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Restructure planning code so that preprocessing of targetlist and quals

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to simplify constant expressions and expand SubLink nodes into SubPlans
is done in a separate routine subquery_planner() that calls union_planner().
We formerly did most of this work in query_planner(), but that's the
wrong place because it may never see the real targetlist.  Splitting
union_planner into two routines also allows us to avoid redundant work
when union_planner is invoked recursively for UNION and inheritance
cases.  Upshot is that it is now possible to do something like
select float8(count(*)) / (select count(*) from int4_tbl)  from int4_tbl
group by f1;
which has never worked before.
This commit is contained in:
Tom Lane
2000-03-21 05:12:12 +00:00
parent aafe86d995
commit 3ee8f7e207
8 changed files with 191 additions and 166 deletions
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3
src/include/optimizer/planner.h
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@@ -7,7 +7,7 @@
* Portions Copyright (c) 1996-2000, PostgreSQL, Inc
* Portions Copyright (c) 1994, Regents of the University of California
*
* $Id: planner.h,v 1.14 2000/02/15 20:49:26 tgl Exp $
* $Id: planner.h,v 1.15 2000/03/21 05:11:51 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@@ -21,6 +21,7 @@
#include "nodes/plannodes.h"
extern Plan *planner(Query *parse);
extern Plan *subquery_planner(Query *parse, double tuple_fraction);
extern Plan *union_planner(Query *parse, double tuple_fraction);
extern void pg_checkretval(Oid rettype, List *querytree_list);