62 lines
2.0 KiB
C
62 lines
2.0 KiB
C
/*-------------------------------------------------------------------------
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*
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* tidbitmap.h
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* PostgreSQL tuple-id (TID) bitmap package
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*
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* This module provides bitmap data structures that are spiritually
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* similar to Bitmapsets, but are specially adapted to store sets of
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* tuple identifiers (TIDs), or ItemPointers. In particular, the division
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* of an ItemPointer into BlockNumber and OffsetNumber is catered for.
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* Also, since we wish to be able to store very large tuple sets in
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* memory with this data structure, we support "lossy" storage, in which
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* we no longer remember individual tuple offsets on a page but only the
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* fact that a particular page needs to be visited.
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*
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*
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* Copyright (c) 2003-2008, PostgreSQL Global Development Group
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*
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* $PostgreSQL: pgsql/src/include/nodes/tidbitmap.h,v 1.7 2008/04/10 22:25:26 tgl Exp $
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*
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*-------------------------------------------------------------------------
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*/
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#ifndef TIDBITMAP_H
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#define TIDBITMAP_H
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#include "storage/itemptr.h"
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/*
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* Actual bitmap representation is private to tidbitmap.c. Callers can
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* do IsA(x, TIDBitmap) on it, but nothing else.
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*/
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typedef struct TIDBitmap TIDBitmap;
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/* Result structure for tbm_iterate */
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typedef struct
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{
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BlockNumber blockno; /* page number containing tuples */
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int ntuples; /* -1 indicates lossy result */
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bool recheck; /* should the tuples be rechecked? */
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/* Note: recheck is always true if ntuples < 0 */
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OffsetNumber offsets[1]; /* VARIABLE LENGTH ARRAY */
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} TBMIterateResult; /* VARIABLE LENGTH STRUCT */
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/* function prototypes in nodes/tidbitmap.c */
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extern TIDBitmap *tbm_create(long maxbytes);
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extern void tbm_free(TIDBitmap *tbm);
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extern void tbm_add_tuples(TIDBitmap *tbm,
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const ItemPointer tids, int ntids,
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bool recheck);
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extern void tbm_union(TIDBitmap *a, const TIDBitmap *b);
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extern void tbm_intersect(TIDBitmap *a, const TIDBitmap *b);
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extern bool tbm_is_empty(const TIDBitmap *tbm);
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extern void tbm_begin_iterate(TIDBitmap *tbm);
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extern TBMIterateResult *tbm_iterate(TIDBitmap *tbm);
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#endif /* TIDBITMAP_H */
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