BitKeeper vs Subversion

This is a response to http://www.bitkeeper.com/Comparisons.Subversion.html. BitMover's comparison is biased and inaccurate, and I felt the need to correct a few things. Besides, with the recent news that Linus dropped BitKeeper, it's relevant at the moment.

BitKeeper has always been controversial because of its license. Should we use a tool written by a company who doesn't want to play nicely? Is it an ethical problem that Linux, the flagship of free software, depends on a company who rejects the core philosophies of Open Source? Will BitKeeper ever be free?

BitKeeper can be used without charge for only one reason: to help Linus not burn out. As Larry McVoy said (2): "BK makes it really easy to do what Linus is doing." But there is only one Linus; what about the rest of us? Which tools are best for what we're doing?

My personal opinion is that developers should use Subversion and/or Darcs, depending on project style and general preferences. If you want to use a central repository (cvs-style), use Subversion. If you want decentralized, BitKeeper-style private branches, use Darcs. Or, for really complex projects, SVK offers the best of both worlds.

Anyway, onto the comparison.

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Tigris provides a nice set of corrections to part of the BitMover article, but does not include the comparison matrix. Here is what Tigris left out (and some things BitMover left out):

BitKeeper/Subversion Feature Comparison Matrix

Feature	BK/Pro	Subversion	Notes
Open Source license	No	Yes	Why useOpen-Source Software?
Freely usable for any purpose	No	Yes	BK prohibits development of certain types of products, and use by certain types of developers.
Change sets	Yes	Yes	Every change is a reproducible snap shot Aids in debugging and release management
Change sets are atomic	Yes	Yes	Avoids data corruption and synchronization problems.
Partial Checkouts, Subtrees	No	Yes	Allows you to incorporate components from one project into another
Revision Philosophy	Patches	Snapshots	Each approach is well-suited for some tasks and not for others
Graphical Interfaces	One: some small but useful GUI tools come with BK	Several complete GUIs are available: RapidSVN, TortoiseSVN, QSvn, eSvn, and plugins for many popular editors and IDEs (Eclipse, emacs, etc)	Graphical tools help new users learn, and help experienced users use the system more efficiently.
Other interfaces	CLI, Web	CLI, Web (chora, SVN::Web, ViewCVS (HEAD), mod_svn_view, trac, ViewSVN), WebDAV	Web access makes it easy to browse files and revisions. WebDAV lets you mount the repo and use it like a hard drive, allowing you to create a shared "drive" with automatic version control
Dynamic branching	Yes	Yes; two methods: svk for distributed/private repos, or central branches with "svn cp"	Anyone can make their own first-class private branch with BK or SVK. Central branches are easy and cheap with Subversion. Advanced planning for branching is not needed.
"Pro Merge" Technology	Yes	No	Most accurate automerge available (?)
Accurate handling of renames	Yes	Yes, but support is basic	Increased productivity through a well organized source base
Peer to peer architecture	Yes	Yes (svk)	Supports any workflow for enhanced quality control Pyramid architecture introduces bottlenecks at each level, slowing the adoption of patches.
Complete local history	Yes	svn: no svk: Yes	Your developers can keep working even when your server or network doesn't Inherent reliability through replication Can require lots of extra space on each workstation.
True parallel development	?	?	What does this even mean?
Multi-site development	Yes	Yes (svk)	Provides 100% functionality and productivity at all distributed sites
Mobile/Off-network functionality	Yes	svk: Yes svn: No, some commands require network access	Increased development productivity by allowing your developers to work while travelling, while at remote locations, while at customer sites, or without a network
Pre-event triggers	Yes	Yes	Ability to qualify events prior to changes which enhances compliance to your development policies
Post-event triggers	Yes	Yes	Supports notification of events and automated secondary operations which provides easier process management
Replicated repositories	Yes	Yes	Provides enhanced reliability along with the ability to perform transparent, automatic backups
Automatic integrity checks	Yes	Yes	Detects corruptions indicating potential hardware and software problems saving time and money associated with unplanned downtime
Accurate recording of all history	No, only "pushed" changes are recorded	Yes, all changes are forever recorded as a series of fixed snapshots	Accountability: Easy to find Who did What When Provides a complete picture of your parallel development SVK shares the same history problems as BK.
Minimal Administration	Yes	Yes	Head count can be used for development rather than taking care of the SCM system
Minimal hardware requirements	Yes	Yes	No need to purchase additional hardware No requirement for large, expensive server
Easy conversion from CVS	Mostly	Yes	BK takes a while for CVS users to learn. Most CVS users can use SVN in less than 5 minutes, because the basic workflow and commands are identical.
Marketed truthfully	No	Yes (?)	BitMover's Subversion comparison contains false information and FUD.