On Wed, Jul 11, 2012 at 4:45 PM, Bert Huijben <b...@qqmail.nl> wrote: > > >> -----Original Message----- >> From: Johan Corveleyn [mailto:jcor...@gmail.com] >> Sent: woensdag 11 juli 2012 15:51 >> To: Greg Stein >> Cc: dev@subversion.apache.org >> Subject: Re: Format bump for 1.8? >> >> I'd like to continue this discussion a bit more, as there are still >> some things lingering here ... > >> Also, as I said, an auto-upgrade needs at least: >> - To be reversible (need downgrade feature or script). >> - To be fast, and O(1) (consider 1,000,000 nodes WCs). > > Note that there was a repeated expensive table scan in the upgrade process > for 1.7, which was fixed in r1342984 and merged back to 1.7.x in r1349817, > but still not released. > > O(1) is impossible for most database schema changes except adding empty > tables, but O(n) should be doable. (Creating an index on some data is more > expensive than O(n), and simply changing every record O(n)) > The 1.7 upgrade was O(n^2), until r1342984. > > The format bump required for conflict skels is currently still O(n), except > for adding an index on the file move a fields that are always NULL in 1.7.
No problem. Note that I specifically said "an *auto-upgrade* needs ...". And 1.7 is manual-upgrading, so it's much less of an issue (user knows what's going on, he asked for an upgrade after all). Maybe O(1) is a bit overkill (in <= 1.6 the auto-upgrades were at least O(number of directories)). But anyway, since the consensus in this thread is leaning towards "manual upgrade", it's probably a moot discussion about what I expect from auto-upgrade ... -- Johan
