[PERFORM] tsvector_update_trigger performance?

[Chris St Denis]

Is tsvector_update_trigger() smart enough to not bother updating a 
tsvector if the text in that column has not changed?

If not, can I make my own update trigger with something like
   if new.description != old.description
       return tsvector_update_trigger('fti_all', 'pg_catalog.english',
   'title', 'keywords', 'description');
   else
       return new;

or do I need to do it from scratch?


I'm seeing very high cpu load on my database server and my current 
theory is that some of the triggers may be causing it.