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Ensure clause_selectivity() behaves sanely when examining an uplevel Var 

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 * 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; return s1;
if (IsA(clause, Var)) if (IsA(clause, Var))
{ {
Var *var = (Var *) clause;
/* /*
* we have a bool Var. This is exactly equivalent to the clause: * We probably shouldn't ever see an uplevel Var here, but if we
* reln.attribute = 't' so we compute the selectivity as if that * do, return the default selectivity...
* 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.
*/ */
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) if (rte->subquery)
s1 = restriction_selectivity(F_EQSEL, {
BooleanEqualOperator, /*
getrelid(varno, root->rtable), * XXX not smart about subquery references...
((Var *) clause)->varattno, * any way to do better?
BoolGetDatum(true), */
SEL_CONSTANT | SEL_RIGHT); s1 = 0.5;
/* an outer-relation bool var is taken as always true... */ }
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)) else if (IsA(clause, Param))
{ {