Message-ID: <f478f293-5eae-48a8-71be-e2fed1264bfa@joeconway.com>
Date: Wed, 5 Apr 2023 16:38:55 -0400
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Subject: Re: Wrong results with postgres_fdw and merge anti join from RHEL 7.9
 to RHEL 8.7
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To: Jim Mlodgenski <jimmy76@gmail.com>, Tom Lane <tgl@sss.pgh.pa.us>
Cc: "Daniel Westermann (DWE)" <daniel.westermann@dbi-services.com>,
 "pgsql-bugs@lists.postgresql.org" <pgsql-bugs@lists.postgresql.org>
References: 
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 <CAB_5SRcjBeAsBNY-vZzo7cFs2Yxjhu5nG6MEWFwvpnQ=7n9B=w@mail.gmail.com>
From: Joe Conway <mail@joeconway.com>
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On 4/5/23 15:46, Jim Mlodgenski wrote:
> 
> 
> On Wed, Apr 5, 2023 at 2:41 PM Tom Lane <tgl@sss.pgh.pa.us 
> <mailto:tgl@sss.pgh.pa.us>> wrote:
> 
>     "Daniel Westermann (DWE)" <daniel.westermann@dbi-services.com
>     <mailto:daniel.westermann@dbi-services.com>> writes:
>      > I am not sure if this qualifies as  bug, but anyway:
> 
>      > Source instance: PostgreSQL 13.7 on RHEL 7.9
>      > Target instance PostgreSQL 13.7 on RHEL 8.7
> 
> 
> glibc on those 2 versions of RHEL have very different ideas of what the 
> sort order should be. Try running the following and you'll likely see 
> different results on RHEL 7.9 vs 8.7
> 
> CREATE TABLE t1 (c1 varchar PRIMARY KEY);
> INSERT INTO t1 VALUES ('1-a'), ('1a'), ('1-aa');
> SELECT * FROM t1 ORDER BY c1;

Yep -- RHEL 7.9 is glibc 2.17 (likely -326) and 8.7 is glibc 2.28 (-211 
seems to be latest), and they are well known to sort differently even 
for "common" characters (e.g. "-")

-- 
Joe Conway
PostgreSQL Contributors Team
RDS Open Source Databases
Amazon Web Services: https://aws.amazon.com