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) 1996-2000, PostgreSQL, Inc
  14  * Portions Copyright (c) 1994, Regents of the University of California
  15  *
  16  * $Id: tuplesort.h,v 1.3 2000/01/26 05:58:38 momjian Exp $
  17  *
  18  *-------------------------------------------------------------------------
  19  */
  20 #ifndef TUPLESORT_H
  21 #define TUPLESORT_H
  22
  23 #include "access/htup.h"
  24 #include "access/itup.h"
  25 #include "access/skey.h"
  26 #include "access/tupdesc.h"
  27 #include "utils/rel.h"
  28
  29 /* Tuplesortstate is an opaque type whose details are not known outside tuplesort.c. */
  30
  31 typedef struct Tuplesortstate Tuplesortstate;
  32
  33 /*
  34  * We provide two different interfaces to what is essentially the same
  35  * code: one for sorting HeapTuples and one for sorting IndexTuples.
  36  * They differ primarily in the way that the sort key information is
  37  * supplied.
  38  * Yet a third slightly different interface supports sorting bare Datums.
  39  */
  40
  41 extern Tuplesortstate *tuplesort_begin_heap(TupleDesc tupDesc,
  42                                                                                         int nkeys, ScanKey keys,
  43                                                                                         bool randomAccess);
  44 extern Tuplesortstate *tuplesort_begin_index(Relation indexRel,
  45                                                                                          bool enforceUnique,
  46                                                                                          bool randomAccess);
  47 extern Tuplesortstate *tuplesort_begin_datum(Oid datumType,
  48                                                                                          Oid sortOperator,
  49                                                                                          bool randomAccess);
  50
  51 extern void tuplesort_puttuple(Tuplesortstate *state, void *tuple);
  52
  53 extern void tuplesort_putdatum(Tuplesortstate *state, Datum val,
  54                                                            bool isNull);
  55
  56 extern void tuplesort_performsort(Tuplesortstate *state);
  57
  58 extern void *tuplesort_gettuple(Tuplesortstate *state, bool forward,
  59                                                                 bool *should_free);
  60 #define tuplesort_getheaptuple(state, forward, should_free) \
  61         ((HeapTuple) tuplesort_gettuple(state, forward, should_free))
  62 #define tuplesort_getindextuple(state, forward, should_free) \
  63         ((IndexTuple) tuplesort_gettuple(state, forward, should_free))
  64
  65 extern bool tuplesort_getdatum(Tuplesortstate *state, bool forward,
  66                                                            Datum *val, bool *isNull);
  67
  68 extern void tuplesort_end(Tuplesortstate *state);
  69
  70 /*
  71  * These routines may only be called if randomAccess was specified 'true'.
  72  * Likewise, backwards scan in gettuple/getdatum is only allowed if
  73  * randomAccess was specified.
  74  */
  75
  76 extern void tuplesort_rescan(Tuplesortstate *state);
  77 extern void tuplesort_markpos(Tuplesortstate *state);
  78 extern void tuplesort_restorepos(Tuplesortstate *state);
  79
  80 #endif   /* TUPLESORT_H */