QUERYING BIG DATA BY ACCESSING SMALL DATA

摘要

A processor executes instructions stored in non-transitory memory to determine whether a query to big data is bounded evaluable, or may be rewritten to access a bounded amount of data or information in a dataset. A query plan may retrieve the information by using indices in access constraints of the query. The cost associated with obtaining the information by using the query plan may be dependent on the query and access constraints and not the size of the dataset. A query plan to obtain the information may be formed for different types or classes of queries, such as conjunctive queries (CQ), unions of conjunctive queries (UCQ) and positive existential FO (first order) conjunctive queries (ƎFO⁺). When a query is not bounded evaluable, a determination is made whether an approximation to the information may be retrieved. An approximation may be obtained by using upper and lower envelopes or specialized queries.