AUTO_FILTER

Oracle version 10.2.0.4

I have two text indexes that make use of the AUTO_FILTER.  I originally left the default attribute values of timeout 120 timeout_type HEURISTIC, and this has worked fine for most of the documents that come in.  However, we have recently received some documents that take HOURS to filter.  If I change the timeout_type to FIXED (and likely up the timeout to five minutes), does it affect the current text indexes immediately, or do the text indexes have to be recreated to use the new attribute value?  And when the five minutes are up, is an error logged in ctx_user_index_errors, and