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After announcing Redis 5 RC1 in May earlier this year, the stable version of Redis 5 was released yesterday. This release comes with a new Stream data type, LFU/LRU info in RDB, active defragmentation version 2, HyperLogLogs improvements and many other improvements.

What is new in Redis 5?

Redis 5 comes with a new data type called Stream, which models a log data structure in a more abstract way.

Three new modules got important APIs: Cluster API, Timer API, Dictionary API. With these APIs, you can now build a distributed system with Redis using it just as a framework, creating your own protocols.

To provide better-caching accuracy after a restart or when a slave does a full sync, RDB now stores the LFU and LRU information. In the future releases, we are likely to see a new feature that sends TOUCH commands to slaves to update their information about hot keys.

The cluster manager is now ported from Ruby to C and is integrated with redis-cli. Because of this change, it is faster and no longer has any dependency. To learn more about the cluster manager, you can run the redis-cli –cluster help command. Also, many commands with subcommands have a HELP subcommand.

Sorted set commands, ZPOPMIN/MAX, and blocking variants are introduced. These commands are used in applications such as time series and leaderboards.

With active defragmentation version 2, the process of defragmenting the memory of a running server is better than before. This will be very useful for long-running workloads that tend to fragment Jemalloc. Jemalloc is now upgraded to version 5.1

Improvements are made in the implementations of the HyperLogLog data structure with refined algorithms to offer a more accurate cardinality estimation.

This version comes with better memory reporting capabilities. Redis 5 provides improved networking especially related to emitting large objects, CLIENT UNBLOCK and CLIENT ID for useful patterns around connection pools and blocking commands.

Read the full Redis 5 release notes on GitHub.

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