Book excerpt: PostgreSQL offers a comprehensive set of replication related features. Unleashing the power of PostgreSQL provides you with countless opportunities and a competitive advantage over other database systems. This book will guide you through the most important concepts of PostgreSQL replication. It contains all the information you need to design and operate replicated setups. Beginning by giving you an understanding of replication concepts, the PostgreSQL transaction log, and Point-in-time Recovery, we gradually move on to setting up asynchronous and synchronous replication. Next up, you will learn to monitor a PostgreSQL cluster setup, deal with monitoring tools, and then move on to understanding Linux High Availability. Further, we explore widely-used tools such as Slony, SkyTools, Postgres-XC, and walbouncer, and set up PL/Proxy. Finally, you'll get acquainted with the new technology of BDR, which allows bidirectional replication in PostgreSQL.