Normally, every word of four or more characters automatically gets built into the search index after every post, unless an admin has disabled that function. After a major upgrade, though, like when we upgrade to vB 3.5.0, the search index has to be completely rebuilt. If we allow words smaller than four characters to be indexed, the search index becomes bloated. The entire point of a search index is so that searches can be performed quickly and with minimal stress on the database.
