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Commit67bf7b9

Browse files
committed
Make ARRAY(SELECT ...) return an empty array, rather than a NULL, when the
sub-select returns zero rows. Per complaint from Jens Schicke. Since thisis more in the nature of a definition change than a bug, not back-patched.
1 parent75d5f6f commit67bf7b9

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3 files changed

+52
-41
lines changed

3 files changed

+52
-41
lines changed

‎src/backend/executor/nodeSubplan.c

Lines changed: 44 additions & 33 deletions
Original file line numberDiff line numberDiff line change
@@ -7,7 +7,7 @@
77
* Portions Copyright (c) 1994, Regents of the University of California
88
*
99
* IDENTIFICATION
10-
* $PostgreSQL: pgsql/src/backend/executor/nodeSubplan.c,v 1.89 2007/05/17 19:35:08 tgl Exp $
10+
* $PostgreSQL: pgsql/src/backend/executor/nodeSubplan.c,v 1.90 2007/08/26 21:44:25 tgl Exp $
1111
*
1212
*-------------------------------------------------------------------------
1313
*/
@@ -259,10 +259,14 @@ ExecScanSubPlan(SubPlanState *node,
259259
* ROWCOMPARE_SUBLINK.
260260
*
261261
* For EXPR_SUBLINK we require the subplan to produce no more than one
262-
* tuple, else an error is raised. For ARRAY_SUBLINK we allow the subplan
263-
* to produce more than one tuple. In either case, if zero tuples are
264-
* produced, we return NULL. Assuming we get a tuple, we just use its
265-
* first column (there can be only one non-junk column in this case).
262+
* tuple, else an error is raised. If zero tuples are produced, we return
263+
* NULL. Assuming we get a tuple, we just use its first column (there can
264+
* be only one non-junk column in this case).
265+
*
266+
* For ARRAY_SUBLINK we allow the subplan to produce any number of tuples,
267+
* and form an array of the first column's values. Note in particular
268+
* that we produce a zero-element array if no tuples are produced (this
269+
* is a change from pre-8.3 behavior of returning NULL).
266270
*/
267271
result=BoolGetDatum(subLinkType==ALL_SUBLINK);
268272
*isNull= false;
@@ -317,10 +321,10 @@ ExecScanSubPlan(SubPlanState *node,
317321

318322
found= true;
319323
/* stash away current value */
324+
Assert(subplan->firstColType==tdesc->attrs[0]->atttypid);
320325
dvalue=slot_getattr(slot,1,&disnull);
321326
astate=accumArrayResult(astate,dvalue,disnull,
322-
tdesc->attrs[0]->atttypid,
323-
oldcontext);
327+
subplan->firstColType,oldcontext);
324328
/* keep scanning subplan to collect all values */
325329
continue;
326330
}
@@ -385,29 +389,30 @@ ExecScanSubPlan(SubPlanState *node,
385389
}
386390
}
387391

388-
if (!found)
392+
MemoryContextSwitchTo(oldcontext);
393+
394+
if (subLinkType==ARRAY_SUBLINK)
395+
{
396+
/* We return the result in the caller's context */
397+
if (astate!=NULL)
398+
result=makeArrayResult(astate,oldcontext);
399+
else
400+
result=PointerGetDatum(construct_empty_array(subplan->firstColType));
401+
}
402+
elseif (!found)
389403
{
390404
/*
391405
* deal with empty subplan result.result/isNull were previously
392-
* initialized correctly for all sublink types except EXPR, ARRAY, and
406+
* initialized correctly for all sublink types except EXPR and
393407
* ROWCOMPARE; for those, return NULL.
394408
*/
395409
if (subLinkType==EXPR_SUBLINK||
396-
subLinkType==ARRAY_SUBLINK||
397410
subLinkType==ROWCOMPARE_SUBLINK)
398411
{
399412
result= (Datum)0;
400413
*isNull= true;
401414
}
402415
}
403-
elseif (subLinkType==ARRAY_SUBLINK)
404-
{
405-
Assert(astate!=NULL);
406-
/* We return the result in the caller's context */
407-
result=makeArrayResult(astate,oldcontext);
408-
}
409-
410-
MemoryContextSwitchTo(oldcontext);
411416

412417
returnresult;
413418
}
@@ -938,10 +943,10 @@ ExecSetParamPlan(SubPlanState *node, ExprContext *econtext)
938943

939944
found= true;
940945
/* stash away current value */
946+
Assert(subplan->firstColType==tdesc->attrs[0]->atttypid);
941947
dvalue=slot_getattr(slot,1,&disnull);
942948
astate=accumArrayResult(astate,dvalue,disnull,
943-
tdesc->attrs[0]->atttypid,
944-
oldcontext);
949+
subplan->firstColType,oldcontext);
945950
/* keep scanning subplan to collect all values */
946951
continue;
947952
}
@@ -980,7 +985,25 @@ ExecSetParamPlan(SubPlanState *node, ExprContext *econtext)
980985
}
981986
}
982987

983-
if (!found)
988+
if (subLinkType==ARRAY_SUBLINK)
989+
{
990+
/* There can be only one param... */
991+
intparamid=linitial_int(subplan->setParam);
992+
ParamExecData*prm=&(econtext->ecxt_param_exec_vals[paramid]);
993+
994+
prm->execPlan=NULL;
995+
/* We build the result in query context so it won't disappear */
996+
if (astate!=NULL)
997+
prm->value=makeArrayResult(astate,
998+
econtext->ecxt_per_query_memory);
999+
else
1000+
{
1001+
MemoryContextSwitchTo(econtext->ecxt_per_query_memory);
1002+
prm->value=PointerGetDatum(construct_empty_array(subplan->firstColType));
1003+
}
1004+
prm->isnull= false;
1005+
}
1006+
elseif (!found)
9841007
{
9851008
if (subLinkType==EXISTS_SUBLINK)
9861009
{
@@ -1005,18 +1028,6 @@ ExecSetParamPlan(SubPlanState *node, ExprContext *econtext)
10051028
}
10061029
}
10071030
}
1008-
elseif (subLinkType==ARRAY_SUBLINK)
1009-
{
1010-
/* There can be only one param... */
1011-
intparamid=linitial_int(subplan->setParam);
1012-
ParamExecData*prm=&(econtext->ecxt_param_exec_vals[paramid]);
1013-
1014-
Assert(astate!=NULL);
1015-
prm->execPlan=NULL;
1016-
/* We build the result in query context so it won't disappear */
1017-
prm->value=makeArrayResult(astate,econtext->ecxt_per_query_memory);
1018-
prm->isnull= false;
1019-
}
10201031

10211032
MemoryContextSwitchTo(oldcontext);
10221033
}

‎src/backend/optimizer/plan/subselect.c

Lines changed: 5 additions & 5 deletions
Original file line numberDiff line numberDiff line change
@@ -7,7 +7,7 @@
77
* Portions Copyright (c) 1994, Regents of the University of California
88
*
99
* IDENTIFICATION
10-
* $PostgreSQL: pgsql/src/backend/optimizer/plan/subselect.c,v 1.123 2007/07/18 21:40:57 tgl Exp $
10+
* $PostgreSQL: pgsql/src/backend/optimizer/plan/subselect.c,v 1.124 2007/08/26 21:44:25 tgl Exp $
1111
*
1212
*-------------------------------------------------------------------------
1313
*/
@@ -208,10 +208,10 @@ generate_new_param(PlannerInfo *root, Oid paramtype, int32 paramtypmod)
208208
/*
209209
* Get the datatype of the first column of the plan's output.
210210
*
211-
* This isa hack to supportexprType(), which doesn't have any way to get
212-
* at the plan associated with a SubPlan node. We really only need the value
213-
* for EXPR_SUBLINK and ARRAY_SUBLINK subplans, but for consistency we set
214-
* it always.
211+
* This isstored for ARRAY_SUBLINK and forexprType(), which doesn't have any
212+
*way to getat the plan associated with a SubPlan node. We really only need
213+
*the valuefor EXPR_SUBLINK and ARRAY_SUBLINK subplans, but for consistency
214+
*we setit always.
215215
*/
216216
staticOid
217217
get_first_col_type(Plan*plan)

‎src/include/nodes/primnodes.h

Lines changed: 3 additions & 3 deletions
Original file line numberDiff line numberDiff line change
@@ -10,7 +10,7 @@
1010
* Portions Copyright (c) 1996-2007, PostgreSQL Global Development Group
1111
* Portions Copyright (c) 1994, Regents of the University of California
1212
*
13-
* $PostgreSQL: pgsql/src/include/nodes/primnodes.h,v 1.132 2007/06/11 22:22:42 tgl Exp $
13+
* $PostgreSQL: pgsql/src/include/nodes/primnodes.h,v 1.133 2007/08/26 21:44:25 tgl Exp $
1414
*
1515
*-------------------------------------------------------------------------
1616
*/
@@ -388,7 +388,7 @@ typedef struct BoolExpr
388388
* results. ALL and ANY combine the per-row results using AND and OR
389389
* semantics respectively.
390390
* ARRAY requires just one target column, and creates an array of the target
391-
* column's type usingone or more rows resulting from the subselect.
391+
* column's type usingany number of rows resulting from the subselect.
392392
*
393393
* SubLink is classed as an Expr node, but it is not actually executable;
394394
* it must be replaced in the expression tree by a SubPlan node during
@@ -468,7 +468,7 @@ typedef struct SubPlan
468468
List*paramIds;/* IDs of Params embedded in the above */
469469
/* Identification of the Plan tree to use: */
470470
intplan_id;/* Index (from 1) in PlannedStmt.subplans */
471-
/* Extra datasaved forthe convenience of exprType(): */
471+
/* Extra datauseful fordetermining subplan's output type: */
472472
OidfirstColType;/* Type of first column of subplan result */
473473
/* Information about execution strategy: */
474474
booluseHashTable;/* TRUE to store subselect output in a hash

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