1. A method of managing metadata in a relational database system using a processor, the metadata created in a form of rough values corresponding to collections of values, wherein each rough value represents summarized information about values, wherein the values are elements of the corresponding collection of values, and wherein each rough value being substantially smaller than the corresponding collection of values, the method comprising: assigning a collection of values to a structure dictionary, wherein each of the values represents the value of a row for an attribute and has a unique ordinal number within the collection, and wherein the structure dictionary contains structures defined based on at least one of interaction with a user of the system via an interface, automatic detection of structures occurring in data, and predetermined information about structures relevant to data content that is stored in the system; forming a match granule containing summarized information about the assignment of the ordinal numbers of the elements in the collection of values to the structures in the structure dictionary; for each structure in the structure dictionary, forming a structure granule containing summarized information about one or more elements in the collection of values for which an ordinal number was assigned to the structure; and gathering summarized information represented by the match granule and one or more structure granules to form a rough value.