granicus.if.org Git - postgresql/blob - src/include/utils/tuplesort.h

   1 /*-------------------------------------------------------------------------
   2  *
   3  * tuplesort.h
   4  *        Generalized tuple sorting routines.
   5  *
   6  * This module handles sorting of heap tuples, index tuples, or single
   7  * Datums (and could easily support other kinds of sortable objects,
   8  * if necessary).  It works efficiently for both small and large amounts
   9  * of data.  Small amounts are sorted in-memory using qsort().  Large
  10  * amounts are sorted using temporary files and a standard external sort
  11  * algorithm.
  12  *
  13  * Portions Copyright (c) 1996-2001, PostgreSQL Global Development Group
  14  * Portions Copyright (c) 1994, Regents of the University of California
  15  *
  16  * $Id: tuplesort.h,v 1.7 2001/05/07 00:43:26 tgl Exp $
  17  *
  18  *-------------------------------------------------------------------------
  19  */
  20 #ifndef TUPLESORT_H
  21 #define TUPLESORT_H
  22
  23 #include "access/htup.h"
  24 #include "access/itup.h"
  25
  26 /* Tuplesortstate is an opaque type whose details are not known outside tuplesort.c. */
  27
  28 typedef struct Tuplesortstate Tuplesortstate;
  29
  30 /*
  31  * We provide two different interfaces to what is essentially the same
  32  * code: one for sorting HeapTuples and one for sorting IndexTuples.
  33  * They differ primarily in the way that the sort key information is
  34  * supplied.
  35  * Yet a third slightly different interface supports sorting bare Datums.
  36  */
  37
  38 extern Tuplesortstate *tuplesort_begin_heap(TupleDesc tupDesc,
  39                                           int nkeys,
  40                                           Oid *sortOperators, AttrNumber *attNums,
  41                                           bool randomAccess);
  42 extern Tuplesortstate *tuplesort_begin_index(Relation indexRel,
  43                                           bool enforceUnique,
  44                                           bool randomAccess);
  45 extern Tuplesortstate *tuplesort_begin_datum(Oid datumType,
  46                                           Oid sortOperator,
  47                                           bool randomAccess);
  48
  49 extern void tuplesort_puttuple(Tuplesortstate *state, void *tuple);
  50
  51 extern void tuplesort_putdatum(Tuplesortstate *state, Datum val,
  52                                    bool isNull);
  53
  54 extern void tuplesort_performsort(Tuplesortstate *state);
  55
  56 extern void *tuplesort_gettuple(Tuplesortstate *state, bool forward,
  57                                    bool *should_free);
  58
  59 #define tuplesort_getheaptuple(state, forward, should_free) \
  60         ((HeapTuple) tuplesort_gettuple(state, forward, should_free))
  61 #define tuplesort_getindextuple(state, forward, should_free) \
  62         ((IndexTuple) tuplesort_gettuple(state, forward, should_free))
  63
  64 extern bool tuplesort_getdatum(Tuplesortstate *state, bool forward,
  65                                    Datum *val, bool *isNull);
  66
  67 extern void tuplesort_end(Tuplesortstate *state);
  68
  69 /*
  70  * These routines may only be called if randomAccess was specified 'true'.
  71  * Likewise, backwards scan in gettuple/getdatum is only allowed if
  72  * randomAccess was specified.
  73  */
  74
  75 extern void tuplesort_rescan(Tuplesortstate *state);
  76 extern void tuplesort_markpos(Tuplesortstate *state);
  77 extern void tuplesort_restorepos(Tuplesortstate *state);
  78
  79 /*
  80  * This routine selects an appropriate sorting function to implement
  81  * a sort operator as efficiently as possible.
  82  */
  83 typedef enum
  84 {
  85         SORTFUNC_LT,                            /* raw "<" operator */
  86         SORTFUNC_CMP,                           /* -1 / 0 / 1 three-way comparator */
  87         SORTFUNC_REVCMP                         /* 1 / 0 / -1 (reversed) 3-way comparator */
  88 } SortFunctionKind;
  89
  90 extern void SelectSortFunction(Oid sortOperator,
  91                                                            RegProcedure *sortFunction,
  92                                                            SortFunctionKind *kind);
  93
  94 #endif   /* TUPLESORT_H */