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/data/users/matthijs/github_faiss/faiss/IndexIVFPQ.h
1 /**
2 * Copyright (c) 2015-present, Facebook, Inc.
3 * All rights reserved.
4 *
5 * This source code is licensed under the CC-by-NC license found in the
6 * LICENSE file in the root directory of this source tree.
7 */
8
9 // Copyright 2004-present Facebook. All Rights Reserved.
10 // -*- c++ -*-
11
12 #ifndef FAISS_INDEX_IVFPQ_H
13 #define FAISS_INDEX_IVFPQ_H
14
15
16 #include <vector>
17
18 #include "IndexIVF.h"
19 #include "IndexPQ.h"
20
21
22 namespace faiss {
23
24
25
26 /** Inverted file with Product Quantizer encoding. Each residual
27 * vector is encoded as a product quantizer code.
28 */
29 struct IndexIVFPQ: IndexIVF {
30 bool by_residual; ///< Encode residual or plain vector?
31 int use_precomputed_table; ///< if by_residual, build precompute tables
32 size_t code_size; ///< code size per vector in bytes
33 ProductQuantizer pq; ///< produces the codes
34
35 bool do_polysemous_training; ///< reorder PQ centroids after training?
36 PolysemousTraining *polysemous_training; ///< if NULL, use default
37
38 // search-time parameters
39 size_t scan_table_threshold; ///< use table computation or on-the-fly?
40 size_t max_codes; ///< max nb of codes to visit to do a query
41 int polysemous_ht; ///< Hamming thresh for polysemous filtering
42
43 std::vector < std::vector<uint8_t> > codes; // binary codes, size nlist
44
45 /// if use_precompute_table
46 /// size nlist * pq.M * pq.ksub
47 std::vector <float> precomputed_table;
48
49 IndexIVFPQ (
50 Index * quantizer, size_t d, size_t nlist,
51 size_t M, size_t nbits_per_idx);
52
53 void add_with_ids(idx_t n, const float* x, const long* xids = nullptr)
54 override;
55
56 /// same as add_core, also:
57 /// - output 2nd level residuals if residuals_2 != NULL
58 /// - use precomputed list numbers if precomputed_idx != NULL
59 void add_core_o (idx_t n, const float *x,
60 const long *xids, float *residuals_2,
61 const long *precomputed_idx = nullptr);
62
63 void search(
64 idx_t n,
65 const float* x,
66 idx_t k,
67 float* distances,
68 idx_t* labels) const override;
69
70 void reset() override;
71
72 long remove_ids(const IDSelector& sel) override;
73
74 /// trains the product quantizer
75 void train_residual(idx_t n, const float* x) override;
76
77 /// same as train_residual, also output 2nd level residuals
78 void train_residual_o (idx_t n, const float *x, float *residuals_2);
79
80
81 /** Reconstruct a subset of the indexed vectors
82 *
83 * @param i0 first vector to reconstruct
84 * @param ni nb of vectors to reconstruct
85 * @param recons output array of reconstructed vectors, size ni * d
86 */
87 void reconstruct_n(idx_t i0, idx_t ni, float* recons) const override;
88
89 void reconstruct(idx_t key, float* recons) const override;
90
91 /** Find exact duplicates in the dataset.
92 *
93 * the duplicates are returned in pre-allocated arrays (see the
94 * max sizes).
95 *
96 * @params lims limits between groups of duplicates
97 * (max size ntotal / 2 + 1)
98 * @params ids ids[lims[i]] : ids[lims[i+1]-1] is a group of
99 * duplicates (max size ntotal)
100 * @return n number of groups found
101 */
102 size_t find_duplicates (idx_t *ids, size_t *lims) const;
103
104 // map a vector to a binary code knowning the index
105 void encode (long key, const float * x, uint8_t * code) const;
106
107 /** Encode multiple vectors
108 *
109 * @param n nb vectors to encode
110 * @param keys posting list ids for those vectors (size n)
111 * @param x vectors (size n * d)
112 * @param codes output codes (size n * code_size)
113 * @param compute_keys if false, assume keys are precomputed,
114 * otherwise compute them
115 */
116 void encode_multiple (size_t n, long *keys,
117 const float * x, uint8_t * codes,
118 bool compute_keys = false) const;
119
120 /// inverse of encode_multiple
121 void decode_multiple (size_t n, const long *keys,
122 const uint8_t * xcodes, float * x) const;
123
124 /** search a set of vectors, that are pre-quantized by the IVF
125 * quantizer. Fill in the corresponding heaps with the query
126 * results.
127 *
128 * @param nx nb of vectors to query
129 * @param qx query vectors, size nx * d
130 * @param keys coarse quantization indices, size nx * nprobe
131 * @param coarse_dis
132 * distances to coarse centroids, size nx * nprobe
133 * @param res heaps for all the results, gives the nprobe
134 * @param store_pairs store inv list index + inv list offset
135 * instead in upper/lower 32 bit of result,
136 * instead of ids (used for reranking).
137 */
138 virtual void search_knn_with_key (
139 size_t nx,
140 const float * qx,
141 const long * keys,
142 const float * coarse_dis,
143 float_maxheap_array_t* res,
144 bool store_pairs = false) const;
145
146 /// build precomputed table
147 void precompute_table ();
148
149 /// used to implement merging
150 void merge_from_residuals(IndexIVF& other) override;
151
152 /** copy a subset of the entries index to the other index
153 *
154 * if subset_type == 0: copies ids in [a1, a2)
155 * if subset_type == 1: copies ids if id % a1 == a2
156 */
157 void copy_subset_to (IndexIVFPQ & other, int subset_type,
158 long a1, long a2) const;
159
160 IndexIVFPQ ();
161
162 };
163
164
165 /// statistics are robust to internal threading, but not if
166 /// IndexIVFPQ::search is called by multiple threads
167 struct IndexIVFPQStats {
168 size_t nq; // nb of queries run
169 size_t nlist; // nb of inverted lists scanned
170 size_t ncode; // nb of codes visited
171 size_t nrefine; // nb of refines (IVFPQR)
172
173 size_t n_hamming_pass;
174 // nb of passed Hamming distance tests (for polysemous)
175
176 // timings measured with the CPU RTC
177 // on all threads
178 size_t assign_cycles;
179 size_t search_cycles;
180 size_t refine_cycles; // only for IVFPQR
181
182 // single thread (double-counted with search_cycles)
183 size_t init_query_cycles;
184 size_t init_list_cycles;
185 size_t scan_cycles;
186 size_t heap_cycles;
187
188 IndexIVFPQStats () {reset (); }
189 void reset ();
190 };
191
192 // global var that collects them all
193 extern IndexIVFPQStats indexIVFPQ_stats;
194
195
196
197 /** Index with an additional level of PQ refinement */
198 struct IndexIVFPQR: IndexIVFPQ {
199 ProductQuantizer refine_pq; ///< 3rd level quantizer
200 std::vector <uint8_t> refine_codes; ///< corresponding codes
201
202 /// factor between k requested in search and the k requested from the IVFPQ
203 float k_factor;
204
205 IndexIVFPQR (
206 Index * quantizer, size_t d, size_t nlist,
207 size_t M, size_t nbits_per_idx,
208 size_t M_refine, size_t nbits_per_idx_refine);
209
210 void reset() override;
211
212 long remove_ids(const IDSelector& sel) override;
213
214 /// trains the two product quantizers
215 void train_residual(idx_t n, const float* x) override;
216
217 void add_with_ids(idx_t n, const float* x, const long* xids) override;
218
219 /// same as add_with_ids, but optionally use the precomputed list ids
220 void add_core (idx_t n, const float *x, const long *xids,
221 const long *precomputed_idx = nullptr);
222
223 void reconstruct_n(idx_t i0, idx_t ni, float* recons) const override;
224
225 void search(
226 idx_t n,
227 const float* x,
228 idx_t k,
229 float* distances,
230 idx_t* labels) const override;
231
232 void merge_from_residuals(IndexIVF& other) override;
233
234 IndexIVFPQR();
235 };
236
237
238 /** Index with 32-bit ids and flat tables. Must be constructed from an
239 * exisiting IndexIVFPQ. Cannot be copy-constructed/assigned. The
240 * actual data is stored in the compact_* tables, the ids and codes
241 * tables are not used. */
242 struct IndexIVFPQCompact: IndexIVFPQ {
243
244 explicit IndexIVFPQCompact (const IndexIVFPQ &other);
245
246 /// how were the compact tables allocated?
247 enum Alloc_type_t {
248 Alloc_type_none, ///< alloc from outside
249 Alloc_type_new, ///< was allocated with new
250 Alloc_type_mmap ///< was mmapped
251 };
252
253 Alloc_type_t alloc_type;
254
255 uint32_t *limits; ///< size nlist + 1
256 uint32_t *compact_ids; ///< size ntotal
257 uint8_t *compact_codes; ///< size ntotal * code_size
258
259 // file and buffer this was mmapped (will be unmapped when object
260 // is deleted)
261 char * mmap_buffer;
262 long mmap_length;
263
264 void search_knn_with_key(
265 size_t nx,
266 const float* qx,
267 const long* keys,
268 const float* coarse_dis,
269 float_maxheap_array_t* res,
270 bool store_pairs = false) const override;
271
272 /// the three following functions will fail at runtime
273 void add(idx_t, const float*) override;
274 void reset() override;
275 void train(idx_t, const float*) override;
276
277 ~IndexIVFPQCompact() override;
278
279 IndexIVFPQCompact ();
280
281 };
282
283
284
285 } // namespace faiss
286
287
288
289
290
291 #endif
faiss::IndexIVFPQCompact::compact_ids
uint32_t * compact_ids
size ntotal
Definition: IndexIVFPQ.h:256
faiss::IndexIVF
Definition: IndexIVF.h:45
faiss::IndexIVFPQCompact::compact_codes
uint8_t * compact_codes
size ntotal * code_size
Definition: IndexIVFPQ.h:257
faiss::IndexIVFPQ::precompute_table
void precompute_table()
build precomputed table
Definition: IndexIVFPQ.cpp:391
faiss::IndexIVFPQ::copy_subset_to
void copy_subset_to(IndexIVFPQ &other, int subset_type, long a1, long a2) const
Definition: IndexIVFPQ.cpp:332
faiss::IndexIVFPQ::reconstruct
void reconstruct(idx_t key, float *recons) const override
Definition: IndexIVFPQ.cpp:302
faiss::IndexIVFPQR
Definition: IndexIVFPQ.h:198
faiss::IndexIVFPQR::refine_pq
ProductQuantizer refine_pq
3rd level quantizer
Definition: IndexIVFPQ.h:199
faiss::IndexIVFPQ::polysemous_training
PolysemousTraining * polysemous_training
if NULL, use default
Definition: IndexIVFPQ.h:36
faiss::IndexIVFPQCompact::add
void add(idx_t, const float *) override
the three following functions will fail at runtime
Definition: IndexIVFPQ.cpp:1454
faiss::IndexIVFPQStats
Definition: IndexIVFPQ.h:167
faiss::IndexIVFPQCompact::search_knn_with_key
void search_knn_with_key(size_t nx, const float *qx, const long *keys, const float *coarse_dis, float_maxheap_array_t *res, bool store_pairs=false) const override
Definition: IndexIVFPQ.cpp:1482
faiss::IndexIVFPQR::reconstruct_n
void reconstruct_n(idx_t i0, idx_t ni, float *recons) const override
Definition: IndexIVFPQ.cpp:1345
faiss::IDSelector
Definition: AuxIndexStructures.h:52
faiss::IndexIVFPQCompact::Alloc_type_mmap
was mmapped
Definition: IndexIVFPQ.h:250
faiss::IndexIVFPQ::merge_from_residuals
void merge_from_residuals(IndexIVF &other) override
used to implement merging
Definition: IndexIVFPQ.cpp:322
faiss::IndexIVFPQ::decode_multiple
void decode_multiple(size_t n, const long *keys, const uint8_t *xcodes, float *x) const
inverse of encode_multiple
Definition: IndexIVFPQ.cpp:168
faiss::IndexIVFPQ::train_residual_o
void train_residual_o(idx_t n, const float *x, float *residuals_2)
same as train_residual, also output 2nd level residuals
Definition: IndexIVFPQ.cpp:72
faiss::IndexIVFPQ::do_polysemous_training
bool do_polysemous_training
reorder PQ centroids after training?
Definition: IndexIVFPQ.h:35
faiss::IndexIVFPQ::scan_table_threshold
size_t scan_table_threshold
use table computation or on-the-fly?
Definition: IndexIVFPQ.h:39
faiss::IndexIVFPQR::train_residual
void train_residual(idx_t n, const float *x) override
trains the two product quantizers
Definition: IndexIVFPQ.cpp:1213
faiss::IndexIVFPQR::add_core
void add_core(idx_t n, const float *x, const long *xids, const long *precomputed_idx=nullptr)
same as add_with_ids, but optionally use the precomputed list ids
Definition: IndexIVFPQ.cpp:1237
faiss::IndexIVFPQCompact::limits
uint32_t * limits
size nlist + 1
Definition: IndexIVFPQ.h:255
faiss::IndexIVFPQ::precomputed_table
std::vector< float > precomputed_table
Definition: IndexIVFPQ.h:47
faiss::IndexIVFPQ::polysemous_ht
int polysemous_ht
Hamming thresh for polysemous filtering.
Definition: IndexIVFPQ.h:41
faiss::IndexIVFPQ::search_knn_with_key
virtual void search_knn_with_key(size_t nx, const float *qx, const long *keys, const float *coarse_dis, float_maxheap_array_t *res, bool store_pairs=false) const
Definition: IndexIVFPQ.cpp:963
faiss::IndexIVFPQR::reset
void reset() override
removes all elements from the database.
Definition: IndexIVFPQ.cpp:1204
faiss::IndexIVFPQ::add_with_ids
void add_with_ids(idx_t n, const float *x, const long *xids=nullptr) override
Definition: IndexIVFPQ.cpp:185
faiss::IndexIVFPQCompact
Definition: IndexIVFPQ.h:242
faiss::IndexIVF::ids
std::vector< std::vector< long > > ids
Inverted lists for indexes.
Definition: IndexIVF.h:55
faiss::Index::d
int d
vector dimension
Definition: Index.h:64
faiss::IndexIVF::quantizer
Index * quantizer
quantizer that maps vectors to inverted lists
Definition: IndexIVF.h:49
faiss::IndexIVFPQ::max_codes
size_t max_codes
max nb of codes to visit to do a query
Definition: IndexIVFPQ.h:40
faiss::IndexIVFPQCompact::Alloc_type_t
Alloc_type_t
how were the compact tables allocated?
Definition: IndexIVFPQ.h:247
faiss::IndexIVFPQR::refine_codes
std::vector< uint8_t > refine_codes
corresponding codes
Definition: IndexIVFPQ.h:200
faiss::IndexIVFPQ::remove_ids
long remove_ids(const IDSelector &sel) override
Definition: IndexIVFPQ.cpp:1091
faiss::IndexIVFPQ::train_residual
void train_residual(idx_t n, const float *x) override
trains the product quantizer
Definition: IndexIVFPQ.cpp:66
faiss::IndexIVFPQ
Definition: IndexIVFPQ.h:29
faiss::IndexIVFPQ::encode_multiple
void encode_multiple(size_t n, long *keys, const float *x, uint8_t *codes, bool compute_keys=false) const
Definition: IndexIVFPQ.cpp:149
faiss::IndexIVFPQCompact::train
void train(idx_t, const float *) override
Trains the quantizer and calls train_residual to train sub-quantizers.
Definition: IndexIVFPQ.cpp:1462
faiss::HeapArray
Definition: Heap.h:350
faiss::Index::idx_t
long idx_t
all indices are this type
Definition: Index.h:62
faiss::IndexIVFPQ::reset
void reset() override
removes all elements from the database.
Definition: IndexIVFPQ.cpp:1083
faiss::PolysemousTraining
optimizes the order of indices in a ProductQuantizer
Definition: PolysemousTraining.h:125
faiss::IndexIVFPQR::merge_from_residuals
void merge_from_residuals(IndexIVF &other) override
used to implement merging
Definition: IndexIVFPQ.cpp:1362
faiss::IndexIVFPQ::by_residual
bool by_residual
Encode residual or plain vector?
Definition: IndexIVFPQ.h:30
faiss::IndexIVFPQCompact::Alloc_type_none
alloc from outside
Definition: IndexIVFPQ.h:248
faiss::IndexIVFPQ::pq
ProductQuantizer pq
produces the codes
Definition: IndexIVFPQ.h:33
faiss::IndexIVF::nlist
size_t nlist
number of possible key values
Definition: IndexIVF.h:46
faiss::Index
Definition: Index.h:60
faiss::IndexIVFPQ::reconstruct_n
void reconstruct_n(idx_t i0, idx_t ni, float *recons) const override
Definition: IndexIVFPQ.cpp:273
faiss::IndexIVFPQ::add_core_o
void add_core_o(idx_t n, const float *x, const long *xids, float *residuals_2, const long *precomputed_idx=nullptr)
Definition: IndexIVFPQ.cpp:191
faiss::IndexIVFPQ::code_size
size_t code_size
code size per vector in bytes
Definition: IndexIVFPQ.h:32
faiss::IndexIVFPQR::remove_ids
long remove_ids(const IDSelector &sel) override
Definition: IndexIVFPQ.cpp:1371
faiss::ProductQuantizer
Definition: ProductQuantizer.h:25
faiss::IndexIVFPQCompact::reset
void reset() override
removes all elements from the database.
Definition: IndexIVFPQ.cpp:1458
faiss::IndexIVFPQCompact::Alloc_type_new
was allocated with new
Definition: IndexIVFPQ.h:249
faiss::IndexIVFPQR::add_with_ids
void add_with_ids(idx_t n, const float *x, const long *xids) override
Definition: IndexIVFPQ.cpp:1233
faiss::IndexIVFPQR::search
void search(idx_t n, const float *x, idx_t k, float *distances, idx_t *labels) const override
Definition: IndexIVFPQ.cpp:1256
faiss::IndexIVFPQ::search
void search(idx_t n, const float *x, idx_t k, float *distances, idx_t *labels) const override
Definition: IndexIVFPQ.cpp:1062
faiss::IndexIVFPQ::find_duplicates
size_t find_duplicates(idx_t *ids, size_t *lims) const
Definition: IndexIVFPQ.cpp:1148
faiss::IndexIVFPQR::k_factor
float k_factor
factor between k requested in search and the k requested from the IVFPQ
Definition: IndexIVFPQ.h:203
faiss::IndexIVFPQ::use_precomputed_table
int use_precomputed_table
if by_residual, build precompute tables
Definition: IndexIVFPQ.h:31