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Cache eval cost of qualification expressions in RestrictInfo nodes to

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avoid repeated evaluations in cost_qual_eval().  This turns out to save
a useful fraction of planning time.  No change to external representation
of RestrictInfo --- although that node type doesn't appear in stored
rules anyway.
This commit is contained in:
Tom Lane
2000-12-12 23:33:34 +00:00
parent 77c443f8cd
commit 17b843d677
7 changed files with 54 additions and 24 deletions
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10
src/include/nodes/relation.h
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@@ -7,7 +7,7 @@
* Portions Copyright (c) 1996-2000, PostgreSQL, Inc
* Portions Copyright (c) 1994, Regents of the University of California
*
* $Id: relation.h,v 1.50 2000/11/12 00:37:01 tgl Exp $
* $Id: relation.h,v 1.51 2000/12/12 23:33:32 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@@ -373,9 +373,9 @@ typedef JoinPath NestPath;
* A mergejoin path has these fields.
*
* path_mergeclauses lists the clauses (in the form of RestrictInfos)
* that will be used in the merge. (Before 7.0, this was a list of
* bare clause expressions, but we can save on list memory by leaving
* it in the form of a RestrictInfo list.)
* that will be used in the merge. (Before 7.0, this was a list of bare
* clause expressions, but we can save on list memory and cost_qual_eval
* work by leaving it in the form of a RestrictInfo list.)
*
* Note that the mergeclauses are a subset of the parent relation's
* restriction-clause list. Any join clauses that are not mergejoinable
@@ -491,6 +491,8 @@ typedef struct RestrictInfo
Expr *clause; /* the represented clause of WHERE or JOIN */
Cost eval_cost; /* eval cost of clause; -1 if not yet set */
bool ispusheddown; /* TRUE if clause was pushed down in level */
/* only used if clause is an OR clause: */