Thank you to all that replied to my question, and thank you Mr. Reardon for telling me about the "log_file_usage.sql" script from Steve Adams/Ixora.
I have to make a confession - I've been unfaithful to the list! (blushing) I also posted the question on Metalink, and found the answer there. create table ... as select ... always uses nologging if the database is in noarchivelog mode. However someone (a certain Jonathan Lewis :) ) suggested that the same is not true for indexes. I'm off to try that now.
