How do you divide a repository?

[John Arbash Meinel]

Joris Putcuyps wrote:
> Hello
> 
> Is there a way to devide a big repository into parts and keep the history?
> 
> Joris

The easiest way to split a branch is:

# Create a new branch which will just hold part of the stuff
$ bzr branch complete-project just-lib1
$ cd just-lib1
# Remove all the other stuff you don't want
$ rm -rf other-stuff1 other-stuff2
# Move the stuff you do want to the top-level directory
$ bzr mv dir/to/lib1/* .
# And get rid of other stuff
$ rm -rf dir/to/lib1

$ bzr commit -m "Pruning the tree down to just lib1"


Now you have a branch, which only has the files for lib1. There are good 
and bad things to say.

First, you can pick one direction, wherin merges will be easy. (So if 
you will always merge from complete-project => lib1, or if you always 
merge from lib1 => complete-project).

The downside is that at present bzr won't let you merge both ways very 
easy. Because to bzr, it will always look like you either deleted a 
bunch of files, or created a bunch of files, and it will want to 
propogate that change.

I've done this on my stuff, and I add one more step, which is:

$ cd ../complete-project
# Pretend like you are merging the lib1 project
$ bzr merge ../just-lib1
# Remove all of the actual changes, but keep the 'pending-merge'
# 'bzr revert *' says revert all of the changes to these files,
# but it doesn't revert the metadata
$ bzr revert *
$ bzr commit -m "Fake merge from lib1"

At this point, you can make changes to 'lib1' and merge them into 
'complete-project' without any problems. You can also 'cherrypick' 
changes from 'complete-project' to apply them to 'lib1', using a second 
argument to --revision. For example:

$ cd just-lib1 ; bzr merge -r 10..11 ../complete-project

bzr doesn't remember cherry-picks, though, so they are a little more 
difficult to use.

Does this help, or did I give you too much info?

John
=:->