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authorTom Lane <tgl@sss.pgh.pa.us>2005-03-28 00:58:26 +0000
committerTom Lane <tgl@sss.pgh.pa.us>2005-03-28 00:58:26 +0000
commit5db2e83852cc3f25fdea48c4aa0da8696c88a826 (patch)
tree1b6db39b1a6af12052bb93f1a7892a46a0a504d7 /src/backend/utils/cache/relcache.c
parentbf3dbb5881e9b886ee9fe84bca2153c698eea885 (diff)
downloadpostgresql-5db2e83852cc3f25fdea48c4aa0da8696c88a826.tar.gz
postgresql-5db2e83852cc3f25fdea48c4aa0da8696c88a826.zip
Rethink the order of expression preprocessing: eval_const_expressions
really ought to run before canonicalize_qual, because it can now produce forms that canonicalize_qual knows how to improve (eg, NOT clauses). Also, because eval_const_expressions already knows about flattening nested ANDs and ORs into N-argument form, the initial flatten_andors pass in canonicalize_qual is now completely redundant and can be removed. This doesn't save a whole lot of code, but the time and palloc traffic eliminated is a useful gain on large expression trees.
Diffstat (limited to 'src/backend/utils/cache/relcache.c')
-rw-r--r--src/backend/utils/cache/relcache.c29
1 files changed, 14 insertions, 15 deletions
diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c
index d1143381d2d..a6660fc4d32 100644
--- a/src/backend/utils/cache/relcache.c
+++ b/src/backend/utils/cache/relcache.c
@@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
- * $PostgreSQL: pgsql/src/backend/utils/cache/relcache.c,v 1.216 2005/03/07 04:42:16 tgl Exp $
+ * $PostgreSQL: pgsql/src/backend/utils/cache/relcache.c,v 1.217 2005/03/28 00:58:26 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@@ -2788,14 +2788,11 @@ RelationGetIndexExpressions(Relation relation)
pfree(exprsString);
/*
- * Run the expressions through flatten_andors and
- * eval_const_expressions. This is not just an optimization, but is
- * necessary, because the planner will be comparing them to
- * similarly-processed qual clauses, and may fail to detect valid
- * matches without this.
+ * Run the expressions through eval_const_expressions. This is not just an
+ * optimization, but is necessary, because the planner will be comparing
+ * them to similarly-processed qual clauses, and may fail to detect valid
+ * matches without this. We don't bother with canonicalize_qual, however.
*/
- result = (List *) flatten_andors((Node *) result);
-
result = (List *) eval_const_expressions((Node *) result);
/*
@@ -2863,16 +2860,18 @@ RelationGetIndexPredicate(Relation relation)
pfree(predString);
/*
- * Run the expression through canonicalize_qual and
- * eval_const_expressions. This is not just an optimization, but is
- * necessary, because the planner will be comparing it to
- * similarly-processed qual clauses, and may fail to detect valid
- * matches without this.
+ * Run the expression through const-simplification and canonicalization.
+ * This is not just an optimization, but is necessary, because the planner
+ * will be comparing it to similarly-processed qual clauses, and may fail
+ * to detect valid matches without this. This must match the processing
+ * done to qual clauses in preprocess_expression()! (We can skip the
+ * stuff involving subqueries, however, since we don't allow any in
+ * index predicates.)
*/
- result = (List *) canonicalize_qual((Expr *) result);
-
result = (List *) eval_const_expressions((Node *) result);
+ result = (List *) canonicalize_qual((Expr *) result);
+
/*
* Also mark any coercion format fields as "don't care", so that the
* planner can match to both explicit and implicit coercions.