From: Tomas Vondra <tomas.vondra@2ndquadrant.com>
To: Michael Paquier <michael@paquier.xyz>
Cc: Peter Eisentraut <peter.eisentraut@2ndquadrant.com>
Cc: Andrey Borodin <x4mmm@yandex-team.ru>
Cc: Alvaro Herrera <alvherre@2ndquadrant.com>
Cc: Gasper Zejn <zejn@owca.info>
Cc: pgsql-hackers@lists.postgresql.org
Subject: Re: pglz performance
Date: Wed, 27 Nov 2019 10:42:17 +0100
Message-ID: <20191127094217.5caghrkttntybugj@development> (raw)
In-Reply-To: <20191127080147.GB221153@paquier.xyz>
References: <20191101154828.GA15829@alvherre.pgsql>
<20191101165950.b5azncggaqfan5fi@development>
<35c2a448-06b8-eab0-05ea-34a3f51ba9a8@2ndquadrant.com>
<20191125080309.GK99720@paquier.xyz>
<13C6049A-C3D9-4021-9934-41488DE38BE9@yandex-team.ru>
<20191125082940.GP99720@paquier.xyz>
<20191126094324.7y2n3n3houetavwd@development>
<c52bb971-ae60-81eb-be66-57f12d3ae102@2ndquadrant.com>
<20191126200559.7ol33csmuwl6la2h@development>
<20191127080147.GB221153@paquier.xyz>
On Wed, Nov 27, 2019 at 05:01:47PM +0900, Michael Paquier wrote:
>On Tue, Nov 26, 2019 at 09:05:59PM +0100, Tomas Vondra wrote:
>> Yeah, although the difference is minimal. We could probably construct a
>> benchmark where #2 wins, but I think these queries are fairly realistic.
>> So I'd just go with #1.
>
>Nice results. Using your benchmarks it indeed looks like patch 1 is a
>winner here.
>
>> Code-wise I think the patches are mostly fine, although the comments
>> might need some proof-reading.
>>
>> 1) I wasn't really sure what a "nibble" is, but maybe it's just me and
>> it's a well-known term.
>>
>> 2) First byte use lower -> First byte uses lower
>>
>> 3) nibble contain upper -> nibble contains upper
>>
>> 4) to preven possible uncertanity -> to prevent possible uncertainty
>>
>> 5) I think we should briefly explain why memmove would be incompatible
>> with pglz, it's not quite clear to me.
>>
>> 6) I'm pretty sure the comment in the 'while (off < len)' branch will be
>> badly mangled by pgindent.
>>
>> 7) The last change moving "copy" to the next line seems unnecessary.
>
>Patch 1 has a typo as well here:
>+ * When offset is smaller than lengh - source and
>s/lengh/length/
>
>Okay, if we are reaching a conclusion here, Tomas or Peter, are you
>planning to finish brushing the patch and potentially commit it?
I'd like some feedback from Andrey regarding the results and memmove
comment, ant then I'll polish and push.
regards
--
Tomas Vondra http://www.2ndQuadrant.com
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services
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To: pgsql-hackers@postgresql.org
Cc: tomas.vondra@2ndquadrant.com, michael@paquier.xyz, peter.eisentraut@2ndquadrant.com, x4mmm@yandex-team.ru, alvherre@2ndquadrant.com, zejn@owca.info, pgsql-hackers@lists.postgresql.org
Subject: Re: pglz performance
In-Reply-To: <20191127094217.5caghrkttntybugj@development>
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