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Commit0a7abcd

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Fix corner case wherein a WorkTableScan node could get initialized before the
RecursiveUnion to which it refers. It turns out that we can just postpone therelevant initialization steps until the first exec call for the node, by whichtime the ancestor node must surely be initialized. Per report from Greg Stark.
1 parent100aa27 commit0a7abcd

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3 files changed

+144
-24
lines changed

3 files changed

+144
-24
lines changed

‎src/backend/executor/nodeWorktablescan.c

Lines changed: 40 additions & 24 deletions
Original file line numberDiff line numberDiff line change
@@ -8,7 +8,7 @@
88
*
99
*
1010
* IDENTIFICATION
11-
* $PostgreSQL: pgsql/src/backend/executor/nodeWorktablescan.c,v 1.1 2008/10/04 21:56:53 tgl Exp $
11+
* $PostgreSQL: pgsql/src/backend/executor/nodeWorktablescan.c,v 1.2 2008/10/13 00:41:40 tgl Exp $
1212
*
1313
*-------------------------------------------------------------------------
1414
*/
@@ -63,6 +63,40 @@ WorkTableScanNext(WorkTableScanState *node)
6363
TupleTableSlot*
6464
ExecWorkTableScan(WorkTableScanState*node)
6565
{
66+
/*
67+
* On the first call, find the ancestor RecursiveUnion's state
68+
* via the Param slot reserved for it. (We can't do this during node
69+
* init because there are corner cases where we'll get the init call
70+
* before the RecursiveUnion does.)
71+
*/
72+
if (node->rustate==NULL)
73+
{
74+
WorkTableScan*plan= (WorkTableScan*)node->ss.ps.plan;
75+
EState*estate=node->ss.ps.state;
76+
ParamExecData*param;
77+
78+
param=&(estate->es_param_exec_vals[plan->wtParam]);
79+
Assert(param->execPlan==NULL);
80+
Assert(!param->isnull);
81+
node->rustate= (RecursiveUnionState*)DatumGetPointer(param->value);
82+
Assert(node->rustate&&IsA(node->rustate,RecursiveUnionState));
83+
84+
/*
85+
* The scan tuple type (ie, the rowtype we expect to find in the work
86+
* table) is the same as the result rowtype of the ancestor
87+
* RecursiveUnion node. Note this depends on the assumption that
88+
* RecursiveUnion doesn't allow projection.
89+
*/
90+
ExecAssignScanType(&node->ss,
91+
ExecGetResultType(&node->rustate->ps));
92+
93+
/*
94+
* Now we can initialize the projection info. This must be
95+
* completed before we can call ExecScan().
96+
*/
97+
ExecAssignScanProjectionInfo(&node->ss);
98+
}
99+
66100
/*
67101
* use WorkTableScanNext as access method
68102
*/
@@ -78,7 +112,6 @@ WorkTableScanState *
78112
ExecInitWorkTableScan(WorkTableScan*node,EState*estate,inteflags)
79113
{
80114
WorkTableScanState*scanstate;
81-
ParamExecData*prmdata;
82115

83116
/* check for unsupported flags */
84117
Assert(!(eflags&EXEC_FLAG_MARK));
@@ -95,16 +128,7 @@ ExecInitWorkTableScan(WorkTableScan *node, EState *estate, int eflags)
95128
scanstate=makeNode(WorkTableScanState);
96129
scanstate->ss.ps.plan= (Plan*)node;
97130
scanstate->ss.ps.state=estate;
98-
99-
/*
100-
* Find the ancestor RecursiveUnion's state
101-
* via the Param slot reserved for it.
102-
*/
103-
prmdata=&(estate->es_param_exec_vals[node->wtParam]);
104-
Assert(prmdata->execPlan==NULL);
105-
Assert(!prmdata->isnull);
106-
scanstate->rustate= (RecursiveUnionState*)DatumGetPointer(prmdata->value);
107-
Assert(scanstate->rustate&&IsA(scanstate->rustate,RecursiveUnionState));
131+
scanstate->rustate=NULL;/* we'll set this later */
108132

109133
/*
110134
* Miscellaneous initialization
@@ -132,19 +156,9 @@ ExecInitWorkTableScan(WorkTableScan *node, EState *estate, int eflags)
132156
ExecInitScanTupleSlot(estate,&scanstate->ss);
133157

134158
/*
135-
* The scan tuple type (ie, the rowtype we expect to find in the work
136-
* table) is the same as the result rowtype of the ancestor RecursiveUnion
137-
* node. Note this depends on the assumption that RecursiveUnion doesn't
138-
* allow projection.
139-
*/
140-
ExecAssignScanType(&scanstate->ss,
141-
ExecGetResultType(&scanstate->rustate->ps));
142-
143-
/*
144-
* Initialize result tuple type and projection info.
159+
* Initialize result tuple type, but not yet projection info.
145160
*/
146161
ExecAssignResultTypeFromTL(&scanstate->ss.ps);
147-
ExecAssignScanProjectionInfo(&scanstate->ss);
148162

149163
scanstate->ss.ps.ps_TupFromTlist= false;
150164

@@ -190,5 +204,7 @@ void
190204
ExecWorkTableScanReScan(WorkTableScanState*node,ExprContext*exprCtxt)
191205
{
192206
ExecClearTuple(node->ss.ps.ps_ResultTupleSlot);
193-
tuplestore_rescan(node->rustate->working_table);
207+
/* No need (or way) to rescan if ExecWorkTableScan not called yet */
208+
if (node->rustate)
209+
tuplestore_rescan(node->rustate->working_table);
194210
}

‎src/test/regress/expected/with.out

Lines changed: 83 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -292,6 +292,89 @@ SELECT pg_get_viewdef('vsubdepartment'::regclass, true);
292292
FROM subdepartment;
293293
(1 row)
294294

295+
-- corner case in which sub-WITH gets initialized first
296+
with recursive q as (
297+
select * from department
298+
union all
299+
(with x as (select * from q)
300+
select * from x)
301+
)
302+
select * from q limit 24;
303+
id | parent_department | name
304+
----+-------------------+------
305+
0 | | ROOT
306+
1 | 0 | A
307+
2 | 1 | B
308+
3 | 2 | C
309+
4 | 2 | D
310+
5 | 0 | E
311+
6 | 4 | F
312+
7 | 5 | G
313+
0 | | ROOT
314+
1 | 0 | A
315+
2 | 1 | B
316+
3 | 2 | C
317+
4 | 2 | D
318+
5 | 0 | E
319+
6 | 4 | F
320+
7 | 5 | G
321+
0 | | ROOT
322+
1 | 0 | A
323+
2 | 1 | B
324+
3 | 2 | C
325+
4 | 2 | D
326+
5 | 0 | E
327+
6 | 4 | F
328+
7 | 5 | G
329+
(24 rows)
330+
331+
with recursive q as (
332+
select * from department
333+
union all
334+
(with recursive x as (
335+
select * from department
336+
union all
337+
(select * from q union all select * from x)
338+
)
339+
select * from x)
340+
)
341+
select * from q limit 32;
342+
id | parent_department | name
343+
----+-------------------+------
344+
0 | | ROOT
345+
1 | 0 | A
346+
2 | 1 | B
347+
3 | 2 | C
348+
4 | 2 | D
349+
5 | 0 | E
350+
6 | 4 | F
351+
7 | 5 | G
352+
0 | | ROOT
353+
1 | 0 | A
354+
2 | 1 | B
355+
3 | 2 | C
356+
4 | 2 | D
357+
5 | 0 | E
358+
6 | 4 | F
359+
7 | 5 | G
360+
0 | | ROOT
361+
1 | 0 | A
362+
2 | 1 | B
363+
3 | 2 | C
364+
4 | 2 | D
365+
5 | 0 | E
366+
6 | 4 | F
367+
7 | 5 | G
368+
0 | | ROOT
369+
1 | 0 | A
370+
2 | 1 | B
371+
3 | 2 | C
372+
4 | 2 | D
373+
5 | 0 | E
374+
6 | 4 | F
375+
7 | 5 | G
376+
(32 rows)
377+
295378
-- recursive term has sub-UNION
296379
WITH RECURSIVE t(i,j) AS (
297380
VALUES (1,2)

‎src/test/regress/sql/with.sql

Lines changed: 21 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -178,6 +178,27 @@ SELECT * FROM vsubdepartment ORDER BY name;
178178
SELECT pg_get_viewdef('vsubdepartment'::regclass);
179179
SELECT pg_get_viewdef('vsubdepartment'::regclass, true);
180180

181+
-- corner case in which sub-WITH gets initialized first
182+
with recursive qas (
183+
select*from department
184+
union all
185+
(with xas (select*from q)
186+
select*from x)
187+
)
188+
select*from qlimit24;
189+
190+
with recursive qas (
191+
select*from department
192+
union all
193+
(with recursive xas (
194+
select*from department
195+
union all
196+
(select*from qunion allselect*from x)
197+
)
198+
select*from x)
199+
)
200+
select*from qlimit32;
201+
181202
-- recursive term has sub-UNION
182203
WITH RECURSIVE t(i,j)AS (
183204
VALUES (1,2)

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