Why won't SQl MATCH AGAINST find results with only 3 characters in the result?

Question

For Example, I'm search for a person with the last name of Ash so in my query I search for Ash. It will show me people with the last name of Ashley, Ashby etc... but not people with the exact last name of Ash

Here's an example of what my sql looks like:

SELECT * FROM `People`
WHERE MATCH(PersonFirstName, PersonLastName) AGAINST('ash*' IN BOOLEAN MODE) LIMIT 20

Is there some sort of rule that it has to be over 3 characters or something in order for MATCH AGAINST to find it?

Answer 1

See the system variable ft_min_word_len, which specifies the minimum length of words to be indexed by full-text searching. It defaults to 4, so 3-letter words won't be found by full-text searching. More information about parameters of full-text searching can be found at 12.9.6. Fine-Tuning MySQL Full-Text Search. That page explains:

For example, if you want three-character words to be searchable, you can set the ft_min_word_len variable by putting the following lines in an option file:

[mysqld]
ft_min_word_len=3

Then restart the server and rebuild your FULLTEXT indexes. Note particularly the remarks regarding myisamchk in the instructions following this list.