From: elein <elein@varlena.com>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: 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 16:12:51 -0800
Message-ID: <20051228001251.GB20674@varlena.com> (raw)
In-Reply-To: <3697.1135712691@sss.pgh.pa.us>
References: <CCB89282FCE1024EA3DCE687A96A5164039EBD13@ehost010-6.exch010.intermedia.net>
<3697.1135712691@sss.pgh.pa.us>
On Tue, Dec 27, 2005 at 02:44:51PM -0500, Tom Lane wrote:
> "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
In 8.0 we get:
elein=# select 1 in (NULL, 1, 2);
?column?
----------
t
(1 row)
elein=# select 3 not in (NULL, 1, 2);
?column?
----------
(1 row)
For consistency, either both should return NULL or
both return true/false.
For completeness testing, the following are correct.
Select NULL in/not in any list returns NULL.
elein=# select NULL in (1,2);
?column?
----------
(1 row)
elein=# select NULL not in (1,2);
?column?
----------
(1 row)
elein=# select NULL in (NULL, 1,2);
?column?
----------
(1 row)
elein=# select NULL not in (NULL, 1,2);
?column?
----------
(1 row)
elein
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To: pgsql-sql@postgresql.org
Cc: elein@varlena.com, tgl@sss.pgh.pa.us, gpavlov@mynewplace.com
Subject: Re: "large" IN/NOT IN subqueries result in query returning wrong data
In-Reply-To: <20051228001251.GB20674@varlena.com>
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