References on Text Mining (and PgSQL/FTS of course)

Hi all!
I'm looking for references about text mining methods (or text categorization
in general), as much detailed as possible: algorithms, test cases,
examples... of course better if using PgSQL and/or FTS ;)

Why: I'm studing a categorization method using Support Vector Machines (then
supervisioned classification) and I'm using PgSQL extensively, mainly the
FTS functionalities, of course ;)
My method is a little bit unstable and "rough" in categorization, so I'm
looking for a "trigger" to improve it.
Thank you!

Mirko Pace