Per some discussions with a number of different people at pgconfeu, here is a patch that changes the default mode of pg_basebackup to be streaming the wal, as this is what most users would want -- and those that don't want it have to make other changes as well. Doing the "most safe" thing by default is a good idea.
The new option "-x none" is provided to turn this off and get the previous behavior back.
I would have expected that the "stream" method would become the default. Just a short while ago it was proposed to remove the "fetch" method altogether, and it was only kept because of some niche use cases. I don't think "fetch" is the most safe method, because it requires wal_keep_segments to be configured.
IMO, if you are using fetch just using archive_command. Let's rip it out of pg_basebackup or at least deprecate it.
Fetch runs fine without ssh keys. Especially important on platforms without native ssh. It's also pull rather than push. And it fetches just the xlog you need, and not *all* of it, for one-off backups. I think it definitely still has it's uses, but should of course not be the default.
