Re: Synchronous replication - patch status inquiry

On Tue, 2010-09-07 at 10:47 -0400, Tom Lane wrote:
> Simon Riggs <simon@2ndQuadrant.com> writes:
> > On Tue, 2010-09-07 at 09:27 +0300, Heikki Linnakangas wrote:
> >> For the sake of argument, yes that's what I was thinking. Now please 
> >> explain how *you're* thinking it should work.
> 
> > The WAL is sent from master to standby in 8192 byte chunks, frequently
> > including multiple commits. From standby, one reply per chunk. If we
> > need to wait for apply while nothing else is received, we do. 
> 
> That premise is completely false.  SR does not send WAL in page units.
> If it did, it would have the same performance problems as the old
> WAL-file-at-a-time implementation, just with slightly smaller
> granularity.

There's no dependence on pages in that proposal, so don't understand.

What aspect of the above would you change? and to what?

-- Simon Riggs           www.2ndQuadrant.comPostgreSQL Development, 24x7 Support, Training and Services