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

Installing pgpool

The next pooling resource we will explore is named pgpool-II, but we'll refer to it simply as pgpool. This is another popular connection proxy, but it predates PgBouncer by almost a year, having been available since late 2006. The scope of pgpool is also much larger, providing functionality such as query-based replication, connection pooling, load balancing, parallel-query, and more.

Perhaps surprisingly, we won't discuss most of these features in this book. Interesting as they may be, these advanced features don't directly apply to building a highly available PostgreSQL cluster. Of course, we always encourage experimentation.

One feature pgpool exposes, which is directly relevant to this book, is server pooling. What does this mean? If we have two PostgreSQL servers, we can make use of a virtual IP address so that clients need not modify configuration files when we switch the primary database server. However, in order to move the IP address between servers, it must first...