffff4 (diff) | |
Fix best_inner_indexscan to return both the cheapest-total-cost and
cheapest-startup-cost innerjoin indexscans, and make joinpath.c consider
both of these (when different) as the inside of a nestloop join. The
original design was based on the assumption that indexscan paths always
have negligible startup cost, and so total cost is the only important
figure of merit; an assumption that's obviously broken by bitmap
indexscans. This oversight could lead to choosing poor plans in cases
where fast-start behavior is more important than total cost, such as
LIMIT and IN queries. 8.1-vintage brain fade exposed by an example from
Chuck D.
Diffstat (limited to 'src/include/optimizer')
| -rw-r--r-- | src/include/optimizer/paths.h | 7 |
1 files changed, 4 insertions, 3 deletions
diff --git a/src/include/optimizer/paths.h b/src/include/optimizer/paths.h index 39aff9fc436..9b3eaaf4300 100644 --- a/src/include/optimizer/paths.h +++ b/src/include/optimizer/paths.h @@ -7,7 +7,7 @@ * Portions Copyright (c) 1996-2006, PostgreSQL Global Development Group * Portions Copyright (c) 1994, Regents of the University of California * - * $PostgreSQL: pgsql/src/include/optimizer/paths.h,v 1.93.2.1 2007/02/16 00:14:08 tgl Exp $ + * $PostgreSQL: pgsql/src/include/optimizer/paths.h,v 1.93.2.2 2007/05/22 01:40:42 tgl Exp $ * *------------------------------------------------------------------------- */ @@ -45,8 +45,9 @@ extern void create_index_paths(PlannerInfo *root, RelOptInfo *rel); extern List *generate_bitmap_or_paths(PlannerInfo *root, RelOptInfo *rel, List *clauses, List *outer_clauses, RelOptInfo *outer_rel); -extern Path *best_inner_indexscan(PlannerInfo *root, RelOptInfo *rel, - RelOptInfo *outer_rel, JoinType jointype); +extern void best_inner_indexscan(PlannerInfo *root, RelOptInfo *rel, + RelOptInfo *outer_rel, JoinType jointype, + Path **cheapest_startup, Path **cheapest_total); extern List *group_clauses_by_indexkey(IndexOptInfo *index, List *clauses, List *outer_clauses, Relids outer_relids, |