Re: Priority table or Cache table

On Mon, Jun 30, 2014 at 11:08 PM, Beena Emerson <memissemerson(at)gmail(dot)com> wrote:
>
> I also ran the test script after making the same configuration changes that
> you have specified. I found that I was not able to get the same performance
> difference that you have reported.
>
> Following table lists the tps in each scenario and the % increase in
> performance.
>
> Threads Head Patched Diff
> 1 1669 1718 3%
> 2 2844 3195 12%
> 4 3909 4915 26%
> 8 7332 8329 14%
>

coming back to this old thread.

I just tried a new approach for this priority table, instead of a
entirely separate buffer pool,
Just try to use a some portion of shared buffers to priority tables
using some GUC variable
"buffer_cache_ratio"(0-75) to specify what percentage of shared
buffers to be used.

Syntax:

create table tbl(f1 int) with(buffer_cache=true);

Comparing earlier approach, I though of this approach is easier to implement.
But during the performance run, it didn't showed much improvement in
performance.
Here are the test results.

Threads Head Patched Diff
1 3123 3238 3.68%
2 5997 6261 4.40%
4 11102 11407 2.75%

I am suspecting that, this may because of buffer locks that are
causing the problem.
where as in older approach of different buffer pools, each buffer pool
have it's own locks.
I will try to collect the profile output and analyze the same.

Any better ideas?

Here I attached a proof of concept patch.

Regards,
Hari Babu
Fujitsu Australia