Message-ID: <e9427abbe32a10733eb9451fa466e4a591531a27.camel@cybertec.at>
Subject: Re: PostgreSQL Windows Turkish Search Problem
From: Laurenz Albe <laurenz.albe@cybertec.at>
To: Halil =?UTF-8?Q?=C4=B0brahim?= AYHAN <ibrahimayhan@hotmail.com.tr>,
 "pgsql-bugs@lists.postgresql.org"
	 <pgsql-bugs@lists.postgresql.org>
Date: Thu, 11 Sep 2025 15:24:40 +0200
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On Thu, 2025-09-11 at 07:42 +0000, Halil =C4=B0brahim AYHAN wrote:
> I am using PostgreSQL Windows version as Turkish Collation
> The table contains the record "=C5=9E=C4=B0L=C4=B0" and "=C5=9Fili",
> When I Search with ILike, It Does Not Perform Case-Insensitive Searches,
> When I search with uppercase letters, I get 1 result, and when I search w=
ith lowercase letters, I get 1 result.
> There is no problem with Turkish Collection in Linux Version and 2 result=
s are given.
> This problem occurs in Windows version.

There is a lack of SQL statements in your report, but I assume
this is either a user error or a shortcoming of the Windows
C library, both of which are not under our control.

Try like this:

  CREATE COLLATION turkish_ci (
     PROVIDER =3D icu,
     DETERMINISTIC =3D FALSE,
     LOCALE =3D 'tr-TR@colStrength=3Dlevel2'
  );

  CREATE TABLE tr (st text COLLATE turkish_ci);

  INSERT INTO tr VALUES ('=C5=9E=C4=B0L=C4=B0'), ('=C5=9Fili');

  SELECT * FROM tr WHERE st =3D '=C5=9Fili';

    st =20
  =E2=95=90=E2=95=90=E2=95=90=E2=95=90=E2=95=90=E2=95=90
   =C5=9E=C4=B0L=C4=B0
   =C5=9Fili
  (2 rows)

You could also define the column with a different collation and
add the COLLATE clause in the query.

Yours,
Laurenz Albe