Some advanced features and thoughts for replication are covered here.
If you have multiple standby servers, you may want to have one or more servers operating in a delayed apply state, for example, 1 hour behind the master. This can be useful to help recover from user errors such as mistaken transactions or dropped tables.
Normally, a standby will apply changes as soon as possible. When you set the
recovery_min_apply_delay parameter in
recovery.conf, the application of commit records will be delayed by the specified duration. Note that only commit records are delayed, so you may receive Hot Standby cancellations using this feature. You can prevent that by setting