Re: ORDER BY <field not in return list>

From: Tino Wildenhain <tino(at)wildenhain(dot)de>
To: "Marc G(dot) Fournier" <scrappy(at)postgresql(dot)org>
Cc: pgsql-hackers(at)postgresql(dot)org
Subject: Re: ORDER BY <field not in return list>
Date: 2005-07-25 22:17:24
Message-ID: 1122329844.30587.100.camel@Andrea.peacock.de
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Am Montag, den 25.07.2005, 18:11 -0300 schrieb Marc G. Fournier:
> Just curious as to whether or not a warning or something should be issued
> in a case like:
>
> SELECT c.*
> FROM company c, company_summary cs
> WHERE c.id = cs.id
> AND cs.detail = 'test'
> ORDER BY cs.fullname;
>
> Unless I'm missing something, the ORDER BY clause has no effect, but an
> EXPLAIN shows it does take extra time, obviously ...

It just does the sorting as you requested. Check the order of
the resulting c.id.

See:
experiment=# SELECT * FROM A;
a_id | a_value
------+---------
1 | abc
2 | bcd
3 | def
(3 rows)

experiment=# SELECT * FROM B;
b_id | b_value
------+---------
1 | xyz
2 | ijk
3 | abc
(3 rows)

experiment=# SELECT a.* FROM a,b WHERE a.a_id=b.b_id ORDER BY b_value;
a_id | a_value
------+---------
3 | def
2 | bcd
1 | abc
(3 rows)

So no reason for warnings :-)

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