MySQL has fulltext index search ability for text field. but it is word
based index, it cannot be used for no word delimiter laungage like
Japanese or Chinese. and it also can't search charactors in middle of
a words. (cf. searching 'in' will not match word 'ping'.)

Starts from MySQL 5.1, MySQL supports a plugin that allows to change
server components (fulltext search parser) without restarting /
recompiling the server.

This n-gram parser uses this plugin interface to implement a simple
n-gram (bi-gram) fulltext index parser which can be index no word
delimiter laungage.

WWW:	http://mysqlbigram.googlepages.com/