You may have noticed by now that Subversion is extremely flexible. Because it implements branches and tags with the same underlying mechanism (directory copies), and because branches and tags appear in normal filesystem space, many people find Subversion intimidating. It's almost too flexible. In this section, we'll offer some suggestions for arranging and managing your data over time.
There are some standard, recommended ways to organize a
repository. Most people create a
directory to hold the “main line” of development,
branches directory to contain branch
copies, and a
tags directory to contain
tag copies. If a repository holds only one project, then
often people create these top-level directories:
/trunk /branches /tags
If a repository contains multiple projects, admins typically index their layout by project (see the section called “Choosing a Repository Layout” to read more about “project roots”):
/paint/trunk /paint/branches /paint/tags /calc/trunk /calc/branches /calc/tags
Of course, you're free to ignore these common layouts. You can create any sort of variation, whatever works best for you or your team. Remember that whatever you choose, it's not a permanent commitment. You can reorganize your repository at any time. Because branches and tags are ordinary directories, the svn move command can move or rename them however you wish. Switching from one layout to another is just a matter of issuing a series of server-side moves; if you don't like the way things are organized in the repository, just juggle the directories around.
Remember, though, that while moving directories may be easy to do, you need to be considerate of your users as well. Your juggling can be disorienting to users with existing working copies. If a user has a working copy of a particular repository directory, your svn move operation might remove the path from the latest revision. When the user next runs svn update, she will be told that her working copy represents a path that no longer exists, and the user will be forced to svn switch to the new location.
Another nice feature of Subversion's model is that
branches and tags can have finite lifetimes, just like any
other versioned item. For example, suppose you eventually
finish all your work on your personal branch of the
calc project. After merging all of your
changes back into
no need for your private branch directory to stick around
$ svn delete http://svn.example.com/repos/calc/branches/my-calc-branch \ -m "Removing obsolete branch of calc project." Committed revision 375.
And now your branch is gone. Of course it's not really
gone: the directory is simply missing from the
HEAD revision, no longer distracting
anyone. If you use svn checkout,
svn switch, or svn list
to examine an earlier revision, you'll still be able to see
your old branch.
If browsing your deleted directory isn't enough, you can
always bring it back. Resurrecting data is very easy in
Subversion. If there's a deleted directory (or file) that
you'd like to bring back into
use svn copy -r to copy it from the old
$ svn copy -r 374 http://svn.example.com/repos/calc/branches/my-calc-branch \ http://svn.example.com/repos/calc/branches/my-calc-branch Committed revision 376.
In our example, your personal branch had a relatively
short lifetime: you may have created it to fix a bug or
implement a new feature. When your task is done, so is the
branch. In software development, though, it's also common to
have two “main” branches running side-by-side for
very long periods. For example, suppose it's time to release
a stable version of the
calc project to the
public, and you know it's going to take a couple of months to
shake bugs out of the software. You don't want people to add
new features to the project, but you don't want to tell all
developers to stop programming either. So instead, you create
a “stable” branch of the software that won't
$ svn copy http://svn.example.com/repos/calc/trunk \ http://svn.example.com/repos/calc/branches/stable-1.0 \ -m "Creating stable branch of calc project." Committed revision 377.
And now developers are free to continue adding
cutting-edge (or experimental) features to
/calc/trunk, and you can declare a
project policy that only bug fixes are to be committed to
/calc/branches/stable-1.0. That is, as
people continue to work on the trunk, a human selectively
ports bug fixes over to the stable branch. Even after the
stable branch has shipped, you'll probably continue to
maintain the branch for a long time—that is, as long
as you continue to support that release for customers.