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Commitf68e11f

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Implement subselects in target lists. Also, relax requirement that
subselects can only appear on the righthand side of a binary operator.That's still true for quantified predicates like x = ANY (SELECT ...),but a subselect that delivers a single result can now appear anywherein an expression. This is implemented by changing EXPR_SUBLINK sublinksto represent just the (SELECT ...) expression, without any 'left handside' or combining operator --- so they're now more like EXISTS_SUBLINK.To handle the case of '(x, y, z) = (SELECT ...)', I added a new sublinktype MULTIEXPR_SUBLINK, which acts just like EXPR_SUBLINK used to.But the grammar will only generate one for a multiple-left-hand-siderow expression.
1 parent1ecb129 commitf68e11f

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12 files changed

+355
-557
lines changed

12 files changed

+355
-557
lines changed

‎src/backend/executor/nodeSubplan.c

Lines changed: 45 additions & 25 deletions
Original file line numberDiff line numberDiff line change
@@ -3,6 +3,11 @@
33
* nodeSubplan.c
44
* routines to support subselects
55
*
6+
* Copyright (c) 1994, Regents of the University of California
7+
*
8+
* IDENTIFICATION
9+
* $Header: /cvsroot/pgsql/src/backend/executor/nodeSubplan.c,v 1.16 1999/11/15 02:00:01 tgl Exp $
10+
*
611
*-------------------------------------------------------------------------
712
*/
813
/*
@@ -68,19 +73,17 @@ ExecSubPlan(SubPlan *node, List *pvar, ExprContext *econtext, bool *isNull)
6873
* within a tuple (if there are multiple columns) using OR semantics
6974
* if "useor" is true, AND semantics if not. We then combine results
7075
* across tuples (if the subplan produces more than one) using OR
71-
* semantics for ANY_SUBLINK or AND semantics for ALL_SUBLINK. NULL
72-
* results from the combining operators are handled according to the
73-
* usual SQL semantics for OR and AND. The result for no input
74-
* tuples is FALSE for ANY_SUBLINK, TRUE for ALL_SUBLINK.
76+
* semantics for ANY_SUBLINK or AND semantics for ALL_SUBLINK.
77+
* (MULTIEXPR_SUBLINK doesn't allow multiple tuples from the subplan.)
78+
* NULL results from the combining operators are handled according to
79+
* the usual SQL semantics for OR and AND. The result for no input
80+
* tuples is FALSE for ANY_SUBLINK, TRUE for ALL_SUBLINK, NULL for
81+
* MULTIEXPR_SUBLINK.
7582
*
7683
* For EXPR_SUBLINK we require the subplan to produce no more than one
7784
* tuple, else an error is raised. If zero tuples are produced, we
78-
* return NULL. (XXX it would probably be more correct to evaluate
79-
* the combining operator with a NULL input?) Assuming we get a tuple:
80-
* if there is only one column then we just return its result as-is, NULL
81-
* or otherwise. If there is more than one column we combine the results
82-
* per "useor" --- this only makes sense if the combining operators yield
83-
* boolean, and we assume the parser has checked that.
85+
* return NULL. Assuming we get a tuple, we just return its first
86+
* column (there can be only one non-junk column in this case).
8487
*/
8588
result= (Datum) (subLinkType==ALL_SUBLINK ? true : false);
8689
*isNull= false;
@@ -98,13 +101,29 @@ ExecSubPlan(SubPlan *node, List *pvar, ExprContext *econtext, bool *isNull)
98101
if (subLinkType==EXISTS_SUBLINK)
99102
return (Datum) true;
100103

101-
/* cannot allow multiple input tuples for EXPR sublink */
102-
if (subLinkType==EXPR_SUBLINK&&found)
104+
if (subLinkType==EXPR_SUBLINK)
105+
{
106+
/* cannot allow multiple input tuples for EXPR sublink */
107+
if (found)
108+
elog(ERROR,"ExecSubPlan: more than one tuple returned by expression subselect");
109+
found= true;
110+
/* XXX need to copy tuple in case pass by ref */
111+
/* XXX need to ref-count the tuple to avoid mem leak! */
112+
tup=heap_copytuple(tup);
113+
result=heap_getattr(tup,col,tdesc,isNull);
114+
/* keep scanning subplan to make sure there's only one tuple */
115+
continue;
116+
}
117+
118+
/* cannot allow multiple input tuples for MULTIEXPR sublink either */
119+
if (subLinkType==MULTIEXPR_SUBLINK&&found)
103120
elog(ERROR,"ExecSubPlan: more than one tuple returned by expression subselect");
104121

105122
found= true;
106123

107-
/* iterate over combining operators for columns of tuple */
124+
/* For ALL, ANY, and MULTIEXPR sublinks, iterate over combining
125+
* operators for columns of tuple.
126+
*/
108127
foreach(lst,sublink->oper)
109128
{
110129
Expr*expr= (Expr*)lfirst(lst);
@@ -193,7 +212,7 @@ ExecSubPlan(SubPlan *node, List *pvar, ExprContext *econtext, bool *isNull)
193212
}
194213
else
195214
{
196-
/* must beEXPR_SUBLINK */
215+
/* must beMULTIEXPR_SUBLINK */
197216
result=rowresult;
198217
*isNull=rownull;
199218
}
@@ -202,9 +221,10 @@ ExecSubPlan(SubPlan *node, List *pvar, ExprContext *econtext, bool *isNull)
202221
if (!found)
203222
{
204223
/* deal with empty subplan result. result/isNull were previously
205-
* initialized correctly for all sublink types except EXPR.
224+
* initialized correctly for all sublink types except EXPR and
225+
* MULTIEXPR; for those, return NULL.
206226
*/
207-
if (subLinkType==EXPR_SUBLINK)
227+
if (subLinkType==EXPR_SUBLINK||subLinkType==MULTIEXPR_SUBLINK)
208228
{
209229
result= (Datum) false;
210230
*isNull= true;
@@ -242,7 +262,7 @@ ExecInitSubPlan(SubPlan *node, EState *estate, Plan *parent)
242262
* If this plan is un-correlated or undirect correlated one and want
243263
* to set params for parent plan then prepare parameters.
244264
*/
245-
if (node->setParam!=NULL)
265+
if (node->setParam!=NIL)
246266
{
247267
List*lst;
248268

@@ -293,24 +313,24 @@ ExecSetParamPlan(SubPlan *node)
293313
TupleDesctdesc=slot->ttc_tupleDescriptor;
294314
inti=1;
295315

296-
if (sublink->subLinkType==EXPR_SUBLINK&&found)
297-
{
298-
elog(ERROR,"ExecSetParamPlan: more than one tuple returned by expression subselect");
299-
return;
300-
}
301-
302-
found= true;
303-
304316
if (sublink->subLinkType==EXISTS_SUBLINK)
305317
{
306318
ParamExecData*prm=&(plan->state->es_param_exec_vals[lfirsti(node->setParam)]);
307319

308320
prm->execPlan=NULL;
309321
prm->value= (Datum) true;
310322
prm->isnull= false;
323+
found= true;
311324
break;
312325
}
313326

327+
if (found&&
328+
(sublink->subLinkType==EXPR_SUBLINK||
329+
sublink->subLinkType==MULTIEXPR_SUBLINK))
330+
elog(ERROR,"ExecSetParamPlan: more than one tuple returned by expression subselect");
331+
332+
found= true;
333+
314334
/*
315335
* If this is uncorrelated subquery then its plan will be closed
316336
* (see below) and this tuple will be free-ed - bad for not byval

‎src/backend/nodes/copyfuncs.c

Lines changed: 8 additions & 6 deletions
Original file line numberDiff line numberDiff line change
@@ -7,7 +7,7 @@
77
*
88
*
99
* IDENTIFICATION
10-
* $Header: /cvsroot/pgsql/src/backend/nodes/copyfuncs.c,v 1.94 1999/11/01 05:15:13 tgl Exp $
10+
* $Header: /cvsroot/pgsql/src/backend/nodes/copyfuncs.c,v 1.95 1999/11/15 02:00:01 tgl Exp $
1111
*
1212
*-------------------------------------------------------------------------
1313
*/
@@ -86,10 +86,11 @@ CopyPlanFields(Plan *from, Plan *newnode)
8686
newnode->locParam=listCopy(from->locParam);
8787
newnode->chgParam=listCopy(from->chgParam);
8888
Node_Copy(from,newnode,initPlan);
89-
if (from->subPlan!=NULL)
90-
newnode->subPlan=SS_pull_subplan((Node*)newnode->qual);
89+
if (from->subPlan!=NIL)
90+
newnode->subPlan=nconc(SS_pull_subplan((Node*)newnode->targetlist),
91+
SS_pull_subplan((Node*)newnode->qual));
9192
else
92-
newnode->subPlan=NULL;
93+
newnode->subPlan=NIL;
9394
newnode->nParamExec=from->nParamExec;
9495
}
9596

@@ -137,8 +138,9 @@ _copyResult(Result *from)
137138
* We must add subplans in resconstantqual to the new plan's subPlan
138139
* list
139140
*/
140-
newnode->plan.subPlan=nconc(newnode->plan.subPlan,
141-
SS_pull_subplan(newnode->resconstantqual));
141+
if (from->plan.subPlan!=NIL)
142+
newnode->plan.subPlan=nconc(newnode->plan.subPlan,
143+
SS_pull_subplan(newnode->resconstantqual));
142144

143145
returnnewnode;
144146
}

‎src/backend/optimizer/plan/planmain.c

Lines changed: 17 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -7,7 +7,7 @@
77
*
88
*
99
* IDENTIFICATION
10-
* $Header: /cvsroot/pgsql/src/backend/optimizer/plan/planmain.c,v 1.46 1999/10/07 04:23:06 tgl Exp $
10+
* $Header: /cvsroot/pgsql/src/backend/optimizer/plan/planmain.c,v 1.47 1999/11/15 02:00:07 tgl Exp $
1111
*
1212
*-------------------------------------------------------------------------
1313
*/
@@ -87,9 +87,25 @@ query_planner(Query *root,
8787
tlist= (List*)SS_replace_correlation_vars((Node*)tlist);
8888
qual= (List*)SS_replace_correlation_vars((Node*)qual);
8989
}
90+
9091
/* Expand SubLinks to SubPlans */
9192
if (root->hasSubLinks)
93+
{
94+
tlist= (List*)SS_process_sublinks((Node*)tlist);
9295
qual= (List*)SS_process_sublinks((Node*)qual);
96+
if (root->groupClause!=NIL)
97+
{
98+
/*
99+
* Check for ungrouped variables passed to subplans.
100+
* Note we do NOT do this for subplans in WHERE; it's legal
101+
* there because WHERE is evaluated pre-GROUP.
102+
*/
103+
if (check_subplans_for_ungrouped_vars((Node*)tlist,
104+
root->groupClause,
105+
tlist))
106+
elog(ERROR,"Sub-SELECT must use only GROUPed attributes from outer SELECT");
107+
}
108+
}
93109

94110
/*
95111
* If the query contains no relation references at all, it must be

‎src/backend/optimizer/plan/planner.c

Lines changed: 3 additions & 9 deletions
Original file line numberDiff line numberDiff line change
@@ -7,7 +7,7 @@
77
*
88
*
99
* IDENTIFICATION
10-
* $Header: /cvsroot/pgsql/src/backend/optimizer/plan/planner.c,v 1.70 1999/10/07 04:23:06 tgl Exp $
10+
* $Header: /cvsroot/pgsql/src/backend/optimizer/plan/planner.c,v 1.71 1999/11/15 02:00:08 tgl Exp $
1111
*
1212
*-------------------------------------------------------------------------
1313
*/
@@ -343,17 +343,11 @@ union_planner(Query *parse)
343343
{
344344
/* Expand SubLinks to SubPlans */
345345
parse->havingQual=SS_process_sublinks(parse->havingQual);
346-
347-
/*
348-
* Check for ungrouped variables passed to subplans. (Probably
349-
* this should be done for the targetlist as well??? But we
350-
* should NOT do it for the WHERE qual, since WHERE is
351-
* evaluated pre-GROUP.)
352-
*/
346+
/* Check for ungrouped variables passed to subplans */
353347
if (check_subplans_for_ungrouped_vars(parse->havingQual,
354348
parse->groupClause,
355349
parse->targetList))
356-
elog(ERROR,"Sub-SELECTin HAVING clausemust use only GROUPed attributes from outer SELECT");
350+
elog(ERROR,"Sub-SELECT must use only GROUPed attributes from outer SELECT");
357351
}
358352
}
359353

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