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Re: Big Performance drop of Exceptions in UDFs between V11.2 and 13.4

Andrew Dunstan <andrew@dunslane.net>

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From: Andrew Dunstan <andrew@dunslane.net>
To: Julien Rouhaud <rjuju123@gmail.com>, "ldh@laurent-hasson.com" <ldh@laurent-hasson.com>
Cc: Tom Lane <tgl@sss.pgh.pa.us>, Ranier Vilela <ranier.vf@gmail.com>, Justin Pryzby <pryzby@telsasoft.com>, "pgsql-performance@postgresql.org" <pgsql-performance@postgresql.org>
Date: 2021-09-02T15:22:54Z
Lists: pgsql-performance

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On 8/31/21 1:55 PM, Andrew Dunstan wrote:
> On 8/31/21 11:37 AM, Julien Rouhaud wrote:
>> On Tue, Aug 31, 2021 at 10:51 PM ldh@laurent-hasson.com
>> <ldh@laurent-hasson.com> wrote:
>>> OK... I thought that track had been abandoned as per Julien's last message. Anyways, I'll be patient!
>>>
>> I just happened to have both standard installer and locally compiled
>> versions available, so I could confirm that I reproduced the problem
>> at least with the standard installer.  Note that my message also said
>> " if default build on windows has NLS included".  After looking a bit
>> more into the Windows build system, I confirm that NLS isn't included
>> by default so this is not the problem, as Andrew said.
>>
>> After installing gettext and a few other dependencies, adapting
>> config.pl I wish I could also confirm being able to reproduce the
>> problem on my build, but apparently I'm missing something as I can't
>> get any modification in config.pl have any effect.  I'm not gonna
>> waste more time on that since Andrew is already in the middle of the
>> investigation.
>
>
> The culprit turns out to be the precise version of libiconv/libintl
> used. There is a slight difference between the versions used in the
> 11.13 installer and the 13.4 installer. We need to dig into performance
> more (e.g. why does the test take much longer on an NLS enabled build
> even when we are using 'initdb --no-locale'?) But I'm pretty confident
> now that this is the issue. I've started talks with our installer guys
> about fixing it.
>
>


Here are a couple of pictures of profiles made with a tool called
sleepy. The bad profile is from release 13.4 built with the latest
gettext, built with vcpkg. The good profile is the same build but using
the intl-8.dll copied from the release 11.13 installer. The good run
takes about a minute. The bad run takes about 30 minutes.


I'm not exactly sure what the profiles tell us.


cheers


andrew


--
Andrew Dunstan
EDB: https://www.enterprisedb.com