[Mimedefang] Bayes locking

David F. Skoll dfs at roaringpenguin.com
Wed Oct 6 12:32:31 EDT 2004


On Wed, 6 Oct 2004, Paul Murphy wrote:

> the whole area of database locking for Bayes and AWL is a mess.

Indeed. :-)

But doesn't SA 3.0 support flock()-style locking?  (I haven't looked at
the code.)

> The solution is to use a proper database - the latest SA has support
> for MySQL, which will be much more stable and on large databases
> will also probably be faster.

Pros and cons.  I'm not sure I consider MySQL to be a "proper"
database. :-) (We use PostgreSQL in our commercial products, though it
has its annoyances too.)  PostgreSQL actually uses MVCC rather than
locking, so readers are never blocked by a writer.

However, any semi-decent SQL database probably has a more robust
locking mechanism than SA's Perl code, and has the huge advantage of
being easily shared among several mail scanners.  I think a Berkeley
DB will still beat a SQL database quite handily for raw data access
(at least for the access patterns used to look up Bayes tokens.)

Regards,

David.



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