Chapter 1. What Is a PostgreSQL Server?

If you think that a PostgreSQL Server is just a storage system and the only way to communicate with it is by executing SQL statements, you are limiting yourself tremendously. That is, you are using just a tiny part of the database's features.

A PostgreSQL Server is a powerful framework that can be used for all kinds of data processing, and even some non-data server tasks. It is a server platform that allows you to easily mix and match functions and libraries from several popular languages.

Consider this complicated, multilanguage sequence of work:

This multilanguage sequence of work can be implemented as a series of simple function calls using several of the available server programming languages. The developer who needs to accomplish all this work can just call a single PostgreSQL function without the need to be aware of how the data is being passed between languages and libraries:

SELECT convert_to_xslt_and_sign(raw_data_string);

In this book, we will discuss several facets of PostgreSQL Server programming. PostgreSQL has all of the native server-side programming features available in most larger database systems such as triggers, which are automated actions invoked automatically each time data is changed. However, it has uniquely deep abilities to override the built-in behavior down to very basic operators. This unique PostgreSQL ability comes from its catalog-driven design, which stores information about data types, functions, and access methods. The ability of PostgreSQL to load user-defined functions via dynamic loading makes it rapidly changeable without having to recompile the database itself. There are several things you can do with this flexibility of customization. Some examples of this customization include the following:

What sort of things can you do with these features? There are limitless possibilities, such as the ones listed here:

The rest of this chapter is presented as a series of descriptions of common data management tasks, showing how they can be solved in a robust and elegant way via server programming.