Help:Short words in searches
excerpted from http://meta.wikimedia.org/wiki/Help:Short_words_in_searches
Changing minimum and maximum word lengths in MySQL
From MySQL's docs on Fine-Tuning MySQL Full-Text Search:
The minimum and maximum length of words to be indexed is defined by the ft_min_word_len and ft_max_word_len system variables (available as of MySQL 4.0.0). See Section 5.3.3, “Server System Variables”. The default minimum value is four characters. The default maximum depends on your version of MySQL. If you change either value, you must rebuild your FULLTEXT indexes. 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:
Then restart the server and rebuild your FULLTEXT indexes. Also note particularly the remarks regarding myisamchk in the instructions following this list.
Help:Common word searches fail
Fix in MySQL configuration
From MySQL's documentation on Server System Variables:
The file from which to read the list of stopwords for full-text searches. All the words from the file are used; comments are not honored. By default, a built-in list of stopwords is used (as defined in the myisam/ft_static.c file). Setting this variable to the empty string () disables stopword filtering. This variable was added in MySQL 4.0.10.
Note: FULLTEXT indexes must be rebuilt after changing this variable or the contents of the stopword file. Use REPAIR TABLE tbl_name QUICK.