RE: SQL statement performance

From: Daemen, Remco <R.Daemen_at_facent.nl>
Date: Tue, 15 May 2001 02:27:25 -0700
Message-ID: <F001.003035C9.20010515023125@fatcity.com>

Hi Guang,

Try something like this:

select distinct(spid) spid,name,commonname from
(
select distinct(spid) spid,name,commonname from results a
, species
where a.queryspid = species.id
union all
select distinct(spid) spid,name,commonname from results b
, species
where a.subjspid = species.id
);

HTH, Remco

-----Oorspronkelijk bericht-----
Van: Guang Mei [mailto:zlmei_at_hotmail.com] Verzonden: dinsdag 15 mei 2001 1:20
Aan: Multiple recipients of list ORACLE-L Onderwerp: SQL statement performance

Oracle : 8.0.5
Platform : Sun

SQL statement:

select distinct(spid) spid, name, commonname from (

select distinct queryspid spid from results union select distinct subjspid spid from results ) a, species
where a.spid=species.id ;

Table "Species" only has 33 records, while table "results" has about 8000000

records. There are indexes on queryspid and subjspid.

This query is somehow slow. Is there any "easy" way to speed it up?

Thanks.

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Author: Daemen, Remco
INET: R.Daemen_at_facent.nl

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