1 /*-------------------------------------------------------------------------
4 * PostgreSQL tuple-id (TID) bitmap package
6 * This module provides bitmap data structures that are spiritually
7 * similar to Bitmapsets, but are specially adapted to store sets of
8 * tuple identifiers (TIDs), or ItemPointers. In particular, the division
9 * of an ItemPointer into BlockNumber and OffsetNumber is catered for.
10 * Also, since we wish to be able to store very large tuple sets in
11 * memory with this data structure, we support "lossy" storage, in which
12 * we no longer remember individual tuple offsets on a page but only the
13 * fact that a particular page needs to be visited.
16 * Copyright (c) 2003-2014, PostgreSQL Global Development Group
18 * src/include/nodes/tidbitmap.h
20 *-------------------------------------------------------------------------
25 #include "storage/itemptr.h"
29 * Actual bitmap representation is private to tidbitmap.c. Callers can
30 * do IsA(x, TIDBitmap) on it, but nothing else.
32 typedef struct TIDBitmap TIDBitmap;
34 /* Likewise, TBMIterator is private */
35 typedef struct TBMIterator TBMIterator;
37 /* Result structure for tbm_iterate */
40 BlockNumber blockno; /* page number containing tuples */
41 int ntuples; /* -1 indicates lossy result */
42 bool recheck; /* should the tuples be rechecked? */
43 /* Note: recheck is always true if ntuples < 0 */
44 OffsetNumber offsets[1]; /* VARIABLE LENGTH ARRAY */
45 } TBMIterateResult; /* VARIABLE LENGTH STRUCT */
47 /* function prototypes in nodes/tidbitmap.c */
49 extern TIDBitmap *tbm_create(long maxbytes);
50 extern void tbm_free(TIDBitmap *tbm);
52 extern void tbm_add_tuples(TIDBitmap *tbm,
53 const ItemPointer tids, int ntids,
55 extern void tbm_add_page(TIDBitmap *tbm, BlockNumber pageno);
57 extern void tbm_union(TIDBitmap *a, const TIDBitmap *b);
58 extern void tbm_intersect(TIDBitmap *a, const TIDBitmap *b);
60 extern bool tbm_is_empty(const TIDBitmap *tbm);
62 extern TBMIterator *tbm_begin_iterate(TIDBitmap *tbm);
63 extern TBMIterateResult *tbm_iterate(TBMIterator *iterator);
64 extern void tbm_end_iterate(TBMIterator *iterator);
66 #endif /* TIDBITMAP_H */