Re: distinct clause issue for 600000 records

[Øystein Grøvlen]

Hi,

My approach is not applicable to your example since all join conditions are related to your left hand table. A better example is the following (based on your original query):

select *
from prdsl psrl
left join prdgn rn on rn.prdsld=psrl.id
left join be_en bcu on bcu.id=rn.cbed

If every value of rn.cbed is an id in bcu, the above query is equivalent to

select *
from prdsl psrl
left join
(prdgn rn join be_en bcu on bcu.id=rn.cbed)
on rn.prdsld=psrl.id;

Øystein Grøvlen,
Senior Principal Software Engineer,
MySQL Group, Oracle,
Trondheim, Norway