Re: Synchronization levels in SR

On Wed, Sep 08, 2010 at 03:22:46PM +0100, Simon Riggs wrote:
> On Wed, 2010-09-08 at 09:50 -0400, Robert Haas wrote:
>
> > So that means we have to make sure that none of the effects of a
> > transaction can be seen until WAL is fsync'd on the master AND the
> > slave has acked.
>
> Yes, that's right. And I like your example; one for the docs.
>
> There is a slight complexity there: An application might connect to
> the standby and see the changes made by the transaction, even though
> the master has not yet been notified, but will be in a moment. I
> don't see that as an issue though, but worth mentioning cos its just
> the "Byzantine Generals" problem.

For completeness, a reference to the aforementioned Byzantine
Generals: http://en.wikipedia.org/wiki/Byzantine_fault_tolerance

Cheers,
David.
--
David Fetter <david(at)fetter(dot)org> http://fetter.org/
Phone: +1 415 235 3778 AIM: dfetter666 Yahoo!: dfetter
Skype: davidfetter XMPP: david(dot)fetter(at)gmail(dot)com
iCal: webcal://www.tripit.com/feed/ical/people/david74/tripit.ics

Remember to vote!
Consider donating to Postgres: http://www.postgresql.org/about/donate