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Join operation processing system in relational model

  • US 4,497,039 A
  • Filed: 06/30/1982
  • Issued: 01/29/1985
  • Est. Priority Date: 06/30/1981
  • Status: Expired due to Term
First Claim
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1. A join operation processing system responsive to user instructions for performing join operations in a relational model in a data processing system where a data base storing a plurality of data tables, each data table comprising a plurality of information fields with a plurality of data entries within each field, further storing pertinent index tables arranged such that entries in each index table are in an ascending or descending sequence, the entries in the index table corresponding to the data entries in an information field in one or plurality of said data tables and storing dictionary information for each table defining the information fields, and processings are executed by providing a data base processing mechanism and using said tables of said data base, said data base processing mechanism at least comprising:

  • maximum/minimum calculation execution means for preliminarily judging a tuple extraction range for a join field in a join object table based on a join predicate described by users and the dictionary information for the index table which can be utilized for said join processing;

    reduction sort execution means for sorting one of unsorted tables or one of the tables which cannot use the index tables based on the preliminary judged tuple extraction range and for executing the sorting for a succeeding table based on the extraction range limited by the sorting by said reduction sort execution means; and

    join calculation execution means for executing join processing by extracting the join object tuple for the join object table based on the extraction range for the index table for the table which can use the index and the extraction range of the table sorted by said reduction sort execution means, whereby the processing instructed by users is executed on the basis of the limited relationship defined by the join object table.

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