Re: git filter-branch --subdirectory-filter not working as expected, history of other folders is preserved

From: Seaders Oloinsigh <seaders69@gmail.com>
Date: Oct 10, 2016, 16:12 UTC
Message-ID: <CAN40BKoWroM4ZJHHdMvO8YvvCho0FnWzV9BG9E5xnCZbYOO2pg@mail.gmail.com>
In-Reply-To: <20161010153032.v2x773cbs4ifvzec@sigill.intra.peff.net>

Thanks for the reply, Jeff.

Clearing the backups of the branches, those starting with "refs/original" has gotten me closer, but I also needed to do that with "refs/tags" as well, or change my filter-branch command to,

  git filter-branch -f --prune-empty --tag-name-filter cat
--subdirectory-filter android -- --all

I still have remnants of that other history, though.

Due to the structure of this repo, it looks like there are some branches that never had anything to do with the android/ subdirectory, so they're not getting wiped out. My branch is in a better state to how I want it, but still, if I run your suggestion,

  git log --all --source -- unity/

I get output like

Show 5 quoted lines

> commit 4853c... refs/heads/unity-sdk-3_1_3
> Author: serg... <serg...@...ve.com>
> Date:   Thu Sep 11 16:30:01 2014 +0100
>
>    Started 3.1.3

Which is basically logs of branches which contain only edits within the unity/ subdirectory of the original root. There are other branches like that for the other platforms / subdirectories of the original root, which if that is the case, I would consider filter-branch with the subdirectory-filter isn't acting as expected, and doesn't get rid of all the history you want it to get rid of.

On Mon, Oct 10, 2016 at 4:30 PM, Jeff King <peff@peff.net> wrote:

Show 54 quoted lines

> On Mon, Oct 10, 2016 at 02:42:36PM +0100, Seaders Oloinsigh wrote:
>
>> We have a git repository that looks like
>>
>> sdk/
>> android/
>> ios/
>> unity/
>> windows/
>>
>> Which we'd like to split into 4 repositories, 1 for each platform.  To
>> start this process (for splitting android out), I ran,
>>
>> git filter-branch -f --prune-empty --subdirectory-filter android -- --all
>
> OK, so that should rewrite each ref to have only the contents of the
> "android" directory at the top-level.
>
> Note that filter-branch saves a copy of the old refs in refs/original.
>
>> Which rewrote a ton of history and commits, and looked like it worked, but
>> on closer inspection had left a ton of history behind.
>>
>> If I run
>>
>> git log --all -- unity/
>>
>> It returns a list of commits that happened in the unity/ subfolder of the
>> original root.
>
> Here you asked for "--all", which includes refs/original. So you are
> seeing the original, unwritten commits (and none of your new ones, of
> course, because they do not have a unity/ directory!).
>
> Try:
>
>   git log --all --source -- unity
>
> to see which ref each commit is coming from.
>
> Or try:
>
>   git log --branches --tags -- unity
>
> to confirm that your branches and tags do not include that path.
>
> Or just:
>
>   git for-each-ref --format='delete %(refname)' refs/original |
>   git update-ref --stdin
>
> to get rid of the backup refs entirely.
>
> -Peff