Query Execution in DIRECT.

Abstract

In this paper query organization, execution, and optimization in the database machine DIRECT are discussed. We demonstrate that the use of a monitor for each relation referenced by a query along with the use of the NEXT PAGE construct permits the DIRECT back-end controller to assign a query to any number of processors for execution. Furthermore, these constructs also permit the controller to balance the load in the back-end by dynamically adjusting how many processors are assigned to each executing query. We also identify the problem of relation fragmentation which occurs when a query is executed by several processors in parallel and develop a technique for estimating the optimal number of processors to compress a relation so that the execution time of the entire query is minimized. These results appear to be applicable to all database machines which employ parallel processing techniques to enhance query execution. (Author)

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Document Details

Document Type
Technical Report
Publication Date
Mar 01, 1979
Accession Number
ADA070195

Entities

People

  • David J. Dewitt

Organizations

  • University of Wisconsin–Madison

Tags

Communities of Interest

  • Materials and Manufacturing Processes

DTIC Thesaurus Topics

  • Algorithms
  • Computer Programs
  • Computers
  • Database Management Systems
  • Databases
  • Mass Storage
  • Mathematics
  • Operating Systems
  • Parallel Computing
  • Parallel Processing
  • Relational Database Management Systems
  • Relational Databases
  • Universities
  • Wisconsin

Fields of Study

  • Computer science
  • Engineering

Readers

  • Database Systems and Applications
  • Regression Analysis.