File IndexIVFFastScan.h

namespace faiss

Copyright (c) Facebook, Inc. and its affiliates.

This source code is licensed under the MIT license found in the LICENSE file in the root directory of this source tree.

Throughout the library, vectors are provided as float * pointers. Most algorithms can be optimized when several vectors are processed (added/searched) together in a batch. In this case, they are passed in as a matrix. When n vectors of size d are provided as float * x, component j of vector i is

x[ i * d + j ]

where 0 <= i < n and 0 <= j < d. In other words, matrices are always compact. When specifying the size of the matrix, we call it an n*d matrix, which implies a row-major storage.

Copyright (c) Facebook, Inc. and its affiliates.

This source code is licensed under the MIT license found in the LICENSE file in the root directory of this source tree. I/O functions can read/write to a filename, a file handle or to an object that abstracts the medium.

The read functions return objects that should be deallocated with delete. All references within these objectes are owned by the object.

Copyright (c) Facebook, Inc. and its affiliates.

This source code is licensed under the MIT license found in the LICENSE file in the root directory of this source tree. Definition of inverted lists + a few common classes that implement the interface.

Copyright (c) Facebook, Inc. and its affiliates.

This source code is licensed under the MIT license found in the LICENSE file in the root directory of this source tree. Since IVF (inverted file) indexes are of so much use for large-scale use cases, we group a few functions related to them in this small library. Most functions work both on IndexIVFs and IndexIVFs embedded within an IndexPreTransform.

Copyright (c) Facebook, Inc. and its affiliates.

This source code is licensed under the MIT license found in the LICENSE file in the root directory of this source tree. In this file are the implementations of extra metrics beyond L2 and inner product

Copyright (c) Facebook, Inc. and its affiliates.

This source code is licensed under the MIT license found in the LICENSE file in the root directory of this source tree. Defines a few objects that apply transformations to a set of vectors Often these are pre-processing steps.

Variables

FAISS_API IVFFastScanStats IVFFastScan_stats
struct IndexIVFFastScan : public faiss::IndexIVF
#include <IndexIVFFastScan.h>

Fast scan version of IVFPQ and IVFAQ. Works for 4-bit PQ/AQ for now.

The codes in the inverted lists are not stored sequentially but grouped in blocks of size bbs. This makes it possible to very quickly compute distances with SIMD instructions.

Implementations (implem): 0: auto-select implementation (default) 1: orig’s search, re-implemented 2: orig’s search, re-ordered by invlist 10: optimizer int16 search, collect results in heap, no qbs 11: idem, collect results in reservoir 12: optimizer int16 search, collect results in heap, uses qbs 13: idem, collect results in reservoir

Subclassed by faiss::IndexIVFAdditiveQuantizerFastScan, faiss::IndexIVFPQFastScan

Public Functions

IndexIVFFastScan(Index *quantizer, size_t d, size_t nlist, size_t code_size, MetricType metric = METRIC_L2)
IndexIVFFastScan()
void init_fastscan(size_t M, size_t nbits, size_t nlist, MetricType metric, int bbs)
~IndexIVFFastScan() override
virtual void add_with_ids(idx_t n, const float *x, const idx_t *xids) override

default implementation that calls encode_vectors

virtual bool lookup_table_is_3d() const = 0
virtual void compute_LUT(size_t n, const float *x, const idx_t *coarse_ids, const float *coarse_dis, AlignedTable<float> &dis_tables, AlignedTable<float> &biases) const = 0
void compute_LUT_uint8(size_t n, const float *x, const idx_t *coarse_ids, const float *coarse_dis, AlignedTable<uint8_t> &dis_tables, AlignedTable<uint16_t> &biases, float *normalizers) const
virtual void search(idx_t n, const float *x, idx_t k, float *distances, idx_t *labels, const SearchParameters *params = nullptr) const override

assign the vectors, then call search_preassign

template<bool is_max, class Scaler>
void search_dispatch_implem(idx_t n, const float *x, idx_t k, float *distances, idx_t *labels, const Scaler &scaler) const
template<class C, class Scaler>
void search_implem_1(idx_t n, const float *x, idx_t k, float *distances, idx_t *labels, const Scaler &scaler) const
template<class C, class Scaler>
void search_implem_2(idx_t n, const float *x, idx_t k, float *distances, idx_t *labels, const Scaler &scaler) const
template<class C, class Scaler>
void search_implem_10(idx_t n, const float *x, idx_t k, float *distances, idx_t *labels, int impl, size_t *ndis_out, size_t *nlist_out, const Scaler &scaler) const
template<class C, class Scaler>
void search_implem_12(idx_t n, const float *x, idx_t k, float *distances, idx_t *labels, int impl, size_t *ndis_out, size_t *nlist_out, const Scaler &scaler) const
template<class C, class Scaler>
void search_implem_14(idx_t n, const float *x, idx_t k, float *distances, idx_t *labels, int impl, const Scaler &scaler) const
virtual void reconstruct_from_offset(int64_t list_no, int64_t offset, float *recons) const override

Reconstruct a vector given the location in terms of (inv list index + inv list offset) instead of the id.

Useful for reconstructing when the direct_map is not maintained and the inv list offset is computed by search_preassigned() with store_pairs set.

void reconstruct_orig_invlists()

Public Members

int bbs
size_t M
size_t nbits
size_t ksub
size_t M2
int implem = 0
int skip = 0
bool by_residual = false
int qbs = 0
size_t qbs2 = 0
InvertedLists *orig_invlists = nullptr

orig’s inverted lists (for debugging)

struct IVFFastScanStats

Public Functions

inline double Mcy_at(int i)
inline double Mcy_reservoir_at(int i)
inline IVFFastScanStats()
inline void reset()

Public Members

uint64_t times[10]
uint64_t t_compute_distance_tables
uint64_t t_round
uint64_t t_copy_pack
uint64_t t_scan
uint64_t t_to_flat
uint64_t reservoir_times[4]
double t_aq_encode
double t_aq_norm_encode