8000 The result of a FULL or RIGHT join can't be assumed to be sorted by the · larkly/postgres-docker@66bb44c · GitHub
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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.
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3 files changed

+16
-5
lines changed

3 files changed

+16
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lines changed

‎src/backend/optimizer/path/joinpath.c

Lines changed: 4 additions & 3 deletions
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* $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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@@ -8,7 +8,7 @@
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*
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*
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* IDENTIFICATION
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* $Header: /cvsroot/pgsql/src/backend/optimizer/path/joinpath.c,v 1.67 2001/11/11 19:18:54 tgl Exp $
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*
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*-------------------------------------------------------------------------
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*/
@@ -253,7 +253,8 @@ sort_inner_and_outer(Query *root,
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cur_mergeclauses,
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innerrel);
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/* Build pathkeys representing output sort order. */
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merge_pathkeys = build_join_pathkeys(root, joinrel, outerkeys);
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merge_pathkeys = build_join_pathkeys(root, joinrel, jointype,
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outerkeys);
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/*
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* And now we can make the path. We only consider the cheapest-
@@ -371,7 +372,7 @@ match_unsorted_outer(Query *root,
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* as a nestloop, and even if some of the mergeclauses are
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* implemented by qpquals rather than as true mergeclauses):
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*/
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merge_pathkeys = build_jo 8000 in_pathkeys(root, joinrel,
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merge_pathkeys = build_join_pathkeys(root, joinrel, jointype,
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outerpath->pathkeys);
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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 @@
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* Portions Copyright (c) 1994, Regents of the University of California
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*
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* IDENTIFICATION
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* $Header: /cvsroot/pgsql/src/backend/optimizer/path/pathkeys.c,v 1.36 2001/11/11 20:33:53 tgl Exp $
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* $Header: /cvsroot/pgsql/src/backend/optimizer/path/pathkeys.c,v 1.36.2.1 2005/01/23 02:25:30 tgl Exp $
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*
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*-------------------------------------------------------------------------
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*/
@@ -621,16 +621,25 @@ find_indexkey_var(Query *root, RelOptInfo *rel, AttrNumber varattno)
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* vars they were joined with; furthermore, it doesn't matter what kind
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* of join algorithm is actually used.
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*
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* EXCEPTION: in a FULL or RIGHT join, we cannot treat the result as
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* having the outer path's path keys, because null lefthand rows may be
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* inserted at random points. It must be treated as unsorted.
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*
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* 'joinrel' is the join relation that paths are being formed for
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* 'jointype' is the join type (inner, left, full, etc)
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* 'outer_pathkeys' is the list of the current outer path's path keys
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*
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* Returns the list of new path keys.
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*/
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List *
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build_join_pathkeys(Query *root,
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RelOptInfo *joinrel,
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JoinType jointype,
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List *outer_pathkeys)
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{
640+
if (jointype == JOIN_FULL 8000 || jointype == JOIN_RIGHT)
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return NIL;
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/*
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* This used to be quite a complex bit of code, but now that all
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* 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 @@
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* Portions Copyright (c) 1996-2001, PostgreSQL Global Development Group
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* Portions Copyright (c) 1994, Regents of the University of California
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*
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* $Id: paths.h,v 1.59 2001/11/05 17:46:34 momjian Exp $
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* $Id: paths.h,v 1.59.2.1 2005/01/23 02:26:05 tgl Exp $
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*
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*-------------------------------------------------------------------------
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*/
@@ -112,6 +112,7 @@ extern List *build_index_pathkeys(Query *root, RelOptInfo *rel,
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ScanDirection scandir);
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extern List *build_join_pathkeys(Query *root,
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RelOptInfo *joinrel,
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JoinType jointype,
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List *outer_pathkeys);
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extern List *make_pathkeys_for_sortclauses(List *sortclauses,
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List *tlist);

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