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Clean up handling of FOR UPDATE inside views and subselects ... make it
work where we can (given that the executor only handles it at top level) and generate an error where we can't. Note that while the parser has been allowing views to say SELECT FOR UPDATE for a few weeks now, that hasn't actually worked until just now.
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5 files changed

+85
-42
lines changed

5 files changed

+85
-42
lines changed

‎src/backend/optimizer/plan/planner.c

Lines changed: 34 additions & 6 deletions
Original file line numberDiff line numberDiff line change
@@ -8,7 +8,7 @@
88
*
99
*
1010
* IDENTIFICATION
11-
* $Header: /cvsroot/pgsql/src/backend/optimizer/plan/planner.c,v 1.96 2000/11/12 00:36:58 tgl Exp $
11+
* $Header: /cvsroot/pgsql/src/backend/optimizer/plan/planner.c,v 1.97 2000/12/06 23:55:17 tgl Exp $
1212
*
1313
*-------------------------------------------------------------------------
1414
*/
@@ -25,6 +25,7 @@
2525
#include "optimizer/subselect.h"
2626
#include "optimizer/tlist.h"
2727
#include "optimizer/var.h"
28+
#include "parser/analyze.h"
2829
#include "parser/parsetree.h"
2930
#include "parser/parse_expr.h"
3031
#include "rewrite/rewriteManip.h"
@@ -255,6 +256,7 @@ pull_up_subqueries(Query *parse, Node *jtnode)
255256
int rtoffset;
256257
Node *subjointree;
257258
List *subtlist;
259+
List *l;
258260

259261
/*
260262
* First, recursively pull up the subquery's subqueries,
@@ -289,10 +291,22 @@ pull_up_subqueries(Query *parse, Node *jtnode)
289291
parse->havingQual =
290292
ResolveNew(parse->havingQual,
291293
varno, 0, subtlist, CMD_SELECT, 0);
294+
/*
295+
* Pull up any FOR UPDATE markers, too.
296+
*/
297+
foreach(l, subquery->rowMarks)
298+
{
299+
int submark = lfirsti(l);
300+
301+
parse->rowMarks = lappendi(parse->rowMarks,
302+
submark + rtoffset);
303+
}
292304
/*
293305
* Miscellaneous housekeeping.
294306
*/
295307
parse->hasSubLinks |= subquery->hasSubLinks;
308+
/* subquery won't be pulled up if it hasAggs, so no work there */
309+
296310
/*
297311
* Return the adjusted subquery jointree to replace the
298312
* RangeTblRef entry in my jointree.
@@ -340,11 +354,6 @@ is_simple_subquery(Query *subquery)
340354
subquery->into != NULL ||
341355
subquery->isPortal)
342356
elog(ERROR, "is_simple_subquery: subquery is bogus");
343-
/*
344-
* Also check for currently-unsupported features.
345-
*/
346-
if (subquery->rowMarks)
347-
elog(ERROR, "FOR UPDATE is not supported in subselects");
348357
/*
349358
* Can't currently pull up a query with setops.
350359
* Maybe after querytree redesign...
@@ -707,6 +716,13 @@ grouping_planner(Query *parse, double tuple_fraction)
707716

708717
tlist = postprocess_setop_tlist(result_plan->targetlist, tlist);
709718

719+
/*
720+
* Can't handle FOR UPDATE here (parser should have checked already,
721+
* but let's make sure).
722+
*/
723+
if (parse->rowMarks)
724+
elog(ERROR, "SELECT FOR UPDATE is not allowed with UNION/INTERSECT/EXCEPT");
725+
710726
/*
711727
* We set current_pathkeys NIL indicating we do not know sort
712728
* order. This is correct when the top set operation is UNION ALL,
@@ -744,6 +760,18 @@ grouping_planner(Query *parse, double tuple_fraction)
744760
{
745761
List *l;
746762

763+
/*
764+
* We've got trouble if the FOR UPDATE appears inside grouping,
765+
* since grouping renders a reference to individual tuple CTIDs
766+
* invalid. This is also checked at parse time, but that's
767+
* insufficient because of rule substitution, query pullup, etc.
768+
*/
769+
CheckSelectForUpdate(parse);
770+
771+
/* Currently the executor only supports FOR UPDATE at top level */
772+
if (PlannerQueryLevel > 1)
773+
elog(ERROR, "SELECT FOR UPDATE is not allowed in subselects");
774+
747775
foreach(l, parse->rowMarks)
748776
{
749777
Index rti = lfirsti(l);

‎src/backend/parser/analyze.c

Lines changed: 1 addition & 3 deletions
Original file line numberDiff line numberDiff line change
@@ -6,7 +6,7 @@
66
* Portions Copyright (c) 1996-2000, PostgreSQL, Inc
77
* Portions Copyright (c) 1994, Regents of the University of California
88
*
9-
* $Id: analyze.c,v 1.170 2000/12/05 19:57:55 tgl Exp $
9+
* $Id: analyze.c,v 1.171 2000/12/06 23:55:19 tgl Exp $
1010
*
1111
*-------------------------------------------------------------------------
1212
*/
@@ -37,8 +37,6 @@
3737
#include "mb/pg_wchar.h"
3838
#endif
3939

40-
void CheckSelectForUpdate(Query *qry); /* no points for style... */
41-
4240
static Query *transformStmt(ParseState *pstate, Node *stmt);
4341
static Query *transformDeleteStmt(ParseState *pstate, DeleteStmt *stmt);
4442
static Query *transformInsertStmt(ParseState *pstate, InsertStmt *stmt);

‎src/backend/rewrite/rewriteHandler.c

Lines changed: 1 addition & 29 deletions
Original file line numberDiff line numberDiff line change
@@ -7,7 +7,7 @@
77
*
88
*
99
* IDENTIFICATION
10-
* $Header: /cvsroot/pgsql/src/backend/rewrite/rewriteHandler.c,v 1.84 2000/12/05 19:15:09 tgl Exp $
10+
* $Header: /cvsroot/pgsql/src/backend/rewrite/rewriteHandler.c,v 1.85 2000/12/06 23:55:18 tgl Exp $
1111
*
1212
*-------------------------------------------------------------------------
1313
*/
@@ -31,9 +31,6 @@
3131
#include "utils/lsyscache.h"
3232

3333

34-
extern void CheckSelectForUpdate(Query *rule_action); /* in analyze.c */
35-
36-
3734
static RewriteInfo *gatherRewriteMeta(Query *parsetree,
3835
Query *rule_action,
3936
Node *rule_qual,
@@ -100,29 +97,6 @@ gatherRewriteMeta(Query *parsetree,
10097
ChangeVarNodes(info->rule_qual,
10198
PRS2_OLD_VARNO + rt_length, rt_index, 0);
10299

103-
/*
104-
* Update resultRelation too ... perhaps this should be done by
105-
* Offset/ChangeVarNodes?
106-
*/
107-
if (sub_action->resultRelation)
108-
{
109-
int result_reln;
110-
int new_result_reln;
111-
112-
result_reln = sub_action->resultRelation;
113-
switch (result_reln)
114-
{
115-
case PRS2_OLD_VARNO:
116-
new_result_reln = rt_index;
117-
break;
118-
case PRS2_NEW_VARNO:
119-
default:
120-
new_result_reln = result_reln + rt_length;
121-
break;
122-
}
123-
sub_action->resultRelation = new_result_reln;
124-
}
125-
126100
/*
127101
* We want the main parsetree's rtable to end up as the concatenation
128102
* of its original contents plus those of all the relevant rule
@@ -336,8 +310,6 @@ ApplyRetrieveRule(Query *parsetree,
336310
{
337311
Index innerrti = 1;
338312

339-
CheckSelectForUpdate(rule_action);
340-
341313
/*
342314
* Remove the view from the list of rels that will actually be
343315
* marked FOR UPDATE by the executor. It will still be access-

‎src/backend/rewrite/rewriteManip.c

Lines changed: 46 additions & 3 deletions
Original file line numberDiff line numberDiff line change
@@ -7,7 +7,7 @@
77
*
88
*
99
* IDENTIFICATION
10-
* $Header: /cvsroot/pgsql/src/backend/rewrite/rewriteManip.c,v 1.52 2000/12/05 19:15:09 tgl Exp $
10+
* $Header: /cvsroot/pgsql/src/backend/rewrite/rewriteManip.c,v 1.53 2000/12/06 23:55:18 tgl Exp $
1111
*
1212
*-------------------------------------------------------------------------
1313
*/
@@ -169,8 +169,29 @@ OffsetVarNodes(Node *node, int offset, int sublevels_up)
169169
* sublevels_up doesn't get incremented prematurely.
170170
*/
171171
if (node && IsA(node, Query))
172-
query_tree_walker((Query *) node, OffsetVarNodes_walker,
172+
{
173+
Query *qry = (Query *) node;
174+
List *l;
175+
176+
/*
177+
* If we are starting at a Query, and sublevels_up is zero, then we
178+
* must also fix rangetable indexes in the Query itself --- namely
179+
* resultRelation and rowMarks entries. sublevels_up cannot be zero
180+
* when recursing into a subquery, so there's no need to have the
181+
* same logic inside OffsetVarNodes_walker.
182+
*/
183+
if (sublevels_up == 0)
184+
{
185+
if (qry->resultRelation)
186+
qry->resultRelation += offset;
187+
foreach(l, qry->rowMarks)
188+
{
189+
lfirsti(l) += offset;
190+
}
191+
}
192+
query_tree_walker(qry, OffsetVarNodes_walker,
173193
(void *) &context, true);
194+
}
174195
else
175196
OffsetVarNodes_walker(node, &context);
176197
}
@@ -252,8 +273,30 @@ ChangeVarNodes(Node *node, int rt_index, int new_index, int sublevels_up)
252273
* sublevels_up doesn't get incremented prematurely.
253274
*/
254275
if (node && IsA(node, Query))
255-
query_tree_walker((Query *) node, ChangeVarNodes_walker,
276+
{
277+
Query *qry = (Query *) node;
278+
List *l;
279+
280+
/*
281+
* If we are starting at a Query, and sublevels_up is zero, then we
282+
* must also fix rangetable indexes in the Query itself --- namely
283+
* resultRelation and rowMarks entries. sublevels_up cannot be zero
284+
* when recursing into a subquery, so there's no need to have the
285+
* same logic inside ChangeVarNodes_walker.
286+
*/
287+
if (sublevels_up == 0)
288+
{
289+
if (qry->resultRelation == rt_index)
290+
qry->resultRelation = new_index;
291+
foreach(l, qry->rowMarks)
292+
{
293+
if (lfirsti(l) == rt_index)
294+
lfirsti(l) = new_index;
295+
}
296+
}
297+
query_tree_walker(qry, ChangeVarNodes_walker,
256298
(void *) &context, true);
299+
}
257300
else
258301
ChangeVarNodes_walker(node, &context);
259302
}

‎src/include/parser/analyze.h

Lines changed: 3 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -6,7 +6,7 @@
66
* Portions Copyright (c) 1996-2000, PostgreSQL, Inc
77
* Portions Copyright (c) 1994, Regents of the University of California
88
*
9-
* $Id: analyze.h,v 1.12 2000/10/07 00:58:21 tgl Exp $
9+
* $Id: analyze.h,v 1.13 2000/12/06 23:55:18 tgl Exp $
1010
*
1111
*-------------------------------------------------------------------------
1212
*/
@@ -17,4 +17,6 @@
1717

1818
extern List *parse_analyze(Node *parseTree, ParseState *parentParseState);
1919

20+
extern void CheckSelectForUpdate(Query *qry);
21+
2022
#endif /* ANALYZE_H */

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