Re: sql optimization question

select distinct n.cognateid, m.isirefid,4, linkdate from mt.externallink l, refidmatch m, nametag n where l.objectid = n.geneid
and m.pubmedid = l.identifier
and externaldbid = 9
and l.identifier in
(select identifier from mt.externallink
where externaldbid = 9
group by identifier
having count(distinct objectid) < 6);

HTH,
Dave

gmei_at_incyte.com wrote:
> Hi,
>
> This query took a few minues to return 126K rows (fast):
>
> select distinct n.cognateid, m.isirefid,4, linkdate
> from mt.externallink l, refidmatch m, nametag n
> where l.objectid = n.geneid
> and m.pubmedid = l.identifier
> and externaldbid = 9;
>
> But this query took hours and still no result, I had to kill it:
>
> select distinct n.cognateid, m.isirefid,4, linkdate
> from mt.externallink l, refidmatch m, nametag n
> where l.objectid = n.geneid
> and m.pubmedid = l.identifier
> and externaldbid = 9
> and (select count(distinct objectid) from mt.externallink k
> where k.identifier = l.identifier
> and externaldbid = 9
> and l.objectid !=k.objectid)<5;
>
>
> All the related columns are indexed and table are analyzed. Is there a way
> to re-write the part
>
> select count(distinct objectid) from mt.externallink k
> where k.identifier = l.identifier
> and externaldbid = 9
> and l.objectid !=k.objectid)<5
>
> to make the whole thing faster?
>
> TIA.
>
> Guang
>

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Author: Dave Hau
  INET: davehau123_at_netscape.net

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