This document discusses PostgreSQL replication. It provides an overview of replication use cases like high availability and scalability. It describes the different replication mechanisms in PostgreSQL, including trigger-based and log-based replication. It outlines developments in log shipping in different PostgreSQL versions. It details the new streaming replication feature introduced in version 9.0, including the wal sender and receiver components and hot standby capability. Finally, it discusses capabilities, management tools, and future directions for replication.