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Self-adjusting database-query optimizer

  • US 9,886,492 B2
  • Filed: 11/17/2005
  • Issued: 02/06/2018
  • Est. Priority Date: 12/22/2004
  • Status: Active Grant
First Claim
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1. A computer-implemented method for use in executing a query in a database system, the method comprising:

  • formulating an initial query-execution plan that identifies an expected path for execution of the query;

    formulating, prior to an execution of said query according to said initial query-execution plan, an alternative query-execution plan for execution of the query, said alternative query-execution plan differing from the initial query-execution plan from a point that occurs after an intermediate checkpoint in the initial query-execution plan;

    initiating the execution of the query according to said initial query-execution plan;

    at said intermediate checkpoint in the initial query-execution plan;

    concluding that an actual result obtained at the intermediate checkpoint in the initial query-execution plan does not match an expected result; and

    in response, choosing said alternative query-execution plan for the execution of the query;

    continuing the execution of the query according to said alternative query-execution plan from said point that occurs after said intermediate checkpoint; and

    abandoning the execution of the query according to said initial query-execution plan from said point that occurs after said intermediate checkpoint.

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