Re: Git: Having trouble merging two repositories by interweaving their histories

From: THILLOSEN Andreas <thillosen@free.fr>
Date: Sep 10, 2013, 00:19 UTC
Message-ID: <522E65A2.3060401@free.fr>
In-Reply-To: <87fvtdbnna.fsf@igel.home>

Le 09/10/13 01:06, Andreas Schwab a écrit :

Show 12 quoted lines

> THILLOSEN Andreas <thillosen@free.fr> writes:
> 
>> It implies "interweaving" their histories, so that I can get a "state"
>> of both RepA and RepB around a same time period of time.
> 
> This is only possible by rewriting every commit to point to a new tree
> containing the combined trees of the two repositories.  To get a
> meaningful result this requires that both repositories have a completely
> linear history.
> 
> Andreas.
>

Thanks for your answer...

I searched a little more around the web, and found some trick called "grafting repositories". But examples were all of the same kind: They supposed that all commits in RepA were done before commits in RepB. For instance:

http://stackoverflow.com/questions/2428137/how-to-rebase-one-git-repository-onto-another-one

This is not my case, because I had work done in parallel in both repositories. So I'm not really sure that "grafting" could help in my particular case...

To make the graft permanent, they use git filter-branch, which rewrites history (all SHA1s are changed etc.)... but as long as dates could be kept, it would not annoy me that much.

I also found a script called git-stitch-repo in CPAN... I have not yet tested it, but it is reported that it only works on repositories with linear history (no merges): http://search.cpan.org/~book/Git-FastExport-0.09/script/git-stitch-repo

This is also not my case: Merges have been done regularly on my two repositories...

There is also this tool: CombineRepo... no idea how reliable it is, or what limitations it entails: https://github.com/geppo12/GitCombineRepo

So... if I understand correctly, there will be no real practical way to merge my two repositories, in order to get an interweaving history? (not criticizing, I only want to know where I am heading now!)

Greetings,

Andreas THILLOSEN.