[svn.haxx.se] · SVN Dev · SVN Users · SVN Org · TSVN Dev · TSVN Users · Subclipse Dev · Subclipse Users · this month's index

Re: Is FSFS compressing stored data?

From: Garrett Rooney <rooneg_at_electricjellyfish.net>
Date: 2004-10-14 14:38:39 CEST

Scott Palmer wrote:
> On Oct 13, 2004, at 8:05 PM, Greg Hudson wrote:
>>> They both compress. The reasons BDB is bigger are complex, and have
>>> to do with how databases allocate storage.
>> Er, no, BDB stores the head revision in uncompressed plaintext,
>> whereas FSFS stores all file revisions as deltas against something.
>> (The first rev of a file is stored as a delta against empty.)
> How does FSFS store the HEAD revision then? If it needs to process
> deltas to get the HEAD revision that would lead to performance problems
> would it not? I was under the impression that the usually way to store
> versions is to use reverse deltas from the HEAD revision to get the
> older revision, so generally the HEAD revision is stored verbatim (as
> you say it is for BDB).

It uses skip deltas, so it only needs to apply at most log(n) deltas to
get to any given revision. It's a little bit slower, but not noticable
in my experience.


To unsubscribe, e-mail: users-unsubscribe@subversion.tigris.org
For additional commands, e-mail: users-help@subversion.tigris.org
Received on Thu Oct 14 14:39:07 2004

This is an archived mail posted to the Subversion Users mailing list.