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 a custom PostgreSQL monitor to collectd

The primary reason we chose to install collectd stems from its ability to monitor arbitrary data points. Due to the existence of a PostgreSQL plugin for collectd, we can actually collect data from the database itself. Monitoring PostgreSQL becomes as easy as writing a query!

We'll include a few sample queries we developed for monitoring PostgreSQL servers. Feel free to develop your own as we explain how to leverage the PostgreSQL collectd module.

Getting ready

As the collectd PostgreSQL module needs to log in to a database within the cluster to gather its statistics, we should create a user specifically for this purpose. Execute this SQL query with an appropriate password:

CREATE USER perf_mon WITH PASSWORD 'testpw';

In addition, follow the instructions in the Installing and configuring collectd recipe so that there is a fully-functional collectd client and server.

How to do it...

To create a collectd custom PostgreSQL query, simply follow these steps...