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High-speed data base query method and apparatus

  • US 5,852,821 A
  • Filed: 06/25/1997
  • Issued: 12/22/1998
  • Est. Priority Date: 04/16/1993
  • Status: Expired due to Term
First Claim
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1. In a database system for representing information in database tables and for retrieving information from database tables in response to database queries, each database table comprising data records storing information categorized into one or more database fields, each database field storing information in a particular data type, a method for optimizing database range queries, the method comprising:

  • (a) receiving a database range query having a query condition which specifies selection of data records satisfying a particular range;

    (b) if the query condition specifies selection of values of a particular database field of the data records which are less than or equal to a maximum key value, performing substeps of;

    (i) if the maximum key value represents the maximum value possible for the particular data type of the particular database field, creating a result set indicating that all data records have values for the particular database field which satisfy the query condition, otherwise(ii) incrementing the maximum key value by one and creating a result set indicating those data records having values for the particular database field which are less than the incremented maximum key value; and

    (c) if the query condition specifies selection of values of a particular database field of the data records which are greater than or equal to a minimum key value, performing substeps of;

    (i) if the minimum key value represents the minimum value possible for the particular data type of the particular database field, creating a result set indicating that all data records have values for the particular database field which satisfy the query condition, otherwise(ii) decrementing the minimum key value by one and creating a result set indicating those data records having values for the particular database field which are greater than the decremented minimum key value.

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