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Using MySQL with memcached

memcachedis a simple, highly scalable key-based cache that Stores data and objects wherever

dedicated or spare RAM is available for quick access by applications, without going through layers of

parsing or disk l/O. To use, you run the memcachedcommand on one or morę hosts and then use the

shared cache to storę objects. For morę usage instructions, see Section 15.6.2, “Using memcached”

Benefits of using memcachedinclude:

•    Because all information is stored in RAM, the access speed is faster than loading the information

each time from disk.

•    Because the “value" portion of the key-value pair does not have any data type restrictions, you can

cache data such as complex structures, documents, images, or a mixture of such things.

•    If you use the in-memory cache to hołd transient information, or as a read-only cache for information

also stored in a database, the failure of any memcachedserver is not critical. For persistent data, you

can fali back to an alternative lookup method using database queries, and reload the data into RAM on a different server.

The typical usage environment is to modify your application so that information is read from the cache

provided by memcached. If the information is not in memcached, then the data is loaded from the

MySQL database and written into the cache so that futurę requests for the same object benefit from the cached data.

For a typical deployment layout see Figurę 15.4, “memcachedArchitecture OvervieW\