Mailinglist Archive: opensuse (818 mails)

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Re: [opensuse] Re: (Dovecot is faster and supports multiple formats -- unlike Cyrus
On Thu, 2011-09-08 at 14:47 -0400, Anton Aylward wrote:
Adam Tauno Williams said the following on 09/08/2011 02:06 PM:
On Sun, 2011-08-28 at 02:12 -0700, Linda Walsh wrote:
[...]
I went from UoW IMAP to dovecot -- unlike Cyrus, it didn't require
I reformat my
email boxes (all in unix 'mbox format', as they all started as
Unix-mbox's)... into
it's custom format. And Dovecot is very fast....
mbox is fast? I don't believe that for a second. I doubt Dovecot uses
mbox; it probably converted the mail to maildir or UoW was already using
maildir. mbox is a broken and obsolete mailbox format; and very slow.
How do you get to that conclusion?

Long experience and an understanding of how mbox works.

On the one hand dealing with a mbox involves opening two files: index
and data. Using index, seek.

Incorrect; if there is an index it is *not* mbox. It is some extension
to mbox; mbox does not specify, describe, or require an index.

On the other maildir requires a dirread, the opening a file and a read.
If its just the one message, then its probably about the same. I you
are reading though a logical mail folder reading each message in turn
then compare the overhead of file open to the overhead on a seek on an
already open file. Maybe that file is cached so there is no syscall.
If I were writing a mail user agent entirely in shell, I'd pick maildir.
Dovecot uses mbox. I have over 200 such mboxes in my mail 'catalogue'
and there is a dovecot.index.log, dovecot.index and dovecot.index.cache
for each.
I doubt very much that mbox format under Dovecot is slow.

Okay. But then it isn't using mbox; it has extended mbox [maybe we can
call it mbox+]. If you modify the mbox directly the indexes will be
out-of-date.


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