Обсуждение: how to measure pglogical replication lag

It's the same as normal streaming replication. Use pg_stat_replication and/or pg_replication_slots to compare the LSN received by the client to the current server xlog insert position.

Like streaming replication there's currently no way to find out from the client side how far behind the client is. I think we should actually change that by sending an occasional message to the client with the server's current xlog insert position, though, so the client knows how far behind it is...