faiss/CHANGELOG.md

# Changelog
All notable changes to this project will be documented in this file.

The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
and this project DOES NOT adhere to [Semantic Versioning](https://semver.org/spec/v2.0.0.html)
at the moment.

## [Unreleased]
### Added
- Support for building C bindings through the `FAISS_ENABLE_C_API` CMake option.
- Serializing the indexes with the python pickle module
- Support for the NNDescent k-NN graph building method
- Support for the NSG indexing method

### Changed
- The order of xb an xq was different between `faiss.knn` and `faiss.knn_gpu`.
Also the metric argument was called distance_type.

### Fixed
- Fixed a bug causing kNN search functions for IndexBinaryHash and
IndexBinaryMultiHash to return results in a random order.
- Copy constructor of AlignedTable had a bug leading to crashes when cloning
IVFPQ indices.

## [1.7.0] - 2021-01-27

## [1.6.5] - 2020-11-22

## [1.6.4] - 2020-10-12
### Added
- Arbitrary dimensions per sub-quantizer now allowed for `GpuIndexIVFPQ`.
- Brute-force kNN on GPU (`bfKnn`) now accepts `int32` indices.
- Nightly conda builds now available (for CPU).
- Faiss is now supported on Windows.

## [1.6.3] - 2020-03-24
### Added
- Support alternative distances on GPU for GpuIndexFlat, including L1, Linf and
Lp metrics.
- Support METRIC_INNER_PRODUCT for GpuIndexIVFPQ.
- Support float16 coarse quantizer for GpuIndexIVFFlat and GpuIndexIVFPQ. GPU
Tensor Core operations (mixed-precision arithmetic) are enabled on supported
hardware when operating with float16 data.
- Support k-means clustering with encoded vectors. This makes it possible to
train on larger datasets without decompressing them in RAM, and is especially
useful for binary datasets (see https://github.com/facebookresearch/faiss/blob/master/tests/test_build_blocks.py#L92).
- Support weighted k-means. Weights can be associated to each training point
(see https://github.com/facebookresearch/faiss/blob/master/tests/test_build_blocks.py).
- Serialize callback in python, to write to pipes or sockets (see
https://github.com/facebookresearch/faiss/wiki/Index-IO,-cloning-and-hyper-parameter-tuning).
- Reconstruct arbitrary ids from IndexIVF + efficient remove of a small number
of ids. This avoids 2 inefficiencies: O(ntotal) removal of vectors and
IndexIDMap2 on top of indexIVF. Documentation here:
https://github.com/facebookresearch/faiss/wiki/Special-operations-on-indexes.
- Support inner product as a metric in IndexHNSW (see
https://github.com/facebookresearch/faiss/blob/master/tests/test_index.py#L490).
- Support PQ of sizes other than 8 bit in IndexIVFPQ.
- Demo on how to perform searches sequentially on an IVF index. This is useful
for an OnDisk index with a very large batch of queries. In that case, it is
worthwhile to scan the index sequentially (see
https://github.com/facebookresearch/faiss/blob/master/tests/test_ivflib.py#L62).
- Range search support for most binary indexes.
- Support for hashing-based binary indexes (see
https://github.com/facebookresearch/faiss/wiki/Binary-indexes).

### Changed
- Replaced obj table in Clustering object: now it is a ClusteringIterationStats
structure that contains additional statistics.

### Removed
- Removed support for useFloat16Accumulator for accumulators on GPU (all
accumulations are now done in float32, regardless of whether float16 or float32
input data is used).

### Fixed
- Some python3 fixes in benchmarks.
- Fixed GpuCloner (some fields were not copied, default to no precomputed tables
with IndexIVFPQ).
- Fixed support for new pytorch versions.
- Serialization bug with alternative distances.
- Removed test on multiple-of-4 dimensions when switching between blas and AVX
implementations.

## [1.6.2] - 2020-03-10

## [1.6.1] - 2019-12-04

## [1.6.0] - 2019-09-24
### Added
- Faiss as a codec: We introduce a new API within Faiss to encode fixed-size
vectors into fixed-size codes. The encoding is lossy and the tradeoff between
compression and reconstruction accuracy can be adjusted.
- ScalarQuantizer support for GPU, see gpu/GpuIndexIVFScalarQuantizer.h. This is
particularly useful as GPU memory is often less abundant than CPU.
- Added easy-to-use serialization functions for indexes to byte arrays in Python
(faiss.serialize_index, faiss.deserialize_index).
- The Python KMeans object can be used to use the GPU directly, just add
gpu=True to the constuctor see gpu/test/test_gpu_index.py test TestGPUKmeans.

### Changed
- Change in the code layout: many C++ sources are now in subdirectories impl/
and utils/.

## [1.5.3] - 2019-06-24
### Added
- Basic support for 6 new metrics in CPU IndexFlat and IndexHNSW (https://github.com/facebookresearch/faiss/issues/848).
- Support for IndexIDMap/IndexIDMap2 with binary indexes (https://github.com/facebookresearch/faiss/issues/780).

### Changed
- Throw python exception for OOM (https://github.com/facebookresearch/faiss/issues/758).
- Make DistanceComputer available for all random access indexes.
- Gradually moving from long to uint64_t for portability.

### Fixed
- Slow scanning of inverted lists (https://github.com/facebookresearch/faiss/issues/836).

## [1.5.2] - 2019-05-28
### Added
- Support for searching several inverted lists in parallel (parallel_mode != 0).
- Better support for PQ codes where nbit != 8 or 16.
- IVFSpectralHash implementation: spectral hash codes inside an IVF.
- 6-bit per component scalar quantizer (4 and 8 bit were already supported).
- Combinations of inverted lists: HStackInvertedLists and VStackInvertedLists.
- Configurable number of threads for OnDiskInvertedLists prefetching (including
0=no prefetch).
- More test and demo code compatible with Python 3 (print with parentheses).

### Changed
- License was changed from BSD+Patents to MIT.
- Exceptions raised in sub-indexes of IndexShards and IndexReplicas are now
propagated.
- Refactored benchmark code: data loading is now in a single file.

## [1.5.1] - 2019-04-05
### Added
- MatrixStats object, which reports useful statistics about a dataset.
- Option to round coordinates during k-means optimization.
- An alternative option for search in HNSW.
- Support for range search in IVFScalarQuantizer.
- Support for direct uint_8 codec in ScalarQuantizer.
- Better support for PQ code assignment with external index.
- Support for IMI2x16 (4B virtual centroids).
- Support for k = 2048 search on GPU (instead of 1024).
- Support for renaming an ondisk invertedlists.
- Support for nterrupting computations with interrupt signal (ctrl-C) in python.
- Simplified build system (with --with-cuda/--with-cuda-arch options).

### Changed
- Moved stats() and imbalance_factor() from IndexIVF to InvertedLists object.
- Renamed IndexProxy to IndexReplicas.
- Most CUDA mem alloc failures now throw exceptions instead of terminating on an
assertion.
- Updated example Dockerfile.
- Conda packages now depend on the cudatoolkit packages, which fixes some
interferences with pytorch. Consequentially, faiss-gpu should now be installed
by conda install -c pytorch faiss-gpu cudatoolkit=10.0.

## [1.5.0] - 2018-12-19
### Added
- New GpuIndexBinaryFlat index.
- New IndexBinaryHNSW index.

## [1.4.0] - 2018-08-30
### Added
- Automatic tracking of C++ references in Python.
- Support for non-intel platforms, some functions optimized for ARM.
- Support for overriding nprobe for concurrent searches.
- Support for floating-point quantizers in binary indices.

### Fixed
- No more segfaults due to Python's GC.
- GpuIndexIVFFlat issues for float32 with 64 / 128 dims.
- Sharding of flat indexes on GPU with index_cpu_to_gpu_multiple.

## [1.3.0] - 2018-07-10
### Added
- Support for binary indexes (IndexBinaryFlat, IndexBinaryIVF).
- Support fp16 encoding in scalar quantizer.
- Support for deduplication in IndexIVFFlat.
- Support for index serialization.

### Fixed
- MMAP bug for normal indices.
- Propagation of io_flags in read func.
- k-selection for CUDA 9.
- Race condition in OnDiskInvertedLists.

## [1.2.1] - 2018-02-28
### Added
- Support for on-disk storage of IndexIVF data.
- C bindings.
- Extended tutorial to GPU indices.

[Unreleased]: https://github.com/facebookresearch/faiss/compare/v1.7.0...HEAD
[1.7.0]: https://github.com/facebookresearch/faiss/compare/v1.6.5...v1.7.0
[1.6.5]: https://github.com/facebookresearch/faiss/compare/v1.6.4...v1.6.5
[1.6.4]: https://github.com/facebookresearch/faiss/compare/v1.6.3...v1.6.4
[1.6.3]: https://github.com/facebookresearch/faiss/compare/v1.6.2...v1.6.3
[1.6.2]: https://github.com/facebookresearch/faiss/compare/v1.6.1...v1.6.2
[1.6.1]: https://github.com/facebookresearch/faiss/compare/v1.6.0...v1.6.1
[1.6.0]: https://github.com/facebookresearch/faiss/compare/v1.5.3...v1.6.0
[1.5.3]: https://github.com/facebookresearch/faiss/compare/v1.5.2...v1.5.3
[1.5.2]: https://github.com/facebookresearch/faiss/compare/v1.5.1...v1.5.2
[1.5.1]: https://github.com/facebookresearch/faiss/compare/v1.5.0...v1.5.1
[1.5.0]: https://github.com/facebookresearch/faiss/compare/v1.4.0...v1.5.0
[1.4.0]: https://github.com/facebookresearch/faiss/compare/v1.3.0...v1.4.0
[1.3.0]: https://github.com/facebookresearch/faiss/compare/v1.2.1...v1.3.0
[1.2.1]: https://github.com/facebookresearch/faiss/releases/tag/v1.2.1