alexxnica / keyvi

Keyvi - a key value index that powers Cliqz search engine. It is an in-memory FST-based data structure highly optimized for size and lookup performance.

Keyvi is developed and maintained by Cliqz Engineering Team and Hendrik Muhs. Cliqz is a provider of innovative, privacy-focused browser technologies with integrated quick-search functionality and anti-tracking.

Keyvi - the short form for "Key value index" - defines a special subtype of the popular key value store (KVS) technologies. As you can imagine from the name, keyvi is an immutable key value store, therefore an index not a store. Keyvi's strengths: high compression ratio and extreme scalability. So if you need online read/writes keyvi is not for you, however, if your use case is mostly reads and infrequent writes you might be interested in checking keyvi out.

Introduction

• BBuzz2016 talk
• Announcement blog post
• Search Meetup Munich Slidedeck

Install

Quick

Precompiled binary wheels are available for OS X and Linux on PyPi. To install use:

pip install pykeyvi

From Source

The core part is a C++ header-only library, but the TPIE 3rdparty library needs to be compiled once. The commandline tools are also part of the C++ code. For instructions check the Readme file.

For the python extension pykeyvi check the Readme file in the pykeyvi subfolder.

Usage

• Howtos
  • Compiling Dictionaries/Indexes
  • Pykeyvi
    • Compiling
• Crashcourse
• Using pykeyvi with EMR (mrjob or pyspark)

Internals

• Construction Basics
• Persistence Basics
• Minimization
• Scaling
• Extensibility

If you like to go deep down in the basics, keyvi is inspired by the following 2 papers:

• Sparse Array (See Storing a Sparse Table, Robert E. Tarjan et al. http://infolab.stanford.edu/pub/cstr/reports/cs/tr/78/683/CS-TR-78-683.pdf)
• Incremental, which means minimization is done on the fly (See Incremental Construction of Minimal Acyclic Finite-State Automata, J. Daciuk et al.: http://www.mitpressjournals.org/doi/pdf/10.1162/089120100561601)

Licence and 3rdparty dependencies

keyvi is licenced under apache license 2.0, see licence for details.

In addition keyvi uses 3rdparty libraries which define their own licence. Please check their respective licence. The 3rdparty libraries can be found at keyvi/3rdparty.

Contributing

• Bug reports, feature requests and general question can be added as an Issue.

• PRs are welcome.

• Questions? Concerns? Feel free to contact us.