String / int columns

Found a table of ours:
hashid bigint
value_a varchar(16)
value_b varchar(16)

In MyISAM, yes, this is a dynamically sized table. Turns out, data was only integers. Altered the table to be

hashid bigint
value_a integer
value_b integer

Goes to fixed size rows which is great. Also dropped size from 411M to 350M.

Remember the golden rule:
Optimize your dataset before your hardware...