Stacked branching question

Colin D Bennett colin at
Mon Jul 21 17:23:19 BST 2008

On Mon, 21 Jul 2008 18:20:10 +0200
David Ingamells <david.ingamells at> wrote:

>  My point is exactly that there should be enough information in a
> shallow branch to be able to do a diff and thus derive a delta.
> That is what I meant by a _little_ bit of depth. The little bit of
> depth being one revision deep. (In other word not zero revisions
> deep). It is exactly from the use-case you mentioned that I am coming
> from. If you think about what I said should be possible (e.g diff on
> local changes)
> it is implicit that there should be something local to diff on (and
> thus provide a basis for the deltas you say are essential)

But in some cases you *don't* want to duplicate past revisions.  Say
you are stacking on another local branch, as you might on a code
hosting server:  then you are trying to save space by not duplicating
data on the server.

And it would be nice to be able to use the entire revision history to
get an optimum delta, rather than only having the past few revisions to
base it on.


> -----Original message-----
> From: Colin D Bennett <colin at>
> Sent: Mon 07/21/08 17:57:15
> To: David Ingamells <david.ingamells at>; 
> CC: Nicholas Allen <allen at>; Martin Pool
> <mbp at>; Bazaar <bazaar at>; Subject:
> Re: Stacked branching question
> On Mon, 21 Jul 2008 16:24:03 +0200
> David Ingamells <david.ingamells at> wrote:
> > I concur with Nicholas. It is my hope that one should be able to do 
> > everything that moves forward from the branched revno without any
> > need for the repositories further down the stack. Thus "commit",
> > "diff" (on local changes) and "status" should all work without
> > needing to look outside the local branch. 
> However, when stacked branches are used as a more flexible substitute
> for shared repositories (think: a multi user hosting service or a
> team's multi user VCS server), it is desirable to have commits be
> able to be stored as deltas from past revision data, especially when
> dealing with large files.
> So I think that if at some point an offline commit to a stacked branch
> is permitted, it should be an optional feature since it would
> eliminate the possibility of storing the new revision as a delta
> based on revision data from the stacked-on branch.
> > Obviously "missing", "diff"
> > with old revno's, "log" etc will be crippled without access to the
> > repos below the top of the stack.
> > After all, this enhancement did start off life with the name
> > 'shallow branches' and the term 'shallow' does imply a _little_ bit
> > of depth ;-)
> > 
> Regards,
> Colin

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