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Cache eval cost of qualification expressions in RestrictInfo nodes to 

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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3
src/backend/nodes/copyfuncs.c
View File

@ -15,7 +15,7 @@
* Portions Copyright (c) 1994, Regents of the University of California
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/nodes/copyfuncs.c,v 1.133 2000/11/24 20:16:39 petere Exp $
* $Header: /cvsroot/pgsql/src/backend/nodes/copyfuncs.c,v 1.134 2000/12/12 23:33:32 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -1418,6 +1418,7 @@ _copyRestrictInfo(RestrictInfo *from)
* ----------------
*/
Node_Copy(from, newnode, clause);
newnode->eval_cost = from->eval_cost;
newnode->ispusheddown = from->ispusheddown;
Node_Copy(from, newnode, subclauseindices);
newnode->mergejoinoperator = from->mergejoinoperator;

6
src/backend/nodes/equalfuncs.c
View File

@ -20,7 +20,7 @@
* Portions Copyright (c) 1994, Regents of the University of California
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/nodes/equalfuncs.c,v 1.83 2000/11/24 20:16:39 petere Exp $
* $Header: /cvsroot/pgsql/src/backend/nodes/equalfuncs.c,v 1.84 2000/12/12 23:33:33 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -514,6 +514,10 @@ _equalRestrictInfo(RestrictInfo *a, RestrictInfo *b)
{
if (!equal(a->clause, b->clause))
return false;
/*
* ignore eval_cost, since it may not be set yet, and should be
* derivable from the clause anyway
*/
if (a->ispusheddown != b->ispusheddown)
return false;
if (!equal(a->subclauseindices, b->subclauseindices))

5
src/backend/nodes/readfuncs.c
View File

@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/nodes/readfuncs.c,v 1.100 2000/11/12 00:36:57 tgl Exp $
* $Header: /cvsroot/pgsql/src/backend/nodes/readfuncs.c,v 1.101 2000/12/12 23:33:33 tgl Exp $
*
* NOTES
* Most of the read functions for plan nodes are tested. (In fact, they
@ -1846,6 +1846,9 @@ _readRestrictInfo(void)
token = lsptok(NULL, &length); /* now read it */
local_node->hashjoinoperator = (Oid) atol(token);
/* eval_cost is not part of saved representation; compute on first use */
local_node->eval_cost = -1;
return local_node;
}

46
src/backend/optimizer/path/costsize.c
View File

@ -42,7 +42,7 @@
* Portions Copyright (c) 1994, Regents of the University of California
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/optimizer/path/costsize.c,v 1.64 2000/10/05 19:48:26 momjian Exp $
* $Header: /cvsroot/pgsql/src/backend/optimizer/path/costsize.c,v 1.65 2000/12/12 23:33:33 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -672,8 +672,38 @@ Cost
cost_qual_eval(List *quals)
{
Cost total = 0;
List *l;
cost_qual_eval_walker((Node *) quals, &total);
/* We don't charge any cost for the implicit ANDing at top level ... */
foreach(l, quals)
{
Node *qual = (Node *) lfirst(l);
/*
* RestrictInfo nodes contain an eval_cost field reserved for this
* routine's use, so that it's not necessary to evaluate the qual
* clause's cost more than once. If the clause's cost hasn't been
* computed yet, the field will contain -1.
*/
if (qual && IsA(qual, RestrictInfo))
{
RestrictInfo *restrictinfo = (RestrictInfo *) qual;
if (restrictinfo->eval_cost < 0)
{
restrictinfo->eval_cost = 0;
cost_qual_eval_walker((Node *) restrictinfo->clause,
&restrictinfo->eval_cost);
}
total += restrictinfo->eval_cost;
}
else
{
/* If it's a bare expression, must always do it the hard way */
cost_qual_eval_walker(qual, &total);
}
}
return total;
}
@ -748,18 +778,6 @@ cost_qual_eval_walker(Node *node, Cost *total)
}
/* fall through to examine args of Expr node */
}
/*
* expression_tree_walker doesn't know what to do with RestrictInfo
* nodes, but we just want to recurse through them.
*/
if (IsA(node, RestrictInfo))
{
RestrictInfo *restrictinfo = (RestrictInfo *) node;
return cost_qual_eval_walker((Node *) restrictinfo->clause, total);
}
/* Otherwise, recurse. */
return expression_tree_walker(node, cost_qual_eval_walker,
(void *) total);
}

3
src/backend/optimizer/plan/initsplan.c
View File

@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/optimizer/plan/initsplan.c,v 1.53 2000/11/23 03:57:31 tgl Exp $
* $Header: /cvsroot/pgsql/src/backend/optimizer/plan/initsplan.c,v 1.54 2000/12/12 23:33:33 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -338,6 +338,7 @@ distribute_qual_to_rels(Query *root, Node *clause,
bool can_be_equijoin;
restrictinfo->clause = (Expr *) clause;
restrictinfo->eval_cost = -1; /* not computed until needed */
restrictinfo->subclauseindices = NIL;
restrictinfo->mergejoinoperator = InvalidOid;
restrictinfo->left_sortop = InvalidOid;

5
src/backend/optimizer/prep/prepunion.c
View File

@ -14,7 +14,7 @@
*
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/optimizer/prep/prepunion.c,v 1.56 2000/11/12 00:36:59 tgl Exp $
* $Header: /cvsroot/pgsql/src/backend/optimizer/prep/prepunion.c,v 1.57 2000/12/12 23:33:34 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -652,7 +652,7 @@ adjust_inherited_attrs_mutator(Node *node,
/*
* We have to process RestrictInfo nodes specially: we do NOT want to
* copy the original subclauseindices list, since the new rel may have
* different indices. The list will be rebuilt during planning anyway.
* different indices. The list will be rebuilt during later planning.
*/
if (IsA(node, RestrictInfo))
{
@ -666,6 +666,7 @@ adjust_inherited_attrs_mutator(Node *node,
adjust_inherited_attrs_mutator((Node *) oldinfo->clause, context);
newinfo->subclauseindices = NIL;
newinfo->eval_cost = -1; /* reset this too */
return (Node *) newinfo;
}

10
src/include/nodes/relation.h
View File

@ -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: */