In the last episode (Apr 24), Fan, Wellington said:
> If I have a table:
>
> CREATE TABLE t (
> id int(11) NOT NULL auto_increment,
> fk1 mediumint(9) NOT NULL default '0',
> fk2 smallint(6) NOT NULL default '0',
> PRIMARY KEY (id),
> UNIQUE KEY idxfk1 (fk1,fk2),
> UNIQUE KEY idxfk2 (fk2,fk1)
> ) TYPE=MyISAM;
>
> I will about half the time have a query "WHERE fk1 IN (....)" and
> about the other half the time have "WHERE fk2 IN (....)"
>
> Does it make sense to define the UNIQUE KEYS the way I have?
You only need one unique index to enforce uniqueness, so you can safely
convert your idxfk2 to a single-column regular index and save a little
bit of space.
ALTER TABLE t drop key idxfk2, add key idxfk2 (fk2);
--
Dan Nelson
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