Re: Merging two Git-Repositories

From: Roger Gammans <rgammans@gammascience.co.uk>
Date: Dec 17, 2019, 10:02 UTC
Message-ID: <fd4bd9c49d7d4daf4275b19a9b5f7478f2e4e145.camel@gammascience.co.uk>
In-Reply-To: <trinity-c6dbf360-5abe-43df-8428-85514195a7a6-1576574916643@3c-app-gmx-bs62>

On Tue, 2019-12-17 at 10:28 +0100, Steve Keller wrote:

Show 6 quoted lines

> Is it possible to merge one Git-Repository into another?  I have
> developed two independent repositories A and B, and now I find that
> B should be part of A in new sub-directory, e.g. A/B.  I want to
> move B into A while keeping the whole development history of B.
> 
> How can I do that?

It is possible bit isn't straightforward, at least not if you want to interleave the commits.

If you don't want to interleave the commits, just rename everything (*) in B to B/*' and merge the repo with A's repo. Then you will have a the structure you want going forward, all the history together; but if you check out a historic commit you will have to decide to check out on the 'A' or 'B' branches.

If you do want to interleave the comits the best found was ( https://metacpan.org/pod/distribution/Git-FastExport/script/git-stitch-repo to merge the repos. (from https://github.com/book/Git-FastExport/ )

I've got some updates ( https://github.com/rgammans/Git-FastExport/tree/hintfiles ) to it when I did some work on this a couple of years ago but the it looks like the upstream has improved a little since then. My changes allow you to try to give it hints in case in make mistakes, on choosing the correct parent for a commit. The whole system worked pretty well except where there were a lot a diverging/remerging branches.

My process was to write a shell script to actually drive the process, and tweak the script to improve the results iteratively.

Hope this helps a little.

-- 
Roger Gammans <rgammans@gammascience.co.uk>