Sunday, November 08, 2009

svn: BAD

svn is just broken.

Google for git commit. First link points to the current documentation. Dito for svn commit. First hits point to outdated versions of the manual (usually 1.0, maximum 1.5).

Checkout a module. Unfortunately, the URL to check out usually ends on trunk so the default sandbox directory name isn't really helpful. Likewise, it took 'til 1.6 that they found out that typing the repository URL in many commands is a waste, and allowed ^/repo-relative paths not only in svn:externals but also in commands.

Just for kicks try an svn ls http://... operation over GPRS. Will take on the order of half a minute because GPRS round trip time is about a second, and svn ls does a good dozen http requests to the server, all serialized, but not reusing the connection. It is actually a good idea to prefix commands with ssh elsewhere; the ssh login is faster, and the svn command is then done on fast links. (Doesn't work for commands involving a sandbox, of course.)

svn import can only import a given tree into a new location within the svn repo; it can't do updates, like they are needed to import newer versions of vendor software and keep the file identity that will be needed to keep future merges smooth. There is a script in contrib that can do that, but it never got integrated into the import command proper.

Likewise, don't even expect a command that can create an archive (tar/zip) from the versioned files in the current directory (git archive), or that can delete all unversioned files in the sandbox (git clean). Or that tells you a human-readable name for the current revision based on the last tag (git describe).

And, of course, there is the big thing: the hyped merge support of svn 1.5 is broken by design. Isn't fixed in 1.6, and probably can't be fixed without changing the repository format. (I suspect the whole mergeinfo property stuff is just wrong.) In the meanwhile, and in a much shorter timespan than from the announcement of svm merge support to its eventual functional delivery, git appeared, and just did it right.

I don't like that. We've been waiting for svn 1.5 because of the merge support, and then started to switch. At the same time git appeared on my radar; I could use git cvsimport and git filter-branch to do our conversion from cvs to svn, in a way that allows to pull future changes from cvs to svn as well, and without manual intervention. Unfortunately I lost all liking for svn in the process, because git turned out to be just much better tooled, capable, and flexible. And faster in its development, its version number is bound to pass that of svn soon.

No comments: