RE: SQL statement performance

From: Toepke, Kevin M <ktoepke_at_cms.cendant.com>
Date: Tue, 15 May 2001 04:52:26 -0700
Message-ID: <F001.003036E7.20010515043027@fatcity.com>

Here's another version of the query that has only 1 sort.

        SELECT a.spid, s.name, s.commonname
        FROM   (SELECT /+* NO_MERGE(b) */ DISTINCT spid
                FROM   (SELECT r.queryspid  AS spid
                        FROM   results      r
                              ,species      s
                        WHERE  r.subjspid  = s.id
                        UNION ALL
                        SELECT r.subjspid
                        FROM   results      r
                              ,species      s
                        WHERE  r.subjspid != r.queryspid
                        AND    r.subjspid  = s.id) b
               ) a
              ,specias      s
        WHERE  a.spid = s.id;

Kevin
-----Original Message-----
Sent: Tuesday, May 15, 2001 6:31 AM
To: Multiple recipients of list ORACLE-L

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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Received on Tue May 15 2001 - 06:52:26 CDT