From: Sebastian Hennebrueder <usenet@laliluna.de>
Cc: pgsql-performance@postgresql.org
Subject: Re: tricky query
Date: Tue, 28 Jun 2005 22:38:54 +0200
Message-ID: <42C1B55E.40405@laliluna.de> (raw)
In-Reply-To: <42C16FE4.2020803@arbash-meinel.com>
References: <6EE64EF3AB31D5448D0007DD34EEB3415C2BEC@Herge.rcsinc.local>
<42C167C6.5070108@arbash-meinel.com>
<42C16FE4.2020803@arbash-meinel.com>
John A Meinel schrieb:
> John A Meinel wrote:
>
>>
>
> Well, I was able to improve it to using appropriate index scans.
> Here is the query:
>
> SELECT t1.id+1 as id_new FROM id_test t1
> WHERE NOT EXISTS
> (SELECT t2.id FROM id_test t2 WHERE t2.id = t1.id+1)
> ORDER BY t1.id LIMIT 1;
>
> I created a test table which has 90k randomly inserted rows. And this is
> what EXPLAIN ANALYZE says:
>
>
As Cosimo stated the result can be wrong. The result is always wrong
when the id with value 1 does not exist.
--
Best Regards / Viele Grüße
Sebastian Hennebrueder
----
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To: pgsql-performance@postgresql.org
Cc: usenet@laliluna.de
Subject: Re: tricky query
In-Reply-To: <42C1B55E.40405@laliluna.de>
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