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Commit3576820

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committed
Ensure that a cursor is scanned under the same scanCommandId it was
originally created with, so that the set of visible tuples does notchange as a result of other activity. This essentially makes PG cursorsINSENSITIVE per the SQL92 definition. See bug report of 13-Feb-02.
1 parent1392042 commit3576820

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4 files changed

+48
-13
lines changed

4 files changed

+48
-13
lines changed

‎src/backend/commands/command.c

Lines changed: 16 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -8,7 +8,7 @@
88
*
99
*
1010
* IDENTIFICATION
11-
* $Header: /cvsroot/pgsql/src/backend/commands/Attic/command.c,v 1.152 2002/01/03 23:19:30 tgl Exp $
11+
* $Header: /cvsroot/pgsql/src/backend/commands/Attic/command.c,v 1.153 2002/02/14 15:24:06 tgl Exp $
1212
*
1313
* NOTES
1414
* The PerformAddAttribute() code, like most of the relation
@@ -103,6 +103,7 @@ PerformPortalFetch(char *name,
103103
QueryDesc*queryDesc;
104104
EState*estate;
105105
MemoryContextoldcontext;
106+
CommandIdsavedId;
106107
booltemp_desc= false;
107108

108109
/*
@@ -156,7 +157,7 @@ PerformPortalFetch(char *name,
156157
}
157158

158159
/*
159-
*tell the destination to prepare to receive some tuples.
160+
*Tell the destination to prepare to receive some tuples.
160161
*/
161162
BeginCommand(name,
162163
queryDesc->operation,
@@ -168,6 +169,14 @@ PerformPortalFetch(char *name,
168169
tag,
169170
queryDesc->dest);
170171

172+
/*
173+
* Restore the scanCommandId that was current when the cursor was
174+
* opened. This ensures that we see the same tuples throughout the
175+
* execution of the cursor.
176+
*/
177+
savedId=GetScanCommandId();
178+
SetScanCommandId(PortalGetCommandId(portal));
179+
171180
/*
172181
* Determine which direction to go in, and check to see if we're
173182
* already at the end of the available tuples in that direction. If
@@ -214,6 +223,11 @@ PerformPortalFetch(char *name,
214223
}
215224
}
216225

226+
/*
227+
* Restore outer command ID.
228+
*/
229+
SetScanCommandId(savedId);
230+
217231
/*
218232
* Clean up and switch back to old context.
219233
*/

‎src/backend/executor/spi.c

Lines changed: 24 additions & 7 deletions
Original file line numberDiff line numberDiff line change
@@ -8,7 +8,7 @@
88
*
99
*
1010
* IDENTIFICATION
11-
* $Header: /cvsroot/pgsql/src/backend/executor/spi.c,v 1.64 2002/01/03 20:30:47 tgl Exp $
11+
* $Header: /cvsroot/pgsql/src/backend/executor/spi.c,v 1.65 2002/02/14 15:24:08 tgl Exp $
1212
*
1313
*-------------------------------------------------------------------------
1414
*/
@@ -740,9 +740,9 @@ SPI_cursor_open(char *name, void *plan, Datum *Values, char *Nulls)
740740
_SPI_current->processed=0;
741741
_SPI_current->tuptable=NULL;
742742

743-
/* Make up a portal name if none given */
744743
if (name==NULL)
745744
{
745+
/* Make up a portal name if none given */
746746
for (;;)
747747
{
748748
unnamed_portal_count++;
@@ -755,11 +755,13 @@ SPI_cursor_open(char *name, void *plan, Datum *Values, char *Nulls)
755755

756756
name=portalname;
757757
}
758-
759-
/* Ensure the portal doesn't exist already */
760-
portal=GetPortalByName(name);
761-
if (portal!=NULL)
762-
elog(ERROR,"cursor \"%s\" already in use",name);
758+
else
759+
{
760+
/* Ensure the portal doesn't exist already */
761+
portal=GetPortalByName(name);
762+
if (portal!=NULL)
763+
elog(ERROR,"cursor \"%s\" already in use",name);
764+
}
763765

764766
/* Create the portal */
765767
portal=CreatePortal(name);
@@ -1228,6 +1230,7 @@ _SPI_cursor_operation(Portal portal, bool forward, int count,
12281230
QueryDesc*querydesc;
12291231
EState*estate;
12301232
MemoryContextoldcontext;
1233+
CommandIdsavedId;
12311234
CommandDestolddest;
12321235

12331236
/* Check that the portal is valid */
@@ -1245,6 +1248,7 @@ _SPI_cursor_operation(Portal portal, bool forward, int count,
12451248

12461249
/* Switch to the portals memory context */
12471250
oldcontext=MemoryContextSwitchTo(PortalGetHeapMemory(portal));
1251+
12481252
querydesc=PortalGetQueryDesc(portal);
12491253
estate=PortalGetState(portal);
12501254

@@ -1253,6 +1257,14 @@ _SPI_cursor_operation(Portal portal, bool forward, int count,
12531257
olddest=querydesc->dest;
12541258
querydesc->dest=dest;
12551259

1260+
/*
1261+
* Restore the scanCommandId that was current when the cursor was
1262+
* opened. This ensures that we see the same tuples throughout the
1263+
* execution of the cursor.
1264+
*/
1265+
savedId=GetScanCommandId();
1266+
SetScanCommandId(PortalGetCommandId(portal));
1267+
12561268
/* Run the executor like PerformPortalFetch and remember states */
12571269
if (forward)
12581270
{
@@ -1279,6 +1291,11 @@ _SPI_cursor_operation(Portal portal, bool forward, int count,
12791291
}
12801292
}
12811293

1294+
/*
1295+
* Restore outer command ID.
1296+
*/
1297+
SetScanCommandId(savedId);
1298+
12821299
/* Restore the old command destination and switch back to callers */
12831300
/* memory context */
12841301
querydesc->dest=olddest;

‎src/backend/utils/mmgr/portalmem.c

Lines changed: 3 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -8,7 +8,7 @@
88
*
99
*
1010
* IDENTIFICATION
11-
* $Header: /cvsroot/pgsql/src/backend/utils/mmgr/portalmem.c,v 1.44 2001/10/25 05:49:51 momjian Exp $
11+
* $Header: /cvsroot/pgsql/src/backend/utils/mmgr/portalmem.c,v 1.45 2002/02/14 15:24:09 tgl Exp $
1212
*
1313
*-------------------------------------------------------------------------
1414
*/
@@ -168,6 +168,7 @@ PortalSetQuery(Portal portal,
168168

169169
portal->queryDesc=queryDesc;
170170
portal->attinfo=attinfo;
171+
portal->commandId=GetScanCommandId();
171172
portal->state=state;
172173
portal->atStart= true;/* Allow fetch forward only */
173174
portal->atEnd= false;
@@ -213,6 +214,7 @@ CreatePortal(char *name)
213214
/* initialize portal query */
214215
portal->queryDesc=NULL;
215216
portal->attinfo=NULL;
217+
portal->commandId=0;
216218
portal->state=NULL;
217219
portal->atStart= true;/* disallow fetches until query is set */
218220
portal->atEnd= true;

‎src/include/utils/portal.h

Lines changed: 5 additions & 3 deletions
Original file line numberDiff line numberDiff line change
@@ -7,7 +7,7 @@
77
* Portions Copyright (c) 1996-2001, PostgreSQL Global Development Group
88
* Portions Copyright (c) 1994, Regents of the University of California
99
*
10-
* $Id: portal.h,v 1.31 2001/11/05 17:46:36 momjian Exp $
10+
* $Id: portal.h,v 1.32 2002/02/14 15:24:10 tgl Exp $
1111
*
1212
*-------------------------------------------------------------------------
1313
*/
@@ -31,6 +31,7 @@ typedef struct PortalData
3131
MemoryContextheap;/* subsidiary memory */
3232
QueryDesc*queryDesc;/* Info about query associated with portal */
3333
TupleDescattinfo;
34+
CommandIdcommandId;/* Command counter value for query */
3435
EState*state;/* Execution state of query */
3536
boolatStart;/* T => fetch backwards is not allowed */
3637
boolatEnd;/* T => fetch forwards is not allowed */
@@ -48,8 +49,9 @@ typedef struct PortalData
4849
*/
4950
#definePortalGetQueryDesc(portal)((portal)->queryDesc)
5051
#definePortalGetTupleDesc(portal)((portal)->attinfo)
51-
#definePortalGetState(portal)((portal)->state)
52-
#definePortalGetHeapMemory(portal) ((portal)->heap)
52+
#definePortalGetCommandId(portal)((portal)->commandId)
53+
#definePortalGetState(portal)((portal)->state)
54+
#definePortalGetHeapMemory(portal)((portal)->heap)
5355

5456
/*
5557
* estimate of the maximum number of open portals a user would have,

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