How to know what fields can be searched?

[Bill Arduino]

Hi All,
So I have Nutch set up and running, I indexed +1 million PDF files.
Searching content works great, I figured out how to sort by date and reverse
sorts.  I would like to be able to search a date range, but am not sure if
date is indexed.  I think it must be if I can sort by date, just have no
idea how to do this.  Also would be nice to see if any other useful fields
can be used in queries.
Is there any way to look at the database to tell what I can search on?
Thanks!