System and method for asynchronous view maintenance
AssigneeInternational Business Machines Corporation
InventorsKevin Scott Beyer, Roberta Jo Cochrane, Bruce Gilbert Lindsay, Kenneth Mark Salem
Life of this patent
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Abstract
A method and system for refreshing materialized join views includes asynchronously evaluating changes to the base tables, i.e., evaluating changes for an intended time tintended at an evaluation time teval that is later than the intended time. Changes made to the base table between the intended time tintended and evaluation time teval are recursively compensated for. The results of the evaluating and compensating are then applied to the materialized view to refresh the view.
Claims30
A computer system, comprising:
- at least one general purpose computer executing method acts to refresh a view table, the method acts comprising:
- deriving changes to at least one base table accessible to the computer to render at least one delta table, the base table being combinable with other tables to render the view table;
- associating at least one record timestamp with at least one record in at least one delta table;
- combining at least one delta table with at least one base table to render a combination table;
- computing at least one combination timestamp representing the combining act;
- using the combination timestamp, computing at least one compensation table;
- and
- combining at least one compensation table with at least one combination table to render a view delta table useful for refreshing the view table.
A computer-implemented method for refreshing a materialized view, comprising the acts of:
- evaluating changes for an intended time tintended to at least one base table associated with the view at an evaluation time teval later than the intended time;
- recursively compensating for changes made to at least one base table associated with the view between the intended time tintended and evaluation time teval;
- and
- applying the results of the evaluating and compensating acts to the materialized view to refresh the view.
A computer program device comprising:
- a computer program storage device readable by a digital processing apparatus;
- and
- a program on the program storage device and including instructions executable by the digital processing apparatus to incrementally compute changes to a materialized join view which reflect changes to base tables, the program comprising:
- computer readable code means for recording updates to a plurality of base tables as they occur;
- computer readable code means for, at subsequent times, extracting the updates that occurred to selected base tables over given time intervals;
- computer readable code means for combining extracted updates with the base tables in multiple steps to compute changes to the materialized join view;
- wherein the means for combining includes:
- computer readable code means for evaluating changes for an intended time tintended to at least one base table associated with the view at an evaluation time teval later than the intended time;
- computer readable code means for recursively compensating for changes made to the base table between the intended time tintended and evaluation time teval;
- and
- computer readable code means for applying the results of the evaluating and compensating means to the materialized view to refresh the view.
Dependencies are inferred from the claim text.