In case you missed and are interested in such things, perl.com ran a good article recently on building a full text search engine with Perl and any old relational database.
http://www.perl.com/pub/a/2003/09/25/searching.html
It provides examples of how to build and use a reverse (inverted) index
effeciently, touches fancy re-indexing techniques using Class::Trigger,
handy math tricks for normalizing your scores, and tips on using
Lingua::Stem::En to implement word stemming.
//Ed
