17.20.6 Writing Applications for the InnoDB memcached Plugin (original) (raw)

17.20.6 Writing Applications for the InnoDB memcached Plugin

Typically, writing an application for theInnoDB memcached plugin involves some degree of rewriting or adapting existing code that uses MySQL or the memcached API.

• With the daemon_memcached plugin, instead of many traditional memcached servers running on low-powered machines, you have the same number ofmemcached servers as MySQL servers, running on relatively high-powered machines with substantial disk storage and memory. You might reuse some existing code that works with the memcached API, but adaptation is likely required due to the different server configuration.
• The data stored through thedaemon_memcached plugin goes intoVARCHAR,TEXT, orBLOB columns, and must be converted to do numeric operations. You can perform the conversion on the application side, or by using theCAST() function in queries.
• Coming from a database background, you might be used to general-purpose SQL tables with many columns. The tables accessed by memcached code likely have only a few or even a single column holding data values.
• You might adapt parts of your application that perform single-row queries, inserts, updates, or deletes, to improve performance in critical sections of code. Bothqueries (read) andDML (write) operations can be substantially faster when performed through theInnoDB memcached interface. The performance improvement for writes is typically greater than the performance improvement for reads, so you might focus on adapting code that performs logging or records interactive choices on a website.

The following sections explore these points in more detail.