[Question #84518]: Stacked branch that will allow you to specify from what revision you want locally stored

[John Arbash Meinel]

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Martin Pool wrote:
> Question #84518 on Bazaar changed:
> https://answers.edge.launchpad.net/bzr/+question/84518
> 
>     Status: Open => Answered
> 
> Martin Pool proposed the following answer:
> No, it's not possible.  This feature you're asking about is referred to
> as 'shallow branches' and it's different from stacked branches, though
> it shares some infrastructure with them.
> 
> With stacked branches, the stacked branch repository starts out empty
> and all new data written to that branch goes into that repository.
> 

I was thinking about shallow a bit more. And I think the main point
where we would run into bugs is that read-only operations would be
writing to the repository, because when we fetch from remote, we would
want to cache that data in the local shallow branch's repository.

And that would probably get us into similar troubles that we have now
with stacked branches needed to fetch more than the minimal set. Because
if you fill in the parent revision, then you need to fill in *its*
parent inventories, etc.

I suppose some other potential issues. Like I think it would be useful
to have a shallow branch cache the entire revision history, so that it
could still pick a useful merge basis, etc. However, then you couldn't
use that as a trivial way to determine what revisions are
'fully-installed' locally, etc.

John
=:->

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