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Diffstat (limited to 'src/backend/tcop/pquery.c')
-rw-r--r--src/backend/tcop/pquery.c84
1 files changed, 41 insertions, 43 deletions
diff --git a/src/backend/tcop/pquery.c b/src/backend/tcop/pquery.c
index cf5f2784142..a4afab04025 100644
--- a/src/backend/tcop/pquery.c
+++ b/src/backend/tcop/pquery.c
@@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
- * $PostgreSQL: pgsql/src/backend/tcop/pquery.c,v 1.122 2008/03/26 18:48:59 alvherre Exp $
+ * $PostgreSQL: pgsql/src/backend/tcop/pquery.c,v 1.123 2008/05/12 20:02:02 alvherre Exp $
*
*-------------------------------------------------------------------------
*/
@@ -70,8 +70,9 @@ CreateQueryDesc(PlannedStmt *plannedstmt,
qd->operation = plannedstmt->commandType; /* operation */
qd->plannedstmt = plannedstmt; /* plan */
qd->utilitystmt = plannedstmt->utilityStmt; /* in case DECLARE CURSOR */
- qd->snapshot = snapshot; /* snapshot */
- qd->crosscheck_snapshot = crosscheck_snapshot; /* RI check snapshot */
+ qd->snapshot = RegisterSnapshot(snapshot); /* snapshot */
+ /* RI check snapshot */
+ qd->crosscheck_snapshot = RegisterSnapshot(crosscheck_snapshot);
qd->dest = dest; /* output dest */
qd->params = params; /* parameter values passed into query */
qd->doInstrument = doInstrument; /* instrumentation wanted? */
@@ -98,7 +99,7 @@ CreateUtilityQueryDesc(Node *utilitystmt,
qd->operation = CMD_UTILITY; /* operation */
qd->plannedstmt = NULL;
qd->utilitystmt = utilitystmt; /* utility command */
- qd->snapshot = snapshot; /* snapshot */
+ qd->snapshot = RegisterSnapshot(snapshot); /* snapshot */
qd->crosscheck_snapshot = InvalidSnapshot; /* RI check snapshot */
qd->dest = dest; /* output dest */
qd->params = params; /* parameter values passed into query */
@@ -120,6 +121,11 @@ FreeQueryDesc(QueryDesc *qdesc)
{
/* Can't be a live query */
Assert(qdesc->estate == NULL);
+
+ /* forget our snapshots */
+ UnregisterSnapshot(qdesc->snapshot);
+ UnregisterSnapshot(qdesc->crosscheck_snapshot);
+
/* Only the QueryDesc itself need be freed */
pfree(qdesc);
}
@@ -152,16 +158,15 @@ ProcessQuery(PlannedStmt *plan,
elog(DEBUG3, "ProcessQuery");
/*
- * Must always set snapshot for plannable queries. Note we assume that
- * caller will take care of restoring ActiveSnapshot on exit/error.
+ * Must always set a snapshot for plannable queries.
*/
- ActiveSnapshot = CopySnapshot(GetTransactionSnapshot());
+ PushActiveSnapshot(GetTransactionSnapshot());
/*
* Create the QueryDesc object
*/
queryDesc = CreateQueryDesc(plan,
- ActiveSnapshot, InvalidSnapshot,
+ GetActiveSnapshot(), InvalidSnapshot,
dest, params, false);
/*
@@ -216,15 +221,14 @@ ProcessQuery(PlannedStmt *plan,
/* Now take care of any queued AFTER triggers */
AfterTriggerEndQuery(queryDesc->estate);
+ PopActiveSnapshot();
+
/*
* Now, we close down all the scans and free allocated resources.
*/
ExecutorEnd(queryDesc);
FreeQueryDesc(queryDesc);
-
- FreeSnapshot(ActiveSnapshot);
- ActiveSnapshot = NULL;
}
/*
@@ -446,7 +450,6 @@ void
PortalStart(Portal portal, ParamListInfo params, Snapshot snapshot)
{
Portal saveActivePortal;
- Snapshot saveActiveSnapshot;
ResourceOwner saveResourceOwner;
MemoryContext savePortalContext;
MemoryContext oldContext;
@@ -460,13 +463,11 @@ PortalStart(Portal portal, ParamListInfo params, Snapshot snapshot)
* Set up global portal context pointers.
*/
saveActivePortal = ActivePortal;
- saveActiveSnapshot = ActiveSnapshot;
saveResourceOwner = CurrentResourceOwner;
savePortalContext = PortalContext;
PG_TRY();
{
ActivePortal = portal;
- ActiveSnapshot = NULL; /* will be set later */
CurrentResourceOwner = portal->resowner;
PortalContext = PortalGetHeapMemory(portal);
@@ -487,21 +488,18 @@ PortalStart(Portal portal, ParamListInfo params, Snapshot snapshot)
{
case PORTAL_ONE_SELECT:
- /*
- * Must set snapshot before starting executor. Be sure to
- * copy it into the portal's context.
- */
+ /* Must set snapshot before starting executor. */
if (snapshot)
- ActiveSnapshot = CopySnapshot(snapshot);
+ PushActiveSnapshot(snapshot);
else
- ActiveSnapshot = CopySnapshot(GetTransactionSnapshot());
+ PushActiveSnapshot(GetTransactionSnapshot());
/*
* Create QueryDesc in portal's context; for the moment, set
* the destination to DestNone.
*/
queryDesc = CreateQueryDesc((PlannedStmt *) linitial(portal->stmts),
- ActiveSnapshot,
+ GetActiveSnapshot(),
InvalidSnapshot,
None_Receiver,
params,
@@ -545,6 +543,8 @@ PortalStart(Portal portal, ParamListInfo params, Snapshot snapshot)
portal->atEnd = false; /* allow fetches */
portal->portalPos = 0;
portal->posOverflow = false;
+
+ PopActiveSnapshot();
break;
case PORTAL_ONE_RETURNING:
@@ -608,7 +608,6 @@ PortalStart(Portal portal, ParamListInfo params, Snapshot snapshot)
/* Restore global vars and propagate error */
ActivePortal = saveActivePortal;
- ActiveSnapshot = saveActiveSnapshot;
CurrentResourceOwner = saveResourceOwner;
PortalContext = savePortalContext;
@@ -619,7 +618,6 @@ PortalStart(Portal portal, ParamListInfo params, Snapshot snapshot)
MemoryContextSwitchTo(oldContext);
ActivePortal = saveActivePortal;
- ActiveSnapshot = saveActiveSnapshot;
CurrentResourceOwner = saveResourceOwner;
PortalContext = savePortalContext;
@@ -707,7 +705,6 @@ PortalRun(Portal portal, long count, bool isTopLevel,
ResourceOwner saveTopTransactionResourceOwner;
MemoryContext saveTopTransactionContext;
Portal saveActivePortal;
- Snapshot saveActiveSnapshot;
ResourceOwner saveResourceOwner;
MemoryContext savePortalContext;
MemoryContext saveMemoryContext;
@@ -751,14 +748,12 @@ PortalRun(Portal portal, long count, bool isTopLevel,
saveTopTransactionResourceOwner = TopTransactionResourceOwner;
saveTopTransactionContext = TopTransactionContext;
saveActivePortal = ActivePortal;
- saveActiveSnapshot = ActiveSnapshot;
saveResourceOwner = CurrentResourceOwner;
savePortalContext = PortalContext;
saveMemoryContext = CurrentMemoryContext;
PG_TRY();
{
ActivePortal = portal;
- ActiveSnapshot = NULL; /* will be set later */
CurrentResourceOwner = portal->resowner;
PortalContext = PortalGetHeapMemory(portal);
@@ -839,7 +834,6 @@ PortalRun(Portal portal, long count, bool isTopLevel,
else
MemoryContextSwitchTo(saveMemoryContext);
ActivePortal = saveActivePortal;
- ActiveSnapshot = saveActiveSnapshot;
if (saveResourceOwner == saveTopTransactionResourceOwner)
CurrentResourceOwner = TopTransactionResourceOwner;
else
@@ -855,7 +849,6 @@ PortalRun(Portal portal, long count, bool isTopLevel,
else
MemoryContextSwitchTo(saveMemoryContext);
ActivePortal = saveActivePortal;
- ActiveSnapshot = saveActiveSnapshot;
if (saveResourceOwner == saveTopTransactionResourceOwner)
CurrentResourceOwner = TopTransactionResourceOwner;
else
@@ -940,9 +933,10 @@ PortalRunSelect(Portal portal,
nprocessed = RunFromStore(portal, direction, count, dest);
else
{
- ActiveSnapshot = queryDesc->snapshot;
+ PushActiveSnapshot(queryDesc->snapshot);
ExecutorRun(queryDesc, direction, count);
nprocessed = queryDesc->estate->es_processed;
+ PopActiveSnapshot();
}
if (!ScanDirectionIsNoMovement(direction))
@@ -982,9 +976,10 @@ PortalRunSelect(Portal portal,
nprocessed = RunFromStore(portal, direction, count, dest);
else
{
- ActiveSnapshot = queryDesc->snapshot;
+ PushActiveSnapshot(queryDesc->snapshot);
ExecutorRun(queryDesc, direction, count);
nprocessed = queryDesc->estate->es_processed;
+ PopActiveSnapshot();
}
if (!ScanDirectionIsNoMovement(direction))
@@ -1140,6 +1135,8 @@ static void
PortalRunUtility(Portal portal, Node *utilityStmt, bool isTopLevel,
DestReceiver *dest, char *completionTag)
{
+ bool active_snapshot_set;
+
elog(DEBUG3, "ProcessUtility");
/*
@@ -1152,9 +1149,6 @@ PortalRunUtility(Portal portal, Node *utilityStmt, bool isTopLevel,
* hacks. Beware of listing anything that can modify the database --- if,
* say, it has to update an index with expressions that invoke
* user-defined functions, then it had better have a snapshot.
- *
- * Note we assume that caller will take care of restoring ActiveSnapshot
- * on exit/error.
*/
if (!(IsA(utilityStmt, TransactionStmt) ||
IsA(utilityStmt, LockStmt) ||
@@ -1167,9 +1161,12 @@ PortalRunUtility(Portal portal, Node *utilityStmt, bool isTopLevel,
IsA(utilityStmt, NotifyStmt) ||
IsA(utilityStmt, UnlistenStmt) ||
IsA(utilityStmt, CheckPointStmt)))
- ActiveSnapshot = CopySnapshot(GetTransactionSnapshot());
+ {
+ PushActiveSnapshot(GetTransactionSnapshot());
+ active_snapshot_set = true;
+ }
else
- ActiveSnapshot = NULL;
+ active_snapshot_set = false;
ProcessUtility(utilityStmt,
portal->sourceText,
@@ -1181,9 +1178,15 @@ PortalRunUtility(Portal portal, Node *utilityStmt, bool isTopLevel,
/* Some utility statements may change context on us */
MemoryContextSwitchTo(PortalGetHeapMemory(portal));
- if (ActiveSnapshot)
- FreeSnapshot(ActiveSnapshot);
- ActiveSnapshot = NULL;
+ /*
+ * Some utility commands may pop the ActiveSnapshot stack from under us,
+ * so we only pop the stack if we actually see a snapshot set. Note that
+ * the set of utility commands that do this must be the same set
+ * disallowed to run inside a transaction; otherwise, we could be popping
+ * a snapshot that belongs to some other operation.
+ */
+ if (active_snapshot_set && ActiveSnapshotSet())
+ PopActiveSnapshot();
}
/*
@@ -1321,7 +1324,6 @@ PortalRunFetch(Portal portal,
{
long result;
Portal saveActivePortal;
- Snapshot saveActiveSnapshot;
ResourceOwner saveResourceOwner;
MemoryContext savePortalContext;
MemoryContext oldContext;
@@ -1341,13 +1343,11 @@ PortalRunFetch(Portal portal,
* Set up global portal context pointers.
*/
saveActivePortal = ActivePortal;
- saveActiveSnapshot = ActiveSnapshot;
saveResourceOwner = CurrentResourceOwner;
savePortalContext = PortalContext;
PG_TRY();
{
ActivePortal = portal;
- ActiveSnapshot = NULL; /* will be set later */
CurrentResourceOwner = portal->resowner;
PortalContext = PortalGetHeapMemory(portal);
@@ -1388,7 +1388,6 @@ PortalRunFetch(Portal portal,
/* Restore global vars and propagate error */
ActivePortal = saveActivePortal;
- ActiveSnapshot = saveActiveSnapshot;
CurrentResourceOwner = saveResourceOwner;
PortalContext = savePortalContext;
@@ -1402,7 +1401,6 @@ PortalRunFetch(Portal portal,
portal->status = PORTAL_READY;
ActivePortal = saveActivePortal;
- ActiveSnapshot = saveActiveSnapshot;
CurrentResourceOwner = saveResourceOwner;
PortalContext = savePortalContext;
generated by cgit v1.2.3 (git 2.25.1) at 2025-05-23 07:01:58 +0000