Book Image

PostgreSQL Server Programming

Book Image

PostgreSQL Server Programming

Overview of this book

Learn how to work with PostgreSQL as if you spent the last decade working on it. PostgreSQL is capable of providing you with all of the options that you have in your favourite development language and then extending that right on to the database server. With this knowledge in hand, you will be able to respond to the current demand for advanced PostgreSQL skills in a lucrative and booming market."PostgreSQL Server Programming" will show you that PostgreSQL is so much more than a database server. In fact, it could even be seen as an application development framework, with the added bonuses of transaction support, massive data storage, journaling, recovery and a host of other features that the PostgreSQL engine provides. This book will take you from learning the basic parts of a PostgreSQL function, then writing them in languages other than the built-in PL/PgSQL. You will see how to create libraries of useful code, group them into even more useful components, and distribute them to the community. You will see how to extract data from a multitude of foreign data sources, and then extend PostgreSQL to do it natively. And you can do all of this in a nifty debugging interface that will allow you to do it efficiently and with reliability.
Table of Contents (17 chapters)
PostgreSQL Server Programming
Credits
About the Authors
About the Reviewer
www.PacktPub.com
Preface
Index

Quick introduction to PL/Python


In the previous chapters, we discussed PL/pgSQL which is one of the standard procedural languages distributed with PostgreSQL. PL/pgSQL is a language unique to PostgreSQL and was designed to add blocks of computation and SQL inside the database. While it has grown in its breath of functionality, it still lacks the completeness of syntax of a full programming language. PL/Python allows your database functions to be written in Python with all the depth and maturity of writing a Python code outside the database.

A minimal PL/Python function

Let's start from the very beginning (again):

CREATE FUNCTION hello(name text)
  RETURNS text
AS $$
    return 'hello %s !' %  name
$$ LANGUAGE plpythonu;

Here, we see that creating the function starts by defining it as any other PostgreSQL function with a RETURNS definition of a text field:

CREATE FUNCTION hello(name text)
  RETURNS text

The difference from what we have seen before is that the language part is specifying plpythonu...