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Message-ID: <4D871A6E.6050608@gmail.com>
Date: Mon, 21 Mar 2011 11:29:18 +0200
From: Tambet Matiisen <tambet.matiisen@gmail.com>
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To: pgsql-sql@postgresql.org
Subject: Obscure behavior of ORDER BY
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Hi everyone!

I recently noticed obscure behavior of ORDER BY. Consider this example:

select email from
(
select '@'::text as email
union all
select '.'::text as email
) a
order by email;

The result is:
  email
-------
  .
  @
(2 rows)

This is all normal - I expect, that dot is smaller than ampersand. But 
if I add anything after dot, the order is reversed:

select email from
(
select '@'::text as email
union all
select '.m'::text as email
) a
order by email

The result is:
  email
-------
  @
  .m
(2 rows)

Why is this happening? As dot is smaller than ampersand, anything after 
dot shouldn't matter.

I'm using PostgreSQL 8.4.7 on 32-bit Debian.

Thanks in advance,
   Tambet