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An Efficient Algorithm for Processing Multi-Relation Queries in Relational Databases

Liu Weiyi;   

  1. Yunnan University;
  • Online:1990-05-10 Published:1990-05-10

After a relation scheme R is decomposed into the set of schemes ρ={R_1,...,R_n},we may pose queries as if R existed in the database,taking a join of R_i s,when it is necessary to implement the query.Suppose a query involves a set of attributes S(?)R,we want to find the smallest subset of ρ whose union includes S.We prove that the problem is NP-complete and present a polynomial-bounded approximation algorithm.A subset of ρ whose union includes S and has a decomposition into 3NF with a lossless join and prese...

Key words: leakage current; dont care bits; minimum leakage vector; leakage power;



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[3] Ellis Horowitz and Sartaj Sahani, Fundamentals of Computer Algorithm, Computer Science Press, Potomac, Md., 1978.
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ISSN 1000-9000(Print)

         1860-4749(Online)
CN 11-2296/TP

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