A look inside a Daemon plugin

Unlike UDFs, MySQL plugins store all of the metadata in the plugins shared library. So when installing a plugin you only need to specify the name of the plugin and its shared library filename. This eliminates much of the user error while installing. With UDFs it is very easy to choose the wrong return type or forget the AGGREGATE keyword, but with plugins this is not possible.

Why write a Daemon plugin

Just like UDFs and other MySQL plugin types the Daemon plugin can be used to add extra functionality to MySQL with the same advantages and disadvantages.

Daemon plugins are ideal for writing code that needs to reside in the server but does not need to communicate with it—such as a heartbeat plugin or monitoring plugins—because the simple Daemon plugin API does not provide any means for a server and a plugin to communicate with each other.

Installing and using Daemon plugins

Installing plugins is relatively easy because all of the information about a plugin is stored...