Hi: I am not sure it is ok to ask this question in this lislt. I met this problem using RDS Postgres. (I think the normal postgres may have the same problem). I have posted the question on StackOverflow here: https://stackoverflow.com/questions/52589058/aws-rds-postgresql-transaction-logs-keep-going-when-there-is-no-data-change I also try to got some suggestion from psycopg. (And got suggestion asking there) https://github.com/psycopg/psycopg2/issues/780 The problem may be described like this in simple words: When there is no modification, the postgres wal( or transaction logs in RDS) keep going increase. pg_current_wal_lsn is keeping increase, however the confirmed_flush_lsn in (select * from pg_replication_slots;) can not be advanced. In this case my problem using pgyscopy can't read message from the slot. Someone have give me a answer: RDS dms service https://docs.aws.amazon.com/dms/latest/userguide/CHAP_ReleaseNotes.html there is a wal-heartbeat concept: Added a write-ahead log (WAL) heartbeat (that is, running dummy queries) for replication from a PostgreSQL source. This feature was added so that idle logical replication slots don't hold onto old WAL logs, which can result in storage full situations on the source. This heartbeat keeps restart_lsn moving and prevents storage full scenarios. Any more suggestion? I am more or less a application level programmer. I think this problem need to understand more about the inner of postgres and some protocol on replication mechanism. Thanks.
