[lukaseder]

I agree that automatic creation of indexes looks like a reasonable thing to do for a database like Oracle. Oracle could gather statistics and auto-create indexes where it seems fit, i.e. where there is a lot of querying and little writing going on.

In a way, this is what caches can do. Besides that, Oracle is already very good at giving you statistics and tuning hints to help you assess where you could add an index:

http://stackoverflow.com/a/2937047/521799

DB2 and SQL Server probably have similar tools. As far as I know, they all don't go as far as automatically creating or dropping any indexes.