From 34f8ee973742d6a72840184c15aff7718022fae7 Mon Sep 17 00:00:00 2001
From: Tom Lane <tgl@sss.pgh.pa.us>
Date: Sat, 14 Jan 2006 00:14:12 +0000
Subject: [PATCH] Add selectivity-calculation code for RowCompareExpr nodes.
Simplistic, but a lot better than nothing at all ...
---
src/backend/optimizer/path/clausesel.c | 10 ++++-
src/backend/utils/adt/selfuncs.c | 61 +++++++++++++++++++++++++-
src/include/utils/selfuncs.h | 5 ++-
3 files changed, 73 insertions(+), 3 deletions(-)
diff --git a/src/backend/optimizer/path/clausesel.c b/src/backend/optimizer/path/clausesel.c
index eba6bf1d148..d3e28dc9650 100644
--- a/src/backend/optimizer/path/clausesel.c
+++ b/src/backend/optimizer/path/clausesel.c
@@ -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 */
diff --git a/src/backend/utils/adt/selfuncs.c b/src/backend/utils/adt/selfuncs.c
index 20ae7ddc1c4..336c1deaeaa 100644
--- a/src/backend/utils/adt/selfuncs.c
+++ b/src/backend/utils/adt/selfuncs.c
@@ -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 "="
*/
diff --git a/src/include/utils/selfuncs.h b/src/include/utils/selfuncs.h
index 2c021ad2502..541b58e5467 100644
--- a/src/include/utils/selfuncs.h
+++ b/src/include/utils/selfuncs.h
@@ -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,
--
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