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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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4
src/backend/optimizer/plan/subselect.c
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@@ -7,7 +7,7 @@
* Portions Copyright (c) 1994, Regents of the University of California
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/optimizer/plan/subselect.c,v 1.32 2000/03/17 02:36:15 tgl Exp $
* $Header: /cvsroot/pgsql/src/backend/optimizer/plan/subselect.c,v 1.33 2000/03/21 05:12:02 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@@ -163,7 +163,7 @@ make_subplan(SubLink *slink)
else
tuple_fraction = -1.0; /* default behavior */
node->plan = plan = union_planner(subquery, tuple_fraction);
node->plan = plan = subquery_planner(subquery, tuple_fraction);
/*
* Assign subPlan, extParam and locParam to plan nodes. At the moment,