Learn "NOLOGGING" from forums

I often learn something(oracle) and find idea from OTN Forums.

And This Topic(Wait Events "log file parallel write" / "log file sync" during CREATE INDEX), It wrote about nologging option, “log file sync” and “log file parallel write” waits, and it's replied by Jonathan Lewis and Uwe Hesse.

Jonathan Lewis noted 2 points with "create index" nologging option:

it's "only" an index, so you could always rebuild it in the event of media corruption, but if you had lots of indexes created nologging this might cause an unreasonable delay before the system was usable again - so you should decide on a fallback option, such as taking a new backup of the tablespace as soon as all the nologging operatons had completed.

If the database, or that tablespace, is in "force logging" mode, the nologging will not work.