nested select query take too long

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От Arsalan Zaidi
Тема nested select query take too long
Дата
Msg-id 003c01c170e5$63100320$4301a8c0@directi.com
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Ответы Re: nested select query take too long  (Stephan Szabo <sszabo@megazone23.bigpanda.com>)
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Hi.

The following query takes absolutely *ages* to run. Even with just a 1000
records in each table. It seems to me that the nested query is being run for
*every* value in the dom_ns table.

SELECT DISTINCT dom_ns.domname, dom_ns.tldtype FROM dom_ns WHERE
dom_ns.domname NOT IN (SELECT domname FROM domains WHERE domname IS NOT
NULL);

Why should is this happening? I just want the nested query to run once!

Thanks in advance.

--Arsalan.


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People often hate those things which they do not know, or cannot understand.
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