On Mon, Nov 24, 2014 at 4:32 PM, Julian Foad <julianf...@btopenworld.com> wrote:
> Stefan Fuhrmann wrote: > [...] > > I'm in favour of phasing linear repos out. We still have to support > > them but forgetting to check for shard size 0 is more likely to > > happen for new code than existing code.I also tend to issuing > > a warning or even failure when trying to upgrade a linear repos. [...] > > Can we feasibly convert an unsharded repo to sharded during an upgrade? > Yes, that would be feasible. OTOH, there is already /tools/server-side/fsfs-reshard.py > I think the current upgrade takes O(1) time, Well for packed repos, the upgrade from f4 to f6 or f7 already is O(N) because the revprops get packed. > and sharding would take at least Order(N) time (N = number of revs) to > move each rev file into a shard directory, and possibly much higher order > if there are disk file systems that have slow 'move' performance (given > that the original directory might have a very large number of rev files in > it), but it might be acceptable given that in those cases the performance > of adding new revs was probably degrading for the same reason. > I guess the most tricky part will be recovery from a failed upgrade. Given that active linear repos that people want to upgrade should be rare by now, I think simply directing them to the reshard script is acceptable and clearly the lower risk option. -- Stefan^2.
