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

From: Peter Geoghegan <pg(at)heroku(dot)com>
To: Marc-Olaf Jaschke <marc-olaf(dot)jaschke(at)s24(dot)com>
Cc: pgsql-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 00:34:17
Message-ID: CAM3SWZQiesUyoYdk01E2D+yAasdbVjZK30kJFuxq2fvbtkRkzw@mail.gmail.com
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On Mon, Mar 21, 2016 at 1:40 PM, Marc-Olaf Jaschke
<marc-olaf(dot)jaschke(at)s24(dot)com> wrote:
> PostgreSQL 9.5 ignores rows with the following test case:

At one point, Robert wrote a small self-contained tool to show OS
strxfrm() blobs:

http://www.postgresql.org/message-id/CA+TgmoaOCyQpo8HK9yr6VTuyknWWvqgo7JeXi2kb=gpNveKR+g@mail.gmail.com

It would be great if you showed us the output for your test case
strings, both on an affected and on an unaffected system. As Robert
mentioned, our use of strxfrm() quite reasonably relies on it
producing blobs that compare with strcmp() in a way that gives the
same result as a strcoll() on the original strings, per ISO C90.

Thanks
--
Peter Geoghegan

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