Creating your own extension
In this section, we will build an extension from scratch so that you will better understand how they are made up. The idea is to let you know how to convert even your own SQL scripts into an extension, with all the advantages that an extension can provide in terms of manageability.
Defining an example extension
In order to demonstrate how to build your own extension, we are going to create a simple set of capabilities that apply to the forum database, providing some more features. In particular, we are going to define an extension named tagext that will provide a utility function that, given a particular tag within the tag table, will return the full path to that tag with all ancestors.
For example, the Linux tag is a child of the Operating Systems tag, and therefore the path to the Linux tag is Operating System > Linux.
In particular, we want our extension to provide us with a function named tag_path that, given a tag, provides the...
