Query folding refers to the activity of determining if and how a query can be answered using a set of resources, which might be materialized views, cached results of previous queries, or queries answerable by another database. We investigate query folding in the context where queries and resources are conjunctive queries. We develop an exponential-time algorithm that finds all foldings, and a polynomial-time algorithm for the subclass of acyclic queries. Our results can be applied to query optimization in centralized databases, to query processing in distributed databases, and to query answering in federated databases.

@techreport{SRI-CSL-95-09,
    AUTHOR = {Xiaolei Qian},
    TITLE = {Query Folding},
    INSTITUTION = {Computer Science Laboratory, {SRI} International},
    YEAR = {1995},
    NUMBER = {{SRI-CSL-95-09}},
    ADDRESS = {Menlo Park, {CA}},
    MONTH = {July},
    URL = {http://www.csl.sri.com/papers/sri-csl-95-09/}
}

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