You probably at least need to change the following
parameters in my.cnf
(MySQL only indexes words of length >= 4 by default:
[mysqld]
ft_min_word_len=3
I didn't set this variable and yet the searchindex table contains words like
"aaa", "ada", "yr", "tl", "ei",
"xz", "rz", "lw", etc.
Best,
Plamen