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/*-------------------------------------------------------------------------
*
* tuplestore.h
* Generalized routines for temporary tuple storage.
*
* This module handles temporary storage of tuples for purposes such
* as Materialize nodes, hashjoin batch files, etc. It is essentially
* a dumbed-down version of tuplesort.c; it does no sorting of tuples
* but can only store and regurgitate a sequence of tuples. However,
* because no sort is required, it is allowed to start reading the sequence
* before it has all been written. This is particularly useful for cursors,
* because it allows random access within the already-scanned portion of
* a query without having to process the underlying scan to completion.
* A temporary file is used to handle the data if it exceeds the
* space limit specified by the caller.
*
* Portions Copyright (c) 1996-2005, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
* $PostgreSQL: pgsql/src/include/utils/tuplestore.h,v 1.16 2004/12/31 22:03:46 pgsql Exp $
*
*-------------------------------------------------------------------------
*/
#ifndef TUPLESTORE_H
#define TUPLESTORE_H
#include "access/htup.h"
/* Tuplestorestate is an opaque type whose details are not known outside
* tuplestore.c.
*/
typedef struct Tuplestorestate Tuplestorestate;
/*
* Currently we only need to store HeapTuples, but it would be easy
* to support the same behavior for IndexTuples and/or bare Datums.
*/
extern Tuplestorestate *tuplestore_begin_heap(bool randomAccess,
bool interXact,
int maxKBytes);
extern void tuplestore_puttuple(Tuplestorestate *state, void *tuple);
/* tuplestore_donestoring() used to be required, but is no longer used */
#define tuplestore_donestoring(state) ((void) 0)
/* backwards scan is only allowed if randomAccess was specified 'true' */
extern void *tuplestore_gettuple(Tuplestorestate *state, bool forward,
bool *should_free);
#define tuplestore_getheaptuple(state, forward, should_free) \
((HeapTuple) tuplestore_gettuple(state, forward, should_free))
extern void tuplestore_end(Tuplestorestate *state);
extern bool tuplestore_ateof(Tuplestorestate *state);
extern void tuplestore_rescan(Tuplestorestate *state);
extern void tuplestore_markpos(Tuplestorestate *state);
extern void tuplestore_restorepos(Tuplestorestate *state);
#endif /* TUPLESTORE_H */
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