File IDSelector.h

namespace faiss

Implementation of k-means clustering with many variants.

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.

IDSelector is intended to define a subset of vectors to handle (for removal or as subset to search)

PQ4 SIMD packing and accumulation functions

The basic kernel accumulates nq query vectors with bbs = nb * 2 * 16 vectors and produces an output matrix for that. It is interesting for nq * nb <= 4, otherwise register spilling becomes too large.

The implementation of these functions is spread over 3 cpp files to reduce parallel compile times. Templates are instantiated explicitly.

This file contains callbacks for kernels that compute distances.

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.

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.

Definition of inverted lists + a few common classes that implement the interface.

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.

In this file are the implementations of extra metrics beyond L2 and inner product

Implements a few neural net layers, mainly to support QINCo

Defines a few objects that apply transformations to a set of vectors Often these are pre-processing steps.

struct IDSelector

#include <IDSelector.h>

Encapsulates a set of ids to handle.

Subclassed by PyCallbackIDSelector, faiss::IDSelectorAll, faiss::IDSelectorAnd, faiss::IDSelectorArray, faiss::IDSelectorBatch, faiss::IDSelectorBitmap, faiss::IDSelectorNot, faiss::IDSelectorOr, faiss::IDSelectorRange, faiss::IDSelectorTranslated, faiss::IDSelectorXOr

Public Functions

virtual bool is_member(idx_t id) const = 0

inline virtual ~IDSelector()

struct IDSelectorRange : public faiss::IDSelector 

#include <IDSelector.h>

ids between [imin, imax)

Public Functions

IDSelectorRange(idx_t imin, idx_t imax, bool assume_sorted = false)

virtual bool is_member(idx_t id) const final

void find_sorted_ids_bounds(size_t list_size, const idx_t *ids, size_t *jmin, size_t *jmax) const: for sorted ids, find the range of list indices where the valid ids are stored

inline ~IDSelectorRange() override

Public Members

idx_t imin

idx_t imax

bool assume_sorted: Assume that the ids to handle are sorted. In some cases this can speed up processing

struct IDSelectorArray : public faiss::IDSelector 

#include <IDSelector.h>

Simple array of elements

is_member calls are very inefficient, but some operations can use the ids directly.

Public Functions

IDSelectorArray(size_t n, const idx_t *ids)

Construct with an array of ids to process

Parameters:

n – number of ids to store
ids – elements to store. The pointer should remain valid during IDSelectorArray’s lifetime

virtual bool is_member(idx_t id) const final

inline ~IDSelectorArray() override

Public Members

size_t n

const idx_t *ids

struct IDSelectorBatch : public faiss::IDSelector 

#include <IDSelector.h>

Ids from a set.

Repetitions of ids in the indices set passed to the constructor does not hurt performance.

The hash function used for the bloom filter and GCC’s implementation of unordered_set are just the least significant bits of the id. This works fine for random ids or ids in sequences but will produce many hash collisions if lsb’s are always the same

Public Functions

IDSelectorBatch(size_t n, const idx_t *indices)

Construct with an array of ids to process

Parameters:

n – number of ids to store
ids – elements to store. The pointer can be released after construction

virtual bool is_member(idx_t id) const final

inline ~IDSelectorBatch() override

Public Members

std::unordered_set<idx_t> set

std::vector<uint8_t> bloom

int nbits

idx_t mask

struct IDSelectorBitmap : public faiss::IDSelector 

#include <IDSelector.h>

One bit per element. Constructed with a bitmap, size ceil(n / 8).

Public Functions

IDSelectorBitmap(size_t n, const uint8_t *bitmap)

Construct with a binary mask

Parameters:

n – size of the bitmap array
bitmap – id will be selected iff id / 8 < n and bit number (i%8) of bitmap[floor(i / 8)] is 1.

virtual bool is_member(idx_t id) const final

inline ~IDSelectorBitmap() override

Public Members

size_t n

const uint8_t *bitmap

struct IDSelectorNot : public faiss::IDSelector 

#include <IDSelector.h>

reverts the membership test of another selector

Public Functions

inline IDSelectorNot(const IDSelector *sel)

inline virtual bool is_member(idx_t id) const final

inline virtual ~IDSelectorNot()

Public Members

const IDSelector *sel

struct IDSelectorAll : public faiss::IDSelector 

#include <IDSelector.h>

selects all entries (useful for benchmarking)

Public Functions

inline virtual bool is_member(idx_t id) const final

inline virtual ~IDSelectorAll()

struct IDSelectorAnd : public faiss::IDSelector 

#include <IDSelector.h>

does an AND operation on the the two given IDSelector’s is_membership results.

Public Functions

inline IDSelectorAnd(const IDSelector *lhs, const IDSelector *rhs)

inline virtual bool is_member(idx_t id) const final

inline virtual ~IDSelectorAnd()

Public Members

const IDSelector *lhs

const IDSelector *rhs

struct IDSelectorOr : public faiss::IDSelector 

#include <IDSelector.h>

does an OR operation on the the two given IDSelector’s is_membership results.

Public Functions

inline IDSelectorOr(const IDSelector *lhs, const IDSelector *rhs)

inline virtual bool is_member(idx_t id) const final

inline virtual ~IDSelectorOr()

Public Members

const IDSelector *lhs

const IDSelector *rhs

struct IDSelectorXOr : public faiss::IDSelector 

#include <IDSelector.h>

does an XOR operation on the the two given IDSelector’s is_membership results.

Public Functions

inline IDSelectorXOr(const IDSelector *lhs, const IDSelector *rhs)

inline virtual bool is_member(idx_t id) const final

inline virtual ~IDSelectorXOr()

Public Members

const IDSelector *lhs

const IDSelector *rhs