1. A data processing system implemented method of directing a data processing system to execute a query against a database having data objects, the query having sub-queries being subject of a union operator, the database being operatively coupled to the data processing system, the method comprising: analyzing a sub-query of the union operator for structural uniformity and statistical uniformity with any previously analyzed sub-query; generating groupings of the sub-queries being structurally and statistically uniform; generating a parameterized sub-query for each of the groupings, the parameterized sub-query being one of the sub-queries of the grouping and including a parameter for each table or index object of the sub-query; and generating access plans for each parameterized sub-query and for the sub-queries not being part of any of the groupings, wherein the structural uniformity indicates that the structure of the sub-queries are identical, wherein the structure of a sub-query includes expression of each sub-query, predicates of each sub-query, distribution of tables to multiple nodes and definition of underlying data objects including indexes, columns and data types of each column, wherein the statistical uniformity indicates that the statistics of data objects of the sub-queries are similar based on a pre-determined performance criteria, and wherein the statistics of a data object includes performance, size and data distribution of the data object.