Re: gprof SELECT COUNT(*) results

[Qingqing Zhou <zhouqq(at)cs(dot)toronto(dot)edu>]

On Thu, 24 Nov 2005, Tom Lane wrote:
>
> I don't see those costing nearly as much as your results show
> ... perhaps there's something platform-specific at work?
> What I see, down to the 1% level, is
>

I can see your computer is really slow, so my theory is that since it is
easy to hold a running-slowly horse than a fast one, so my spinlock on a
2.4G modern machine should takes relatively longer time to get effective.
Just kidding. I am not sure what's happened, but in previous email there
is a program I wrote to test the spinlock performance. In my machine, the
profiling results matches the single spinlock test.

>
> The only other objection I can think of is that if there are any broken
> tuples on a page, this approach would likely make it impossible to fetch
> any of the non-broken ones :-(
>

What do you mean by "broken tuple"? An data corrupted tuple? So you mean
if scan operator find a broken tuple on a page, then it will abort the
operation without returning any other good tuples? I think this is
acceptable.

Regards,
Qingqing