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| author | Tom Lane <tgl@sss.pgh.pa.us> | 1999-08-21 03:49:17 +0000 |
|---|---|---|
| committer | Tom Lane <tgl@sss.pgh.pa.us> | 1999-08-21 03:49:17 +0000 |
| commit | db436adf761bd5cb7990745ceba2959ac4bfca7c (patch) | |
| tree | 8878ce970fd9b3ac480f3c5ef953fbc85827e685 /src/backend/optimizer/path/joinpath.c | |
| parent | 5588c559e6e21fae6ba1f162616f4fb4f680fb31 (diff) | |
| download | postgresql-db436adf761bd5cb7990745ceba2959ac4bfca7c.tar.gz postgresql-db436adf761bd5cb7990745ceba2959ac4bfca7c.zip | |
Major revision of sort-node handling: push knowledge of query
sort order down into planner, instead of handling it only at the very top
level of the planner. This fixes many things. An explicit sort is now
avoided if there is a cheaper alternative (typically an indexscan) not
only for ORDER BY, but also for the internal sort of GROUP BY. It works
even when there is no other reason (such as a WHERE condition) to consider
the indexscan. It works for indexes on functions. It works for indexes
on functions, backwards. It's just so cool...
CAUTION: I have changed the representation of SortClause nodes, therefore
THIS UPDATE BREAKS STORED RULES. You will need to initdb.
Diffstat (limited to 'src/backend/optimizer/path/joinpath.c')
| -rw-r--r-- | src/backend/optimizer/path/joinpath.c | 8 |
1 files changed, 5 insertions, 3 deletions
diff --git a/src/backend/optimizer/path/joinpath.c b/src/backend/optimizer/path/joinpath.c index 55891d87a95..c1ac6a2c4d8 100644 --- a/src/backend/optimizer/path/joinpath.c +++ b/src/backend/optimizer/path/joinpath.c @@ -7,7 +7,7 @@ * * * IDENTIFICATION - * $Header: /cvsroot/pgsql/src/backend/optimizer/path/joinpath.c,v 1.45 1999/08/16 02:17:51 tgl Exp $ + * $Header: /cvsroot/pgsql/src/backend/optimizer/path/joinpath.c,v 1.46 1999/08/21 03:49:00 tgl Exp $ * *------------------------------------------------------------------------- */ @@ -408,7 +408,8 @@ match_unsorted_outer(RelOptInfo *joinrel, trialinnerpath = get_cheapest_path_for_pathkeys(innerrel->pathlist, ltruncate(clausecount, - trialsortkeys)); + trialsortkeys), + false); if (trialinnerpath != NULL && trialinnerpath->path_cost < cheapest_cost) { @@ -488,7 +489,8 @@ match_unsorted_inner(RelOptInfo *joinrel, /* Look for an outer path already ordered well enough to merge */ mergeouterpath = get_cheapest_path_for_pathkeys(outerrel->pathlist, - outersortkeys); + outersortkeys, + false); /* Should we use the mergeouter, or sort the cheapest outer? */ if (mergeouterpath != NULL && |