Oracle Client for Rails on FC5

It seems to be quite an issue to get an Oracle 10g client running on Fedora 5 (FC5) Linux.

Does rails (or active record to be more concise) really need the full
(300 MB) Oracle client or is this small easy-to-install Oracle-Instant-Client sufficient?

Or is there a pure-Ruby solution that works without any Oracle-client installation?

Best regards