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/*-------------------------------------------------------------------------
*
* tstore_receiver.c
* an implementation of DestReceiver that stores the result tuples in
* a Tuplestore
*
*
* Portions Copyright (c) 1996-2002, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/executor/tstoreReceiver.c,v 1.3 2003/05/02 20:54:34 tgl Exp $
*
*-------------------------------------------------------------------------
*/
#include "postgres.h"
#include "executor/tstoreReceiver.h"
#include "utils/memutils.h"
#include "utils/portal.h"
typedef struct
{
DestReceiver pub;
Tuplestorestate *tstore;
MemoryContext cxt;
} TStoreState;
/*
* Prepare to receive tuples from executor.
*
* XXX: As currently implemented, this routine is a hack: there should
* be no tie between this code and the portal system. Instead, the
* receiver function that is part of DestFunction should be passed a
* QueryDesc, so that the call site of ExecutorRun can "sub-class"
* QueryDesc and pass in any necessary addition information (in this
* case, the Tuplestore to use).
*/
static void
tstoreSetupReceiver(DestReceiver *self, int operation,
const char *portalname, TupleDesc typeinfo)
{
TStoreState *myState = (TStoreState *) self;
/* Should only be called within a suitably-prepped portal */
if (CurrentPortal == NULL ||
CurrentPortal->holdStore == NULL)
elog(ERROR, "Tuplestore destination used in wrong context");
/* Debug check: make sure portal's result tuple desc is correct */
Assert(CurrentPortal->tupDesc != NULL);
Assert(equalTupleDescs(CurrentPortal->tupDesc, typeinfo));
myState->tstore = CurrentPortal->holdStore;
myState->cxt = CurrentPortal->holdContext;
}
/*
* Receive a tuple from the executor and store it in the tuplestore.
*/
static void
tstoreReceiveTuple(HeapTuple tuple, TupleDesc typeinfo, DestReceiver *self)
{
TStoreState *myState = (TStoreState *) self;
MemoryContext oldcxt = MemoryContextSwitchTo(myState->cxt);
tuplestore_puttuple(myState->tstore, tuple);
MemoryContextSwitchTo(oldcxt);
}
/*
* Clean up
*/
static void
tstoreCleanupReceiver(DestReceiver *self)
{
/* do nothing */
}
/*
* Initially create a DestReceiver object.
*/
DestReceiver *
tstoreReceiverCreateDR(void)
{
TStoreState *self = (TStoreState *) palloc(sizeof(TStoreState));
self->pub.receiveTuple = tstoreReceiveTuple;
self->pub.setup = tstoreSetupReceiver;
self->pub.cleanup = tstoreCleanupReceiver;
self->tstore = NULL;
self->cxt = NULL;
return (DestReceiver *) self;
}
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