Christian G. Warden wrote: > I was thinking about the case where a server doesn't go down, but is
disconnected from the rest of the servers. Any latency in synchronizingthe databases illustrates the problem, though.
Disconnected operation isn't a problem from a GUID uniqueness point of view. As long as the scheme is designed correctly it will guarantee uniqueness (at least it is statistically very unlikely to fail). A scheme based on second-resolution timestamp, PID and host ID has never produced a clash in our network, with message volumes in the billions.
Example: Say there two smtp servers each injecting messages into separate database servers which are setup in a multiple master scenario. One server inserts message 2004090202104527001 and the other inserts message 2004090202104527002. Before the databases have synchronized, an IMAP server connects to the second database server and asks for a list of messages. It gets 2004090202104527002. Later, after the databases have synchronized, it again asks for the messages and gets 2004090202104527001 and 2004090202104527002. From the client's perspective, the unique id's have now decreased.
This might be a little more tricky to resolve.. but without knowing the internals of the IMAP protocol, is it such a problem? Does the protocol not allow for a client to receive one "view" of a mailbox at time point A, and a different view at point B? It's not as if the GUID of a specific message is going to change over time; just that other messages might appear in a mailbox with GUIDs numerically lower.
A prev message in thread discussed this solution in project. Apparently it works great.Are you referring to Simon Cocking's message? I don't think he was referring to IMAP.
No, I wasn't. Our replication scheme doesn't care about messages' sequence; just that their IDs are unique.
-- Simon Cocking <[EMAIL PROTECTED]> Network Operations MailGuard Pty. Limited Email anti-virus, anti-spam and content filtering Melbourne 68-72 York St South Melbourne VIC 3205 P +61 3 9694 4444 Sydney Level 39, 2 Park Street Sydney NSW 2000 P +61 2 9004 7889 http://www.mailguard.com.au/mg
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