Re: Questions about git-fast-import for cvs2svn

On Sun, 15 Jul 2007 16:11:41 +0200
Michael Haggerty [off-list ref] wrote:

Hi Michael,

Will take a stab at answering your questions...

1. Is it a problem to create blobs that are never referenced?  The
easiest point to create blobs is when the RCS files are originally
parsed, but later we discard some CVS revisions, meaning that the
corresponding blobs would never be needed.  Would this be a problem?

Not a problem.  Running "git gc" later will cleanup any unused objects.

2. It appears that author/committer require an email address.  How
important is a valid email address here?

It's not necessary for the operation of Git itself; it's up to you to
decide how important the information is to your project.  You should
be able to set an empty email address for author or committer in
git fast-import as "name <>".

   a. CVS commits include a username but not an email address.  If an
email address is really required, then I suppose the person doing the
conversion would have to supply a lookup table mapping username -> email
address.

Yes, take a look at the format supported by git-cvsimport and git-svnimport,
which can map each username into an appropriate name and email addy for Git.

   b. CVS tag/branch creation events do not even include a username.
Any suggestions for what to use here?

Perhaps just use your own username or one specifically created to
run the conversion process.

3. I expect we should set 'committer' to the value determined from CVS
and leave 'author' unused.  But I suppose another possibility would be
to set the 'committer' to 'cvs2svn' and the 'author' to the original CVS
author.  Which one makes sense?

Another option is to just allow Git to set author and committer to the
same value.  As noted in the man page: "If author is omitted then
fast-import will automatically use the committer's information for
the author portion of the commit".

4. It appears that a commit can only have a single 'from', which I
suppose means that files can only be added to one branch from a single
source branch/revision in a single commit.  But CVS branches and tags
can include files from multiple source branches and/or revisions.  What
would be the most git-like way to handle this situation?  Should the
branch be created in one commit, then have files from other sources
added to it in other commits?  Or should (is this even possible?) all
files be added to the branch in a single commit, using multiple "merge"
sources?

Git supports the ability to merge from multiple branches at once (known
as an octopus merge).  So it's possible to start a new branch, drawing
in files from more than one source branch in a single commit.  As i
understand it, fast-import allows only a single "from" line for a commit,
but allows multiple "merge" lines for additional parentage info. 

5. Is there any significance at all to the order that commits are output
to git-fast-import?  Obviously, blobs have to be defined before they are
used, and '<committish>'s have to be defined before they are referenced.
 But is there any other significance to the order of commits?

Don't think so, except perhaps for the packfile optimization issues
mentioned in the man page.

HTH,
Sean