/*
* PopActiveSnapshot
*
* Remove the topmost snapshot from the active snapshot stack, decrementing the
* reference count, and free it if this was the last reference.
*/
void
PopActiveSnapshot(void)
{
ActiveSnapshotElt *newstack;
newstack = ActiveSnapshot->as_next;
Assert(ActiveSnapshot->as_snap->active_count > 0);
ActiveSnapshot->as_snap->active_count--;
if (ActiveSnapshot->as_snap->active_count == 0 &&
ActiveSnapshot->as_snap->regd_count == 0)
FreeSnapshot(ActiveSnapshot->as_snap);
pfree(ActiveSnapshot);
ActiveSnapshot = newstack;
SnapshotResetXmin();
}
/*
* UnregisterSnapshotFromOwner
* As above, but use the specified resource owner
*/
void
UnregisterSnapshotFromOwner(Snapshot snapshot, ResourceOwner owner)
{
if (snapshot == NULL)
return;
Assert(snapshot->regd_count > 0);
Assert(!pairingheap_is_empty(&RegisteredSnapshots));
ResourceOwnerForgetSnapshot(owner, snapshot);
snapshot->regd_count--;
if (snapshot->regd_count == 0)
pairingheap_remove(&RegisteredSnapshots, &snapshot->ph_node);
if (snapshot->regd_count == 0 && snapshot->active_count == 0)
{
FreeSnapshot(snapshot);
SnapshotResetXmin();
}
}
/*
* ProcessQuery
* Execute a single plannable query within a PORTAL_MULTI_QUERY
* or PORTAL_ONE_RETURNING portal
*
* parsetree: the query tree
* plan: the plan tree for the query
* params: any parameters needed
* dest: where to send results
* completionTag: points to a buffer of size COMPLETION_TAG_BUFSIZE
* in which to store a command completion status string.
*
* completionTag may be NULL if caller doesn't want a status string.
*
* Must be called in a memory context that will be reset or deleted on
* error; otherwise the executor's memory usage will be leaked.
*/
static void
ProcessQuery(Query *parsetree,
Plan *plan,
ParamListInfo params,
DestReceiver *dest,
char *completionTag)
{
int operation = parsetree->commandType;
QueryDesc *queryDesc;
ereport(DEBUG3,
(errmsg_internal("ProcessQuery")));
/*
* Must always set snapshot for plannable queries. Note we assume that
* caller will take care of restoring ActiveSnapshot on exit/error.
*/
ActiveSnapshot = CopySnapshot(GetTransactionSnapshot());
/*
* Create the QueryDesc object
*/
queryDesc = CreateQueryDesc(parsetree, plan,
ActiveSnapshot, InvalidSnapshot,
dest, params, false);
/*
* Set up to collect AFTER triggers
*/
AfterTriggerBeginQuery();
/*
* Call ExecutorStart to prepare the plan for execution
*/
ExecutorStart(queryDesc, 0);
/*
* Run the plan to completion.
*/
ExecutorRun(queryDesc, ForwardScanDirection, 0L);
/*
* Build command completion status string, if caller wants one.
*/
if (completionTag)
{
Oid lastOid;
switch (operation)
{
case CMD_SELECT:
strcpy(completionTag, "SELECT");
break;
case CMD_INSERT:
if (queryDesc->estate->es_processed == 1)
lastOid = queryDesc->estate->es_lastoid;
else
lastOid = InvalidOid;
snprintf(completionTag, COMPLETION_TAG_BUFSIZE,
"INSERT %u %u", lastOid, queryDesc->estate->es_processed);
break;
case CMD_UPDATE:
snprintf(completionTag, COMPLETION_TAG_BUFSIZE,
"UPDATE %u", queryDesc->estate->es_processed);
break;
case CMD_DELETE:
snprintf(completionTag, COMPLETION_TAG_BUFSIZE,
"DELETE %u", queryDesc->estate->es_processed);
break;
default:
strcpy(completionTag, "???");
break;
}
}
/* Now take care of any queued AFTER triggers */
AfterTriggerEndQuery(queryDesc->estate);
/*
* Now, we close down all the scans and free allocated resources.
*/
ExecutorEnd(queryDesc);
FreeQueryDesc(queryDesc);
FreeSnapshot(ActiveSnapshot);
ActiveSnapshot = NULL;
}
