branching via hard links

[John A Meinel]

Ramon Diaz-Uriarte wrote:
> On 5/14/06, Jan Hudec <bulb at ucw.cz> wrote:
>> On Sun, May 14, 2006 at 12:28:28 +0200, Ramon Diaz-Uriarte wrote:
>> > Dear All,
>> >
>> > Just out of curiosity: Would it make sense (at least undir Linux/Unix)
>> > systems to use, when doing a "bzr branch" some kind of  "cp -r -l"?
>> > The main advantage is speed (and storage). Sure, there would be a need
>> > to unlink the modified files, so maybe this is more trouble than is
>> > worth it. The nice thing about hard links  is that it makes
>> > branching/cloning a lot more inexpensve. (I think Mercurial uses hard
>> > links when possible, and this I think accounts in part for the 5x to
>> > 8x faster "cloning" compared to bazaar).
>>
>> Now there are repositories, branching inside repository is even
>> faster, since
>> it copies just a few bytes.
>>
> 
> Thanks for the answer. However, if I understood correctly, that is
> only when we do not use the "trees" option. But I often want the trees
> option when I clone local repos (I want to edit in those branches),
> and I think the gain then goes down. (I actually just tested on a
> couple of local repos).
> 
> R.
> 

You still have the speed gain. The problem is that building a working
tree is still slow with bzr. (It takes about 10s to build the bzr source
tree).

I haven't investigated why. I'm thinking it is because Aaron worked
really hard to make TreeTransform correct and complete, and we haven't
focused on making it fast yet.

John
=:->


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