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

Exploring the magic of virtual IPs

As we're running a highly-available database, we have at least one standby copy available at all times, right? Of course we do. However, after promoting a standby copy to act as a primary, we need to redirect traffic to the new server. How can we do this easily?

One common method is to use a database connection pool. The pool acts as a connection proxy and simply needs each known node to be registered so that it can redirect connections to the proper primary database server. We will eventually discuss this approach, but there's actually a simpler tool available to us that requires no additional software.

Another method is to change DNS to redirect network connections to the new server. The beauty of this technique is that it masquerades the entire access path to the server so that services other than PostgreSQL can access the new server as well. Unfortunately, subdomains are tied to a single IP address. As DBAs, we probably don't have access to most of the...