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

Combining the power of PgBouncer and pgpool

While pgpool works well as an abstraction layer above PostgreSQL, its handling of excess client connection attempts is less than ideal. If the maximum number of clients per pool was 20, for instance, any connections over 20 with the same login credentials and target database will simply wait indefinitely. Furthermore, there is no concept of transaction-level connection reuse.

PgBouncer can allow prospective client connections to number in the thousands and still maintain high throughput. We can also tell it to reuse connections after any client completes a transaction so that clients do not have to disconnect between operations. Yet, it cannot balance connections across multiple PostgreSQL servers, and it certainly has no concept of primary server or replica. In this respect, it really is a bouncer, holding users at the door with minimal knowledge of what's inside the building.

Until there's a product that combines the best elements of these two...