diff options
| author | Tom Lane <tgl@sss.pgh.pa.us> | 2004-04-06 18:46:25 +0000 |
|---|---|---|
| committer | Tom Lane <tgl@sss.pgh.pa.us> | 2004-04-06 18:46:25 +0000 |
| commit | 2fde46613503cb72cf2937835d8d078b16e24a16 (patch) | |
| tree | 421ede4d93740658b04e2a8f1ece56ea912942cb /src/backend/optimizer/path/costsize.c | |
| parent | 79d48449d703bbca6fa90d2857190ba4b5e46624 (diff) | |
Support FULL JOIN with no join clauses, such as X FULL JOIN Y ON TRUE.
That particular corner case is not exactly compelling, but given 7.4's
ability to discard redundant join clauses, it is possible for the situation
to arise from queries that are not so obviously silly. Per bug report
of 6-Apr-04.
Diffstat (limited to 'src/backend/optimizer/path/costsize.c')
| -rw-r--r-- | src/backend/optimizer/path/costsize.c | 36 |
1 files changed, 22 insertions, 14 deletions
diff --git a/src/backend/optimizer/path/costsize.c b/src/backend/optimizer/path/costsize.c index 4b500bc03a5..c151ddd5f16 100644 --- a/src/backend/optimizer/path/costsize.c +++ b/src/backend/optimizer/path/costsize.c @@ -49,7 +49,7 @@ * Portions Copyright (c) 1994, Regents of the University of California * * IDENTIFICATION - * $Header: /cvsroot/pgsql/src/backend/optimizer/path/costsize.c,v 1.115.2.1 2003/12/03 17:45:36 tgl Exp $ + * $Header: /cvsroot/pgsql/src/backend/optimizer/path/costsize.c,v 1.115.2.2 2004/04/06 18:46:25 tgl Exp $ * *------------------------------------------------------------------------- */ @@ -928,23 +928,31 @@ cost_mergejoin(MergePath *path, Query *root) * all mergejoin paths associated with the merge clause, we cache the * results in the RestrictInfo node. */ - firstclause = (RestrictInfo *) lfirst(mergeclauses); - if (firstclause->left_mergescansel < 0) /* not computed yet? */ - mergejoinscansel(root, (Node *) firstclause->clause, - &firstclause->left_mergescansel, - &firstclause->right_mergescansel); - - if (bms_is_subset(firstclause->left_relids, outer_path->parent->relids)) + if (mergeclauses) { - /* left side of clause is outer */ - outerscansel = firstclause->left_mergescansel; - innerscansel = firstclause->right_mergescansel; + firstclause = (RestrictInfo *) lfirst(mergeclauses); + if (firstclause->left_mergescansel < 0) /* not computed yet? */ + mergejoinscansel(root, (Node *) firstclause->clause, + &firstclause->left_mergescansel, + &firstclause->right_mergescansel); + + if (bms_is_subset(firstclause->left_relids, outer_path->parent->relids)) + { + /* left side of clause is outer */ + outerscansel = firstclause->left_mergescansel; + innerscansel = firstclause->right_mergescansel; + } + else + { + /* left side of clause is inner */ + outerscansel = firstclause->right_mergescansel; + innerscansel = firstclause->left_mergescansel; + } } else { - /* left side of clause is inner */ - outerscansel = firstclause->right_mergescansel; - innerscansel = firstclause->left_mergescansel; + /* cope with clauseless mergejoin */ + outerscansel = innerscansel = 1.0; } /* convert selectivity to row count; must scan at least one row */ |