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

Adding additional nodes to the mix

Eventually we may decide to expand our cluster of PostgreSQL servers to accommodate more traffic, further increase availability, or retire an old system. Once we've established an etcd + HAProxy + Patroni stack, how difficult is the process of adding further nodes?

We wish it were possible to follow the previous recipes and consider ourselves finished. Unfortunately, modifying an operating cluster stack requires a small amount of finesse. Luckily, the extra steps are somewhat minimal, and our reward is an adaptable architecture.

Let's get started.

Getting ready

This recipe is somewhat unique. It depends primarily on the Installing and configuring etcd, Installing and configuring Patroni, and Installing and configuring HAProxy recipes. However, we must stress that they should not be followed exactly. The steps outlined here will explain necessary deviations, so pay close attention.

How to do it...

For the purposes of this recipe, we are going to be adding a new...