Performance evaluation of a relational associative processor

Ozkarahan, Esen A.; Schuster, S. A.; Sevcik, Kenneth C.

doi:10.1145/320544.320553

Cited by 77 publications

(13 citation statements)

References 7 publications

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“…Several associative memory database machines provide hardware semijoin instructions in lieu of join. Examples include CAFS [l], CASSM [29], and RAP [21].6 To apply our algorithm to these machines, it is only necessary to modify our cost estimation techniques. Semijoin ' Semijoin is called "join-project" in [17].…”

Section: Discussionmentioning

confidence: 99%

Query processing in a system for distributed databases (SDD-1)

Bernstein

Goodman

Wong

et al. 1981

ACM Trans. Database Syst.

401

125

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Thii 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 sem@oin. 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.

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Section: Discussionmentioning

confidence: 99%

Query processing in a system for distributed databases (SDD-1)

Bernstein

Goodman

Wong

et al. 1981

ACM Trans. Database Syst.

401

125

View full text Add to dashboard Cite

show abstract

“…Such a comparison for a SIMD version of DIRECT and several other database machines-DBC [3], RAP [17], CASSM [25], associative disks [21], and CAFS [2]-can be found in [13]. A comparison of RAP and a relational database system on a conventional computer is presented in [18]. We believe that this paper demonstrates that the performance of DIRECT is generally superior to that of SIMD architectures.…”

Section: Introductionmentioning

confidence: 89%

Processor allocation strategies for multiprocessor database machines

Boral

DeWitt

1981

ACM Trans. Database Syst.

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In this paper four alternative strategies for assigning processors to queries in multiprocessor database machines are described and evaluated. The results demonstrate that SIMD database machines are indeed a poor design when their performance is compared with that of the three MIMD strategies presented.Also introduced is the application of data-flow machine techniques to the processing of relational algebra queries. A strategy that employs data-flow techniques is shown to be superior to the other strategies decribed by several experiments. Furthermore, if the data-flow query processing strategy is employed, the results indicate that a two-level storage hierarchy (in which relations are paged between a shared data cache and mass storage) does not have a significant impact on performance.

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“…To perform a semi-join of, say, Ri on domains A and B with R/ on domains C and D requires projecting Rj on a pair of domains C and D. The size of such a projection will generally be quite large and therefore the benefit of the semijoin is unlikely to exceed its cost. For this reason, multidomain semi-joins are ignored in SDD-I [14] and RAP [9]. Still, we do allow multidomain semi-joins in a limited context.…”

Section: Relations and Semi-joinsmentioning

confidence: 99%

Using Semi-Joins to Solve Relational Queries

Bernstein

Chiu

1981

J. ACM

388

202

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The semi-join is a relational algebraic operation that selects a set of tuples in one relation that match one or more tuples of another relation on the joining domains. Semi-joins have been used as a basic ingredient in query processing strategies for a number of hardware and software database systems. However, not all queries can be solved entirely using semi-joins. In this paper the exact class of relational queries that can be solved using semi-joins is shown. It is also shown that queries outside of this class may not even be partially solvable using "short" semi-join programs. In addition, a linear-time membership test for this class is presented.KEY WORDS AND PHRASES: semi-join, relational database, relational query processing cR CATEGORIES: 3.74, 4.33, 5.25

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Performance evaluation of a relational associative processor

Cited by 77 publications

References 7 publications

Query processing in a system for distributed databases (SDD-1)

Query processing in a system for distributed databases (SDD-1)

Processor allocation strategies for multiprocessor database machines

Using Semi-Joins to Solve Relational Queries

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