[dovecot] Re: [bincimap] Re: Re: bincimap

[Timo Sirainen]

On Mon, 2003-02-17 at 20:07, Andreas Aardal Hanssen wrote:
> Now I will not claim that Maildir is indefinitely much better, but it's
> almost, but not quite, much much better than mbox.

The main difference is if there should be one file per message or one
file per mailbox. Per-mailbox files are faster (less syscalls, less
filesystem stress) as long as mails aren't being expunged from the
middle of it. I'm still personally using mbox and I know I usually
delete only mails that I've received recently so only small parts of the
file needs to be rewritten.

So which one is faster depends mostly on the user. I'm not sure about
"better" argument. mbox needs a more work to make it work well. UW imapd
supports also another flat file format "mbx" which should be more
IMAP-friendly.

UW imapd author also says that mbox is slow and changing to mbx would
give a lot higher performance, but I think that's mostly commenting UW
imapd implementation than mbox format itself. There are some ugly
slowing hacks that have to be done, but they're not _that_ slow if
implemented well. And that slowness shows just in CPU usage which is
cheap in IMAP servers compared to I/O.

> With Maildir there's no need to lock the depository when deleting or
> delivering mails (even on NFS), but you can't store (append) a message
> with a timestamp nor with flags without breaking consistency,

I don't understand this. What's the problem with setting timestamp or
flags when appending a message? You create it in tmp/ with wanted name
and timestamp, then rename() it.

>  and servers
> have to search for lost messages when an external client changes a flag.

Yes, this is annoying.