9bd27b7c9e
There are probably still some adjustments to be made in the details of the output, but this gets the basic structure in place. Robert Haas
119 lines
4.4 KiB
C
119 lines
4.4 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) 1996-2009, 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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* $PostgreSQL: pgsql/src/include/utils/tuplesort.h,v 1.34 2009/08/10 05:46:50 tgl Exp $
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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 two different interfaces to what is essentially the same
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* code: one for sorting HeapTuples and one for sorting IndexTuples.
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* They differ primarily in the way that the sort key information is
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* supplied. Also, the HeapTuple case actually stores MinimalTuples,
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* which means it doesn't preserve the "system columns" (tuple identity and
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* transaction visibility info). The IndexTuple case does preserve all
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* the header fields of an index entry. In the HeapTuple case we can
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* save some cycles by passing and returning the tuples in TupleTableSlots,
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* rather than forming actual HeapTuples (which'd have to be converted to
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* MinimalTuples).
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*
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* The IndexTuple case is itself broken into two subcases, one for btree
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* indexes and one for hash indexes; the latter variant actually sorts
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* the tuples by hash code. The API is the same except for the "begin"
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* routine.
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*
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* Yet another slightly different interface supports sorting bare Datums.
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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, bool *nullsFirstFlags,
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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, 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_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 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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/* Setup for ApplySortFunction */
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extern void SelectSortFunction(Oid sortOperator, bool nulls_first,
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Oid *sortFunction,
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int *sortFlags);
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/*
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* Apply a sort function (by now converted to fmgr lookup form)
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* and return a 3-way comparison result. This takes care of handling
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* reverse-sort and NULLs-ordering properly.
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*/
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extern int32 ApplySortFunction(FmgrInfo *sortFunction, int sortFlags,
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Datum datum1, bool isNull1,
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Datum datum2, bool isNull2);
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#endif /* TUPLESORT_H */
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