[Raw Msg Headers][Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: zmailer & SQL Databases

On Thu, 22 Jul 1999, Karl Pitrich wrote:
> i think it will also be a performance increase using a DB instead of
> /var/spool/mail
> because no locking is needed, the database has chaching, and 
> any number of deliveries can happen concurently, because the db manages
> the accesses.

But it does all that by using locks.  When's the last time you got an
unresolvable deadlock error trying to read your mail from
/var/spool/mail?... :-)

> btw, the usage will be a smaller xoom.com or hotmail like system. 

I think, if you're looking for performance and scalability, you're better
off improving message access time by evolving the file system utilization.
The current unix-style mailboxes and /var/spool/mail schemes date back to
System7, when 100 users on a system was alot.  You could do the following:

- hash mailboxes into numerous directories (just like the scheduler does)

- store individual mail messages in individual files in a directory (which
is the "mailbox folder", rather than stacking them into one unix-style
^From_ seperated file.  This can yield a very significant improvement in
performance for deletes, addition of new messages, and changing message
headers (like changing the Status: header line), through simplfying those
tasks and eliminating alot of file contention (and lock contention).