1. A computer-implemented method executed by one or more processors, the method comprising: identifying a first object hierarchy including one or more objects, each of the one or more objects representing a query associated with a data set, each of the objects in the first object hierarchy associated with a key value; identifying a second object hierarchy including one or more objects, each of the objects in the second object hierarchy associated with a key value; and generating a merged object hierarchy including the one or more objects from the first object hierarchy and the one or more objects from the second object hierarchy, wherein generating the merged hierarchy includes, for each object in the second object hierarchy: determining whether the object in the second object hierarchy matches an object in the first object hierarchy; and in response to a determination that the object in the second object hierarchy matches an object in the first hierarchy: determining whether the object in the second object hierarchy has a parent object and determining whether the object in the first object hierarchy has a parent object; in response to a determination that the object in the second object hierarchy has a parent object and the object in the first object hierarchy does not have a parent object, merging the object in the first object hierarchy and the object in the second object hierarchy; in response to a determination that the object in the second object hierarchy and the object in the first object hierarchy have a common parent object, merging the object in the first object hierarchy and the object in the second object hierarchy; and in response to a determination that the object in the second object hierarchy and the object in the first object hierarchy have different parent objects, separately maintaining the object in the first object hierarchy and the object in the second object hierarchy.