Method and apparatus for accessing data as it existed at a previous point in time
First Claim
1. A computer-implemented method for processing flashback queries, the method comprising the steps of:
- receiving a flashback query;
determining a flashback time associated with said flashback query;
determining whether the flashback query satisfies a set of conditions relative to a flashback cursor that was created prior to receipt of said flashback query;
wherein one condition in said set of conditions is that the flashback time associated with the flashback query satisfies a condition relative to a time period associated with the flashback cursor; and
if the flashback query satisfies said set of conditions relative to said flashback cursor, then using the flashback cursor to process said flashback query.
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Accused Products
Abstract
Techniques are provided for sharing of flashback cursors by adding a time domain property to flashback cursors. This time domain property defines the range of flashback times for which the flashback cursor is valid. According to one embodiment, this “validity range” is closed at the lower bound and open at the upper bound. A subsequent flashback query can share an existing flashback cursor if the flashback time of the subsequent flashback query falls within the validity range of the existing flashback cursor. In one embodiment, the validity range of a flashback cursor is established based on times associated with indexes used to process the flashback query for which the flashback cursor was made. Consequently, an existing flashback cursor is less likely to be used by a subsequent flashback query when it would be inefficient to do so.
83 Citations
26 Claims
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1. A computer-implemented method for processing flashback queries, the method comprising the steps of:
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receiving a flashback query; determining a flashback time associated with said flashback query; determining whether the flashback query satisfies a set of conditions relative to a flashback cursor that was created prior to receipt of said flashback query; wherein one condition in said set of conditions is that the flashback time associated with the flashback query satisfies a condition relative to a time period associated with the flashback cursor; and if the flashback query satisfies said set of conditions relative to said flashback cursor, then using the flashback cursor to process said flashback query. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A computer-implemented method for generating a flashback cursor, the method comprising the steps of:
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receiving a particular flashback query; generating said flashback cursor to use to process said particular flashback query; determining a time range based on a point in time associated with said particular flashback query and times associated with indexes that are to be used to process said particular flashback query; and associating said time range with said flashback cursor. - View Dependent Claims (10, 11, 12, 13)
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14. A computer-readable medium carrying instructions for processing flashback queries, the instructions including instructions which, when executed by one or more processors, cause the one or more processors to perform the steps of:
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receiving a flashback query; determining a flashback time associated with said flashback query; determining whether the flashback query satisfies a set of conditions relative to a flashback cursor that was created prior to receipt of said flashback query; wherein one condition in said set of conditions is that the flashback time associated with the flashback query satisfies a condition relative to a time period associated with the flashback cursor; and if the flashback query satisfies said set of conditions relative to said flashback cursor, then using the flashback cursor to process said flashback query. - View Dependent Claims (15, 16, 17, 18, 19, 20, 21)
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22. A computer-readable medium carrying instructions for generating a flashback cursor, the instructions including instructions which, when executed by one or more processors, cause the one or more processors to perform the steps of:
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receiving a particular flashback query; generating said flashback cursor to use to process said particular flashback query; determining a time range based on a point in time associated with said particular flashback query and times associated with indexes that are to be used to process said particular flashback query; and associating said time range with said flashback cursor. - View Dependent Claims (23, 24, 25, 26)
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Specification