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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/readfuncs.c
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@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/nodes/readfuncs.c,v 1.101 2000/12/12 23:33:33 tgl Exp $
* $Header: /cvsroot/pgsql/src/backend/nodes/readfuncs.c,v 1.102 2000/12/14 22:30:42 tgl Exp $
*
* NOTES
* Most of the read functions for plan nodes are tested. (In fact, they
@ -1848,6 +1848,11 @@ _readRestrictInfo(void)
/* eval_cost is not part of saved representation; compute on first use */
local_node->eval_cost = -1;
/* ditto for cached pathkeys and dispersion */
local_node->left_pathkey = NIL;
local_node->right_pathkey = NIL;
local_node->left_dispersion = -1;
local_node->right_dispersion = -1;
return local_node;
}