1 /*-------------------------------------------------------------------------
4 * Generalized tuple sorting routines.
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
13 * Portions Copyright (c) 1996-2008, PostgreSQL Global Development Group
14 * Portions Copyright (c) 1994, Regents of the University of California
16 * $PostgreSQL: pgsql/src/include/utils/tuplesort.h,v 1.28 2008/01/01 19:45:59 momjian Exp $
18 *-------------------------------------------------------------------------
23 #include "access/itup.h"
24 #include "executor/tuptable.h"
27 /* Tuplesortstate is an opaque type whose details are not known outside
30 typedef struct Tuplesortstate Tuplesortstate;
33 * We provide two different interfaces to what is essentially the same
34 * code: one for sorting HeapTuples and one for sorting IndexTuples.
35 * They differ primarily in the way that the sort key information is
36 * supplied. Also, the HeapTuple case actually stores MinimalTuples,
37 * which means it doesn't preserve the "system columns" (tuple identity and
38 * transaction visibility info). The IndexTuple case does preserve all
39 * the header fields of an index entry. In the HeapTuple case we can
40 * save some cycles by passing and returning the tuples in TupleTableSlots,
41 * rather than forming actual HeapTuples (which'd have to be converted to
44 * Yet a third slightly different interface supports sorting bare Datums.
47 extern Tuplesortstate *tuplesort_begin_heap(TupleDesc tupDesc,
48 int nkeys, AttrNumber *attNums,
49 Oid *sortOperators, bool *nullsFirstFlags,
50 int workMem, bool randomAccess);
51 extern Tuplesortstate *tuplesort_begin_index(Relation indexRel,
53 int workMem, bool randomAccess);
54 extern Tuplesortstate *tuplesort_begin_datum(Oid datumType,
55 Oid sortOperator, bool nullsFirstFlag,
56 int workMem, bool randomAccess);
58 extern void tuplesort_set_bound(Tuplesortstate *state, int64 bound);
60 extern void tuplesort_puttupleslot(Tuplesortstate *state,
61 TupleTableSlot *slot);
62 extern void tuplesort_putindextuple(Tuplesortstate *state, IndexTuple tuple);
63 extern void tuplesort_putdatum(Tuplesortstate *state, Datum val,
66 extern void tuplesort_performsort(Tuplesortstate *state);
68 extern bool tuplesort_gettupleslot(Tuplesortstate *state, bool forward,
69 TupleTableSlot *slot);
70 extern IndexTuple tuplesort_getindextuple(Tuplesortstate *state, bool forward,
72 extern bool tuplesort_getdatum(Tuplesortstate *state, bool forward,
73 Datum *val, bool *isNull);
75 extern void tuplesort_end(Tuplesortstate *state);
77 extern char *tuplesort_explain(Tuplesortstate *state);
79 extern int tuplesort_merge_order(long allowedMem);
82 * These routines may only be called if randomAccess was specified 'true'.
83 * Likewise, backwards scan in gettuple/getdatum is only allowed if
84 * randomAccess was specified.
87 extern void tuplesort_rescan(Tuplesortstate *state);
88 extern void tuplesort_markpos(Tuplesortstate *state);
89 extern void tuplesort_restorepos(Tuplesortstate *state);
91 /* Setup for ApplySortFunction */
92 extern void SelectSortFunction(Oid sortOperator, bool nulls_first,
97 * Apply a sort function (by now converted to fmgr lookup form)
98 * and return a 3-way comparison result. This takes care of handling
99 * reverse-sort and NULLs-ordering properly.
101 extern int32 ApplySortFunction(FmgrInfo *sortFunction, int sortFlags,
102 Datum datum1, bool isNull1,
103 Datum datum2, bool isNull2);
105 #endif /* TUPLESORT_H */