What does redis mean

redis is the remote dictionary service. It is an open source log-type, "Key-Value" database written in ANSI C language, supports the network, can be memory-based and persistent, and provides APIs in multiple languages. ;Redis will periodically write updated data to disk or write modification operations to appended record files.

#A friend asked the editor what Redis is. The editor of this article will take you to understand what Redis is and what it is used for.

Redis (Remote Dictionary Server), the remote dictionary service, is an open source log-type, Key-Value database written in ANSI C language, supports the network, can be based on memory and can be persisted, and provides multiple language API. Since March 15, 2010, the development of Redis has been hosted by VMware. Since May 2013, the development of Redis has been sponsored by Pivotal.

The emergence of redis has largely compensated for the shortcomings of key/value storage such as memcached, and can play a very good supplementary role to relational databases in some situations.

It provides Java, C/C, C#, PHP, JavaScript, Perl, Object-C, Python, Ruby, Erlang and other clients, which is very convenient to use.

Similar to Memcached, it supports relatively more stored value types, including string (string), list (linked list), set (collection), zset (sorted set - ordered set) and hash ( hash type). These data types all support push/pop, add/remove, intersection, union, difference, and richer operations, and these operations are all atomic. On this basis, redis supports various different ways of sorting. Like memcached, data is cached in memory to ensure efficiency.

The difference is that redis will periodically write updated data to disk or write modification operations to additional record files, and on this basis, master-slave (master-slave) synchronization is achieved.

Data can be synchronized from the master server to any number of slave servers. The slave server can be the master server associated with other slave servers. This allows Redis to perform single-level tree replication. Saving can write data intentionally or unintentionally. Since the publish/subscribe mechanism is fully implemented, when the slave database synchronizes the tree anywhere, it can subscribe to a channel and receive the complete message release record of the master server. Synchronization is helpful for scalability and data redundancy of read operations.

The official website address of redis is very easy to remember, it is redis.io. (The domain name suffix io ​​belongs to the national domain name, which is the British Indian Ocean territory, that is, the British Indian Ocean Territory)

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