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Features (DRAFT)

Checking Redis for the first time? Here your will find the most important features, and pointers to a lot more information.

Speed

Redis is written in ANSI C, and loads the whole dataset in memory, so it is wicked fast! Up to 110,000 SETs/second, 81,000 GETs/second can be achieved in an entry level Linux box. Read more about Redis Speed.

Also Redis supports Pipelining of commands and getting and setting múltiple values in a single command to speed up communication with the client libraries.

Persistence

While all the data lives in memory, changes are asynchronously saved on disk using flexible policies based on elapsed time and/or number of updates since last save.

If you can't afford losing some data, starting on version 1.1 (currently in beta but you can download it from the Git repository) Redis supports an append-only file persistence mode. Check more on Persistence, or read the AppendOnlyFileHowto for more information.

Support for Data Structures

Values in Redis can be Strings as in a conventional key-value store, but also Lists, Sets, and SortedSets (to be support in version 1.1). This data types allow pushing/poping elements, or adding/removing them, also perform server side union, intersection, difference between sets, and so forth depending on the types. Redis supports different kind of sorting abilities for Sets and Lists.

You can think in Redis as a Data Structures Server, that allows you to model non trivial problems. Read Data Types to learn more about the way Redis handle Strings, and the Commands supported by Lists, Sets and SortedSets

Atomic Operations

Redis operations working on the different Data Types are atomic, so setting or increasing a key, adding and removing elements from a set, increasing a counter will all be accomplished safely.

Variety of Supported Languages

Ruby, Python, Twisted Python, PHP, Erlang, Tcl, Perl, Lua, Java, Scala, Clojure, choose your poison. Check the list of Supported Languages for all the details.

If your favorite language is not supported yet, you can write your own client library, as the Protocol is pretty simple.

Master/Slave Replication

Redis supports a very simple and fast Master/Slave replication. Is so simple it takes only one line in the configuration file to set it up, and 21 seconds for a Slave to complete the initial sync of 10 MM key set in a Amazon EC2 instance.

Read more about Master/Slave Replication.

Sharding

Distributing the dataset across multiple Redis instances is easy in Redis, as in any other key-value store. And this depends basically on the Languages client libraries being able to do so.

Read more about Sharding if you want to know more abour distributing data and workload in Redis.

Hot Backups

TODO

Simple to Install, Setup and Manage

Installing Redis requires little more than downloading it, uncompressing it and running make. Management is near zero, so you can start using Redis in a matter of minutes.

Go on and read about Redis installation, its Setup and Management.

Portable

Redis is written in ANSI C and works in most POSIX systems like Linux, BSD, Mac OS X, Solaris, and so on. Redis is reported to compile and work under WIN32 if compiled with Cygwin, but there is no official support for Windows currently.

Liberal Licensing

Redis is free software released under the very liberal BSD license.

What's next?

Want to get started with Redis? Try the Quick Start you will be up and running in just a matter of minutes.

Check the Code Samples and find how you can use Redis with your favorite programming language.

Compare Redis with other key-value stores, like Tokyo Cabinet or Memcached.