Use explain to see what MySQL is doing.
My guess is that MySQL is trying to figure out if it would be faster to
use the index or scan the whole table. MySQL is probably deciding that
it is quicker to scan the whole table based on the low cardinality of
the indices it can use. Thus, you've just a
I was playing around with a table that had 100 tinyint fields. Each
record contained other a '0' or a '1' for each field.
A query such as SELECT * FROM `foobar` WHERE `f01` =1 AND `f02` =1 AND
`f03` =1 AND `f04` =1 AND `f05` =1 AND `f06` =1 AND `f07` =1 AND `f08` =1
AND `f09` =1 AND `f10` =
