DELETING A CONTINUOUS QUERY FROM A DATA STREAM MANAGEMENT SYSTEM CONTINUING TO OPERATE ON OTHER QUERIES
First Claim
1. A computer-implemented method of processing streams of data using continuous queries, the method comprising:
- receiving an instruction to delete a first continuous query;
deleting a second continuous query on which is built a view referenced by the first continuous query, if said view is not referenced by any continuous query other than the first continuous query;
compiling the second continuous query, in response to said deleting; and
updating said view to refer to a newly-compiled version of the second continuous query, in response to said compiling.
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Abstract
A first continuous query is deleted from several continuous queries that are being executed, by performing different actions that depend on how resources are shared therebetween. As an example, a second continuous query is deleted if a view is referenced by the first continuous query, and if the view is built on the second continuous query, and if the view is not referenced by any query other than the first continuous query. Such deletion is followed by compiling the second continuous query, followed by updating the view to refer to a newly-compiled version of the second continuous query. As another example, if an operator in the first continuous query is not used by any other query, this operator is de-scheduled from execution, and any exclusively-owned resources are released. Also, data to be read by the operator and data generated by the operator, if present in shared resources, are deleted therefrom.
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Citations
12 Claims
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1. A computer-implemented method of processing streams of data using continuous queries, the method comprising:
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receiving an instruction to delete a first continuous query; deleting a second continuous query on which is built a view referenced by the first continuous query, if said view is not referenced by any continuous query other than the first continuous query; compiling the second continuous query, in response to said deleting; and updating said view to refer to a newly-compiled version of the second continuous query, in response to said compiling. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A computer-readable storage medium encoded with instructions to process streams of data using continuous queries, the instructions comprising:
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instructions to receive an identity of a first continuous query to be deleted; instructions to check if an output of the first continuous query is used by any view, thereby to obtain a first result; instructions to check if the first continuous query receives input from any view among the predetermined plurality, thereby to obtain a second result; instructions responsive to each of the first result and second result being false, to further check if an operator used by the first continuous query is also used by any other continuous query, thereby to obtain a third result; and instructions responsive to the third result being true, to remove any reference to the first continuous query from the operator. - View Dependent Claims (8, 9, 10, 11)
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12. A data stream management system comprising:
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means for receiving an instruction to delete a first continuous query; means, coupled to the means for receiving, for returning without changing execution of the first continuous query if an output of the first continuous query is used by any view among a predetermined plurality of views; means, coupled to the means for receiving, for deleting a second continuous query used in a view referenced by the first continuous query if the first continuous query receives input from said view, compiling the second continuous query after deletion, and updating said view to refer to a compiled version of the second continuous query resulting from compilation; and means, coupled to the means for receiving, for de-scheduling execution of an operator in the first continuous query, dropping any output queue owned by the operator, dropping any store owned by the operator, deleting input data still to be processed by the operator if a first queue holding the input data is shared with another operator and alternatively marking the first queue for deletion if the first queue is not shared, and deleting output data generated by the first continuous query from a store if an owner of the store is shared by other queries and alternatively marking said store for deletion if the store is not shared.
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Specification