11. Streaming Replication
Synchronous streaming replication was implemented in version 9.1. It is a single-master-multi-slaves type of replication, where the terms “master” and “slaves” are usually referred to as primary and standbys respectively.
This native replication feature is based on log shipping, a general replication technique in which the primary server continuously sends WAL (Write-Ahead Log) data to the standby servers, which then replay the received data immediately.
This chapter focuses on how streaming replication works and covers the following topics:
- How streaming replication starts up.
- How data is transferred between the primary and standby servers.
- How the primary server manages multiple standby servers.
- How the primary server detects failures of standby servers.
Although the first replication feature, which was only for asynchronous replication, was implemented in version 9.0, it was replaced with a new implementation (currently in use) for synchronous replication in version 9.1.