Age Owner TLA Line data Source code
1 : /*-------------------------------------------------------------------------
2 : *
3 : * tidbitmap.h
4 : * PostgreSQL tuple-id (TID) bitmap package
5 : *
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.
14 : *
15 : *
16 : * Copyright (c) 2003-2025, PostgreSQL Global Development Group
17 : *
18 : * src/include/nodes/tidbitmap.h
19 : *
20 : *-------------------------------------------------------------------------
21 : */
22 : #ifndef TIDBITMAP_H
23 : #define TIDBITMAP_H
24 :
25 : #include "access/htup_details.h"
26 : #include "storage/itemptr.h"
27 : #include "utils/dsa.h"
28 :
29 : /*
30 : * The maximum number of tuples per page is not large (typically 256 with
31 : * 8K pages, or 1024 with 32K pages). So there's not much point in making
32 : * the per-page bitmaps variable size. We just legislate that the size
33 : * is this:
34 : */
35 : #define TBM_MAX_TUPLES_PER_PAGE MaxHeapTuplesPerPage
36 :
37 : /*
38 : * Actual bitmap representation is private to tidbitmap.c. Callers can
39 : * do IsA(x, TIDBitmap) on it, but nothing else.
40 : */
41 : typedef struct TIDBitmap TIDBitmap;
42 :
43 : /* Likewise, TBMPrivateIterator is private */
44 : typedef struct TBMPrivateIterator TBMPrivateIterator;
45 : typedef struct TBMSharedIterator TBMSharedIterator;
46 :
47 : /*
48 : * Callers with both private and shared implementations can use this unified
49 : * API.
50 : */
51 : typedef struct TBMIterator
52 : {
53 : bool shared;
54 : union
55 : {
56 : TBMPrivateIterator *private_iterator;
57 : TBMSharedIterator *shared_iterator;
58 : } i;
59 : } TBMIterator;
60 :
61 : /* Result structure for tbm_iterate */
62 : typedef struct TBMIterateResult
63 : {
64 : BlockNumber blockno; /* block number containing tuples */
65 :
66 : bool lossy;
67 :
68 : /*
69 : * Whether or not the tuples should be rechecked. This is always true if
70 : * the page is lossy but may also be true if the query requires recheck.
71 : */
72 : bool recheck;
73 :
74 : /*
75 : * Pointer to the page containing the bitmap for this block. It is a void *
76 : * to avoid exposing the details of the tidbitmap PagetableEntry to API
77 : * users.
78 : */
79 : void *internal_page;
80 : } TBMIterateResult;
81 :
82 : /* function prototypes in nodes/tidbitmap.c */
83 :
84 : extern TIDBitmap *tbm_create(Size maxbytes, dsa_area *dsa);
85 : extern void tbm_free(TIDBitmap *tbm);
86 : extern void tbm_free_shared_area(dsa_area *dsa, dsa_pointer dp);
87 :
88 : extern void tbm_add_tuples(TIDBitmap *tbm,
89 : const ItemPointer tids, int ntids,
90 : bool recheck);
91 : extern void tbm_add_page(TIDBitmap *tbm, BlockNumber pageno);
92 :
93 : extern void tbm_union(TIDBitmap *a, const TIDBitmap *b);
94 : extern void tbm_intersect(TIDBitmap *a, const TIDBitmap *b);
95 :
96 : extern int tbm_extract_page_tuple(TBMIterateResult *iteritem,
97 : OffsetNumber *offsets,
98 : uint32 max_offsets);
99 :
100 : extern bool tbm_is_empty(const TIDBitmap *tbm);
101 :
102 : extern TBMPrivateIterator *tbm_begin_private_iterate(TIDBitmap *tbm);
103 : extern dsa_pointer tbm_prepare_shared_iterate(TIDBitmap *tbm);
104 : extern bool tbm_private_iterate(TBMPrivateIterator *iterator, TBMIterateResult *tbmres);
105 : extern bool tbm_shared_iterate(TBMSharedIterator *iterator, TBMIterateResult *tbmres);
106 : extern void tbm_end_private_iterate(TBMPrivateIterator *iterator);
107 : extern void tbm_end_shared_iterate(TBMSharedIterator *iterator);
108 : extern TBMSharedIterator *tbm_attach_shared_iterate(dsa_area *dsa,
109 : dsa_pointer dp);
110 : extern int tbm_calculate_entries(Size maxbytes);
111 :
112 : extern TBMIterator tbm_begin_iterate(TIDBitmap *tbm,
113 : dsa_area *dsa, dsa_pointer dsp);
114 : extern void tbm_end_iterate(TBMIterator *iterator);
115 :
116 : extern bool tbm_iterate(TBMIterator *iterator, TBMIterateResult *tbmres);
117 :
118 : static inline bool
262 melanieplageman@gmai 119 CBC 19977 : tbm_exhausted(TBMIterator *iterator)
120 : {
121 : /*
122 : * It doesn't matter if we check the private or shared iterator here. If
123 : * tbm_end_iterate() was called, they will be NULL
124 : */
125 19977 : return !iterator->i.private_iterator;
126 : }
127 :
128 : #endif /* TIDBITMAP_H */
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