Posted by universalbitmapper on 09/07/06 14:48

FFMG wrote:
> Given the query bellow, what keys would you create?
>
> SELECT
> t2.t1_a
> FROM
> table1 as t1,
> table2 as t2,
> table3 as t3
> WHERE
> t2.t2_b = t3.t3_b
> AND
> t2.t2_c = t3.t3_d
> AND
> t3.t3_e != 25
> AND
> t1_a = '3'
> AND
> t2_d ='0'
> ORDER BY en.t1_a DESC
> LIMIT 0, 15
>
> Thanks
>
> FFMG

thanks Arjen for that link.
Just in case a newbie read this, don't confuse a "key" as in relational
model "primary key and foreign key", and an index.
An index is a way to store rows physical adresses and data, in a way
that an index block loaded in memory allows to quickly find physical
rows related to that block.
MySQL seems to encourage that confusion, as its use of the word key
means: create an index on that primary key or foreign key.
It's so strange that there is a strong possibility that I'm confusing
things.
What do you think?

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