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/nodes/list.c | 18 +++++++++++++++++- 1 file changed, 17 insertions(+), 1 deletion(-) (limited to 'src/backend/nodes/list.c') diff --git a/src/backend/nodes/list.c b/src/backend/nodes/list.c index e896b479018..bf9e5c10d6f 100644 --- a/src/backend/nodes/list.c +++ b/src/backend/nodes/list.c @@ -8,7 +8,7 @@ * * * IDENTIFICATION - * $Header: /cvsroot/pgsql/src/backend/nodes/list.c,v 1.44 2003/01/20 18:54:47 tgl Exp $ + * $Header: /cvsroot/pgsql/src/backend/nodes/list.c,v 1.45 2003/01/24 03:58:34 tgl Exp $ * * NOTES * XXX a few of the following functions are duplicated to handle @@ -357,6 +357,7 @@ set_union(List *l1, List *l2) return retval; } +/* set_union for integer lists */ List * set_unioni(List *l1, List *l2) { @@ -371,6 +372,21 @@ set_unioni(List *l1, List *l2) return retval; } +/* set_union when pointer-equality comparison is sufficient */ +List * +set_ptrUnion(List *l1, List *l2) +{ + List *retval = listCopy(l1); + List *i; + + foreach(i, l2) + { + if (!ptrMember(lfirst(i), retval)) + retval = lappend(retval, lfirst(i)); + } + return retval; +} + /* * Generate the intersection of two lists, * ie, all members of both l1 and l2. -- cgit v1.2.3