Oracle 10g: Oracle Virtual Indexes - How to

Virtual index is a feature of Oracle 10 and Oracle 9. The purpose of virtual indexes is simulate the existence of an index, without actually building it, so you can explain plan as if the index existed. It is important to drop the index after you're done with it.

Managing Oracle on Windows

If you manage Oracle on Windows, you probably have wondered why it is so difficult to work out which Oracle instances are running and which ORACLE_HOMEs they use.