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Commit94e4778

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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 parentd08889a commit94e4778

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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 @@
88
*
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*
1010
* IDENTIFICATION
11-
* $PostgreSQL: pgsql/src/backend/optimizer/path/joinpath.c,v 1.91 2004/12/31 22:00:04 pgsql Exp $
11+
* $PostgreSQL: pgsql/src/backend/optimizer/path/joinpath.c,v 1.92 2005/01/23 02:21:26 tgl Exp $
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*
1313
*-------------------------------------------------------------------------
1414
*/
@@ -271,7 +271,8 @@ sort_inner_and_outer(Query *root,
271271
cur_mergeclauses,
272272
innerrel);
273273
/* Build pathkeys representing output sort order. */
274-
merge_pathkeys=build_join_pathkeys(root,joinrel,outerkeys);
274+
merge_pathkeys=build_join_pathkeys(root,joinrel,jointype,
275+
outerkeys);
275276

276277
/*
277278
* And now we can make the path.
@@ -431,7 +432,7 @@ match_unsorted_outer(Query *root,
431432
* as a nestloop, and even if some of the mergeclauses are
432433
* implemented by qpquals rather than as true mergeclauses):
433434
*/
434-
merge_pathkeys=build_join_pathkeys(root,joinrel,
435+
merge_pathkeys=build_join_pathkeys(root,joinrel,jointype,
435436
outerpath->pathkeys);
436437

437438
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
1212
*
1313
* IDENTIFICATION
14-
* $PostgreSQL: pgsql/src/backend/optimizer/path/pathkeys.c,v 1.63 2004/12/31 22:00:04 pgsql Exp $
14+
* $PostgreSQL: pgsql/src/backend/optimizer/path/pathkeys.c,v 1.64 2005/01/23 02:21:26 tgl Exp $
1515
*
1616
*-------------------------------------------------------------------------
1717
*/
@@ -858,16 +858,25 @@ build_subquery_pathkeys(Query *root, RelOptInfo *rel, Query *subquery)
858858
* vars they were joined with; furthermore, it doesn't matter what kind
859859
* of join algorithm is actually used.
860860
*
861+
* EXCEPTION: in a FULL or RIGHT join, we cannot treat the result as
862+
* having the outer path's path keys, because null lefthand rows may be
863+
* inserted at random points. It must be treated as unsorted.
864+
*
861865
* 'joinrel' is the join relation that paths are being formed for
866+
* 'jointype' is the join type (inner, left, full, etc)
862867
* 'outer_pathkeys' is the list of the current outer path's path keys
863868
*
864869
* Returns the list of new path keys.
865870
*/
866871
List*
867872
build_join_pathkeys(Query*root,
868873
RelOptInfo*joinrel,
874+
JoinTypejointype,
869875
List*outer_pathkeys)
870876
{
877+
if (jointype==JOIN_FULL||jointype==JOIN_RIGHT)
878+
returnNIL;
879+
871880
/*
872881
* This used to be quite a complex bit of code, but now that all
873882
* 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) 1996-2005, PostgreSQL Global Development Group
99
* Portions Copyright (c) 1994, Regents of the University of California
1010
*
11-
* $PostgreSQL: pgsql/src/include/optimizer/paths.h,v 1.77 2004/12/31 22:03:36pgsql Exp $
11+
* $PostgreSQL: pgsql/src/include/optimizer/paths.h,v 1.78 2005/01/23 02:21:36tgl Exp $
1212
*
1313
*-------------------------------------------------------------------------
1414
*/
@@ -114,6 +114,7 @@ extern List *build_subquery_pathkeys(Query *root, RelOptInfo *rel,
114114
Query*subquery);
115115
externList*build_join_pathkeys(Query*root,
116116
RelOptInfo*joinrel,
117+
JoinTypejointype,
117118
List*outer_pathkeys);
118119
externList*make_pathkeys_for_sortclauses(List*sortclauses,
119120
List*tlist);

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