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Abstract

Database system and methods are described for updating records, such as are commonly used in a relational database environment. Updates are carried out in a manner which allows a substantial portion of the work to be performed in direct mode (when possible), thereby avoiding the inefficiency of re-reading records. In this fashion, a scenario which requires deferred updating can, in accordance with the present invention, be treated mostly as a direct update, with minimal deferred updating. Given a query involving an 'unsafe' unique index (i.e., query includes update to key field), for instance, the present invention provides a method whereby each data row is updated in direct mode. In conjunction with this, the corresponding index row is deleted in direct mode. The system will not insert an index row at this point, however. Instead, updating of the index is deferred. The index is inserted later during the deferred or default mode. By updating data rows in direct mode (when possible), system performance is enhanced.

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First Claim