From: Michael Haggerty Date: Mon, 06 May 2013 10:28:03 GMT Subject: Re: [PATCH 4/4] fast-import: only store commit objects Message-ID: <518785B3.3050606@alum.mit.edu> In-Reply-To: On 05/03/2013 08:23 PM, Felipe Contreras wrote: > On Fri, May 3, 2013 at 12:56 PM, Thomas Rast wrote: >> Felipe Contreras writes: > >> How do we know that this doesn't break any users of fast-import? Your >> comment isn't very reassuring: >> >>> the vast majority of them will never be used again >> >> So what's with the minority? > > Actually I don't think there's any minority. If the client program > doesn't store blobs, the blob marks are not used anyway. So there's no > change. I haven't been following this conversation in detail, but your proposed change sounds like something that would break cvs2git [1]. Let me explain what cvs2git does and why: CVS stores all of the revisions of a single file in a single filename,v file in rcsfile(5) format. The revisions are stored as deltas ordered so that a single revision can be reconstructed from a single serial read of the file. cvs2git reads each of these files once, reconstructing *all* of the revisions for a file in a single go. It then pours them into a git-fast-import stream as blobs and sets a mark on each blob. Only much later in the conversion does it have enough information to reconstruct tree-wide commits. At that time it outputs git-fast-import data (to a second file) defining the git commits and their ancestry. The contents are defined by referring to the marks of blobs from the first git-fast-import stream file. This strategy speeds up the conversion *enormously*. So if I understand correctly that you are proposing to stop allowing marks on blob objects to be set and/or referred to later, then I object vociferously. If I've misunderstood then I'll go back into my hole :-) Michael [1] http://cvs2svn.tigris.org/cvs2git.html -- Michael Haggerty mhagger@alum.mit.edu http://softwareswirl.blogspot.com/