Re: [MORG] Why IMAP extensions are (not) used

[Barry Leiba <barryleiba at computer.org>]

> Locking the mailbox in order to compute RECENT isn't free for anyone.
> Scanning for UNSEEN and EXISTS isn't free for anyone. Many databases and
> libraries that will use indexes to search quickly are available to everyone.
> Maybe the query planner I use is better than most. So what?

If you have (say) a DB2 back-end to your mail store, a search of 350
mailboxes might be very efficient.

If you have (say) a set of Unix mailboxes as the back-end to your mail
store, a search of 350 mailboxes might be pretty much the same,
whether you do it in one command or 700, apart from the protocol
overhead.

Mark's point is that for a lot of these sorts of things, you kind of
need to know something about the server to know whether doing [X] is a
good idea or not.

Perhaps one might say that a server SHOULD only implement multimailbox
search if it has the sort of back-end that makes it significantly more
efficient.  Or perhaps there should also be some sort of clue to the
client as to the efficiency.  Or perhaps clients and servers should do
what they like, and the market will sort out which ones match users'
expectations best.

Whatever the decision, Mark's point, which is correct, is that you
can't make assumptions.  A client that wants to let a user search 350
mailboxes will do it, one way or another.  But it might or might not
perform badly with or without the extension, and you can't know in
advance which it'll be.

Barry