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Commitecbed6e

Browse files
committed
create_unique_plan() should not discard existing output columns of the
subplan it starts with, as they may be needed at upper join levels.See comments added to code for the non-obvious reason why. Per bug reportfrom Robert Creager.
1 parentd862045 commitecbed6e

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5 files changed

+95
-38
lines changed

5 files changed

+95
-38
lines changed

‎src/backend/optimizer/plan/createplan.c‎

Lines changed: 69 additions & 32 deletions
Original file line numberDiff line numberDiff line change
@@ -10,7 +10,7 @@
1010
*
1111
*
1212
* IDENTIFICATION
13-
* $Header: /cvsroot/pgsql/src/backend/optimizer/plan/createplan.c,v 1.151 2003/08/04 02:40:00 momjian Exp $
13+
* $Header: /cvsroot/pgsql/src/backend/optimizer/plan/createplan.c,v 1.152 2003/08/07 19:20:22 tgl Exp $
1414
*
1515
*-------------------------------------------------------------------------
1616
*/
@@ -504,52 +504,87 @@ create_unique_plan(Query *root, UniquePath * best_path)
504504
{
505505
Plan*plan;
506506
Plan*subplan;
507-
List*sub_targetlist;
507+
List*uniq_exprs;
508+
intnumGroupCols;
509+
AttrNumber*groupColIdx;
510+
intgroupColPos;
511+
List*newtlist;
512+
intnextresno;
513+
boolnewitems;
508514
List*my_tlist;
509515
List*l;
510516

511517
subplan=create_plan(root,best_path->subpath);
512518

513519
/*
514-
* If the subplan came from an IN subselect (currently always the
515-
* case), we need to instantiate the correct output targetlist for the
516-
* subselect, rather than using the flattened tlist.
520+
* As constructed, the subplan has a "flat" tlist containing just the
521+
* Vars needed here and at upper levels. The values we are supposed
522+
* to unique-ify may be expressions in these variables. We have to
523+
* add any such expressions to the subplan's tlist. We then build
524+
* control information showing which subplan output columns are to be
525+
* examined by the grouping step. (Since we do not remove any existing
526+
* subplan outputs, not all the output columns may be used for grouping.)
527+
*
528+
* Note: the reason we don't remove any subplan outputs is that there
529+
* are scenarios where a Var is needed at higher levels even though it
530+
* is not one of the nominal outputs of an IN clause. Consider
531+
*WHERE x IN (SELECT y FROM t1,t2 WHERE y = z)
532+
* Implied equality deduction will generate an "x = z" clause, which may
533+
* get used instead of "x = y" in the upper join step. Therefore the
534+
* sub-select had better deliver both y and z in its targetlist. It is
535+
* sufficient to unique-ify on y, however.
536+
*
537+
* To find the correct list of values to unique-ify, we look in the
538+
* information saved for IN expressions. If this code is ever used in
539+
* other scenarios, some other way of finding what to unique-ify will
540+
* be needed.
517541
*/
518-
sub_targetlist=NIL;
542+
uniq_exprs=NIL;/* just to keep compiler quiet */
519543
foreach(l,root->in_info_list)
520544
{
521545
InClauseInfo*ininfo= (InClauseInfo*)lfirst(l);
522546

523547
if (bms_equal(ininfo->righthand,best_path->path.parent->relids))
524548
{
525-
sub_targetlist=ininfo->sub_targetlist;
549+
uniq_exprs=ininfo->sub_targetlist;
526550
break;
527551
}
528552
}
529-
530-
if (sub_targetlist)
553+
if (l==NIL)/* fell out of loop? */
554+
elog(ERROR,"could not find UniquePath in in_info_list");
555+
556+
/* set up to record positions of unique columns */
557+
numGroupCols=length(uniq_exprs);
558+
groupColIdx= (AttrNumber*)palloc(numGroupCols*sizeof(AttrNumber));
559+
groupColPos=0;
560+
/* not sure if tlist might be shared with other nodes, so copy */
561+
newtlist=copyObject(subplan->targetlist);
562+
nextresno=length(newtlist)+1;
563+
newitems= false;
564+
565+
foreach(l,uniq_exprs)
531566
{
532-
/*
533-
* Transform list of plain Vars into targetlist
534-
*/
535-
List*newtlist=NIL;
536-
intresno=1;
567+
Node*uniqexpr=lfirst(l);
568+
TargetEntry*tle;
537569

538-
foreach(l,sub_targetlist)
570+
tle=tlistentry_member(uniqexpr,newtlist);
571+
if (!tle)
539572
{
540-
Node*tlexpr=lfirst(l);
541-
TargetEntry*tle;
542-
543-
tle=makeTargetEntry(makeResdom(resno,
544-
exprType(tlexpr),
545-
exprTypmod(tlexpr),
573+
tle=makeTargetEntry(makeResdom(nextresno,
574+
exprType(uniqexpr),
575+
exprTypmod(uniqexpr),
546576
NULL,
547577
false),
548-
(Expr*)tlexpr);
578+
(Expr*)uniqexpr);
549579
newtlist=lappend(newtlist,tle);
550-
resno++;
580+
nextresno++;
581+
newitems= true;
551582
}
583+
groupColIdx[groupColPos++]=tle->resdom->resno;
584+
}
552585

586+
if (newitems)
587+
{
553588
/*
554589
* If the top plan node can't do projections, we need to add a
555590
* Result node to help it along.
@@ -563,21 +598,15 @@ create_unique_plan(Query *root, UniquePath * best_path)
563598
subplan->targetlist=newtlist;
564599
}
565600

601+
/* Copy tlist again to make one we can put sorting labels on */
566602
my_tlist=copyObject(subplan->targetlist);
567603

568604
if (best_path->use_hash)
569605
{
570-
intnumGroupCols=length(my_tlist);
571606
longnumGroups;
572-
AttrNumber*groupColIdx;
573-
inti;
574607

575608
numGroups= (long)Min(best_path->rows, (double)LONG_MAX);
576609

577-
groupColIdx= (AttrNumber*)palloc(numGroupCols*sizeof(AttrNumber));
578-
for (i=0;i<numGroupCols;i++)
579-
groupColIdx[i]=i+1;
580-
581610
plan= (Plan*)make_agg(root,
582611
my_tlist,
583612
NIL,
@@ -590,9 +619,17 @@ create_unique_plan(Query *root, UniquePath * best_path)
590619
}
591620
else
592621
{
593-
List*sortList;
622+
List*sortList=NIL;
594623

595-
sortList=addAllTargetsToSortList(NULL,NIL,my_tlist, false);
624+
for (groupColPos=0;groupColPos<numGroupCols;groupColPos++)
625+
{
626+
TargetEntry*tle;
627+
628+
tle=nth(groupColIdx[groupColPos]-1,my_tlist);
629+
Assert(tle->resdom->resno==groupColIdx[groupColPos]);
630+
sortList=addTargetToSortList(NULL,tle,sortList,
631+
my_tlist,NIL, false);
632+
}
596633
plan= (Plan*)make_sort_from_sortclauses(root,my_tlist,
597634
subplan,sortList);
598635
plan= (Plan*)make_unique(my_tlist,plan,sortList);

‎src/backend/parser/parse_clause.c‎

Lines changed: 2 additions & 5 deletions
Original file line numberDiff line numberDiff line change
@@ -8,7 +8,7 @@
88
*
99
*
1010
* IDENTIFICATION
11-
* $Header: /cvsroot/pgsql/src/backend/parser/parse_clause.c,v 1.120 2003/08/04 02:40:01 momjian Exp $
11+
* $Header: /cvsroot/pgsql/src/backend/parser/parse_clause.c,v 1.121 2003/08/07 19:20:22 tgl Exp $
1212
*
1313
*-------------------------------------------------------------------------
1414
*/
@@ -59,9 +59,6 @@ static Node *buildMergedJoinVar(ParseState *pstate, JoinType jointype,
5959
Var*l_colvar,Var*r_colvar);
6060
staticTargetEntry*findTargetlistEntry(ParseState*pstate,Node*node,
6161
List*tlist,intclause);
62-
staticList*addTargetToSortList(ParseState*pstate,TargetEntry*tle,
63-
List*sortlist,List*targetlist,
64-
List*opname,boolresolveUnknown);
6562

6663

6764
/*
@@ -1478,7 +1475,7 @@ addAllTargetsToSortList(ParseState *pstate, List *sortlist,
14781475
*
14791476
* Returns the updated ORDER BY list.
14801477
*/
1481-
staticList*
1478+
List*
14821479
addTargetToSortList(ParseState*pstate,TargetEntry*tle,
14831480
List*sortlist,List*targetlist,
14841481
List*opname,boolresolveUnknown)

‎src/include/parser/parse_clause.h‎

Lines changed: 4 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -7,7 +7,7 @@
77
* Portions Copyright (c) 1996-2003, PostgreSQL Global Development Group
88
* Portions Copyright (c) 1994, Regents of the University of California
99
*
10-
* $Id: parse_clause.h,v 1.35 2003/08/04 02:40:14 momjian Exp $
10+
* $Id: parse_clause.h,v 1.36 2003/08/07 19:20:23 tgl Exp $
1111
*
1212
*-------------------------------------------------------------------------
1313
*/
@@ -35,6 +35,9 @@ extern List *transformDistinctClause(ParseState *pstate, List *distinctlist,
3535
externList*addAllTargetsToSortList(ParseState*pstate,
3636
List*sortlist,List*targetlist,
3737
boolresolveUnknown);
38+
externList*addTargetToSortList(ParseState*pstate,TargetEntry*tle,
39+
List*sortlist,List*targetlist,
40+
List*opname,boolresolveUnknown);
3841
externIndexassignSortGroupRef(TargetEntry*tle,List*tlist);
3942
externbooltargetIsInSortList(TargetEntry*tle,List*sortList);
4043

‎src/test/regress/expected/join.out‎

Lines changed: 12 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -2127,6 +2127,18 @@ on (x1 = xx1) where (xx2 is not null);
21272127
4 | 44 | 4 | | 4 | 44
21282128
(3 rows)
21292129

2130+
--
2131+
-- regression test: check for bug with propagation of implied equality
2132+
-- to outside an IN
2133+
--
2134+
select count(*) from tenk1 a where unique1 in
2135+
(select unique1 from tenk1 b join tenk1 c using (unique1)
2136+
where b.unique2 = 42);
2137+
count
2138+
-------
2139+
1
2140+
(1 row)
2141+
21302142
--
21312143
-- Clean up
21322144
--

‎src/test/regress/sql/join.sql‎

Lines changed: 8 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -330,6 +330,14 @@ on (x1 = xx1) where (y2 is not null);
330330
select*from (xleft join yon (x1= y1))left join x xx(xx1,xx2)
331331
on (x1= xx1)where (xx2is not null);
332332

333+
--
334+
-- regression test: check for bug with propagation of implied equality
335+
-- to outside an IN
336+
--
337+
selectcount(*)from tenk1 awhere unique1in
338+
(select unique1from tenk1 bjoin tenk1 c using (unique1)
339+
whereb.unique2=42);
340+
333341

334342
--
335343
-- Clean up

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