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

Functions based on views


Creating a function based on a view definition is a very powerful and flexible way of providing information to users. As an example of this, I will tell a story of how I started a simple utility view for answering the question, "What queries are running now and which ones have been running the longest time?" It evolved into a function based on this view plus a few more views based on the function.

The way to get all data to answer this question in PostgreSQL is by using the following query:

hannu=# select * from pg_stat_activity;

-[ RECORD 1 ]----+--------------------------------
datid            | 17557
datname          | hannu
pid              | 8933
usesysid         | 10
usename          | postgres
application_name | psql
client_addr      | 
client_hostname  | 
client_port      | -1
backend_start    | 2013-03-19 13:47:45.920902-04
xact_start       | 2013-03-19 14:05:47.91225-04
query_start      | 2013-03-19 14:05:47.91225-04
state_change     | 2013-03-19 14:05...