Book Image

PostgreSQL High Availability Cookbook - Second Edition

By : Shaun Thomas
Book Image

PostgreSQL High Availability Cookbook - Second Edition

By: Shaun Thomas

Overview of this book

Databases are nothing without the data they store. In the event of a failure - catastrophic or otherwise - immediate recovery is essential. By carefully combining multiple servers, it’s even possible to hide the fact a failure occurred at all. From hardware selection to software stacks and horizontal scalability, this book will help you build a versatile PostgreSQL cluster that will survive crashes, resist data corruption, and grow smoothly with customer demand. It all begins with hardware selection for the skeleton of an efficient PostgreSQL database cluster. Then it’s on to preventing downtime as well as troubleshooting some real life problems that administrators commonly face. Next, we add database monitoring to the stack, using collectd, Nagios, and Graphite. And no stack is complete without replication using multiple internal and external tools, including the newly released pglogical extension. Pacemaker or Raft consensus tools are the final piece to grant the cluster the ability to heal itself. We even round off by tackling the complex problem of data scalability. This book exploits many new features introduced in PostgreSQL 9.6 to make the database more efficient and adaptive, and most importantly, keep it running.
Table of Contents (18 chapters)
Title Page
Credits
About the Author
About the Reviewer
www.Packtpub.com
Customer Feedback
Preface

Creating a foreign table


The last step in initializing foreign data access is the creation of the foreign table itself. While doing so, we are limited to specifying column names, types, default values, and whether or not each column is nullable. This table skeleton helps the PostgreSQL query planner interact with the remote data as efficiently as possible.

In this recipe, we will create a foreign table and make it ready for use by our mapped user.

Getting ready

As we will be using a foreign server and a user mapping in this recipe, please follow all the previous recipes before proceeding.

How to do it...

For this recipe, we will perform all actions on the pg-report PostgreSQL server in the pgbench database. Follow these steps as the postgres user to create a table in pg-report, which refers to a table on pg-primary within pgbench:

  1. Create a user mapping for the postgres user with this SQL statement:
CREATE USER MAPPING FOR postgres        SERVER primary_db        OPTIONS (user 'postgres');
  1. Drop any...