Alan Grow <agrow@thegotonerd.com> wrote on 04/08/2005 10:44:39 AM:
> FSFS is great, but I'm a little worried about checkout slowdown,
especially
> as a project ages. Instead of reconstructing the current revision each
time
> from an ever-lengthening sequence of forward diffs, why doesn't FSFS
optimize
> for the common case and store the full current revision and a sequence
of
> reverse diffs? (Ala rdiff-backup: http://www.nongnu.org/rdiff-backup/.)
>
> I'll pack my bags & go to dev with this question if you think I
should. :)
> Thought I'd try here first though.
FSFS doesn't work quite the way you think. It uses something called
skip-deltas. The bad thing about reverse diffs is that the database has
to be constantly rewritten. FSFS wanted to support a permissions
structure where you only need to have enough permission to write a new
file. Existing files are in the database are NEVER updated after they
have been written. This also makes for a good incremental backup
solution.
The skip-deltas approach is a great compromise. It yields good
performance, and better space utilization. Read the design notes.
http://svn.collab.net/repos/svn/trunk/notes/skip-deltas
Mark
_____________________________________________________________________________
Scanned for SoftLanding Systems, Inc. by IBM Email Security Management Services powered by MessageLabs.
_____________________________________________________________________________
---------------------------------------------------------------------
To unsubscribe, e-mail: users-unsubscribe@subversion.tigris.org
For additional commands, e-mail: users-help@subversion.tigris.org
Received on Fri Apr 8 17:16:09 2005