9. An apparatus for executing a query to retrieve data, comprising: a computer having a memory and a data storage device coupled thereto that stores the data; one or more computer programs, performed by the computer, for while accessing one or more indexes to retrieve row identifiers, applying index matching predicates in the query to select row identifiers and applying index screening predicates to eliminate one or more selected row identifiers.
10. The apparatus of claim 9, further comprising the means for identifying index matching predicates in the query.