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/*-------------------------------------------------------------------------
*
* tidbitmap.h
* PostgreSQL tuple-id (TID) bitmap package
*
* This module provides bitmap data structures that are spiritually
* similar to Bitmapsets, but are specially adapted to store sets of
* tuple identifiers (TIDs), or ItemPointers. In particular, the division
* of an ItemPointer into BlockNumber and OffsetNumber is catered for.
* Also, since we wish to be able to store very large tuple sets in
* memory with this data structure, we support "lossy" storage, in which
* we no longer remember individual tuple offsets on a page but only the
* fact that a particular page needs to be visited.
*
*
* Copyright (c) 2003-2009, PostgreSQL Global Development Group
*
* $PostgreSQL: pgsql/src/include/nodes/tidbitmap.h,v 1.11 2009/06/11 14:49:11 momjian Exp $
*
*-------------------------------------------------------------------------
*/
#ifndef TIDBITMAP_H
#define TIDBITMAP_H
#include "storage/itemptr.h"
/*
* Actual bitmap representation is private to tidbitmap.c. Callers can
* do IsA(x, TIDBitmap) on it, but nothing else.
*/
typedef struct TIDBitmap TIDBitmap;
/* Likewise, TBMIterator is private */
typedef struct TBMIterator TBMIterator;
/* Result structure for tbm_iterate */
typedef struct
{
BlockNumber blockno; /* page number containing tuples */
int ntuples; /* -1 indicates lossy result */
bool recheck; /* should the tuples be rechecked? */
/* Note: recheck is always true if ntuples < 0 */
OffsetNumber offsets[1]; /* VARIABLE LENGTH ARRAY */
} TBMIterateResult; /* VARIABLE LENGTH STRUCT */
/* function prototypes in nodes/tidbitmap.c */
extern TIDBitmap *tbm_create(long maxbytes);
extern void tbm_free(TIDBitmap *tbm);
extern void tbm_add_tuples(TIDBitmap *tbm,
const ItemPointer tids, int ntids,
bool recheck);
extern void tbm_add_page(TIDBitmap *tbm, BlockNumber pageno);
extern void tbm_union(TIDBitmap *a, const TIDBitmap *b);
extern void tbm_intersect(TIDBitmap *a, const TIDBitmap *b);
extern bool tbm_is_empty(const TIDBitmap *tbm);
extern TBMIterator *tbm_begin_iterate(TIDBitmap *tbm);
extern TBMIterateResult *tbm_iterate(TBMIterator *iterator);
extern void tbm_end_iterate(TBMIterator *iterator);
#endif /* TIDBITMAP_H */
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