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An Erlang implementation of Redis

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README.md

An Erlang version of Redis, with the goal of similar algorithmic performance but support for multiple master nodes and larger-than-RAM datasets. For More info, see this PDF of a Talk at Erlang Factory 2012.

Usage

Just run $ make run and open connections with your favourite redis client.

Differences with Redis

Different Behaviour

  • SAVE, BGSAVE and LASTSAVE are database dependent. The original Redis saves all databases at once, edis saves just the one you SELECT'ed.
  • INFO provides much less information and no statistics (so, CONFIG RESETSTAT does nothing at all)
  • MULTI doesn't support:
    • cross-db commands (i.e. FLUSHALL, SELECT, MOVE)
    • non-db commands (i.e AUTH, CONFIG *, SHUTDOWN, MONITOR)
    • pub/sub commands (i.e. PUBLISH, SUBSCRIBE, UNSUBSCRIBE, PSUBSCRIBE, PUNSUBSCRIBE)
  • (P)UNSUBSCRIBE commands are not allowed outside PUBSUB mode
  • PUBLISH response is not precise: it's the amount of all clients subscribed to any channel and/or pattern, not just those that will handle the message. On the other hand it runs in O(1) because it's asynchronous, it just dispatches the message.

Missing Features

  • Dynamic node configuration (i.e. the SLAVEOF command is not implemented)
  • Encoding optimization (i.e. all objects are encoded as binary representations of erlang terms, so for instance "123" will never be stored as an int)
  • OBJECT REFCOUNT allways returns 1 for existing keys and (nil) otherwise

Unsupported Commands

SYNC, SLOWLOG, SLAVEOF, DEBUG *

License

edis is licensed by Electronic Inaka, LLC under the Apache 2.0 license; see the LICENSE file in this repository.

TODO

  • Backends
    • HanoiDB
      • Make use of the efficient range searchs with start/end for searching ranges
      • Make use of time-based key expiry
      • Finish the TODO items
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