Bazaar as a client to existing Subversion repositories

[Russel Winder]

Ben,

On Sat, 2008-08-09 at 19:33 +1000, Ben Finney wrote:
> Russel Winder <russel.winder at concertant.com> writes:

> > 1. Ensure that the Subversion commit hook doesn't write the property
> > changes.
> 
> I have no control over how the Subversion installation is set up; it's
> at a hosted site providing hundreds of Subversion repositories.

This is the problem I have with Codehaus.  They use svnlook as their
commit hook.

> > 2. Use bzr dpush
> 
> New to me.

Indeed, it is a new feature of this release.

> > My experience is that using the Python script commit hook for
> > Subversion, the commit emails do not have the ever increasing
> > property list problem, I just get a one liner saying the property
> > changed. Sites that use svnlook as the commit hook do get the huge
> > emails.
> 
> Are you saying this is new since revent versions of 'bzr-svn', or that
> this will be the case with any arbitrary version?

This is nothing to do with bzr-svn, it is all to do with the Subversion
repository set up.  If you have no influence over that then this is a
fixed point of pain for you.

> Not knowing anything about the Subversion repository setup, how can I
> know what's causing the commit messages and whether it will benefit
> from what you describe above?

I am not sure there is any way of telling.  But given that you are
getting the huge commit emails and have no control over the Subversion
repository, there is not a lot you can do.

> > dpush does the whole "do not dump the Bazaar history into
> > Subversion" thing, at the cost of lots of rebasing and therefore
> > changing identities of commits.
> 
> I'm very much desirous of not doing history-altering changes, so
> procedures involving 'rebase' aren't an option I'm interested in.
> Thanks for clarifying.

It is not as black and white as that.  The question is whether the
Subversion repository history or the Bazaar branch history is the
master.  If the Subversion repository history is the master and must not
be altered then rebase and dpush in Bazaar are exactly the right thing
to do since the Bazaar branch history must be changed to match the
Subversion repository history.    Rebasing is the right thing to do in
this case.  This is why Git does things the way it does, and now Bazaar
has this same capability.

> > The upside is no property changes in the Subversion repository, the
> > downside is that you can't sensibly branch from the Bazaar branch of
> > the Subversion repository.
> 
> That's yet another reason to avoid that option then. For me, one of
> the primary reasons to use Bazaar is ease of branching and sensible
> merging of local and remote branches. If I lose that, Bazaar is
> significantly less useful as a client to the repository.

I agree completely on this one.  I am treating my Bazaar branch of Gant
as the master and the Subversion repository that everyone thinks of as
the master as a mirror.  This is exactly so I can branch locally as and
how I want.  It does mean though that dpush is not an option.  This then
leads to 50K commit emails for a 1 line change :-(

In this situation, I think Git is probably better simply because of the
different way it manages branches, revisions and changesets.

> > That is the standard model, and it works well -- but only if you
> > don't get the horrible commit emails from Subversion. This is a
> > Subversion installation set up issue though, it is not something
> > that Bazaar is in control of.
> 
> Where can I learn more about this? I won't be the one making whatever
> changes are necessary to the Subversion repository, so I need to at
> least know enough to be confident that what I propose will be a
> solution.

Pass (at least for the moment),  I'm afraid. I have accreted this
knowledge over time, via experimentation and email exchanges with
Jelmer.  It's all going in the book though.
-- 
Russel.
====================================================
Dr Russel Winder                 Partner

Concertant LLP                   t: +44 20 7585 2200, +44 20 7193 9203
41 Buckmaster Road,              f: +44 8700 516 084
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