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/*-------------------------------------------------------------------------
*
* tuplesort.h
* Generalized tuple sorting routines.
*
* This module handles sorting of heap tuples, index tuples, or single
* Datums (and could easily support other kinds of sortable objects,
* if necessary). It works efficiently for both small and large amounts
* of data. Small amounts are sorted in-memory using qsort(). Large
* amounts are sorted using temporary files and a standard external sort
* algorithm.
*
* Portions Copyright (c) 1996-2001, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
* $Id: tuplesort.h,v 1.9 2001/10/25 05:50:11 momjian Exp $
*
*-------------------------------------------------------------------------
*/
#ifndef TUPLESORT_H
#define TUPLESORT_H
#include "access/htup.h"
#include "access/itup.h"
#include "fmgr.h"
/* Tuplesortstate is an opaque type whose details are not known outside tuplesort.c. */
typedef struct Tuplesortstate Tuplesortstate;
/*
* We provide two different interfaces to what is essentially the same
* code: one for sorting HeapTuples and one for sorting IndexTuples.
* They differ primarily in the way that the sort key information is
* supplied.
* Yet a third slightly different interface supports sorting bare Datums.
*/
extern Tuplesortstate *tuplesort_begin_heap(TupleDesc tupDesc,
int nkeys,
Oid *sortOperators, AttrNumber *attNums,
bool randomAccess);
extern Tuplesortstate *tuplesort_begin_index(Relation indexRel,
bool enforceUnique,
bool randomAccess);
extern Tuplesortstate *tuplesort_begin_datum(Oid datumType,
Oid sortOperator,
bool randomAccess);
extern void tuplesort_puttuple(Tuplesortstate *state, void *tuple);
extern void tuplesort_putdatum(Tuplesortstate *state, Datum val,
bool isNull);
extern void tuplesort_performsort(Tuplesortstate *state);
extern void *tuplesort_gettuple(Tuplesortstate *state, bool forward,
bool *should_free);
#define tuplesort_getheaptuple(state, forward, should_free) \
((HeapTuple) tuplesort_gettuple(state, forward, should_free))
#define tuplesort_getindextuple(state, forward, should_free) \
((IndexTuple) tuplesort_gettuple(state, forward, should_free))
extern bool tuplesort_getdatum(Tuplesortstate *state, bool forward,
Datum *val, bool *isNull);
extern void tuplesort_end(Tuplesortstate *state);
/*
* These routines may only be called if randomAccess was specified 'true'.
* Likewise, backwards scan in gettuple/getdatum is only allowed if
* randomAccess was specified.
*/
extern void tuplesort_rescan(Tuplesortstate *state);
extern void tuplesort_markpos(Tuplesortstate *state);
extern void tuplesort_restorepos(Tuplesortstate *state);
/*
* This routine selects an appropriate sorting function to implement
* a sort operator as efficiently as possible.
*/
typedef enum
{
SORTFUNC_LT, /* raw "<" operator */
SORTFUNC_REVLT, /* raw "<" operator, but reverse NULLs */
SORTFUNC_CMP, /* -1 / 0 / 1 three-way comparator */
SORTFUNC_REVCMP /* 1 / 0 / -1 (reversed) 3-way comparator */
} SortFunctionKind;
extern void SelectSortFunction(Oid sortOperator,
RegProcedure *sortFunction,
SortFunctionKind *kind);
/*
* Apply a sort function (by now converted to fmgr lookup form)
* and return a 3-way comparison result. This takes care of handling
* NULLs and sort ordering direction properly.
*/
extern int32 ApplySortFunction(FmgrInfo *sortFunction, SortFunctionKind kind,
Datum datum1, bool isNull1,
Datum datum2, bool isNull2);
#endif /* TUPLESORT_H */
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