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author | Tom Lane <tgl@sss.pgh.pa.us> | 2003-01-24 03:58:44 +0000 |
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committer | Tom Lane <tgl@sss.pgh.pa.us> | 2003-01-24 03:58:44 +0000 |
commit | f5e83662d06a40f90ceb3516fc88674eb6c1e4f9 (patch) | |
tree | 5b682c9bcbc9dd88b7bcc19f1ca1bf43c8335a83 /src/backend/optimizer/util/relnode.c | |
parent | ef7422510e93266e5aa9bb926d6747d5f2ae21f4 (diff) | |
download | postgresql-f5e83662d06a40f90ceb3516fc88674eb6c1e4f9.tar.gz postgresql-f5e83662d06a40f90ceb3516fc88674eb6c1e4f9.zip |
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/util/relnode.c')
-rw-r--r-- | src/backend/optimizer/util/relnode.c | 13 |
1 files changed, 9 insertions, 4 deletions
diff --git a/src/backend/optimizer/util/relnode.c b/src/backend/optimizer/util/relnode.c index 144fac75501..06a73bf4e9e 100644 --- a/src/backend/optimizer/util/relnode.c +++ b/src/backend/optimizer/util/relnode.c @@ -8,7 +8,7 @@ * * * IDENTIFICATION - * $Header: /cvsroot/pgsql/src/backend/optimizer/util/relnode.c,v 1.44 2003/01/20 18:54:56 tgl Exp $ + * $Header: /cvsroot/pgsql/src/backend/optimizer/util/relnode.c,v 1.45 2003/01/24 03:58:43 tgl Exp $ * *------------------------------------------------------------------------- */ @@ -549,14 +549,19 @@ subbuild_joinrel_joinlist(RelOptInfo *joinrel, /* * These clauses are still join clauses at this level, so find * or make the appropriate JoinInfo item for the joinrel, and - * add the clauses to it (eliminating duplicates). + * add the clauses to it, eliminating duplicates. (Since + * RestrictInfo nodes are normally multiply-linked rather than + * copied, pointer equality should be a sufficient test. If + * two equal() nodes should happen to sneak in, no great harm + * is done --- they'll be detected by redundant-clause testing + * when they reach a restriction list.) */ JoinInfo *new_joininfo; new_joininfo = make_joininfo_node(joinrel, new_unjoined_relids); new_joininfo->jinfo_restrictinfo = - set_union(new_joininfo->jinfo_restrictinfo, - joininfo->jinfo_restrictinfo); + set_ptrUnion(new_joininfo->jinfo_restrictinfo, + joininfo->jinfo_restrictinfo); } } } |