Assuming a master & replica set up using streaming replication, hot standby, 9.3.
I'd like to have a single script on both machines distinguish whether it's running on the machine with the master or replica, and take different actions accordingly.
Is the way to do this to check for the presence of wal sender process vs wal receiver process? Or is there a query that could executed against sys tables to find current running config of the local postmaster?
