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

Configuration - managing scary settings

When it comes to highly-available database servers and configuration, a very important aspect is whether or not a changed setting requires a database restart before taking effect. While it is true that many of these are important enough and they should be set correctly before starting the server, sometimes our requirements evolve.

If or when this happens, there is no alternative but to restart the PostgreSQL service. There are, of course, steps we can take to avoid this fate. Perhaps, an existing server didn't need the WAL output to be compatible with hot standby servers. Maybe, we need to move the logfile, enable WAL archival, or increase the amount of connections.

These are all scenarios that require us to restart PostgreSQL. We can avoid this by identifying these settings early and paying special attention to them.

Getting ready

PostgreSQL has a lot of useful views for DBAs to get information about the database and its current state. For this section...