split

[Daniel Oberhoff]

Am 08.04.2008 um 21:45 schrieb Talden:

>> Daniel Oberhoff wrote:
>>> Hmm, so there is no way to modify history?
>>
>> Not in a decentralized VCS.  decentralized systems like this must be
>> write-once at the logical level, or else you have an inconsistent  
>> system.
>>
>> Aaron
>
> Though there's no reason why any holder of a branch can't make the
> decision to divorce themselves from their peers and make such changes
> - indeed sometimes there is an obligation to do so.
>
> This is sometimes a necessary evil for a central/official branch which
> needs to dramatically alter project structure or break-down to make
> itself more accessible to users (in this case by reducing the volume
> of content) for size or content reasons.
>
> Of course it requires breaking history completely as you would be
> doing the following in a destination partial copy:
>
>   * filtering content from existing revisions in the new branch.
>   * Removing revisions which have no paths to keep in this branch.

Well, in my case, and maybe in others too, the subtree that I am  
looking at is not heavily related to the rest. The repository is/was  
project related. But it consisted of several subfolders which were  
only conceptually related. I.e. in my case there is a c++ application  
in one, a bunch of matlab/octave-files in another, and a new  
lightweight c++ framework in the third. The do not share any files, so  
splitting these would not lose any history at all.

> I think such a facility is an important tool for the Bazaar toolbox
> but the importance of absolutely minimising its use cannot be
> overstated.  Unless you have a true repo-size _problem_ and not just a
> _desire_ to reduce repo-size you should never undertake such a change.


I think the point, that only a subfolder is needed in further  
development, which is maybe only 10% of the original code base, and  
the desire not to have to check out 200Mb when only 20 are needed is  
quite valid.

Anyhow, it really does look like fast-export/import could do the  
trick, as it enables one to sit on top of the history stream and do  
"flow-control" actively. I am not sure if I can get round to doing  
this anytime soon though.

Best

Daniel