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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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19
src/backend/optimizer/plan/initsplan.c
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@@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/optimizer/plan/initsplan.c,v 1.48 2000/08/08 15:41:38 tgl Exp $
* $Header: /cvsroot/pgsql/src/backend/optimizer/plan/initsplan.c,v 1.49 2000/08/13 02:50:07 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@@ -184,7 +184,7 @@ add_restrict_and_join_to_rel(Query *root, Node *clause)
/*
* There is only one relation participating in 'clause', so
* 'clause' must be a restriction clause for that relation.
* 'clause' is a restriction clause for that relation.
*/
RelOptInfo *rel = get_base_rel(root, lfirsti(relids));
@@ -201,11 +201,11 @@ add_restrict_and_join_to_rel(Query *root, Node *clause)
*/
check_mergejoinable(restrictinfo);
}
else
else if (relids != NIL)
{
/*
* 'clause' is a join clause, since there is more than one atom in
* 'clause' is a join clause, since there is more than one rel in
* the relid list. Set additional RestrictInfo fields for
* joining.
*
@@ -219,8 +219,6 @@ add_restrict_and_join_to_rel(Query *root, Node *clause)
/*
* Add clause to the join lists of all the relevant relations.
* (If, perchance, 'clause' contains NO vars, then nothing will
* happen...)
*/
add_join_info_to_rels(root, restrictinfo, relids);
@@ -232,6 +230,15 @@ add_restrict_and_join_to_rel(Query *root, Node *clause)
*/
add_vars_to_targetlist(root, vars);
}
else
{
/*
* 'clause' references no rels, and therefore we have no place to
* attach it. This means query_planner() screwed up --- it should
* treat variable-less clauses separately.
*/
elog(ERROR, "add_restrict_and_join_to_rel: can't cope with variable-free clause");
}
/*
* If the clause has a mergejoinable operator, then the two sides