Since SSL compression seems to be a busted flush, I would like to see pg_basebackup be able to do compression on the server end, not just the client end, in order to spare network bandwidth.
Any comments on how hard this would be, or why we don't want it?
I think we want it at protocol level rather than pg_basebackup level. If SSL compression is busted on base backups, it's equally busted on regular connection and replication streams. People do ask for compression on that (in particular I've had a lot of requests when it comes to replication), and our response there has traditionally been "ssl compression"...