18. The non-transitory medium of claim 17 , comprising instructions compatible with: the set of characteristics including aggregate statistical characteristics comprising at least one of generic aggregate statistics and scenario aggregate statistics, the generic aggregate statistics being calculated in a manner that is independent of a set of semantics of the attributes, and the scenario aggregate statistics being defined through a domain expert and being relevant in a particular scenario to enable incorporation of a domain-specific interpretation of the semantics of the each attribute and each set of data of the at least one of the initial result set and the subsequent result set.
19. The non-transitory medium of claim 18 , comprising instructions compatible with: the generic aggregate statistics including: a number of rows in the at least one of the initial result set and the subsequent result set, a count of distinct values in the each attribute, a distribution of attribute values including frequency per attribute value, a pattern of the attribute values, and a set of functional dependencies among attribute value pairs, and the generic aggregate statistics being applicable with no customization by the user.