Is an index clustered or unclustered in Oracle?

Question

How can I determine if an Oracle index is clustered or unclustered?

I\'ve done

select FIELD from TABLE where rownum <100

where

Answer 1

"Clustered" indices, as implemented in Sybase, MS SQL Server and possibly others, where rows are physically stored in the order of the indexed column(s) don't exist as such in Oracle. "Cluster" has a different meaning in Oracle, relating, I believe, to the way blocks and tables are organized.

Oracle does have "Index Organized Tables", which are physically equivalent, but they're used much less frequently because the query optimizer works differently.

The closest I can get to an answer to the identification question is to try something like this:

SELECT IOT_TYPE FROM user_tables
WHERE table_name = ''

My 10g instance reports IOT or null accordingly.