Re: [Exim] Washington mbx again

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Szerző: Nigel Metheringham
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Címzett: exim-users
Tárgy: Re: [Exim] Washington mbx again
tom@??? said:
> Maildir is quite slow if the mailbox contains many different messges.
> The directory has be opened, and each file (message) must be opened to
> get the header information. Maildir is particularly bad for IMAP,
> where mail is left in the mailbox.


Lets rephrase that somewhat....
Maildir works great for pop - you only need look at a file (as opposed
to the directory list) if you are retrieving that message (pop RETR or
HEAD commands). UIDL is implemented without touching the message file,
so pop and leave mail on server works very well as long as you don'g
have serious OS performance problems on large directories.

For IMAP, Maildir has some serious problems since IMAP may need to know
the headers and structure of the message, which requires fiddling
around in the file contents. IMAP Flags are normally embedded in the
message file name so write into the message file is never needed.

A sensible approach would be to cache the read IMAP per-message data in
per directory index, giving you a structure remarkably similar to that
used by the cyrus imap daemon (there are never new solutions to these
things). The only drawback with doing this sort of thing is making it
NFS safe and avoiding multiple write access (or making multiple write
access non disruptive).

    Nigel.
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[ Nigel Metheringham                  Nigel.Metheringham@??? ]
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