* roger:
Try selecting FROM the cities table and JOIN with the recommendations
table.
* andy
SELECT count(DISTINCT user_recommending)
FROM geo.cities c
INNER JOIN recommendations AS t ON t.city_id = c.ID AND c.country_code
= 'gm'
same result. So do u think I would be better off if I save the country_code
in the recommendations table as well? I did read in a sql book not to
include the same data twice, but if performance is that bad?!
Would you recommend to denormalize it?
Andy
----- Original Message -----
From: "Roger Baklund" <[EMAIL PROTECTED]>
To: <[EMAIL PROTECTED]>
Cc: "andy" <[EMAIL PROTECTED]>
Sent: Monday, May 20, 2002 4:01 PM
Subject: RE: Join takes way too long. Query optimizing, or denormalizing?
> * andy
>
> > > > SELECT count(DISTINCT user_recommending)
> > > > FROM recommendations t
> > > > INNER JOIN geo.cities AS c ON t.city_id = c.ID AND
> > > > c.country_code = 'gm'
>
> > I guess this is not an issue on the index. Explain select says it is
using
> > the index. So I assume, that I did just write down the join syntax
wrong.
> > MySQL is joining all 32000 records with the city table and then looks
for
> > the country code. So this looks ok to me. Maybe I should
> > denormalize my data
> > and include the country code in the other table as well?
>
> Try selecting FROM the cities table and JOIN with the recommendations
table.
>
> --
> Roger
> sql
>
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