Data processing: database and file management or data structures – Database and file access – Query optimization
Reexamination Certificate
2004-09-30
2011-10-25
Mofiz, Apu (Department: 2161)
Data processing: database and file management or data structures
Database and file access
Query optimization
C707S713000, C706S014000, C706S015000, C706S045000
Reexamination Certificate
active
08046354
ABSTRACT:
A query facility for database queries saves and re-uses query execution strategies, and automatically detects that a strategy should be re-optimized as a result of changes to an indexed variable value. Preferably, the number of records evaluated and selected by the index value condition is dynamically monitored during execution, and an alternative query strategy is initiated when this number appears to be out of proportion to expectations. In an exemplary embodiment, an indexed search strategy is changed to a table scan strategy (or vice versa) as a result of a change to the number of records eliminated by the indexed value, although other examples are possible. Preferably, the query engine initiates an alternative search strategy and concurrently continues to execute the original search strategy as separate threads. Search results are obtained from whichever thread completes first.
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Day Paul Reuben
Jameson Lee William
Mittelstadt Roger Alan
Muras Brian Robert
International Business Machines - Corporation
Le Hung
Mofiz Apu
Truelson Roy W.
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