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) 1996-2007, PostgreSQL Global Development Group
14 * Portions Copyright (c) 1994, Regents of the University of California
16 * $PostgreSQL: pgsql/src/include/utils/tuplesort.h,v 1.24 2007/01/05 22:20:00 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,
49 Oid *sortOperators, AttrNumber *attNums,
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,
56 int workMem, bool randomAccess);
58 extern void tuplesort_puttupleslot(Tuplesortstate *state,
59 TupleTableSlot *slot);
60 extern void tuplesort_putindextuple(Tuplesortstate *state, IndexTuple tuple);
61 extern void tuplesort_putdatum(Tuplesortstate *state, Datum val,
64 extern void tuplesort_performsort(Tuplesortstate *state);
66 extern bool tuplesort_gettupleslot(Tuplesortstate *state, bool forward,
67 TupleTableSlot *slot);
68 extern IndexTuple tuplesort_getindextuple(Tuplesortstate *state, bool forward,
70 extern bool tuplesort_getdatum(Tuplesortstate *state, bool forward,
71 Datum *val, bool *isNull);
73 extern void tuplesort_end(Tuplesortstate *state);
75 extern int tuplesort_merge_order(long allowedMem);
78 * These routines may only be called if randomAccess was specified 'true'.
79 * Likewise, backwards scan in gettuple/getdatum is only allowed if
80 * randomAccess was specified.
83 extern void tuplesort_rescan(Tuplesortstate *state);
84 extern void tuplesort_markpos(Tuplesortstate *state);
85 extern void tuplesort_restorepos(Tuplesortstate *state);
88 * This routine selects an appropriate sorting function to implement
89 * a sort operator as efficiently as possible.
93 SORTFUNC_LT, /* raw "<" operator */
94 SORTFUNC_REVLT, /* raw "<" operator, but reverse NULLs */
95 SORTFUNC_CMP, /* -1 / 0 / 1 three-way comparator */
96 SORTFUNC_REVCMP /* 1 / 0 / -1 (reversed) 3-way comparator */
99 extern void SelectSortFunction(Oid sortOperator,
100 RegProcedure *sortFunction,
101 SortFunctionKind *kind);
104 * Apply a sort function (by now converted to fmgr lookup form)
105 * and return a 3-way comparison result. This takes care of handling
106 * NULLs and sort ordering direction properly.
108 extern int32 ApplySortFunction(FmgrInfo *sortFunction, SortFunctionKind kind,
109 Datum datum1, bool isNull1,
110 Datum datum2, bool isNull2);
112 #endif /* TUPLESORT_H */