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Ensure clause_selectivity() behaves sanely when examining an uplevel Var

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or a Var that references a subquery output.
This commit is contained in:
Tom Lane
2000-10-25 21:48:12 +00:00
parent 4ad9fe4ce5
commit 09a8912f73
1 changed files with 31 additions and 15 deletions
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46
src/backend/optimizer/path/clausesel.c
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@@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/optimizer/path/clausesel.c,v 1.39 2000/08/13 02:50:04 tgl Exp $
* $Header: /cvsroot/pgsql/src/backend/optimizer/path/clausesel.c,v 1.40 2000/10/25 21:48:12 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@@ -371,24 +371,40 @@ clause_selectivity(Query *root,
return s1;
if (IsA(clause, Var))
{
Var *var = (Var *) clause;
/*
* we have a bool Var. This is exactly equivalent to the clause:
* reln.attribute = 't' so we compute the selectivity as if that
* is what we have. The magic #define constants are a hack. I
* didn't want to have to do system cache look ups to find out all
* of that info.
* We probably shouldn't ever see an uplevel Var here, but if we
* do, return the default selectivity...
*/
Index varno = ((Var *) clause)->varno;
if (var->varlevelsup == 0 &&
(varRelid == 0 || varRelid == (int) var->varno))
{
RangeTblEntry *rte = rt_fetch(var->varno, root->rtable);
if (varRelid == 0 || varRelid == (int) varno)
s1 = restriction_selectivity(F_EQSEL,
BooleanEqualOperator,
getrelid(varno, root->rtable),
((Var *) clause)->varattno,
BoolGetDatum(true),
SEL_CONSTANT | SEL_RIGHT);
/* an outer-relation bool var is taken as always true... */
if (rte->subquery)
{
/*
* XXX not smart about subquery references...
* any way to do better?
*/
s1 = 0.5;
}
else
{
/*
* A Var at the top of a clause must be a bool Var.
* This is equivalent to the clause reln.attribute = 't',
* so we compute the selectivity as if that is what we have.
*/
s1 = restriction_selectivity(F_EQSEL,
BooleanEqualOperator,
rte->relid,
var->varattno,
BoolGetDatum(true),
SEL_CONSTANT | SEL_RIGHT);
}
}
}
else if (IsA(clause, Param))
{