Tom Lane escribió:
> Alvaro Herrera <alvherre@xxxxxxxxxxxxxxxxx> writes:
> > Tom Lane escribi� >> I think we need to ensure that when a cursor is created, it obtains a
> >> private copy of the current snapshot ... but I'm not sure where that
> >> ought to happen. Thoughts?
>
> > Maybe you are right, but I don't think that's the only bug here.
>
> Well, the first problem is that 8.4 is failing to duplicate the
> historical behavior.
Oh! That's easy.
> After that we can think about whether we'd like to
> change the historical behavior. I'm not entirely convinced about that
> yet (and it certainly wouldn't be something I'd want to back-patch).
I don't care enough about that to spend much time on it ...
--
Alvaro Herrera http://www.CommandPrompt.com/
The PostgreSQL Company - Command Prompt, Inc.
*** src/backend/commands/portalcmds.c 11 Jun 2009 14:48:56 -0000 1.79
--- src/backend/commands/portalcmds.c 1 Oct 2009 01:24:11 -0000
***************
*** 47,52 ****
--- 47,53 ----
DeclareCursorStmt *cstmt = (DeclareCursorStmt *) stmt->utilityStmt;
Portal portal;
MemoryContext oldContext;
+ Snapshot snapshot;
if (cstmt == NULL || !IsA(cstmt, DeclareCursorStmt))
elog(ERROR, "PerformCursorOpen called for non-cursor query");
***************
*** 118,127 ****
portal->cursorOptions |= CURSOR_OPT_NO_SCROLL;
}
/*
* Start execution, inserting parameters if any.
*/
! PortalStart(portal, params, GetActiveSnapshot());
Assert(portal->strategy == PORTAL_ONE_SELECT);
--- 119,135 ----
portal->cursorOptions |= CURSOR_OPT_NO_SCROLL;
}
+ /* Set up snapshot for portal */
+ if (stmt->rowMarks != NIL)
+ snapshot = RegisterCopiedSnapshot(GetActiveSnapshot(),
+ portal->resowner);
+ else
+ snapshot = GetActiveSnapshot();
+
/*
* Start execution, inserting parameters if any.
*/
! PortalStart(portal, params, snapshot);
Assert(portal->strategy == PORTAL_ONE_SELECT);
*** src/backend/utils/time/snapmgr.c 11 Jun 2009 14:49:06 -0000 1.10
--- src/backend/utils/time/snapmgr.c 1 Oct 2009 01:19:51 -0000
***************
*** 385,390 ****
--- 385,403 ----
}
/*
+ * As above, but create a new, independeny copy of the snapshot.
+ */
+ Snapshot
+ RegisterCopiedSnapshot(Snapshot snapshot, ResourceOwner owner)
+ {
+ if (snapshot == InvalidSnapshot)
+ return InvalidSnapshot;
+
+ snapshot = CopySnapshot(snapshot);
+ return RegisterSnapshotOnOwner(snapshot, owner);
+ }
+
+ /*
* UnregisterSnapshot
*
* Decrement the reference count of a snapshot, remove the corresponding
*** src/include/utils/snapmgr.h 11 Jun 2009 14:49:13 -0000 1.5
--- src/include/utils/snapmgr.h 1 Oct 2009 01:20:12 -0000
***************
*** 36,41 ****
--- 36,42 ----
extern Snapshot RegisterSnapshot(Snapshot snapshot);
extern void UnregisterSnapshot(Snapshot snapshot);
extern Snapshot RegisterSnapshotOnOwner(Snapshot snapshot, ResourceOwner owner);
+ extern Snapshot RegisterCopiedSnapshot(Snapshot snapshot, ResourceOwner owner);
extern void UnregisterSnapshotFromOwner(Snapshot snapshot, ResourceOwner owner);
extern void AtSubCommit_Snapshot(int level);
--
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