Hi,

I will be using a lot of statements like this ...

select sum(qty)
from table
where id = :id and status = :status

in a table with tens of thousand record and eventually it will grow to
hundreds of thousand record.

What are the things I have to know/do to achieve maximum performace
... the id field is a integer field where in the same value can be
enormous in the table or just a few, while the status is a char(3)
field where the possible value can be only 10, where in one of the
value is dominating, like around 95% of the records have this same
value and the rest share the other 9 possible value.

So... my question is which field should be index or not... and are
there other concerns I have to notice?

Please advice. Thanks.

Regards,
James