Pete Maclean (aaddict@maclean.com)
Mon, 17 Dec 2001 18:47:13 -0500
>Ah - you didn't catch one internal detail (and it's an important one
>:)):
>
> If a message exists in a folder, it MUST have a UID.
Do you say this based on IMAP's assertion that "as each message is added to
the mailbox it is assigned a higher UID..."? In my view, this is IMAP
poking its nose in where it has no business being. I hope I am not missing
anything, but I cannot see that it makes any difference if UIDs are
assigned only when the IMAP server opens a folder. But you say this detail
is important, Larry, and I wonder why...or should I read your smiley as
belying that?
>Any alternative imposes a significant penalty during the SELECT phase of
>the mailbox. In the current implementation for Exchange, select needs
>to modify one column in one row in the database (it needs to update the
>last selected UID property in the folder). Since the UID's are assigned
>when the messages are added to the folder, the SELECT command doesn't
>have to write to the messages table (ok, to be exact, the message-folder
>table, but...). If we were to to assign UIDs on select, every the row
>in the message-folder table for each new message would need to be
>rewritten - which could conceivably be several hundred database writes
>(if there are enough messages in the folder). It's far better to take a
>very small hit when adding messages (when you're already writing the
>message-folder table to add the message) then it is to modify the table
>after the message has been created.
No question but my method is far from ideal in terms of performance. Maybe
I could set a hook and issue UIDs as messages are added to folders -- and
maybe I will at some future point -- but for now I am satisfied with what I
have. Performance is less of an issue for me than for you. You're dealing
with a heavy-duty server environment where there can be a large number of
simultaneous users. My market is more shared and remote access to Outlook
often in the absence of Exchange.
Pete
This archive was generated by hypermail 2.0b3 on Tue Dec 18 2001 - 01:48:21 IST