From 17b843d67718a716c1abb4afd2abf8a5edba9f32 Mon Sep 17 00:00:00 2001
From: Tom Lane <tgl@sss.pgh.pa.us>
Date: Tue, 12 Dec 2000 23:33:34 +0000
Subject: [PATCH] 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.
---
src/backend/nodes/copyfuncs.c | 3 +-
src/backend/nodes/equalfuncs.c | 6 +++-
src/backend/nodes/readfuncs.c | 5 ++-
src/backend/optimizer/path/costsize.c | 46 ++++++++++++++++++--------
src/backend/optimizer/plan/initsplan.c | 3 +-
src/backend/optimizer/prep/prepunion.c | 5 +--
src/include/nodes/relation.h | 10 +++---
7 files changed, 54 insertions(+), 24 deletions(-)
diff --git a/src/backend/nodes/copyfuncs.c b/src/backend/nodes/copyfuncs.c
index 1e03e04418..3e4a6d91dd 100644
--- a/src/backend/nodes/copyfuncs.c
+++ b/src/backend/nodes/copyfuncs.c
@@ -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;
diff --git a/src/backend/nodes/equalfuncs.c b/src/backend/nodes/equalfuncs.c
index 51dbd24976..2f6a93b95b 100644
--- a/src/backend/nodes/equalfuncs.c
+++ b/src/backend/nodes/equalfuncs.c
@@ -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))
diff --git a/src/backend/nodes/readfuncs.c b/src/backend/nodes/readfuncs.c
index 6a6dce48bf..d8aa2a5d2d 100644
--- a/src/backend/nodes/readfuncs.c
+++ b/src/backend/nodes/readfuncs.c
@@ -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;
}
diff --git a/src/backend/optimizer/path/costsize.c b/src/backend/optimizer/path/costsize.c
index 8251b8d451..c19ae3883d 100644
--- a/src/backend/optimizer/path/costsize.c
+++ b/src/backend/optimizer/path/costsize.c
@@ -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);
}
diff --git a/src/backend/optimizer/plan/initsplan.c b/src/backend/optimizer/plan/initsplan.c
index ee037c750b..12698f5e5f 100644
--- a/src/backend/optimizer/plan/initsplan.c
+++ b/src/backend/optimizer/plan/initsplan.c
@@ -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;
diff --git a/src/backend/optimizer/prep/prepunion.c b/src/backend/optimizer/prep/prepunion.c
index ebb09f5939..d52ed8fb92 100644
--- a/src/backend/optimizer/prep/prepunion.c
+++ b/src/backend/optimizer/prep/prepunion.c
@@ -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;
}
diff --git a/src/include/nodes/relation.h b/src/include/nodes/relation.h
index 45d53be5f6..366392df0d 100644
--- a/src/include/nodes/relation.h
+++ b/src/include/nodes/relation.h
@@ -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: */
--
2.40.0