Question

I’m using the Versions application on a Mac to handle an SVN repository for my files. My working copy is around 6 MB, yet my repository is only 1.4 MB, and I am holding five revisions in the repository!

How can this be?

Answer 1

SVN compresses one version of your code the differences between each version. That is why it does not take much space.

To keep the repository small,
Subversion uses deltification (or
deltified storage) within the
repository itself. Deltification
involves encoding the representation
of a chunk of data as a collection of
differences against some other chunk
of data. If the two pieces of data are
very similar, this deltification
results in storage savings for the
deltified chunk—rather than taking up
space equal to the size of the
original data, it takes up only enough
space to say, “I look just like this
other piece of data over here, except
for the following couple of changes.”
The result is that most of the
repository data that tends to be
bulky—namely, the contents of
versioned files—is stored at a much
smaller size than the original
full-text representation of that data.
And for repositories created with
Subversion 1.4 or later, the space
savings are even better—now those
full-text representations of file
contents are themselves compressed.

More detail can be found here