Book Image

PostgreSQL 9 High Availability Cookbook

By : Shaun Thomas
Book Image

PostgreSQL 9 High Availability Cookbook

By: Shaun Thomas

Overview of this book

A comprehensive series of dependable recipes to design, build, and implement a PostgreSQL server architecture free of common pitfalls that can operate for years to come. Each chapter is packed with instructions and examples to simplify even highly complex database operations. If you are a PostgreSQL DBA working on Linux systems who want a database that never gives up, this book is for you. If you've ever experienced a database outage, restored from a backup, spent hours trying to repair a malfunctioning cluster, or simply want to guarantee system stability, this book is definitely for you.
Table of Contents (12 chapters)
11
Index

Swapping active nodes with repmgr


Creating a clone can be surprisingly dangerous. When using a utility such as rsync, accidentally transposing the source and target can result in erasing the source PostgreSQL data directory. This is especially true when swapping from one node to another and then reversing the process. It's all too easy to accidentally invoke the wrong script when the source and target are so readily switched.

We've already established how repmgr can ease the process of clone creation, and now it's time to discuss node promotion. There are two questions we will answer in this recipe. How do we swap from one active PostgreSQL node to another? How do we then reactivate the original node without risking our data? The second question is perhaps more important due to the fact that we are at reduced capacity following node deactivation.

Let's explore how to keep our database available through multiple node swaps.

Getting ready

This recipe depends on repmgr being installed on both a...