Chapter 10. Publishing Your Code as PostgreSQL Extensions
If you are new to PostgreSQL, now is the time to dance for joy.
Now that you're done dancing, I'll tell you why. You have managed to avoid the "bad old days" of contrib modules. Contrib modules are the installation systems that were used to install related PostgreSQL objects prior to Version 9.1. They may be additional data types, enhanced management functions, or just really any type of module you want to add to PostgreSQL. They consist of any group of related functions, views, tables, operators, types, and indexes that were lumped into an installation file and committed to the database in one fell swoop. Unfortunately, contrib modules only provided for installation, and nothing else. In fact, they were not really an installation system at all. They were just some unrelated SQL scripts that happened to install everything that the author thought you needed.
PostgreSQL extensions provide many new services that a package management system...