The memcached daemon is frequently used as an in-memory caching layer in front of a MySQL database server. With the introduction of the InnoDB memcached plugin, MySQL now allows direct access to InnoDB tables using the memcached protocol and client libraries.

The InnoDB memcached plugin provides an integrated memcached daemon that can automatically store and retrieve data from InnoDB tables, turning the MySQL server into a fast “key-value store”. Instead of formulating queries in SQL, you can perform simple get, set, and increment operations that avoid the performance overhead of SQL parsing and constructing a query optimization plan. You can also access the same InnoDB tables through SQL for convenience, complex queries, bulk operations, application compatibility, and other strengths of traditional database software.

This “NoSQL-style” interface uses the memcached API to speed up database operations, letting InnoDB handle memory caching using its buffer pool mechanism. Data modified through memcached operations such as ADD, SET, INCR are stored to disk, using InnoDB mechanisms such as change buffering, the doublewrite buffer, and crash recovery. The combination of memcached simplicity and InnoDB reliability and consistency provides users with the best of both worlds, as explained in Section 14.18.1, “Benefits of the InnoDB / memcached Combination”. For architectural details about how the components fit together, see Section 14.18.2, “Architecture of InnoDB and memcached Integration”.