Version Control Blog

A well-known SCM comparison resource “Better SCM Initiative” has updated the table, adding three more version control systems: Rational ClearCase, AccuRev, and Mercurial. So, now it has a feature-by-feature breakdown comparison of nineteen systems, open-source and commercial. Sadly, it does not yet cover GIT. Read at: “Better SCM Initiative: Comparison”

Dan Moore writes about MolhadoRef. MolhadoRef is a research project developed by Danny Dig, which implements a version control system where refactoring is first-class concept. That is, when you use well-known refactoring techniques in Java, such as “rename package, rename class, rename method, move class, move method, and changing the method signature”, MolhadoRef detects that you’re doing just that, and records this refactoring information. Later, during merging, it tries to use refactoring history to resolve merging conflicts in a more intelligent way. Usual text-level conflict resolution is left as a fall-back. Dig’s experiments show radical decrease in number of merging conflicts when using this merge strategy (see “Evaluation: effectiveness”). Also, you can see the history of code objects, such as methods and classes: how they evolved over time. See Dan Moore’s post on MolhadoRef for notes from Dig’s talk “Refactoring-Aware Software Merging and Version Control for Object-Oriented Programs”. P.S.: About two years ago during the discussion of early GIT development, Linus Torvalds outlined his idea about tracking the movement of code objects, as opposed to simply tracking file renames and line changes. See the discussion at Linus Torvalds: Re: Merge with git-pasky II
(Message-ID: Pine.LNX.4.58.0504141728590.7211@ppc970.osdl.org).

1. Shane Donnelly shares a set of HOWTOs for several common tasks in Visual SourceSafe. I just love such step-by-step walk-throughs for complicated graphical user interfaces — they save a lot of time. 2. Rob Caron writes on Visual SourceSafe under Windows Vista.

13 Feb 2007: GIT 1.5.0 has been released. This major release includes lots of changes and improvements in such areas like:

• index manipulation;
• repository layout and objects transfer;
• bare repositories handling;
• reflog (history from the view point of the local repository);
• crufts removal;
• detached HEAD;
• packed refs;
• internationalization;
• shallow clones.

(via LWN.net)

For several months, Brian Harry has been telling a fascinating story of TFS deployment at Developer Division at Microsoft, with monthly statistics. It starts in May 2006, with a post “Deploying TFS in the Developer Division at Microsoft”. The numbers impress:

A single branch of our source code is over 600,000 files today. We are in the process of adding all of our test source to our branches (historically they have been in a separate repository). This will add more than 1,000,000 more files to each branch. By the time all is said and done, considering all of the branches we use, the TFS server will contain 100,000,000 files or more (no, that’s not a typo J). This will make it one of the (if not the) largest source code databases on the planet.

Huge scalability issues are to be expected when handling this amount of data. In “What we’ve learned” chapter Brian describes many problems they have met and solved. Brian also posts monthly statisitics on TFS usage:

• February 2007;
• January 2007;
• November 2006;

As of now, more than 1000 active users manage 77 million files in 514Gb of compressed storage. I guess substantial number of those files was not directly created by human beings, but nevertheless. This is important information, it shows that Visual SourceSafe story will not happen again, and the next Microsoft offering in that area will be very strong. (via Version Control Server Team Blog, which alas contains only a couple of posts).