| 摘要 |
PURPOSE:To realize the version management in a small area by moving only a data page including a record to be updated and an index page which retrieves the data page to an extended page so that only the pages that had changes should be copied. CONSTITUTION:When the data R1 is updated, a data page 21 is extended for a new version and the data R1 is updated after both data R1 and R2 stored in a page 20 are copied to the data on the page 21. In this case, the control information showing an extended page is provided on the page 21. At the same time, a page 13 is extended to a free page 11 of an index part 1 and a pointer to the page 20 of a data part 2 is changed to the page 21 after the information on the page 11 is copied. At the same time, the control information is set on the page 13. Thus it is required to copy only the pages that had changes. As a result, the version control is possible in a small area and the influence that deteriorates the response can be avoided.
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