Table of Contents
This appendix is a guide for CVS users new to Subversion. It's essentially a list of differences between the two systems as “viewed from 10,000 feet”. For each section, we provide backreferences to relevant chapters when possible.
Although the goal of Subversion is to take over the current and future CVS user base, some new features and design changes were required to fix certain “broken” behaviors that CVS had. This means that, as a CVS user, you may need to break habits—ones that you forgot were odd to begin with.
In CVS, revision numbers are per-file. This is because CVS uses RCS as a backend; each file has a corresponding RCS file in the repository, and the repository is roughly laid out according to the structure of your project tree.
In Subversion, the repository looks like a single filesystem. Each commit results in an entirely new filesystem tree; in essence, the repository is an array of trees. Each of these trees is labeled with a single revision number. When someone talks about “revision 54”, they're talking about a particular tree (and indirectly, the way the filesystem looked after the 54th commit).
Technically, it's not valid to talk about “revision 5
of foo.c”. Instead, one would say
“foo.c as it appears in revision
5”. Also, be careful when making assumptions about the
evolution of a file. In CVS, revisions 5 and 6 of
foo.c are always different. In Subversion,
it's most likely that foo.c did
not change between revisions 5 and
6.
For more details on this topic, see the section called “Revisions”.