From: T E Schmitz <mailreg@numerixtechnology.de>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: Greg Stark <gsstark@mit.edu>
Cc: pgsql-sql@postgresql.org
Subject: Re: ORDER BY and NULLs
Date: Sun, 19 Sep 2004 21:50:00 +0100
Message-ID: <414DF0F8.4060100@numerixtechnology.de> (raw)
In-Reply-To: <21812.1095625829@sss.pgh.pa.us>
References: <011d01c49e5b$c88fdb20$2766f30a@development.greatgulfhomes.com>
<414DB1AB.5080207@sympatico.ca>
<414DB594.5000300@numerixtechnology.de>
<19733.1095613137@sss.pgh.pa.us>
<414DBF6D.8040500@numerixtechnology.de>
<87zn3mjeaw.fsf@stark.xeocode.com>
<414DEA7F.6050100@numerixtechnology.de>
<21812.1095625829@sss.pgh.pa.us>
Hello Tom,
Tom Lane wrote:
> T E Schmitz <mailreg@numerixtechnology.de> writes:
>
>>Greg Stark wrote:
>>
>>>Which book is it?
>
>
>>PostgreSQL by Korry Douglas + Susan Douglas, ISBN 0-7357-1257-3; Feb 2003
>
>
> Hmm, I've heard of that book but never seen it. The authors are not
> participants in the PG community --- AFAICT neither of them have ever
> posted anything in the mailing lists.
>
>
>>The paragraph continues:
>>"If the SELECT command included the clause WHERE phone NOT NULL,
>>PostgreSQL could use the index to satisfy the ORDER BY clause.
>>An index that covers optional (NOT NULL) columns will not be used to
>>speed table joins either."
>
>
> My goodness, it seems to be a veritable fount of misinformation :-(
Well, that's great. My knowledge of SQL is good enough to model a DB and
do run of the mill queries; but when it comes to some fine details I
rely on sensible input ;-)
Thanks for chipping in here and answering what I thought was a dummy
question.
--
Kind Regards/Gruß,
Tarlika
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To: pgsql-sql@postgresql.org
Cc: mailreg@numerixtechnology.de, tgl@sss.pgh.pa.us, gsstark@mit.edu
Subject: Re: ORDER BY and NULLs
In-Reply-To: <414DF0F8.4060100@numerixtechnology.de>
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