On Sat, Aug 30, 2014 at 3:04 AM, Skip Montanaro <[email protected]> wrote: > On Fri, Aug 29, 2014 at 9:54 AM, Roy Smith <[email protected]> wrote: >> Yeah, schema migration is an ugly problem. > > It's not really any worse than any other sort of complex data > structure change, is it? If your persistent data lived in a pickle > file, it would likely be as bad or worse.
Well, correct. The problem isn't because it's in a database; the problem is a consequence of persistent structured data that can get out of sync. It's easy to solve in a simple way that breaks on any sort of confusion. It takes a bit more complexity (like the scheme I suggested) to handle a few more cases. It takes a lot more complexity (like the migration tools Roy listed) to cope with lots of awkward cases (I suspect at least some of them will handle back-levelling, which my scheme doesn't). And I doubt any of them is absolutely perfect. >> ... suckitude ... > > Nice word. Let's use it more so my polly app will see it as a common > word and maybe offer it to me in a potential XKCD 936 password. :-) > > suckitude suckitude suckitude suckitude suckitude suckitude suckitude > Yeah, it's a great word. As a general rule, suckitude increases with the square of design complexity and superlinearly with number of bugs. I'm not sure how suckitude is affected by bugs, exactly; possibly O(N log N), because each bug has a small probability of affecting another bug. ChrisA -- https://mail.python.org/mailman/listinfo/python-list
