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/*-------------------------------------------------------------------------
*
* discard.c
* The implementation of the DISCARD command
*
* Copyright (c) 1996-2012, PostgreSQL Global Development Group
*
*
* IDENTIFICATION
* src/backend/commands/discard.c
*
*-------------------------------------------------------------------------
*/
#include "postgres.h"
#include "access/xact.h"
#include "catalog/namespace.h"
#include "commands/async.h"
#include "commands/discard.h"
#include "commands/prepare.h"
#include "utils/guc.h"
#include "utils/portal.h"
static void DiscardAll(bool isTopLevel);
/*
* DISCARD { ALL | TEMP | PLANS }
*/
void
DiscardCommand(DiscardStmt *stmt, bool isTopLevel)
{
switch (stmt->target)
{
case DISCARD_ALL:
DiscardAll(isTopLevel);
break;
case DISCARD_PLANS:
ResetPlanCache();
break;
case DISCARD_TEMP:
ResetTempTableNamespace();
break;
default:
elog(ERROR, "unrecognized DISCARD target: %d", stmt->target);
}
}
static void
DiscardAll(bool isTopLevel)
{
/*
* Disallow DISCARD ALL in a transaction block. This is arguably
* inconsistent (we don't make a similar check in the command sequence
* that DISCARD ALL is equivalent to), but the idea is to catch mistakes:
* DISCARD ALL inside a transaction block would leave the transaction
* still uncommitted.
*/
PreventTransactionChain(isTopLevel, "DISCARD ALL");
/* Closing portals might run user-defined code, so do that first. */
PortalHashTableDeleteAll();
SetPGVariable("session_authorization", NIL, false);
ResetAllOptions();
DropAllPreparedStatements();
Async_UnlistenAll();
LockReleaseAll(USER_LOCKMETHOD, true);
ResetPlanCache();
ResetTempTableNamespace();
}
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