From: Tom Lane <tgl@sss.pgh.pa.us>
To: George Pavlov <gpavlov@mynewplace.com>
Cc: pgsql-sql@postgresql.org
Subject: Re: "large" IN/NOT IN subqueries result in query returning wrong data
Date: Tue, 27 Dec 2005 14:44:51 -0500
Message-ID: <3697.1135712691@sss.pgh.pa.us> (raw)
In-Reply-To: <CCB89282FCE1024EA3DCE687A96A5164039EBD13@ehost010-6.exch010.intermedia.net>
References: <CCB89282FCE1024EA3DCE687A96A5164039EBD13@ehost010-6.exch010.intermedia.net>
"George Pavlov" <gpavlov@mynewplace.com> writes:
> select count(*) from t2 where t2.name not in (
> select t1.name from t1 limit 261683)
> --> 13
> select count(*) from t2 where t2.name not in (
> select t1.name from t1 limit 261684)
> --> 0
> What is so magical about 261683?
Most likely, the 261684'th row of t1 has a NULL value of name.
Many people find the behavior of NOT IN with nulls unintuitive,
but it's per SQL spec ...
regards, tom lane
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To: pgsql-sql@postgresql.org
Cc: tgl@sss.pgh.pa.us, gpavlov@mynewplace.com
Subject: Re: "large" IN/NOT IN subqueries result in query returning wrong data
In-Reply-To: <3697.1135712691@sss.pgh.pa.us>
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