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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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6
src/backend/optimizer/prep/prepunion.c
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@@ -14,7 +14,7 @@
*
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/optimizer/prep/prepunion.c,v 1.57 2000/12/12 23:33:34 tgl Exp $
* $Header: /cvsroot/pgsql/src/backend/optimizer/prep/prepunion.c,v 1.58 2000/12/14 22:30:44 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@@ -667,6 +667,10 @@ adjust_inherited_attrs_mutator(Node *node,
newinfo->subclauseindices = NIL;
newinfo->eval_cost = -1; /* reset this too */
newinfo->left_pathkey = NIL; /* and these */
newinfo->right_pathkey = NIL;
newinfo->left_dispersion = -1;
newinfo->right_dispersion = -1;
return (Node *) newinfo;
}