Michael, I did the Subversion filesystem design, and chose Berkeley DB
for this implementation, precisely for its recoverability and
transaction support. I have no idea who put that bit on the web site.
If someone knows of problems with Berkeley DB's recoverability, I'm
also very interested in hearing about them.
As written, the web text seems to make a superstitious association
between reliability and the query language a database uses. It's kind
of embarrassing. I'd like to see it either substantiated, or revised.
Subversion is not yet deployed, but when it is, I think it would be
great to have it on Sleepycat's site, assuming the other developers
don't object.
> I'm Mike Olson. I work at Sleepycat Software. We develop,
> distribute, and support Berkeley DB.
>
> I came across this excerpt on your Web site, and wanted to
> follow up with you about it:
>
> SQL Back-End
>
> The Subversion filesystem will probably use Berkeley DB to store
> data on disk; however, a real SQL database provides much more
> reliable transactions. Someone can rewrite the filesystem back-end
> to speak SQL.
>
> Needless to say, we disagree pretty strongly about the reliable
> transactions statement. Berkeley DB survives failure without loss
> of data, and without corruption. We're a bunch of database
> heavyweights with significant time at the big relational companies.
> We use the same techniques that the other vendors do for transactions,
> including two-phase locking and write-ahead logging. I don't think
> that a relational client/server system would be more reliable, but
> I'm certain that it would be slower.
>
> Have you had problems with Berkeley DB that led you to make that
> statement? If there's a problem, we'd like to know more so that
> we can help you fix it.
>
> If you're in deployment now with Berkeley DB in Milestone 1, we'd
> like to include you on our open source partners page. We've
> recently redesigned the Web site, and will put up a new page in
> the next few weeks that lists the open source projects that rely
> on Berkeley DB. We'd be glad to have Subversion on that list,
> if you're willing.
>
> Please do let me know about the reliability issue.
>
> mike
Received on Sat Oct 21 14:36:23 2006