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Clean up handling of variable-free qual clauses. System now does the

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right thing with variable-free clauses that contain noncachable functions,
such as 'WHERE random() < 0.5' --- these are evaluated once per
potential output tuple.  Expressions that contain only Params are
now candidates to be indexscan quals --- for example, 'var = ($1 + 1)'
can now be indexed.  Cope with RelabelType nodes atop potential indexscan
variables --- this oversight prevents 7.0.* from recognizing some
potentially indexscanable situations.
This commit is contained in:
Tom Lane
2000-08-13 02:50:35 +00:00
parent 766fb7f707
commit 37168b8da4
15 changed files with 410 additions and 177 deletions
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13
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 1.38 2000/06/08 22:37:09 momjian Exp $
* $Header: /cvsroot/pgsql/src/backend/optimizer/path/clausesel.c,v 1.39 2000/08/13 02:50:04 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@@ -123,7 +123,7 @@ clauselist_selectivity(Query *root,
Selectivity s2;
/*
* See if it looks like a restriction clause with a Const or Param
* See if it looks like a restriction clause with a pseudoconstant
* on one side. (Anything more complicated than that might not
* behave in the simple way we are expecting.)
*
@@ -146,7 +146,7 @@ clauselist_selectivity(Query *root,
other = (flag & SEL_RIGHT) ? get_rightop((Expr *) clause) :
get_leftop((Expr *) clause);
if (IsA(other, Const) || IsA(other, Param))
if (is_pseudo_constant_clause((Node *) other))
{
Oid opno = ((Oper *) ((Expr *) clause)->oper)->opno;
RegProcedure oprrest = get_oprrest(opno);
@@ -533,6 +533,13 @@ clause_selectivity(Query *root,
*/
s1 = 1.0;
}
else if (IsA(clause, RelabelType))
{
/* Not sure this case is needed, but it can't hurt */
s1 = clause_selectivity(root,
((RelabelType *) clause)->arg,
varRelid);
}
return s1;
}