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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) 1996-2008, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
* $PostgreSQL: pgsql/src/include/utils/tuplesort.h,v 1.31 2008/06/19 00:46:06 alvherre Exp $
*
*-------------------------------------------------------------------------
*/
#ifndef TUPLESORT_H
#define TUPLESORT_H
#include "access/itup.h"
#include "executor/tuptable.h"
#include "fmgr.h"
#include "utils/relcache.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. Also, the HeapTuple case actually stores MinimalTuples,
* which means it doesn't preserve the "system columns" (tuple identity and
* transaction visibility info). The IndexTuple case does preserve all
* the header fields of an index entry. In the HeapTuple case we can
* save some cycles by passing and returning the tuples in TupleTableSlots,
* rather than forming actual HeapTuples (which'd have to be converted to
* MinimalTuples).
*
* The IndexTuple case is itself broken into two subcases, one for btree
* indexes and one for hash indexes; the latter variant actually sorts
* the tuples by hash code. The API is the same except for the "begin"
* routine.
*
* Yet another slightly different interface supports sorting bare Datums.
*/
extern Tuplesortstate *tuplesort_begin_heap(TupleDesc tupDesc,
int nkeys, AttrNumber *attNums,
Oid *sortOperators, bool *nullsFirstFlags,
int workMem, bool randomAccess);
extern Tuplesortstate *tuplesort_begin_index_btree(Relation indexRel,
bool enforceUnique,
int workMem, bool randomAccess);
extern Tuplesortstate *tuplesort_begin_index_hash(Relation indexRel,
uint32 hash_mask,
int workMem, bool randomAccess);
extern Tuplesortstate *tuplesort_begin_datum(Oid datumType,
Oid sortOperator, bool nullsFirstFlag,
int workMem, bool randomAccess);
extern void tuplesort_set_bound(Tuplesortstate *state, int64 bound);
extern void tuplesort_puttupleslot(Tuplesortstate *state,
TupleTableSlot *slot);
extern void tuplesort_putindextuple(Tuplesortstate *state, IndexTuple tuple);
extern void tuplesort_putdatum(Tuplesortstate *state, Datum val,
bool isNull);
extern void tuplesort_performsort(Tuplesortstate *state);
extern bool tuplesort_gettupleslot(Tuplesortstate *state, bool forward,
TupleTableSlot *slot);
extern IndexTuple tuplesort_getindextuple(Tuplesortstate *state, bool forward,
bool *should_free);
extern bool tuplesort_getdatum(Tuplesortstate *state, bool forward,
Datum *val, bool *isNull);
extern void tuplesort_end(Tuplesortstate *state);
extern char *tuplesort_explain(Tuplesortstate *state);
extern int tuplesort_merge_order(long allowedMem);
/*
* 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);
/* Setup for ApplySortFunction */
extern void SelectSortFunction(Oid sortOperator, bool nulls_first,
Oid *sortFunction,
int *sortFlags);
/*
* Apply a sort function (by now converted to fmgr lookup form)
* and return a 3-way comparison result. This takes care of handling
* reverse-sort and NULLs-ordering properly.
*/
extern int32 ApplySortFunction(FmgrInfo *sortFunction, int sortFlags,
Datum datum1, bool isNull1,
Datum datum2, bool isNull2);
#endif /* TUPLESORT_H */
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