James B Rothnie
IBM
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ACM Transactions on Database Systems | 1981
Philip A. Bernstein; Nathan Goodman; Eugene Wong; Christopher L Reeve; James B Rothnie
This paper describes the techniques used to optimize relational queries in the SDD-1 distributed database system. Queries are submitted to SDD-1 in a high-level procedural language called Datalanguage. Optimization begins by translating each Datalanguage query into a relational calculus form called an envelope, which is essentially an aggregate-free QUEL query. This paper is primarily concerned with the optimization of envelopes. Envelopes are processed in two phases. The first phase executes relational operations at various sites of the distributed database in order to delimit a subset of the database that contains all data relevant to the envelope. This subset is called a reduction of the database. The second phase transmits the reduction to one designated site, and the query is executed locally at that site. The critical optimization problem is to perform the reduction phase efficiently. Success depends on designing a good repertoire of operators to use during this phase, and an effective algorithm for deciding which of these operators to use in processing a given envelope against a given database. The principal reduction operator that we employ is called a semijoin. In this paper we define the semijoin operator, explain why semijoin is an effective reduction operator, and present an algorithm that constructs a cost-effective program of semijoins, given an envelope and a database.
Archive | 1979
Nathan Goodman; Philip A. Bernstein; Eugene Wong; Christopher L Reeve; James B Rothnie
Archive | 1995
Christopher L. Reeve; Tani Shavit; James B Rothnie; Timothy G Peters; Linda Q. Lee; William F. Mann; Jacklin Kotikian
very large data bases | 1977
James B Rothnie; Nathan Goodman
very large data bases | 1978
James B Rothnie
Archive | 1977
Philip A. Bernstein; David W. Shipman; James B Rothnie; Nathan Goodman
Archive | 1977
James B Rothnie; Nathan Goodman
Archive | 1978
Philip A. Bernstein; James B Rothnie; David W. Shipman
Archive | 1992
Christopher L Reeve; Tani Shavit; James B Rothnie; Timothy G Peters; Linda Q. Lee; William F. Mann; Jacklin Kotikian
Archive | 1992
Christopher L Reeve; Tani Shavit; James B Rothnie; Timothy G Peters; Linda Q. Lee; William F. Mann; Jacklin Kotikian