Book Image

PostgreSQL Administration Cookbook, 9.5/9.6 Edition - Third Edition

Book Image

PostgreSQL Administration Cookbook, 9.5/9.6 Edition - Third Edition

Overview of this book

PostgreSQL is a powerful opensource database management system; now recognized as the expert's choice for a wide range of applications, it has an enviable reputation for performance and stability. PostgreSQL provides an integrated feature set comprising relational database features, object-relational, text search, Geographical Info Systems, analytical tools for big data and JSON/XML document management. Starting with short and simple recipes, you will soon dive into core features, such as configuration, server control, tables, and data. You will tackle a variety of problems a database administrator usually encounters, from creating tables to managing views, from improving performance to securing your database, and from using monitoring tools to using storage engines. Recipes based on important topics such as high availability, concurrency, replication, backup and recovery, as well as diagnostics and troubleshooting are also given special importance. By the end of this book, you will have all the knowledge you need to run, manage, and maintain PostgreSQL efficiently.
Table of Contents (13 chapters)

Changing the data type of a column

Thankfully, changing column data types is not an everyday task, but when we need to do it, we must know all the details so that we can perform the conversion on a production system without any errors.

Getting ready

Let's start with a simple example of a table, as follows:

postgres=# select * from birthday;

This gives the following output:

 name  |  dob  
-------+--------
simon | 690926
(1 row)

The preceding table was created using this command:

CREATE TABLE birthday
( name TEXT
, dob INTEGER);

How to do it...

Let's...