I believe that you would have to use a PK or a unique index w/ a Not Null constraint. Unique indexes/constraints do not preclude the existence of NULLS. This is why the PK constraint is not the same as a unique constraint. Daniel Fink "Bobak, Mark" wrote: > Actually, it will ignore the index if the columns are nullable, even if = > no null values currently exist. If you repeat your experiment w/ a = > primary key or unique index, I think you'll find Oracle will use the = > index when directed to do so by a hint, even if it's less efficient to = > do so. > > -Mark ---------------------------------------------------------------- Please see the official ORACLE-L FAQ: http://www.orafaq.com ---------------------------------------------------------------- To unsubscribe send email to: oracle-l-request@xxxxxxxxxxxxx put 'unsubscribe' in the subject line. -- Archives are at //www.freelists.org/archives/oracle-l/ FAQ is at //www.freelists.org/help/fom-serve/cache/1.html -----------------------------------------------------------------