Introduction to Redis

Redis is an open source (BSD licensed), in-memory data structure store used as a database, cache, and message broker. Redis provides data structures such as strings, hashes, lists, sets, sorted sets with range queries, bitmaps, hyperloglogs, geospatial indexes, and streams. Redis has built-in replication, Lua scripting, LRU eviction, transactions, and different levels of on-disk persistence, and provides high availability via Redis Sentinel and automatic partitioning with Redis Cluster.

You can run atomic operations on these types, like appending to a string; incrementing the value in a hash; pushing an element to a list; computing set intersection, union and difference; or getting the member with highest ranking in a sorted set.

To achieve top performance, Redis works with an in-memory dataset. Depending on your use case, Redis can persist your data either by periodically dumping the dataset to disk or by appending each command to a disk-based log. You can also disable persistence if you just need a feature-rich, networked, in-memory cache.

Redis supports asynchronous replication, with fast non-blocking synchronization and auto-reconnection with partial resynchronization on net split.

Redis also includes:

• Transactions
• Pub/Sub
• Lua scripting
• Keys with a limited time-to-live
• LRU eviction of keys
• Automatic failover

You can use Redis from most programming languages.

Redis is written in ANSI C and works on most POSIX systems like Linux, *BSD, and Mac OS X, without external dependencies. Linux and OS X are the two operating systems where Redis is developed and tested the most, and we recommend using Linux for deployment. Redis may work in Solaris-derived systems like SmartOS, but support is best effort. There is no official support for Windows builds.