8. An apparatus for optimizing execution of a query, comprising: a computer having a data store coupled thereto, wherein the data store stores data one or more computer programs, performed by the computer, for: generating cardinality estimates for one or more query execution plans for the query using statistics of one or more automatic summary tables that vertically overlap the query, wherein the statistics of the one or more automatic summary tables are used to improve a combined selectivity estimate of one or more predicates of the query, wherein zero or more predicates of the query are applied by one of the automatic summary tables and wherein the remaining predicates are eligible to be applied on the automatic summary table; using the generated cardinality estimates to determine an optimal query execution plan for the query; and executing the optimal query execution plan for the query in order to access the data stored on the data store connected to a computer and then output the accessed data.
9. The apparatus of claim 8 , a predicate is eligible to be applied on the automatic summary table if it can be evaluated using the output columns and expressions of the automatic summary table.