11. The hierarchical data structure generator according to claim 7 , wherein the analyze tagging tree processor further creates at least one query tree, each query tree within the at least one query tree comprising the plurality of execution nodes configured with parent child relationships similar to the hierarchical structure, and wherein the composite query generator further: estimates, for each non-leaf node of at least one query tree within the at least one query tree, an estimated query result size for each non-leaf node of the at least one query tree; assigns a product of estimated sizes to each leaf node of the at least one query tree, the product of estimated sizes for a particular leaf node of the at least one query tree equaling a product of all estimated query result sizes that were estimated for each ancestor non-leaf node of the particular leaf node of the at least one query tree; selects a highest value leaf node, the highest value leaf node having a largest product of estimated sizes; and forms the single database query by merging the database queries specified by ancestor non-leaf nodes of the highest value leaf node.
11. The hierarchical data structure generator according to claim 7 , wherein the analyze tagging tree processor further creates at least one query tree, each query tree within the at least one query tree comprising the plurality of execution nodes configured with parent child relationships similar to the hierarchical structure, and wherein the composite query generator further: estimates, for each non-leaf node of at least one query tree within the at least one query tree, an estimated query result size for each non-leaf node of the at least one query tree; assigns a product of estimated sizes to each leaf node of the at least one query tree, the product of estimated sizes for a particular leaf node of the at least one query tree equaling a product of all estimated query result sizes that were estimated for each ancestor non-leaf node of the particular leaf node of the at least one query tree; selects a highest value leaf node, the highest value leaf node having a largest product of estimated sizes; and forms the single database query by merging the database queries specified by ancestor non-leaf nodes of the highest value leaf node. 12. The hierarchical data structure generator according to claim 11 , wherein the estimated query result size is estimated by multiplying a size of a target table by a pre-determined percentage.