Re: testing HS/SR - 1 vs 2 performance

On Fri, 2010-04-23 at 19:07 -0400, Robert Haas wrote:
> On Fri, Apr 23, 2010 at 6:39 PM, Simon Riggs <simon(at)2ndquadrant(dot)com> wrote:
> > On Fri, 2010-04-23 at 11:32 -0400, Robert Haas wrote:
> >> >
> >> > 99% of transactions happen in similar times between primary and standby,
> >> > everything dragged down by rare but severe spikes.
> >> >
> >> > We're looking for something that would delay something that normally
> >> > takes <0.1ms into something that takes >100ms, yet does eventually
> >> > return. That looks like a severe resource contention issue.
> >>
> >> Wow. Good detective work.
> >
> > While we haven't fully established the source of those problems, I am
> > now happy that these test results don't present any reason to avoid
> > commiting the main patch tested by Erik (not the smaller additional one
> > I sent). I expect to commit that on Sunday.
>
> Both Heikki and I objected to that patch.

Please explain your objection, based upon the patch and my explanations.

> And apparently it doesn't
> fix the problem, either. So, -1 from me.

There is an issue observed in Erik's later tests, but my interpretation
of the results so far is that the sorted array patch successfully
removes the initially reported loss of performance.

--
Simon Riggs www.2ndQuadrant.com