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:[EMAIL PROTECTED]]
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
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