Re: Handling large files with GIT

[Junio C Hamano <junkio@cox.net>]

Linus Torvalds <torvalds@osdl.org> writes:

> As far as I can tell, the output from git-merge-tree with that fix to only 
> simplify subdirectories that match exactly in all of base/branch1/branch2 
> is precisely the output that git-merge-recursive actually wants.

The matches the recollection I had last time I mucked with the
code.  Currently it is set up to do one path at a time in both
index and working tree, so it would not be a trivial rewrite,
but merge-tree based approach would speed things up quite a
bit.

I was thinking about implementing mergers as a pipeline:

	git-merge-tree O A B |
        git-merge-renaming A |
        git-merge-aggressive A |
        git-merge-filemerge

git-merge-tree (yours) does not do trivial collapsing, and
produce raw-diff from A.  git-merge-renaming reads it, finds
copied/renamed entries (maybe reusing parts of diffcore), and
writes out the results in the same format as merge-tree output
(that's why I am giving A on the command line -- so it can also
read A if it wanted to. it may need to talk about what a path in
A was even when merge-tree did not say anything about that
path).  Then git-merge-aggressive (bad naming, I know, it only
corresponds to the flag of the same name in read-tree) will
collapse git-merge-one-file equivalent stage collapsing.  The
remainder is fed to file-level merger for postprocessing.
Everything except the last step would work on a data format that
merge-tree outputs.