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Re: Git for redundant mail servers

From
David Woodhouse <dwmw2@infradead.org>
Date
Apr 24, 2005, 05:54 UTC
Message-ID
<1114322071.3419.68.camel@localhost.localdomain>
In-Reply-To
<Pine.LNX.4.62.0504232159030.32287@qynat.qvtvafvgr.pbz>
On Sat, 2005-04-23 at 22:12 -0700, David Lang wrote:
Show 5 quoted lines
> 1. when a new message arrives it gets given a numeric messageid, this 
> message id is not supposed to change without fairly drastic things 
> happening (the server telling all clients to forget everything they know 
> about the status of the mailbox). this requires syncronization between 
> servers if both are receiving messages.

Yeah, that's the most interesting part. One option would be to require quorum before a server is allowed to add to a mailbox -- but that would render the thing unsuitable for _intentional_ offline use, where you want to be able to move mails from one folder to another on your laptop while it's disconnected.

Since it should be relatively rare for 'competing' commits to occur during periods of disconnection, I suspect that the solution doesn't have to be particularly efficient. I'm not sure I'd really want to change UIDVALIDITY if it happened, but perhaps we could simply remove _all_ the affected UIDs, and assign new UIDs to the same mails.

In practice, it's far more important that for us to ensure that an existing UID _never_ refers to a different mail, than it is to make sure that a given mail always keeps the same UID.

> 2. git effectivly stores snapshots of things and you deduce the changes by 
> comparing the snapshots. for things like flags changing this is a 
> relativly inefficiant way to replicate changes (although if one server is 
> offline for a while it could be a firly efficiant way to do the merge)

We don't have to stick _precisely_ to Maildir -- but flag changes are just a rename in Maildir, leaving the mail object entirely intact while changing only the tree. That isn't _so_ bad; but yes, it could probably be done a little better than just "Maildir in git".

-- 
dwmw2
Previous: David LangNext: David Lang
Message 4 of 5 in “Git for redundant mail servers”
  1. David WoodhouseApr 23, 2005
  2. Jon SeymourApr 23, 2005
  3. David LangApr 24, 2005
  4. David WoodhouseApr 24, 2005
  5. David LangApr 24, 2005

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