speed up relink script

[TK Soh]

On 3/19/07, Brendan Cully <brendan at kublai.com> wrote:
> If you want to speed it up, you might try searching from the back to
> the front (differences should show up faster that way), or perhaps
> forking off md5sum for the candidate lists and comparing by that
> (possibly hand-checking matches for md5 collisions). I can't convince
> myself that it's safe to assume that a match in the last chunk is
> sufficient.

Coming to think about it again, perhaps reading from back to front
isn't going to help much either. Apart from the fact that it's will be
slow to read that way as pointed out by Bryan, most files in the repos
are likely to stay unchanged over time. So it may actually slow down
the comparison.

I wonder if we can somehow compare the latest chunk of the index or
data files checked in. Or, perhaps the last rev data in the index file
will be representative? I'm not too confident on my understanding on
the inner of hg to decide. Any input?