From f5e83662d06a40f90ceb3516fc88674eb6c1e4f9 Mon Sep 17 00:00:00 2001 From: Tom Lane Date: Fri, 24 Jan 2003 03:58:44 +0000 Subject: Modify planner's implied-equality-deduction code so that when a set of known-equal expressions includes any constant expressions (including Params from outer queries), we actively suppress any 'var = var' clauses that are or could be deduced from the set, generating only the deducible 'var = const' clauses instead. The idea here is to push down the restrictions implied by the equality set to base relations whenever possible. Once we have applied the 'var = const' clauses, the 'var = var' clauses are redundant, and should be suppressed both to save work at execution and to avoid double-counting restrictivity. --- src/backend/optimizer/path/indxpath.c | 10 ++++++---- 1 file changed, 6 insertions(+), 4 deletions(-) (limited to 'src/backend/optimizer/path/indxpath.c') diff --git a/src/backend/optimizer/path/indxpath.c b/src/backend/optimizer/path/indxpath.c index 02a92fd9960..443d54c6473 100644 --- a/src/backend/optimizer/path/indxpath.c +++ b/src/backend/optimizer/path/indxpath.c @@ -9,7 +9,7 @@ * * * IDENTIFICATION - * $Header: /cvsroot/pgsql/src/backend/optimizer/path/indxpath.c,v 1.132 2003/01/20 18:54:49 tgl Exp $ + * $Header: /cvsroot/pgsql/src/backend/optimizer/path/indxpath.c,v 1.133 2003/01/24 03:58:34 tgl Exp $ * *------------------------------------------------------------------------- */ @@ -1596,12 +1596,14 @@ make_innerjoin_index_path(Query *root, * nconc the two lists; then we might have some restriction * clauses appearing twice, which'd mislead * restrictlist_selectivity into double-counting their - * selectivity.) + * selectivity. However, since RestrictInfo nodes aren't copied when + * linking them into different lists, it should be sufficient to use + * pointer comparison to remove duplicates.) */ pathnode->rows = rel->tuples * restrictlist_selectivity(root, - set_union(rel->baserestrictinfo, - clausegroup), + set_ptrUnion(rel->baserestrictinfo, + clausegroup), lfirsti(rel->relids)); /* Like costsize.c, force estimate to be at least one row */ if (pathnode->rows < 1.0) -- cgit v1.2.3