From: Tom Lane <tgl@sss.pgh.pa.us>
To: mailreg@numerixtechnology.de
Cc: pgsql-sql@postgresql.org
Subject: Re: ORDER BY and NULLs
Date: Sun, 19 Sep 2004 15:00:08 -0400
Message-ID: <20623.1095620408@sss.pgh.pa.us> (raw)
In-Reply-To: <414DBF6D.8040500@numerixtechnology.de>
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>
T E Schmitz <mailreg@numerixtechnology.de> writes:
> Tom Lane wrote:
>> Whatever you were reading had it pretty badly garbled :-(
> I just dug out the PostgreSQL book again because I thought I might've
> garbled it:
> Quote: "PostgreSQL will not index NULL values. Because an index will
> never include NULL values, it cannot be used to satisfy the ORDER BY
> clause of a query that returns all rows in a table."
[ shrug ] It's wrong on both counts, and has been since (checks CVS) 1997.
What book is that anyway?
There is a related statement that is still true: "WHERE x IS NULL"
(or NOT NULL) clauses are not indexscannable. This is a shortcoming of
the planner-to-index-access-method interface, though, not a question of
whether the index can store NULLs.
regards, tom lane
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To: pgsql-sql@postgresql.org
Cc: tgl@sss.pgh.pa.us, mailreg@numerixtechnology.de
Subject: Re: ORDER BY and NULLs
In-Reply-To: <20623.1095620408@sss.pgh.pa.us>
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