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

Mapping a remote user

Database users and the permissions they are granted may vary between PostgreSQL clusters. This is especially true if we do not directly administer the remote server. The role of user mappings is to overcome this obstacle by linking a local database user with a remote database user.

User mappings must be created for any local user that is going to utilize the remote server. Furthermore, these mappings are only valid for the remote server for which they're defined. In situations where all or most local users will be accessing remote data, this can be somewhat inconvenient. This is, however, a small price to pay for the security inherent in such a design.

In this recipe, we will create a user mapping to access our remote server.

Getting ready

As we will be using a foreign server in this recipe, please follow the Setting up a foreign PostgreSQL server recipe before proceeding.

How to do it...

For this recipe, we will continue to use two servers: pg-primary as our main data source...