SHADOW PAGING METHOD FOR ACCESSING DATABASE, AND SYSTEM FOR THE SAME

摘要

PROBLEM TO BE SOLVED: To provide a shadow page used for attainment of an atomic transaction and a durable transaction, capable of providing a function performing page operation in a database.;SOLUTION: During a transaction, a page affected thereby is copied to a work space of a volatile memory or the like from a database file, and is changed there. When the transaction is committed, all the pages already changed thereby are written into unused pages of the database file. Because the database file still stores a version present before the copying to the work space, which is an original version of the changed page, during execution of the transaction, a state of the database opened to a user is a state present before the transaction. When the user accesses the database before completion of the transaction or in time of restoration from a failure, the transaction looks like non-occurrence.;COPYRIGHT: (C)2005,JPO&NCIPI