Re: [HACKERS] Small improvement to compactify_tuples

From: Yura Sokolov <funny(dot)falcon(at)gmail(dot)com>
To: Andres Freund <andres(at)anarazel(dot)de>
Cc: Stephen Frost <sfrost(at)snowman(dot)net>, Michael Paquier <michael(dot)paquier(at)gmail(dot)com>, Peter Geoghegan <pg(at)bowt(dot)ie>, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Claudio Freire <klaussfreire(at)gmail(dot)com>, Robert Haas <robertmhaas(at)gmail(dot)com>, Sokolov Yura <funny(dot)falcon(at)postgrespro(dot)ru>, Alvaro Herrera <alvherre(at)2ndquadrant(dot)com>, Heikki Linnakangas <hlinnaka(at)iki(dot)fi>, PostgreSQL-Dev <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: [HACKERS] Small improvement to compactify_tuples
Date: 2018-03-04 09:57:45
Message-ID: 5e5a61fc-961f-9c1a-bc28-2946812da561@gmail.com
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01.03.2018 22:22, Andres Freund пишет:
> Hi,
>
> On 2018-02-25 21:39:46 +0300, Yura Sokolov wrote:
>>> 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.
>
> Why?

It is better to replace use of generic version with templated in
appropriate places.
Generic version uses variable size of element. It will be difficult to
describe through template.

>
>> 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.
>
> Hm, that's a bit underwhelming. It's nice to deduplicate, but 16135tps
> -> 16199tps is barely statistically significant?

I mean bucket sort is measurably faster than both generic and templated
sort (16956 vs 16199 and 16135). So initial goal remains: to add bucket
sort in this place.

BTW, I have small change to templated version that improves sorting of
random tuples a bit (1-1.5%). Will post it a bit later with test.

> - Andres
>

With regards,
Yura.

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