database/postgres
1
0
Fork 0
mirror of https://github.com/postgres/postgres.git synced 2025-10-27 00:12:01 +03:00
Code Activity

Fix best_inner_indexscan to return both the cheapest-total-cost and

Browse Source 
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.
This commit is contained in:
Tom Lane
2007-05-22 01:40:33 +00:00
parent 2415ad9831
commit d7153c5fad
5 changed files with 94 additions and 63 deletions
Download Patch File Download Diff File Expand all files Collapse all files

7
src/include/optimizer/paths.h
View File

@@ -7,7 +7,7 @@
* Portions Copyright (c) 1996-2007, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
* $PostgreSQL: pgsql/src/include/optimizer/paths.h,v 1.97 2007/04/15 20:09:28 tgl Exp $
* $PostgreSQL: pgsql/src/include/optimizer/paths.h,v 1.98 2007/05/22 01:40:33 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,