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120 lines
4.6 KiB
C
120 lines
4.6 KiB
C
/*-------------------------------------------------------------------------
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*
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* tuplesort.h
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* Generalized tuple sorting routines.
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*
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* This module handles sorting of heap tuples, index tuples, or single
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* Datums (and could easily support other kinds of sortable objects,
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* if necessary). It works efficiently for both small and large amounts
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* of data. Small amounts are sorted in-memory using qsort(). Large
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* amounts are sorted using temporary files and a standard external sort
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* algorithm.
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*
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* Portions Copyright (c) 1996-2012, PostgreSQL Global Development Group
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* Portions Copyright (c) 1994, Regents of the University of California
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*
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* src/include/utils/tuplesort.h
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*
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*-------------------------------------------------------------------------
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*/
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#ifndef TUPLESORT_H
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#define TUPLESORT_H
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#include "access/itup.h"
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#include "executor/tuptable.h"
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#include "fmgr.h"
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#include "utils/relcache.h"
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/* Tuplesortstate is an opaque type whose details are not known outside
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* tuplesort.c.
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*/
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typedef struct Tuplesortstate Tuplesortstate;
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/*
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* We provide multiple interfaces to what is essentially the same code,
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* since different callers have different data to be sorted and want to
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* specify the sort key information differently. There are two APIs for
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* sorting HeapTuples and two more for sorting IndexTuples. Yet another
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* API supports sorting bare Datums.
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*
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* The "heap" API actually stores/sorts MinimalTuples, which means it doesn't
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* preserve the system columns (tuple identity and transaction visibility
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* info). The sort keys are specified by column numbers within the tuples
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* and sort operator OIDs. We save some cycles by passing and returning the
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* tuples in TupleTableSlots, rather than forming actual HeapTuples (which'd
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* have to be converted to MinimalTuples). This API works well for sorts
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* executed as parts of plan trees.
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*
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* The "cluster" API stores/sorts full HeapTuples including all visibility
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* info. The sort keys are specified by reference to a btree index that is
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* defined on the relation to be sorted. Note that putheaptuple/getheaptuple
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* go with this API, not the "begin_heap" one!
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*
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* The "index_btree" API stores/sorts IndexTuples (preserving all their
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* header fields). The sort keys are specified by a btree index definition.
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*
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* The "index_hash" API is similar to index_btree, but the tuples are
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* actually sorted by their hash codes not the raw data.
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*/
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extern Tuplesortstate *tuplesort_begin_heap(TupleDesc tupDesc,
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int nkeys, AttrNumber *attNums,
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Oid *sortOperators, Oid *sortCollations,
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bool *nullsFirstFlags,
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int workMem, bool randomAccess);
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extern Tuplesortstate *tuplesort_begin_cluster(TupleDesc tupDesc,
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Relation indexRel,
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int workMem, bool randomAccess);
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extern Tuplesortstate *tuplesort_begin_index_btree(Relation indexRel,
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bool enforceUnique,
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int workMem, bool randomAccess);
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extern Tuplesortstate *tuplesort_begin_index_hash(Relation indexRel,
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uint32 hash_mask,
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int workMem, bool randomAccess);
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extern Tuplesortstate *tuplesort_begin_datum(Oid datumType,
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Oid sortOperator, Oid sortCollation,
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bool nullsFirstFlag,
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int workMem, bool randomAccess);
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extern void tuplesort_set_bound(Tuplesortstate *state, int64 bound);
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extern void tuplesort_puttupleslot(Tuplesortstate *state,
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TupleTableSlot *slot);
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extern void tuplesort_putheaptuple(Tuplesortstate *state, HeapTuple tup);
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extern void tuplesort_putindextuple(Tuplesortstate *state, IndexTuple tuple);
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extern void tuplesort_putdatum(Tuplesortstate *state, Datum val,
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bool isNull);
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extern void tuplesort_performsort(Tuplesortstate *state);
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extern bool tuplesort_gettupleslot(Tuplesortstate *state, bool forward,
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TupleTableSlot *slot);
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extern HeapTuple tuplesort_getheaptuple(Tuplesortstate *state, bool forward,
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bool *should_free);
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extern IndexTuple tuplesort_getindextuple(Tuplesortstate *state, bool forward,
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bool *should_free);
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extern bool tuplesort_getdatum(Tuplesortstate *state, bool forward,
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Datum *val, bool *isNull);
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extern void tuplesort_end(Tuplesortstate *state);
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extern void tuplesort_get_stats(Tuplesortstate *state,
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const char **sortMethod,
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const char **spaceType,
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long *spaceUsed);
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extern int tuplesort_merge_order(long allowedMem);
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/*
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* These routines may only be called if randomAccess was specified 'true'.
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* Likewise, backwards scan in gettuple/getdatum is only allowed if
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* randomAccess was specified.
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*/
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extern void tuplesort_rescan(Tuplesortstate *state);
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extern void tuplesort_markpos(Tuplesortstate *state);
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extern void tuplesort_restorepos(Tuplesortstate *state);
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#endif /* TUPLESORT_H */
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