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

Determining connection costs and limits

Excessive database connections are not without risk. The level of risk we incur and what exactly qualifies as excessive are important to determine early. The company and our customers will find it extremely inconvenient if normal database activity exhausted system memory, caused timeouts due to increased context-switching, or overwhelmed the kernel with an overly large process table.

To maintain a highly available server, we must know the full impact of every single connection in terms of required memory and CPU resources. Servicing several disparate applications from various external servers is difficult, so we must provide availability while simultaneously avoiding resource exhaustion. If we properly assess the ideal balance between connection count and performance early on, we can avoid costly emergencies.

Irrespective of whether we helped specify the hardware that will host our PostgreSQL installation, it's still our job to figure out how many clients...