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Commit66bb44c

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The result of a FULL or RIGHT join can't be assumed to be sorted by the
left input's sorting, because null rows may be inserted at various points.Per report from Ferenc Lutischá¸n.
1 parent2b47146 commit66bb44c

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3 files changed

+16
-5
lines changed

3 files changed

+16
-5
lines changed

‎src/backend/optimizer/path/joinpath.c

Lines changed: 4 additions & 3 deletions
Original file line numberDiff line numberDiff line change
@@ -8,7 +8,7 @@
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*
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*
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* IDENTIFICATION
11-
* $Header: /cvsroot/pgsql/src/backend/optimizer/path/joinpath.c,v 1.67 2001/11/11 19:18:54 tgl Exp $
11+
* $Header: /cvsroot/pgsql/src/backend/optimizer/path/joinpath.c,v 1.67.2.1 2005/01/23 02:25:25 tgl Exp $
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*
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*-------------------------------------------------------------------------
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*/
@@ -253,7 +253,8 @@ sort_inner_and_outer(Query *root,
253253
cur_mergeclauses,
254254
innerrel);
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/* Build pathkeys representing output sort order. */
256-
merge_pathkeys=build_join_pathkeys(root,joinrel,outerkeys);
256+
merge_pathkeys=build_join_pathkeys(root,joinrel,jointype,
257+
outerkeys);
257258

258259
/*
259260
* And now we can make the path. We only consider the cheapest-
@@ -371,7 +372,7 @@ match_unsorted_outer(Query *root,
371372
* as a nestloop, and even if some of the mergeclauses are
372373
* implemented by qpquals rather than as true mergeclauses):
373374
*/
374-
merge_pathkeys=build_join_pathkeys(root,joinrel,
375+
merge_pathkeys=build_join_pathkeys(root,joinrel,jointype,
375376
outerpath->pathkeys);
376377

377378
if (nestjoinOK)

‎src/backend/optimizer/path/pathkeys.c

Lines changed: 10 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -11,7 +11,7 @@
1111
* Portions Copyright (c) 1994, Regents of the University of California
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*
1313
* IDENTIFICATION
14-
* $Header: /cvsroot/pgsql/src/backend/optimizer/path/pathkeys.c,v 1.36 2001/11/11 20:33:53 tgl Exp $
14+
* $Header: /cvsroot/pgsql/src/backend/optimizer/path/pathkeys.c,v 1.36.2.1 2005/01/23 02:25:30 tgl Exp $
1515
*
1616
*-------------------------------------------------------------------------
1717
*/
@@ -621,16 +621,25 @@ find_indexkey_var(Query *root, RelOptInfo *rel, AttrNumber varattno)
621621
* vars they were joined with; furthermore, it doesn't matter what kind
622622
* of join algorithm is actually used.
623623
*
624+
* EXCEPTION: in a FULL or RIGHT join, we cannot treat the result as
625+
* having the outer path's path keys, because null lefthand rows may be
626+
* inserted at random points. It must be treated as unsorted.
627+
*
624628
* 'joinrel' is the join relation that paths are being formed for
629+
* 'jointype' is the join type (inner, left, full, etc)
625630
* 'outer_pathkeys' is the list of the current outer path's path keys
626631
*
627632
* Returns the list of new path keys.
628633
*/
629634
List*
630635
build_join_pathkeys(Query*root,
631636
RelOptInfo*joinrel,
637+
JoinTypejointype,
632638
List*outer_pathkeys)
633639
{
640+
if (jointype==JOIN_FULL||jointype==JOIN_RIGHT)
641+
returnNIL;
642+
634643
/*
635644
* This used to be quite a complex bit of code, but now that all
636645
* pathkey sublists start out life canonicalized, we don't have to do

‎src/include/optimizer/paths.h

Lines changed: 2 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -8,7 +8,7 @@
88
* Portions Copyright (c) 1996-2001, PostgreSQL Global Development Group
99
* Portions Copyright (c) 1994, Regents of the University of California
1010
*
11-
* $Id: paths.h,v 1.59 2001/11/05 17:46:34 momjian Exp $
11+
* $Id: paths.h,v 1.59.2.1 2005/01/23 02:26:05 tgl Exp $
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*
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*-------------------------------------------------------------------------
1414
*/
@@ -112,6 +112,7 @@ extern List *build_index_pathkeys(Query *root, RelOptInfo *rel,
112112
ScanDirectionscandir);
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externList*build_join_pathkeys(Query*root,
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RelOptInfo*joinrel,
115+
JoinTypejointype,
115116
List*outer_pathkeys);
116117
externList*make_pathkeys_for_sortclauses(List*sortclauses,
117118
List*tlist);

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