'fetch'...

[Robert Collins]

On Thu, 2008-04-10 at 21:28 +0300, John Arbash Meinel wrote:
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> Robert Collins wrote:
> | On Tue, 2008-04-08 at 22:41 +0300, John Arbash Meinel wrote:
> |> The other bit is that it would probably disallow optimizations like
> |> "if copying
> |> all revisions from a pack, just copy the raw pack file" or even
> |> hardlinking if
> |> possible.
> |
> | i don't think either of those are good ideas anyhow.
> |
> | -Rob
> 
> Considering that cp -a is about 10x faster than "bzr branch a b" it is something
> we need to consider. Not to mention that "bzr branch http://" is faster than
> "bzr branch bzr+http://", which also indicates that cutting through the layers
> of abstractions has some benefits.
> 
> (not to mention that cp -al would be another 10x or so faster yet again, and yes
> I know shared repos solve the problem, but it doesn't solve the communication of
> how to set things up problem.)

Its true that cp -a is faster; but of the two optimisations you
referenced there are significant issues. Just copying the pack file
won't detect bit errors; so we'd still need to checksum the pack; but
worse it neither garbage collects, nor detects missing texts - so its
entirely possible possible to end up carting private data the user
didn't want published from a private repository into e.g. ~/public_html.
A general principle here is that users should be able to anticipate what
bzr will do. The hardlinking case we've discussed in different threads,
and the issues raised then still pertain: it sets up a situation where
storage optimisation will decay, doesn't provide a way to fix it, and
has the same data exposure issues that copying the packs does.

-Rob

-- 
GPG key available at: <http://www.robertcollins.net/keys.txt>.
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