Merge from old repo to new one?

[ckalisiak at attotech.com]

From:	Richard Wilbur <richard.wilbur at gmail.com>
To:	ckalisiak at attotech.com
Date:	08/03/2016 02:05 AM
Subject:	Re: Merge from old repo to new one?


On Tue, Aug 2, 2016 at 10:12 AM,  <ckalisiak at attotech.com> wrote:
>>    One of the principals has decided it's time to start a new repository
for
>> our code base, and deprecate the old one. As projects wrap up, they'll
merge
>> into a central "launching point" branch, and then we'd like to merge the
>> updates from that branch to a "landing point" in the new repository.
>
>By "repository" are you speaking of a bzr repository?

Correct, this is all in Bazaar. We're at the latest Windows release, 2.5.1.

>Did all the current projects branch from the old repository?

Correct. We've been using the old repository for about five years, and
decided
it's time to start a new one.

>Does the new repository already exist with a branch as the basis for
>new projects?

No, we're just creating the new repository now. It's been created, but do
have
the option of deleting it and starting over if there's a better way to
approach
what were want to do.

>Was the new repository begun with code branched from the old repository?

Yes and no, the new repository contains an "export" of the trunk of the old
one.
Everything in the new repository was started from scratch, with no revision
history.

>So is this an on-going effort as projects wrap up?  Something like the
>attached text art diagram?

Correct, that's the basic idea. Wrap up current development on existing
projects,
but all new projects will be branched from the new repository.

>> Once
>> all current projects have completed their typical lifecycle, the old
>> repository will be marked as obsolete. We're only planning on merging
one
>> way, and if revision history is lost, that's fine. We just want to be
able
>> to make use of the project-wide merge algorithm built in to Bazaar,
instead
>> of having to rely on a Kdiff3 manual merge.
>
>Unless you want to lose some of the revision history, bzr will
>carefully bring it all along.

Gotcha, and what we want to avoid is carrying forward the tens of thousands
of revisions that we have in the old repository.

>Since you plan to retire the old repository after the last project
>based on it completes, why don't we forget merging into it at all and
>simply merge the changes from each project into the "landing point"
>branch directly?

Releases and final integration will take place in the old repo, so there's
a
final state for each of the projects. Then the changes will be brought
forward
en masse to the new repo.

------------------------------

It occurs to me that I don't think we'd want to merge directly after all,
since we don't want the metadata to carry forward. A variant on your
suggestion is certainly an option. It's a combination of brute force and
automation.

Initialize the new repo, and add a branch which is an export of the old
repo/trunk, called "old trunk", and then branch "trunk" off that for new
development.

Then every time a project wraps up in the old repo, update the working tree
in the new repo's "old trunk", commit the changes, then merge that to
"trunk".


Thanks,
Chris


--
Chris Kalisiak
Senior Embedded Systems Engineer
ATTO Technology, Inc.
Phone:  +1.716.691.1999 ext. 274
Fax +1.716.691.9353
"Powering the World's Networks & Storage"

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