With regards to the user agent matching it reminds me of the time I loaded the full useragent database(the same data php get_browser() uses) into postgres and landed my first 3+ hour query.

  from log join ua_data on log.useragent ~ ua_data.match_exp

It was intractable to indexing (gin can almost do it. using like instead of ~ but gin only works on pure prefix or suffix matches) so I moved on to better things.