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 repmgr

It's time to address the elephant in the room. When managing a wide PostgreSQL cluster, we will often need to rebuild, reassign, and repair nodes that are replicas of our primary server. If we remember our rule-of-threes, three or more nodes make it difficult and error prone to perform any task related to replication.

While Barman and OmniPITR are useful, neither of them is capable of managing a wide network of PostgreSQL replicas. This is why we would like to thank 2ndQuadrant for repmgr. With it, we can create new clones and add them to an existing cluster of PostgreSQL servers. We can shut down the existing primary server and promote any node in this network. Further, all of the existing replicas automatically consider the promoted node their new source of streaming updates.

This may not be the first tool to perform this task, but it is one of the best available. We'll tackle the process of installing it in this recipe before moving on to usage scenarios...