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pgsql
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tuplesort.h
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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) 1996-2012, PostgreSQL Global Development Group * Portions Copyright (c) 1994, Regents of the University of California * * src/include/utils/tuplesort.h * *------------------------------------------------------------------------- */ #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 multiple interfaces to what is essentially the same code, * since different callers have different data to be sorted and want to * specify the sort key information differently. There are two APIs for * sorting HeapTuples and two more for sorting IndexTuples. Yet another * API supports sorting bare Datums. * * The "heap" API actually stores/sorts MinimalTuples, which means it doesn't * preserve the system columns (tuple identity and transaction visibility * info). The sort keys are specified by column numbers within the tuples * and sort operator OIDs. We save some cycles by passing and returning the * tuples in TupleTableSlots, rather than forming actual HeapTuples (which'd * have to be converted to MinimalTuples). This API works well for sorts * executed as parts of plan trees. * * The "cluster" API stores/sorts full HeapTuples including all visibility * info. The sort keys are specified by reference to a btree index that is * defined on the relation to be sorted. Note that putheaptuple/getheaptuple * go with this API, not the "begin_heap" one! * * The "index_btree" API stores/sorts IndexTuples (preserving all their * header fields). The sort keys are specified by a btree index definition. * * The "index_hash" API is similar to index_btree, but the tuples are * actually sorted by their hash codes not the raw data. */ extern Tuplesortstate *tuplesort_begin_heap(TupleDesc tupDesc, int nkeys, AttrNumber *attNums, Oid *sortOperators, Oid *sortCollations, bool *nullsFirstFlags, int workMem, bool randomAccess); extern Tuplesortstate *tuplesort_begin_cluster(TupleDesc tupDesc, Relation indexRel, 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, Oid sortCollation, 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_putheaptuple(Tuplesortstate *state, HeapTuple tup); 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 HeapTuple tuplesort_getheaptuple(Tuplesortstate *state, bool forward, bool *should_free); 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 void tuplesort_get_stats(Tuplesortstate *state, const char **sortMethod, const char **spaceType, long *spaceUsed); 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); #endif /* TUPLESORT_H */