SPTAG: A library for fast approximate nearest neighbor search
SPTAG
SPTAG (Space Partition Tree And Graph) is a library for large scale vector approximate nearest neighbor search scenario released by Microsoft Research (MSR) and Microsoft Bing.
Introduction
This library assumes that the samples are represented as vectors and that the vectors can be compared by L2 distances or cosine distances.
Vectors returned for a query vector are the vectors that have smallest L2 distance or cosine distances with the query vector.
SPTAG provides two methods: kd-tree and relative neighborhood graph (SPTAG-KDT)
and balanced k-means tree and relative neighborhood graph (SPTAG-BKT).
SPTAG-KDT is advantageous in index building cost, and SPTAG-BKT is advantageous in search accuracy in very high-dimensional data.
How it works
SPTAG is inspired by the NGS approach [WangL12]. It contains two basic modules: index builder and searcher.
The RNG is built on the k-nearest neighborhood graph [WangWZTG12, WangWJLZZH14]
for boosting the connectivity. Balanced k-means trees are used to replace kd-trees to avoid the inaccurate distance bound estimation in kd-trees for very high-dimensional vectors.
The search begins with the search in the space partition trees for
finding several seeds to start the search in the RNG.
The searches in the trees and the graph are iteratively conducted.
Highlights
- Fresh update: Support online vector deletion and insertion
- Distributed serving: Search over multiple machines
Build
Requirements
- swig >= 3.0
- cmake >= 3.12.0
- boost >= 1.67.0
Install
For Linux:
mkdir build
cd build && cmake .. && make
It will generate a Release folder in the code directory which contains all the build targets.
For Windows:
mkdir build
cd build && cmake -A x64 ..
It will generate a SPTAGLib.sln in the build directory.
Compiling the ALL_BUILD project in the Visual Studio (at least 2015) will generate a Release directory which contains all the build targets.
For detailed instructions on installing Windows binaries, please see here
Using Docker:
docker build -t sptag .
Will build a docker container with binaries in /app/Release/.
Verify
Run the test (or Test.exe) in the Release folder to verify all the tests have passed.
Usage
The detailed usage can be found in Get started. There is also an end-to-end tutorial for building vector search online service using Python Wrapper in Python Tutorial.
The detailed parameters tunning can be found in Parameters.
References
Please cite SPTAG in your publications if it helps your research:
@manual{ChenW18,
author = {Qi Chen and
Haidong Wang and
Mingqin Li and
Gang Ren and
Scarlett Li and
Jeffery Zhu and
Jason Li and
Chuanjie Liu and
Lintao Zhang and
Jingdong Wang},
title = {SPTAG: A library for fast approximate nearest neighbor search},
url = {https://github.com/Microsoft/SPTAG},
year = {2018}
}
@inproceedings{WangL12,
author = {Jingdong Wang and
Shipeng Li},
title = {Query-driven iterated neighborhood graph search for large scale indexing},
booktitle = {ACM Multimedia 2012},
pages = {179--188},
year = {2012}
}
@inproceedings{WangWZTGL12,
author = {Jing Wang and
Jingdong Wang and
Gang Zeng and
Zhuowen Tu and
Rui Gan and
Shipeng Li},
title = {Scalable k-NN graph construction for visual descriptors},
booktitle = {CVPR 2012},
pages = {1106--1113},
year = {2012}
}
@article{WangWJLZZH14,
author = {Jingdong Wang and
Naiyan Wang and
You Jia and
Jian Li and
Gang Zeng and
Hongbin Zha and
Xian{-}Sheng Hua},
title = {Trinary-Projection Trees for Approximate Nearest Neighbor Search},
journal = {{IEEE} Trans. Pattern Anal. Mach. Intell.},
volume = {36},
number = {2},
pages = {388--403},
year = {2014
}
Contribute
This project welcomes contributions and suggestions from all the users.
We use GitHub issues for tracking suggestions and bugs.
License
The entire codebase is under MIT license