NOT IN performance problem

From: Nils Höglund <nils_at_naqua.se>
Date: Tue, 25 Jun 2002 05:08:24 -0800
Message-ID: <F001.0048675D.20020625050824@fatcity.com>

Hello,

I have encountered a performance problem. I use "Oracle8 Enterprise Edition Release 8.0.5.0.0 - Production."

I have two tables. "phonenumber" and "person", each person has none, one or many phonenumbers referenced to him.

The phonenumber-table is structured like: phonenumber.personid
phonenumber.phonenumber

The person-table is structured like:

person.personid
person.name
person.address

I wan't to know which persons that does NOT have any phonenumber(s).

I can write the query as:
SELECT personid FROM phonenumber WHERE personid NOT IN (

   SELECT personid FROM person);    

However, since my tables are quite large, it takes forever to run my query. In the real database both (or
atleast one) of "person" or "phonenumber" are views.

To figure out who _does_ have phonenumbers is SIGNIFICANTLY faster. (SELECT DISTINCT person.personid FROM person, phonenumber WHERE person.personid=phonenumber.personid)

I'm wondering how I could restructure or rewrite my query ("who doesn't have any phoinenumbers?") to run faster,
or if there is anything else I can do to optimize the query?

Any suggestions?

--

/Nils Höglund, Naqua KB

E-mail:         nils_at_naqua.se
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Author: =?iso-8859-1?Q?Nils_H=F6glund?=
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