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The result of a FULL or RIGHT join can't be assumed to be sorted by the

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left input's sorting, because null rows may be inserted at various points.
Per report from Ferenc Lutischá¸n.
This commit is contained in:
Tom Lane
2005-01-23 02:21:36 +00:00
parent d08889aa8b
commit 94e4778a31
3 changed files with 16 additions and 5 deletions
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11
src/backend/optimizer/path/pathkeys.c
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@ -11,7 +11,7 @@
* Portions Copyright (c) 1994, Regents of the University of California
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/optimizer/path/pathkeys.c,v 1.63 2004/12/31 22:00:04 pgsql Exp $
* $PostgreSQL: pgsql/src/backend/optimizer/path/pathkeys.c,v 1.64 2005/01/23 02:21:26 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -858,7 +858,12 @@ build_subquery_pathkeys(Query *root, RelOptInfo *rel, Query *subquery)
* vars they were joined with; furthermore, it doesn't matter what kind
* of join algorithm is actually used.
*
* EXCEPTION: in a FULL or RIGHT join, we cannot treat the result as
* having the outer path's path keys, because null lefthand rows may be
* inserted at random points. It must be treated as unsorted.
*
* 'joinrel' is the join relation that paths are being formed for
* 'jointype' is the join type (inner, left, full, etc)
* 'outer_pathkeys' is the list of the current outer path's path keys
*
* Returns the list of new path keys.
@ -866,8 +871,12 @@ build_subquery_pathkeys(Query *root, RelOptInfo *rel, Query *subquery)
List *
build_join_pathkeys(Query *root,
RelOptInfo *joinrel,
JoinType jointype,
List *outer_pathkeys)
{
if (jointype == JOIN_FULL || jointype == JOIN_RIGHT)
return NIL;
/*
* This used to be quite a complex bit of code, but now that all
* pathkey sublists start out life canonicalized, we don't have to do