This lets a pginstance be monitored based on receiving and sending WAL, so we can monitor the delay between our cascading replication servers. We've also added the ability to limit based on being in the same network as the cluster that's being checked from which is useful for checking only local replicas if you have a hub-and-spoke-style  replication strategy

…it is output on each add_ok invocation)

We need to call `add_ok` once for each instance of `$db` otherwise perfdata doesn't work at all, more frequently and it is duplicated

…positions, which causes this to go critical. In reality, this is not for checking pg_basebackup status