I am not sure what *giant volumes* means to you, but http://sary.sourceforge.net/ might be a place to start.

On one of our systems we run [glimpseindex][1] every night. It produces an index and has a few options for setting the size of the index. The companion search command, glimpse, has numerous options for controlling the search and output.


  [1]: https://github.com/gvelez17/glimpse