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
About the Author
About the Reviewer
Customer Feedback

Installing and configuring HAProxy

The final element on the stack is HAProxy. Patroni uses this to redirect traffic to the primary read/write node in our PostgreSQL cluster. Technically we don't strictly need this component since Patroni will operate without it. But if we want the capability to always reach the primary node regardless of its location, this recipe is essential.

Let's build a high availability connection proxy!

Getting ready

This recipe depends on some necessary libraries and services. Please follow the Preparing systems for the stack and Installing and configuring Patroni recipes before continuing.

If this is a Debian-based system, begin by installing HAProxy from the standard system repository with this apt-get command:

sudo apt-get install haproxy

For Red-Hat-based servers, use an equivalent yum command:

yum install haproxy

How to do it...

For this recipe, we will need at least three PostgreSQL servers. As usual, we'll assume they are named pg1, pg2, and pg3. In addition, assume...