Question

During the setup for WAL based replication, Fivetran recommends setting the wal_sender_timeout value to 0. However, this effectively eliminates crash detection and recovery for standby replicas and it would be preferable to avoid this potential outcome.

Environment

PostgreSQL databases using WAL for incremental replication

Answer

The Support team can make a feature change where the state can be saved every two hours rather than the default of 6 hours. This allows the timeout value to be increased to over two hours rather than being disabled completely.

1. Make a request to the support team asking to be added to this feature
2. Confirm that this change has been made to your account
3. Change the wal_sender_timeout value to 9000 (2.5 hours in seconds)

Cause

The wal_sender_timeout variable (which you can read more about here) is used to terminate replication connections that are inactive for longer than a specified amount of time, either in seconds (default) or milliseconds. By setting this value to 0, the timeout is disabled which allows Fivetran to keep replication connections open for longer to compensate for network latency.