MySQL 5.7 Reference Manual Including MySQL NDB Cluster 7.5 and NDB Cluster 7.6
Typically, writing an application for the
InnoDB
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 of
memcached 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 the
daemon_memcached
plugin goes into
VARCHAR
,
TEXT
, or
BLOB
columns, and must be
converted to do numeric operations. You can perform the
conversion on the application side, or by using the
CAST()
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. Both
queries (read) and
DML (write) operations can be
substantially faster when performed through the
InnoDB
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.