Re: Inconsistent DB data in Streaming Replication

On 2013-04-12 16:58:44 +0530, Pavan Deolasee wrote:
> On Fri, Apr 12, 2013 at 4:29 PM, Andres Freund <andres@2ndquadrant.com>wrote:
> 
> >
> >
> > I don't think that holds true at all. If you look at pg_stat_bgwriter in
> > any remotely bugs cluster with a hot data set over shared_buffers you'll
> > notice that a large percentage of writes will have been done by backends
> > themselves.
> >
> 
> Even if what you are saying it true, which I am sure is, the pages that the
> backend is evicting mustn't be recently used by the LRU algorithm which
> means that the WAL pertaining to the last change to the page in most
> likelihood is already replicated, unless the replication is really lagging
> much behind. Of course, if the standby is not able to keep pace with the
> master in a realistic manner then we have a problem with the approach.

It frequently takes time in the sub to few second range for usagecounts
in zero.

Greetings,

Andres Freund

-- Andres Freund                       http://www.2ndQuadrant.com/PostgreSQL Development, 24x7 Support, Training &
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