Re: absurdly slow git-diff

[Pierre Habouzit <madcoder@debian.org>]

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On Fri, Nov 07, 2008 at 09:37:29PM +0000, Linus Torvalds wrote:
> 
> On Sat, 8 Nov 2008, Abhijit Menon-Sen wrote:
> >
> > If anyone's interested, the files are http://toroid.org/misc/1 and
> > http://toroid.org/misc/2

> I'm also adding Pierre, since he was talking about trying to implement
> another diff algorithm (although I'm not at all sure that the patience 
> diff really would help this case at all).

FWIW Patience diff wouldn't help at all here. Patience diff is just a
matter of preseeding your preferred diff algorithm with better (wrt
human readability) candidate for the invariant lines. IOW it helps
dividing the problem into smaller bits, but requires *unique lines* to
start with. If you haven't any, then basically, Patience diff does
nothing and calls your usual diff algorithm on the whole files.

It does so in a pseudo linear complexity, hence should not make overall
time really worse, but will not help for the ending time usually either.

-- 
·O·  Pierre Habouzit
··O                                                madcoder@debian.org
OOO                                                http://www.madism.org

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