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authorTom Lane <tgl@sss.pgh.pa.us>2003-01-24 03:58:44 +0000
committerTom Lane <tgl@sss.pgh.pa.us>2003-01-24 03:58:44 +0000
commitf5e83662d06a40f90ceb3516fc88674eb6c1e4f9 (patch)
tree5b682c9bcbc9dd88b7bcc19f1ca1bf43c8335a83 /src/backend/optimizer/path/indxpath.c
parentef7422510e93266e5aa9bb926d6747d5f2ae21f4 (diff)
downloadpostgresql-f5e83662d06a40f90ceb3516fc88674eb6c1e4f9.tar.gz
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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.
Diffstat (limited to 'src/backend/optimizer/path/indxpath.c')
-rw-r--r--src/backend/optimizer/path/indxpath.c10
1 files changed, 6 insertions, 4 deletions
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)