mbox vs. Maildir (was: Re: [Evolution] expunge speed)

[Alexander Skwar <ASkwar digitalprojects com>]

So sprach »Dan Berger« am 2001-08-19 um 14:10:35 -0700 :
> the entire file must remain locked during delivery).  2. for mailboxes
> with large numbers of messages, you start to trip over the fact that
> un*x file systems aren't typically tuned for handling directories with
> large numbers of entries.  I did some performance analysis on this a few
> years ago in a former life - and the curve is linear (bad).

Exactly!  That's the reason I like mbox better.  I've just converted a
mbox with >5000 messages to maildir to do some comparison.

I opened the mbox file and the maildir in mutt at the same time (on two
consoles), and while mutt was still reading the maildir, it was already
done sorting/threading the mbox.  To open/sort the mbox, it took mutt ~9
seconds, while opening the Maildir took about 31 seconds!

Now, also deleting messages from the middle of a mbox isn't as bad as
everyone wants to make you believe.  I then deleted the message which
was about in the middle of the file.  This only took 3 seconds.
Granted, with Maildir it would have taken about 0 seconds.  But I very,
very, very rarely delete messages from the middle of a file.  I much
more often delete them from the end.  So I deleted the very last
message.  This took about 1 second.  But deleting the very first message
also took about 4 seconds (which I also very rarely do).

So, performancewise mbox clearly is the winner.  At least with mutt (my
primary mailer) and on my machine (Duron 800, 768 MB RAM, IBM
DDRS-39130W U2W SCSI HDD, reiserfs 3.5, kernel 2.4.8).

I just also installed pine and elm.  pine is even *WAY* faster in
opening the mbox file.  It was open at once.  But deleting the message
in the middle took somewhat longer (~9 seconds).   The last message was
gone in no time, and the first message took 29 seconds (!).

elm also didn't have a problem opening the file: 3 seconds.  Middle
delete: ~5 seconds, last delete: ~5 seconds as well, first delete: ~12
seconds.

They also both opened the file just fine.  So I also don't know what you
mean by "compatibility problems".

To summarize:  mbox is way faster and handled by more clients.  mbox
completely wipes the floor with Maildir.

Alexander Skwar
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