Re: Sync Rep v19

On Fri, Mar 11, 2011 at 09:03:33AM -0500, Robert Haas wrote:
> On Fri, Mar 11, 2011 at 8:21 AM, Fujii Masao <masao.fujii@gmail.com> wrote:
> >
> > In that case, the last write WAL timestamp would become equal to the
> > last replay WAL timestamp. So we can see that there is no lag.
> 
> Oh, I see (I think).  You're talking about write/replay lag, but I was
> thinking of master/slave transmission lag.
> 

Which are both useful numbers to know: the first tells you how "stale"
queries from a Hot Standby will be, the second tells you the maximum
data loss from a "meteor hits the master" scenario where that slave is
promoted, if I understand all the interactions correctly.

Ross
-- 
Ross Reedstrom, Ph.D.                                 reedstrm@rice.edu
Systems Engineer & Admin, Research Scientist        phone: 713-348-6166
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