diff options
| author | Tom Lane <tgl@sss.pgh.pa.us> | 2005-08-27 22:13:44 +0000 |
|---|---|---|
| committer | Tom Lane <tgl@sss.pgh.pa.us> | 2005-08-27 22:13:44 +0000 |
| commit | 4e5fbb34b361102df41642a6ed9676b8b6a1e75f (patch) | |
| tree | 56acd956f301ecd6f33904d5ac05d984ac6bd413 /src/include/optimizer/planmain.h | |
| parent | 9e56c5a4cff7edb145729c7ba2b19dd8cf1c45cf (diff) | |
Change the division of labor between grouping_planner and query_planner
so that the latter estimates the number of groups that grouping will
produce. This is needed because it is primarily query_planner that
makes the decision between fast-start and fast-finish plans, and in the
original coding it was unable to make more than a crude rule-of-thumb
choice when the query involved grouping. This revision helps us make
saner choices for queries like SELECT ... GROUP BY ... LIMIT, as in a
recent example from Mark Kirkwood. Also move the responsibility for
canonicalizing sort_pathkeys and group_pathkeys into query_planner;
this information has to be available anyway to support the first change,
and doing it this way lets us get rid of compare_noncanonical_pathkeys
entirely.
Diffstat (limited to 'src/include/optimizer/planmain.h')
| -rw-r--r-- | src/include/optimizer/planmain.h | 5 |
1 files changed, 3 insertions, 2 deletions
diff --git a/src/include/optimizer/planmain.h b/src/include/optimizer/planmain.h index 474a14da9a0..652431b894f 100644 --- a/src/include/optimizer/planmain.h +++ b/src/include/optimizer/planmain.h @@ -7,7 +7,7 @@ * Portions Copyright (c) 1996-2005, PostgreSQL Global Development Group * Portions Copyright (c) 1994, Regents of the University of California * - * $PostgreSQL: pgsql/src/include/optimizer/planmain.h,v 1.87 2005/08/18 17:51:12 tgl Exp $ + * $PostgreSQL: pgsql/src/include/optimizer/planmain.h,v 1.88 2005/08/27 22:13:44 tgl Exp $ * *------------------------------------------------------------------------- */ @@ -22,7 +22,8 @@ */ extern void query_planner(PlannerInfo *root, List *tlist, double tuple_fraction, - Path **cheapest_path, Path **sorted_path); + Path **cheapest_path, Path **sorted_path, + double *num_groups); /* * prototypes for plan/planagg.c |