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Re: Missing rows with index scan when collation is not "C" (PostgreSQL 9.5)

From:	Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To:	Robert Haas <robertmhaas(at)gmail(dot)com>
Cc:	Peter Geoghegan <pg(at)heroku(dot)com>, Marc-Olaf Jaschke <marc-olaf(dot)jaschke(at)s24(dot)com>, Postgres-Bugs <pgsql-bugs(at)postgresql(dot)org>
Subject:	Re: Missing rows with index scan when collation is not "C" (PostgreSQL 9.5)
Date:	2016-03-22 23:19:44
Message-ID:	19132.1458688784@sss.pgh.pa.us
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Robert Haas <robertmhaas(at)gmail(dot)com> writes:
> I was a little worried that it was too much to hope for that all libc
> vendors on earth would ship a strxfrm() implementation that was actually
> consistent with strcoll(), and here we are.

Indeed. To try to put some scope on the problem, I made an idiot little
program that just generates some random UTF8 strings and sees whether
strcoll and strxfrm sort them alike. Attached are that program, a even
more idiot little shell script that runs it over all available UTF8
locales, and the results on my RHEL6 box. While de_DE seems to be the
worst-broken locale, it's far from the only one.

Please try this on as many platforms as you can get hold of ...

regards, tom lane

Attachment	Content-Type	Size
strcolltest.c	text/x-c	4.3 KB
tryalllocales.sh	text/x-shellscript	148 bytes
rhel6-results	text/plain	29.2 KB

In response to

Re: Missing rows with index scan when collation is not "C" (PostgreSQL 9.5) at 2016-03-22 22:06:37 from Robert Haas

Responses

Re: Missing rows with index scan when collation is not "C" (PostgreSQL 9.5) at 2016-03-22 23:48:31 from Robert Haas
Re: Missing rows with index scan when collation is not "C" (PostgreSQL 9.5) at 2016-03-22 23:51:15 from Tom Lane
Re: Missing rows with index scan when collation is not "C" (PostgreSQL 9.5) at 2016-03-23 01:15:09 from Stephen Frost
Re: Missing rows with index scan when collation is not "C" (PostgreSQL 9.5) at 2016-03-23 01:18:37 from Thomas Munro
Re: Missing rows with index scan when collation is not "C" (PostgreSQL 9.5) at 2016-03-23 01:20:00 from Stephen Frost
Re: Missing rows with index scan when collation is not "C" (PostgreSQL 9.5) at 2016-03-23 01:30:11 from Stephen Frost
Re: Missing rows with index scan when collation is not "C" (PostgreSQL 9.5) at 2016-03-23 01:45:44 from Stephen Frost
Re: Missing rows with index scan when collation is not "C" (PostgreSQL 9.5) at 2016-03-23 01:49:56 from Stephen Frost
Re: Missing rows with index scan when collation is not "C" (PostgreSQL 9.5) at 2016-03-23 02:44:45 from Noah Misch
Re: Missing rows with index scan when collation is not "C" (PostgreSQL 9.5) at 2016-03-23 10:32:06 from Bernd Helmle

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