Scaling PostgreSQL with Hot Standby
The new Hot Standby feature in PostgreSQL 9.0 allows running read-only queries on systems whose only communication with the master are binary log files sent to it. And software is already available to make building read scalable clusters of PostgreSQL nodes using this feature straighforward. If utilized properly, this feature is applicable to many situations where it's acceptable for some clients to read data that might lag real-time by a small amount.
But setting the related server parameters depends heavily on the type of workload you intend to deploy it on. Running queries against a fully decoupled standby is perfect for some applications, but not ideal for others. Tuning for fast replication and long-running reports are also difficult to accomplish at the same time. Understanding how Hot Standby works, and how its parameters interact with one another, is crucial to making systems that scale up reads properly. This talk introduces what you can and can't expect this new form of PostgreSQL scaling to do for you.