I was just trying to upgrade the first of my servers to 1.2, and it wasn't that pretty. As I understand it, compatibility with pre-0.10.0 databases has been dropped. However, this isn't mentioned in the release notes, nor in the Breaking changes. Thus, I had to downgrade to 1.1.1, compact a database and install 1.2.0 again. This is just a PITA, and it seems fairly trivial that something like this should be in the release notes and in the breaking changes.
Apart from that, it's also just a pain to find out if I have any databases in an old version. The only simple way that I can see is looking at the /db page (either in a browser or scripted), for each database. It would be helpful if there was perhaps something like a Futon page listing my databases along with their on-disk version numbers and perhaps other relevant sysadmin information (like on-disk size and the new percentage that's used to trigger auto-compaction). As it is, I wasn't aware of the relevance of the on-disk format version, so some databases that just don't need compaction (either because they don't change that often, or because there's not that many documents in there) didn't get compacted. I think I'm perhaps slightly more attuned to the internals of CouchDB (at least I read the developer mailing list) than the average user, so this might be even worse for other users. Also, perhaps the auto-compaction can be upgraded to (optionally) also compact if the on-disk version if older than current-1, so people don't have to pay as much attention to this. Presumably there's already some scheduling going on to prevent auto-compaction from hitting every database at the same time. Cheers, Dirkjan P.S. I'm slightly annoyed, and it probably shows; I hope that doesn't diminish the value of this feedback.
