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Fix AcquireRewriteLocks to be sure that it acquires the right lock strength
when FOR UPDATE is propagated down into a sub-select expanded from a view. Similar bug to parser's isLockedRel issue that I fixed yesterday; likewise seems not quite worth the effort to back-patch.
1 parent 46e3a16 commit cbcd170

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3 files changed

+45
-23
lines changed

3 files changed

+45
-23
lines changed

‎src/backend/rewrite/rewriteHandler.c‎

Lines changed: 40 additions & 18 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/rewrite/rewriteHandler.c,v 1.190 2009/10/28 14:55:43 tgl Exp $
10+
* $PostgreSQL: pgsql/src/backend/rewrite/rewriteHandler.c,v 1.191 2009/10/28 17:36:50 tgl Exp $
1111
*
1212
*-------------------------------------------------------------------------
1313
*/
@@ -55,7 +55,8 @@ static void markQueryForLocking(Query *qry, Node *jtnode,
5555
bool forUpdate, bool noWait, bool pushedDown);
5656
static List *matchLocks(CmdType event, RuleLock *rulelocks,
5757
int varno, Query *parsetree);
58-
static Query *fireRIRrules(Query *parsetree, List *activeRIRs);
58+
static Query *fireRIRrules(Query *parsetree, List *activeRIRs,
59+
bool forUpdatePushedDown);
5960

6061

6162
/*
@@ -64,6 +65,10 @@ static Query *fireRIRrules(Query *parsetree, List *activeRIRs);
6465
* These locks will ensure that the relation schemas don't change under us
6566
* while we are rewriting and planning the query.
6667
*
68+
* forUpdatePushedDown indicates that a pushed-down FOR UPDATE/SHARE applies
69+
* to the current subquery, requiring all rels to be opened with RowShareLock.
70+
* This should always be false at the start of the recursion.
71+
*
6772
* A secondary purpose of this routine is to fix up JOIN RTE references to
6873
* dropped columns (see details below). Because the RTEs are modified in
6974
* place, it is generally appropriate for the caller of this routine to have
@@ -91,7 +96,7 @@ static Query *fireRIRrules(Query *parsetree, List *activeRIRs);
9196
* construction of a nested join was O(N^2) in the nesting depth.)
9297
*/
9398
void
94-
AcquireRewriteLocks(Query *parsetree)
99+
AcquireRewriteLocks(Query *parsetree, bool forUpdatePushedDown)
95100
{
96101
ListCell *l;
97102
int rt_index;
@@ -129,7 +134,8 @@ AcquireRewriteLocks(Query *parsetree)
129134
*/
130135
if (rt_index == parsetree->resultRelation)
131136
lockmode = RowExclusiveLock;
132-
else if (get_parse_rowmark(parsetree, rt_index) != NULL)
137+
else if (forUpdatePushedDown ||
138+
get_parse_rowmark(parsetree, rt_index) != NULL)
133139
lockmode = RowShareLock;
134140
else
135141
lockmode = AccessShareLock;
@@ -206,7 +212,9 @@ AcquireRewriteLocks(Query *parsetree)
206212
* The subquery RTE itself is all right, but we have to
207213
* recurse to process the represented subquery.
208214
*/
209-
AcquireRewriteLocks(rte->subquery);
215+
AcquireRewriteLocks(rte->subquery,
216+
(forUpdatePushedDown ||
217+
get_parse_rowmark(parsetree, rt_index) != NULL));
210218
break;
211219

212220
default:
@@ -220,7 +228,7 @@ AcquireRewriteLocks(Query *parsetree)
220228
{
221229
CommonTableExpr *cte = (CommonTableExpr *) lfirst(l);
222230

223-
AcquireRewriteLocks((Query *) cte->ctequery);
231+
AcquireRewriteLocks((Query *) cte->ctequery, false);
224232
}
225233

226234
/*
@@ -245,7 +253,7 @@ acquireLocksOnSubLinks(Node *node, void *context)
245253
SubLink *sub = (SubLink *) node;
246254

247255
/* Do what we came for */
248-
AcquireRewriteLocks((Query *) sub->subselect);
256+
AcquireRewriteLocks((Query *) sub->subselect, false);
249257
/* Fall through to process lefthand args of SubLink */
250258
}
251259

@@ -298,7 +306,7 @@ rewriteRuleAction(Query *parsetree,
298306
/*
299307
* Acquire necessary locks and fix any deleted JOIN RTE entries.
300308
*/
301-
AcquireRewriteLocks(rule_action);
309+
AcquireRewriteLocks(rule_action, false);
302310
(void) acquireLocksOnSubLinks(rule_qual, NULL);
303311

304312
current_varno = rt_index;
@@ -1134,7 +1142,8 @@ ApplyRetrieveRule(Query *parsetree,
11341142
int rt_index,
11351143
bool relation_level,
11361144
Relation relation,
1137-
List *activeRIRs)
1145+
List *activeRIRs,
1146+
bool forUpdatePushedDown)
11381147
{
11391148
Query *rule_action;
11401149
RangeTblEntry *rte,
@@ -1148,18 +1157,25 @@ ApplyRetrieveRule(Query *parsetree,
11481157
if (!relation_level)
11491158
elog(ERROR, "cannot handle per-attribute ON SELECT rule");
11501159

1160+
/*
1161+
* If FOR UPDATE/SHARE of view, be sure we get right initial lock on the
1162+
* relations it references.
1163+
*/
1164+
rc = get_parse_rowmark(parsetree, rt_index);
1165+
forUpdatePushedDown |= (rc != NULL);
1166+
11511167
/*
11521168
* Make a modifiable copy of the view query, and acquire needed locks on
11531169
* the relations it mentions.
11541170
*/
11551171
rule_action = copyObject(linitial(rule->actions));
11561172

1157-
AcquireRewriteLocks(rule_action);
1173+
AcquireRewriteLocks(rule_action, forUpdatePushedDown);
11581174

11591175
/*
11601176
* Recursively expand any view references inside the view.
11611177
*/
1162-
rule_action = fireRIRrules(rule_action, activeRIRs);
1178+
rule_action = fireRIRrules(rule_action, activeRIRs, forUpdatePushedDown);
11631179

11641180
/*
11651181
* VIEWs are really easy --- just plug the view query in as a subselect,
@@ -1192,8 +1208,11 @@ ApplyRetrieveRule(Query *parsetree,
11921208
* If FOR UPDATE/SHARE of view, mark all the contained tables as
11931209
* implicit FOR UPDATE/SHARE, the same as the parser would have done
11941210
* if the view's subquery had been written out explicitly.
1211+
*
1212+
* Note: we don't consider forUpdatePushedDown here; such marks will be
1213+
* made by recursing from the upper level in markQueryForLocking.
11951214
*/
1196-
if ((rc = get_parse_rowmark(parsetree, rt_index)) != NULL)
1215+
if (rc != NULL)
11971216
markQueryForLocking(rule_action, (Node *) rule_action->jointree,
11981217
rc->forUpdate, rc->noWait, true);
11991218

@@ -1281,7 +1300,7 @@ fireRIRonSubLink(Node *node, List *activeRIRs)
12811300

12821301
/* Do what we came for */
12831302
sub->subselect = (Node *) fireRIRrules((Query *) sub->subselect,
1284-
activeRIRs);
1303+
activeRIRs, false);
12851304
/* Fall through to process lefthand args of SubLink */
12861305
}
12871306

@@ -1299,7 +1318,7 @@ fireRIRonSubLink(Node *node, List *activeRIRs)
12991318
* Apply all RIR rules on each rangetable entry in a query
13001319
*/
13011320
static Query *
1302-
fireRIRrules(Query *parsetree, List *activeRIRs)
1321+
fireRIRrules(Query *parsetree, List *activeRIRs, bool forUpdatePushedDown)
13031322
{
13041323
int rt_index;
13051324
ListCell *lc;
@@ -1329,7 +1348,9 @@ fireRIRrules(Query *parsetree, List *activeRIRs)
13291348
*/
13301349
if (rte->rtekind == RTE_SUBQUERY)
13311350
{
1332-
rte->subquery = fireRIRrules(rte->subquery, activeRIRs);
1351+
rte->subquery = fireRIRrules(rte->subquery, activeRIRs,
1352+
(forUpdatePushedDown ||
1353+
get_parse_rowmark(parsetree, rt_index) != NULL));
13331354
continue;
13341355
}
13351356

@@ -1406,7 +1427,8 @@ fireRIRrules(Query *parsetree, List *activeRIRs)
14061427
rt_index,
14071428
rule->attrno == -1,
14081429
rel,
1409-
activeRIRs);
1430+
activeRIRs,
1431+
forUpdatePushedDown);
14101432
}
14111433

14121434
activeRIRs = list_delete_first(activeRIRs);
@@ -1421,7 +1443,7 @@ fireRIRrules(Query *parsetree, List *activeRIRs)
14211443
CommonTableExpr *cte = (CommonTableExpr *) lfirst(lc);
14221444

14231445
cte->ctequery = (Node *)
1424-
fireRIRrules((Query *) cte->ctequery, activeRIRs);
1446+
fireRIRrules((Query *) cte->ctequery, activeRIRs, false);
14251447
}
14261448

14271449
/*
@@ -1850,7 +1872,7 @@ QueryRewrite(Query *parsetree)
18501872
{
18511873
Query *query = (Query *) lfirst(l);
18521874

1853-
query = fireRIRrules(query, NIL);
1875+
query = fireRIRrules(query, NIL, false);
18541876

18551877
/*
18561878
* If the query target was rewritten as a view, complain.

‎src/backend/utils/adt/ruleutils.c‎

Lines changed: 3 additions & 3 deletions
Original file line numberDiff line numberDiff line change
@@ -9,7 +9,7 @@
99
*
1010
*
1111
* IDENTIFICATION
12-
* $PostgreSQL: pgsql/src/backend/utils/adt/ruleutils.c,v 1.311 2009/10/28 14:55:44 tgl Exp $
12+
* $PostgreSQL: pgsql/src/backend/utils/adt/ruleutils.c,v 1.312 2009/10/28 17:36:50 tgl Exp $
1313
*
1414
*-------------------------------------------------------------------------
1515
*/
@@ -2175,7 +2175,7 @@ make_ruledef(StringInfo buf, HeapTuple ruletup, TupleDesc rulettc,
21752175
query = getInsertSelectQuery(query, NULL);
21762176

21772177
/* Must acquire locks right away; see notes in get_query_def() */
2178-
AcquireRewriteLocks(query);
2178+
AcquireRewriteLocks(query, false);
21792179

21802180
context.buf = buf;
21812181
context.namespaces = list_make1(&dpns);
@@ -2320,7 +2320,7 @@ get_query_def(Query *query, StringInfo buf, List *parentnamespace,
23202320
* consistent results. Note we assume it's OK to scribble on the passed
23212321
* querytree!
23222322
*/
2323-
AcquireRewriteLocks(query);
2323+
AcquireRewriteLocks(query, false);
23242324

23252325
context.buf = buf;
23262326
context.namespaces = lcons(&dpns, list_copy(parentnamespace));

‎src/include/rewrite/rewriteHandler.h‎

Lines changed: 2 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -7,7 +7,7 @@
77
* Portions Copyright (c) 1996-2009, PostgreSQL Global Development Group
88
* Portions Copyright (c) 1994, Regents of the University of California
99
*
10-
* $PostgreSQL: pgsql/src/include/rewrite/rewriteHandler.h,v 1.31 2009/01/01 17:24:01 momjian Exp $
10+
* $PostgreSQL: pgsql/src/include/rewrite/rewriteHandler.h,v 1.32 2009/10/28 17:36:50 tgl Exp $
1111
*
1212
*-------------------------------------------------------------------------
1313
*/
@@ -18,7 +18,7 @@
1818
#include "nodes/parsenodes.h"
1919

2020
extern List *QueryRewrite(Query *parsetree);
21-
extern void AcquireRewriteLocks(Query *parsetree);
21+
extern void AcquireRewriteLocks(Query *parsetree, bool forUpdatePushedDown);
2222
extern Node *build_column_default(Relation rel, int attrno);
2323

2424
#endif /* REWRITEHANDLER_H */

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