PostgreSQL High Availability Cookbook, 2nd Edition. Shaun Thomas

Welcome to the PostgreSQL 9 High Availability Cookbook! As a database engine, PostgreSQL is settling into its place as a reliable bastion of high-transaction rates and very large data installations. DB-Engines recently listed PostgreSQL as the third most popular database software in the world! With such notoriety comes increasing demand for PostgreSQL to act as a critical piece of infrastructure. System outages in these environments can be spectacularly costly and require a higher caliber of management and tooling.
It is the job of a DBA to ensure that the database is always available for application demands and client needs. Yet this is extremely difficult to accomplish without the necessary skills and experience with common operating-system and PostgreSQL tools. Installing, configuring, and optimizing a PostgreSQL cluster is but a tiny fraction of the process. We also need to know how to find and recognize problems, manage a swarm of logical and physical replicas, and scale to increasing demands, all while preventing or mitigating system outages.