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

Faking replication with pg_receivexlog

Some built-in tools deserve special mention. The pg_receivexlog command was introduced with PostgreSQL 9.2. With this new utility, PostgreSQL has the ability to transmit transaction logs to a remote system without the need for a dedicated PostgreSQL server. This also means that we can avoid ad hoc tools such as rsync when maintaining an archive server to save old WAL files.

This allows us to set up any server to pull transaction logs directly from the primary PostgreSQL server. For highly available servers, PostgreSQL no longer needs to fork an external command to safeguard transaction logs into an archive location. In addition, we can monitor the state of the transmission through the pg_stat_replication system view.

In effect, we remove quite a bit of overhead from our PostgreSQL server and offload it to a less sensitive system. This recipe will provide a quick outline for using this utility.

Getting ready

Before starting with this recipe, ensure that...