From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.org!not-for-mail From: David Kastrup Newsgroups: gmane.emacs.devel Subject: Re: bzr vs. git repository Date: Sat, 01 Jan 2011 11:14:42 +0100 Organization: Organization?!? 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List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Original-Sender: emacs-devel-bounces+ged-emacs-devel=m.gmane.org@gnu.org Errors-To: emacs-devel-bounces+ged-emacs-devel=m.gmane.org@gnu.org Xref: news.gmane.org gmane.emacs.devel:134102 Archived-At: Eli Zaretskii writes: >> Date: Sat, 01 Jan 2011 09:28:38 +0100 (CET) >> From: Werner LEMBERG >> >> As you can see, bzr still needs about three times more bandwidth in >> both receiving and sending... > > So what? In my testing, both on GNU/Linux and on MS-Windows, > update/pull times are very similar (with bzr slightly _faster_ on > GNU/Linux). That includes the initial "bzr branch" vs "git clone" (10 > min for bzr vs 15 for git). Other common operations are mostly > comparable as well. (A great surprise was "annotate", which, for > xdisp.c, took 1 minute with bzr, but a whopping 4.5 minutes with git. > But I see that as a curiosity.) That is not a curiosity but a consequence of git's design choices. git stores file system snapshots and a DAG of commits. Everything else is reconstructed on-the-fly when you ask for it. As a result, renaming files in git is indistinguishable from deleting the old file and creating a new file with the old content. That makes git a handy tool for analyzing, say, a progression of distribution tarballs. You just check in all the tarballs into a git repository, and you get renames, moves, copied content, tracking of material and so on out _gratis_ because git never stores those kind of things but instead knows how to make them up. Now "git annotate" is an example where git constructs a history of content through file renaming and subfile copying, and does it at the time of "git annotate". That's the reason git annotate is _expected_ to be an expensive operation, and you have various options to tell it just how expensive it may do its work, depending on the amount of reconstructed information you'd like to see. Bazaar does not do this. It just reproduces the history according to the file operation history that has been explicitly stored into Bazaar by the user. If you store a sequence of unpacked tarballs into Bazaar and ask for the history of some content, Bazaar will not track the content across subfile copying and file renames because it has not been _told_ about them explicitly. -- David Kastrup