Re: Proposal: Commit timestamp - Mailing list pgsql-hackers

From José Orlando Pereira
Subject Re: Proposal: Commit timestamp
Date
Msg-id 200702211626.33673.jop@lsd.di.uminho.pt
Whole thread Raw
In response to Re: Proposal: Commit timestamp  (Jan Wieck <JanWieck@Yahoo.com>)
List pgsql-hackers
On Friday 09 February 2007, Jan Wieck wrote:
> I am not sure, I would have to look at what exactly that hook provides.
> The key to a Lamport timestamp is that it is advancing it commit order
> (plus some other things ... of course). If the hook can guarantee that
> the calls are made always in commit order, serialized without any race
> condition possible, it would probably be suitable.

Actually what we do is a bit stronger. We use the commit hook to enforce an 
externally defined commit order. In our case, this is defined by a group 
communication protocol, which is even allowed to reorder a pair of 
transactions originating from the same replica. Therefore, achieving a commit 
order that is consistent with a local clock should be straightforward.

Regards,

-- 
Jose Orlando Pereira


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