You can get information on cache hits and the like. I don't have the commands on the tip of my tongue so you'll have to RTFM but I know there's some information available, at least. Sorry I can't be more specific ... actually a lot of folks here would probably be interested in whatever you find out if take the time to dig into the docs.
Wanna write up a teensy snippet for our user docs if you decide to explore the PG docs?
