Quoting John Peacock <jpeacock@rowman.com>:
> Jan Bares wrote:
> > I did simple test with Subversion 1.0. I inserted 55MB Microsoft
> Access
> > database. The whole size of repository (strings) was ~55MB. Then I
> > modified/deleted/added some records and commited the changes. The size
> of
> > the repository (strings) is now ~110MB.
>
> Remember that BDB is a preallocated database, i.e. the file size only grows.
> After the update, but before the deltify, the database has two full copies of
> the original file (hence 110MB). After the delta has been calculated, most of
> that space is recovered. If you were to do the same modify/commit several
> times, you shouldn't see the strings database grow by any significant amount.
>
> You could do a dump/load to a fresh database to see the actual usage
> after a single round-trip.
That won't help, because the dump file contains full contents, too,
and the load goes through the same contortion.
I don't think we actually record these numbers anywhere. I suggest you
take a look at subversion/tests/libsvn_delta/svndiff-test.c -- that
takes two files, computes the vdelta between them and outputs base64
encoded svndiff, which is 4/3 the size of what goes into the repository.
Note also that the repository stores reverse deltas, not forward deltas,
but the size should be about the same. Oh, also, the window size we use
is 100 100 kiB; you can change SVN_STREAM_CHUNK_SIZE to get a different
window size.
-- Brane
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Received on Tue Mar 16 19:12:52 2004