Re: Tune that query (and multi INdexes)

[Erin ONeill]

Ok, I know that one should not SELECT *. If I change the select to look like this:
explain SELECT song, album,type FROM audio_file WHERE song = '447' AND album = '68' AND type = 'clip';
+------------+------+---------------+------+---------+-------------------+------+--------------------------+
| table | type | possible_keys | key | key_len | ref | rows | Extra |
+------------+------+---------------+------+---------+-------------------+------+--------------------------+
| audio_file | ref | song,album | song | 12 | const,const,const | 4 | Using where; Using index |
+------------+------+---------------+------+---------+-------------------+------+--------------------------+

That looks very good. But let's say I need another field too. So I do my SELECT like this:
explain SELECT song, album,type, quality FROM audio_file WHERE song = '447' AND album = '68' AND type = 'clip';
+------------+------+---------------+------+---------+-------------------+------+-------------+
| table | type | possible_keys | key | key_len | ref | rows | Extra |
+------------+------+---------------+------+---------+-------------------+------+-------------+
| audio_file | ref | song,album | song | 12 | const,const,const | 4 | Using where |
+------------+------+---------------+------+---------+-------------------+------+-------------+

and now I'm back to where I was! (though I'm making the programmers SELECT all the fields they need and not to be lazy).

am I missing something obvious?