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Cost based optimization of decision support queries using transient views

  • US 6,275,818 B1
  • Filed: 11/05/1998
  • Issued: 08/14/2001
  • Est. Priority Date: 11/06/1997
  • Status: Expired due to Term
First Claim
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1. A method of modifying a query plan for improved performance, comprising:

  • (a) identifying a plurality of sub-plans within the query plan;

    (b) generating one or more equivalence classes for the query plan, wherein each equivalence class contaims similar ones of the sub-plans;

    (c) generating a transient view to answer all of the sub-plans in an associated one of the equivalence classes, wherein the transient view contains a union of results from all of the sub-plans in the associated one of the equivalence classes;

    (d) utilizing a cost model to identify the transient views that improve the performance of the query plan; and

    (e) applying filters to the identified transient views to obtain results for each sub-plan in the associated equivalence class.

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