6. The apparatus of claim 3 , wherein determining which of the one or more record combinations to evaluate comprises maintaining a current record combination including a last non-discarded, non-ignored record read from the hierarchical data storage.
6. The apparatus of claim 3 , wherein determining which of the one or more record combinations to evaluate comprises maintaining a current record combination including a last non-discarded, non-ignored record read from the hierarchical data storage. 7. The apparatus of claim 6 , wherein evaluating the predicates includes at least one of: determining whether each table participating in the predicates of the received query is present in the current record combination; and determining whether the current record combination includes a record for each table participating in a join operation that is not being joined using a left outer join operation.