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| author | Alvaro Herrera <alvherre@alvh.no-ip.org> | 2009-10-02 17:58:21 +0000 |
|---|---|---|
| committer | Alvaro Herrera <alvherre@alvh.no-ip.org> | 2009-10-02 17:58:21 +0000 |
| commit | ae35363dced47a99178b4a4129e3ea1f990b829c (patch) | |
| tree | c0a113330d1b9039764b82a1e59820c420b6fe7a /src/backend/commands/portalcmds.c | |
| parent | d4bd8423c9939a30f0f29e70745917e4635b4973 (diff) | |
| download | postgresql-ae35363dced47a99178b4a4129e3ea1f990b829c.tar.gz postgresql-ae35363dced47a99178b4a4129e3ea1f990b829c.zip | |
Ensure that a cursor has an immutable snapshot throughout its lifespan.
The old coding was using a regular snapshot, referenced elsewhere, that was
subject to having its command counter updated. Fix by creating a private copy
of the snapshot exclusively for the cursor.
Backpatch to 8.4, which is when the bug was introduced during the snapshot
management rewrite.
Diffstat (limited to 'src/backend/commands/portalcmds.c')
| -rw-r--r-- | src/backend/commands/portalcmds.c | 13 |
1 files changed, 11 insertions, 2 deletions
diff --git a/src/backend/commands/portalcmds.c b/src/backend/commands/portalcmds.c index 17192341739..d31fde65b6b 100644 --- a/src/backend/commands/portalcmds.c +++ b/src/backend/commands/portalcmds.c @@ -14,7 +14,7 @@ * * * IDENTIFICATION - * $PostgreSQL: pgsql/src/backend/commands/portalcmds.c,v 1.79 2009/06/11 14:48:56 momjian Exp $ + * $PostgreSQL: pgsql/src/backend/commands/portalcmds.c,v 1.79.2.1 2009/10/02 17:58:21 alvherre Exp $ * *------------------------------------------------------------------------- */ @@ -47,6 +47,7 @@ PerformCursorOpen(PlannedStmt *stmt, ParamListInfo params, 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"); @@ -119,9 +120,17 @@ PerformCursorOpen(PlannedStmt *stmt, ParamListInfo params, } /* + * Set up snapshot for portal. Note that we need a fresh, independent copy + * of the snapshot because we don't want it to be modified by future + * CommandCounterIncrement calls. We do not register it, because + * portalmem.c will take care of that internally. + */ + snapshot = CopySnapshot(GetActiveSnapshot()); + + /* * Start execution, inserting parameters if any. */ - PortalStart(portal, params, GetActiveSnapshot()); + PortalStart(portal, params, snapshot); Assert(portal->strategy == PORTAL_ONE_SELECT); |