Hello, I've notived that pg_receivewal logic for deciding which LSN to start streaming at consists of: - looking up the latest WAL file in our destination folder, and resume from here - if there isn't, use the current flush location instead.
This behaviour surprised me when using it with a replication slot: I was expecting it to start streaming at the last flushed location from the replication slot instead. If you consider a backup tool which will take pg_receivewal's output and transfer it somewhere else, using the replication slot position would be the easiest way to ensure we don't miss WAL files. Does that make sense ? I don't know if it should be the default, toggled by a command line flag, or if we even should let the user provide a LSN. I'd be happy to implement any of that if we agree. -- Ronan Dunklau
