['pɛgəsəs] A distributed key-value storage system developed and maintained by Xiaomi Cloud Storage Team.

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  1. aca55e7 build: remove restrict to build from non-git-repo (#602) by Wu Tao · 3 days ago master
  2. 8697976 refactor: split read/write hotspot of hotspot_partition_calculator (#592) by Smilencer · 4 days ago
  3. 412492d feat(hotspot): add a function to start hotkey detecting in hotspot_partition_calculator (#601) by Smilencer · 5 days ago
  4. e56690c refactor: use db_get to implement incr (#598) by Wu Tao · 5 days ago
  5. b057848 refactor(collector): sort out the structure of partition hotspot detection (#597) by Smilencer · 11 days ago

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Note: The master branch may be in an unstable or even broken state during development. Please use releases instead of the master branch in order to get stable binaries.

Pegasus is a distributed key-value storage system which is designed to be:

  • horizontally scalable distributed using hash-based partitioning
  • strongly consistent: ensured by PacificA consensus protocol
  • high-performance: using RocksDB as underlying storage engine
  • simple: well-defined, easy-to-use APIs

Pegasus has been widely-used in XiaoMi and serves millions of requests per second. It is a mature, active project. We hope to build a diverse developer and user community and attract contributions from more people.

Background

HBase was recognized as the only large-scale KV store solution in XiaoMi until Pegasus came out in 2015 to solve the problem of high latency of HBase because of its Java GC and RPC overhead of the underlying distributed filesystem.

Pegasus targets to fill the gap between Redis and HBase. As the former is in-memory, low latency, but does not provide a strong-consistency guarantee. And unlike the latter, Pegasus is entirely written in C++ and its write-path relies merely on the local filesystem.

Apart from the performance requirements, we also need a storage system to ensure multiple-level data safety and support fast data migration between data centers, automatic load balancing, and online partition split.

After investigating the existing storage systems in the open source world, we could hardly find a suitable solution to satisfy all the requirements. So the journey of Pegasus begins.

To start using Pegasus

See our documentation on Pegasus Website.

Related Projects

Submodules:

Client libs:

Test tools:

Data import/export tools:

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License

Copyright 2020 The Apache Software Foundation. Licensed under the Apache License, Version 2.0: http://www.apache.org/licenses/LICENSE-2.0