The short answer is: it’s gone.
With PostgreSQL v12, “recovery.conf” is no longer valid. Even if someone were to create a recovery.conf file manually and keep it under the data directory, the server is not going to start and will throw the following error:
The parameter “standby_mode =on”, which used to be the #1 parameter of the recovery.conf file, has also been removed from PostgreSQL v12. Also, the “trigger_file” parameter name has been changed to “promote_trigger_file.”
Other parameters for recovery.conf are valid and can be written in the “postgresql.conf” file of the slave cluster.
It actually makes more sense if all the required information is mentioned in one file—i.e., postgresql.conf—rather than creating and managing separate files.
“standby.signal”—which is an empty file—has replaced the recovery.conf file and the presence of this file will signal to the cluster to run in standby mode.
Continue reading on Postgres Rocks for a step-by-step guide to setting up streaming replication and failover in PostgreSQL v12.