| 摘要 |
In a data warehouse, materialized views are maintained to provide the latest versions thereof. A reader may initiate a reader session where a series of queries are issued against one or more of the views. However, an information inconsistency problem may arise when responses to the queries in the reader session are based on certain common underlying data in the views which is subject to an update by a maintenance transaction. To avoid the information inconsistency problem, each time when a maintenance transaction is performed to update a view, it is executed on a copy of the view, rather than the original view itself to which queries of on-going reader sessions are directed. After the maintenance transaction, the updated copy becomes the current version of the view to which queries of new reader sessions are directed.
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