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Add selectivity-calculation code for RowCompareExpr nodes. Simplistic, 

but a lot better than nothing at all ...
This commit is contained in:
Tom Lane 2006-01-14 00:14:12 +00:00
parent 39fc1fb07a
commit 34f8ee9737
3 changed files with 73 additions and 3 deletions
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10
src/backend/optimizer/path/clausesel.c
View File

@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/optimizer/path/clausesel.c,v 1.76 2005/11/25 19:47:49 tgl Exp $
* $PostgreSQL: pgsql/src/backend/optimizer/path/clausesel.c,v 1.77 2006/01/14 00:14:11 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -663,6 +663,14 @@ clause_selectivity(PlannerInfo *root,
varRelid,
jointype);
}
else if (IsA(clause, RowCompareExpr))
{
/* Use node specific selectivity calculation function */
s1 = rowcomparesel(root,
(RowCompareExpr *) clause,
varRelid,
jointype);
}
else if (IsA(clause, NullTest))
{
/* Use node specific selectivity calculation function */

61
src/backend/utils/adt/selfuncs.c
View File

@ -15,7 +15,7 @@
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/utils/adt/selfuncs.c,v 1.195 2006/01/10 17:35:52 tgl Exp $
* $PostgreSQL: pgsql/src/backend/utils/adt/selfuncs.c,v 1.196 2006/01/14 00:14:11 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -1566,6 +1566,65 @@ scalararraysel(PlannerInfo *root,
return s1;
}
/*
* rowcomparesel - Selectivity of RowCompareExpr Node.
*
* We estimate RowCompare selectivity by considering just the first (high
* order) columns, which makes it equivalent to an ordinary OpExpr. While
* this estimate could be refined by considering additional columns, it
* seems unlikely that we could do a lot better without multi-column
* statistics.
*/
Selectivity
rowcomparesel(PlannerInfo *root,
RowCompareExpr *clause,
int varRelid, JoinType jointype)
{
Selectivity s1;
Oid opno = linitial_oid(clause->opnos);
List *opargs;
bool is_join_clause;
/* Build equivalent arg list for single operator */
opargs = list_make2(linitial(clause->largs), linitial(clause->rargs));
/* Decide if it's a join clause, same as for OpExpr */
if (varRelid != 0)
{
/*
* If we are considering a nestloop join then all clauses are
* restriction clauses, since we are only interested in the one
* relation.
*/
is_join_clause = false;
}
else
{
/*
* Otherwise, it's a join if there's more than one relation used.
* Notice we ignore the low-order columns here.
*/
is_join_clause = (NumRelids((Node *) opargs) > 1);
}
if (is_join_clause)
{
/* Estimate selectivity for a join clause. */
s1 = join_selectivity(root, opno,
opargs,
jointype);
}
else
{
/* Estimate selectivity for a restriction clause. */
s1 = restriction_selectivity(root, opno,
opargs,
varRelid);
}
return s1;
}
/*
* eqjoinsel - Join selectivity of "="
*/

5
src/include/utils/selfuncs.h
View File

@ -8,7 +8,7 @@
* Portions Copyright (c) 1996-2005, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
* $PostgreSQL: pgsql/src/include/utils/selfuncs.h,v 1.26 2005/11/25 19:47:50 tgl Exp $
* $PostgreSQL: pgsql/src/include/utils/selfuncs.h,v 1.27 2006/01/14 00:14:12 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -116,6 +116,9 @@ extern Selectivity scalararraysel(PlannerInfo *root,
ScalarArrayOpExpr *clause,
bool is_join_clause,
int varRelid, JoinType jointype);
extern Selectivity rowcomparesel(PlannerInfo *root,
RowCompareExpr *clause,
int varRelid, JoinType jointype);
extern void mergejoinscansel(PlannerInfo *root, Node *clause,
Selectivity *leftscan,