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Home -> Community -> Mailing Lists -> Oracle-L -> Re: NOT IN performance problem
select personid from person_table
minus
select personid from phonenumber_table
/
Nils Höglund wrote:
> 
> 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
> Web:            http://www.naqua.se/
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> --
> Please see the official ORACLE-L FAQ: http://www.orafaq.com
> --
> Author: =?iso-8859-1?Q?Nils_H=F6glund?=
>   INET: nils_at_naqua.se
> 
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