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

Configuring pgpool for master/slave mode

When creating a highly available PostgreSQL server, one important element to consider is server load. One database server, no matter how powerful its hardware may be, cannot scale infinitely. Regardless of any frontend application-side caching, the database should be able to weather cache failures or unexpected demand.

We can offset much of this risk by leveraging database replicas. Each replica is available for read-only use, and applications are welcome to use them instead of the primary server. Unfortunately, as the amount of replicas increase, the application must track the connection settings for each, and it may even need to know which is currently configured as the primary server.

Server additions, configuration changes, and deep knowledge of the database architecture complicate the application layer and may result in connection management problems. However, we've installed pgpool specifically to avoid mangling the application in order to fit...