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Planner speedup hacking. Avoid saving useless pathkeys, so that path

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comparison does not consider paths different when they differ only in
uninteresting aspects of sort order.  (We had a special case of this
consideration for indexscans already, but generalize it to apply to
ordered join paths too.)  Be stricter about what is a canonical pathkey
to allow faster pathkey comparison.  Cache canonical pathkeys and
dispersion stats for left and right sides of a RestrictInfo's clause,
to avoid repeated computation.  Total speedup will depend on number of
tables in a query, but I see about 4x speedup of planning phase for
a sample seven-table query.
This commit is contained in:
Tom Lane
2000-12-14 22:30:45 +00:00
parent db11f4382a
commit ea166f1146
16 changed files with 622 additions and 365 deletions
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7
src/backend/nodes/copyfuncs.c
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@ -15,7 +15,7 @@
* Portions Copyright (c) 1994, Regents of the University of California
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/nodes/copyfuncs.c,v 1.134 2000/12/12 23:33:32 tgl Exp $
* $Header: /cvsroot/pgsql/src/backend/nodes/copyfuncs.c,v 1.135 2000/12/14 22:30:42 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -1424,7 +1424,12 @@ _copyRestrictInfo(RestrictInfo *from)
newnode->mergejoinoperator = from->mergejoinoperator;
newnode->left_sortop = from->left_sortop;
newnode->right_sortop = from->right_sortop;
/* Do not copy pathkeys, since they'd not be canonical in a copied query */
newnode->left_pathkey = NIL;
newnode->right_pathkey = NIL;
newnode->hashjoinoperator = from->hashjoinoperator;
newnode->left_dispersion = from->left_dispersion;
newnode->right_dispersion = from->right_dispersion;
return newnode;
}