Re: [HACKERS] Small improvement to compactify_tuples

23.01.2018 06:34, Stephen Frost пишет:
> Greetings,
> 
> * Юрий Соколов (funny.falcon@gmail.com) wrote:
>> On Wed, Nov 29, 2017 at 8:00 AM, Peter Geoghegan <pg@bowt.ie> wrote:
>>> On Tue, Nov 28, 2017 at 2:41 PM, Andres Freund <andres@anarazel.de> wrote:
>>>> Maybe it's a stupid question. But would we still want to have this after
>>>> the change? These should be just specializations of the template version
>>>> imo.
>>
>> "generic" version operates on bytes, and it will be a bit hard to combine
>> it with
>> templated version. Not impossible, but it will look ugly.
> 
> If that's the case then does it really make sense to make this change..?

I don't think it is really necessary to implement generic version
through templated. It is much better to replace generic version with
templated in places where it matters for performance.

> 
>> In attach fixed qsort_template version.
>> And version for compactify_tuples with bucket_sort and templated qsort.
> 
> While having the patch is handy, I'm not seeing any performance numbers
> on this version, and I imagine others watching this thread are also
> wondering about things like a test run that just uses the specialized
> qsort_itemIds() without the bucketsort.
> 
> Are you planning to post some updated numbers and/or an updated test
> case that hopefully shows best/worst case with this change?  Would be
> good to get that on a couple of platforms too, if possible, since we've
> seen that the original benchmarks weren't able to be consistently
> repeated across different platforms.  Without someone doing that
> leg-work, this doesn't seem like it'll be moving forward.

Updated numbers are (same benchmark on same notebook, but with new
master, new ubuntu and later patch version) (average among 6 runs):

master               - 16135tps
with templated qsort - 16199tps
with bucket sort     - 16956tps

Difference is still measurable, but less significant. I don't know why.

Rebased version of first patch (qsorted tamplate) is in atttach.

With regards,
Sokolov Yura.