| 摘要 |
PROBLEM TO BE SOLVED: To provide a device and a method which suppress and reduce an increase in storage capacity and facilitate the retrieval of a change point and the restoration of past data. SOLUTION: The device is equipped with an update data file recording means 21 which records an updated and processed data file in a storage device 3, an update log file recording means 22 which records an updated part of the data file as an update log file in the storage device 3, a data-file-before-update erasing means 23 which erases the data file before update from the storage device 3 after the updated data file is recorded in the storage device 3, a file retrieving means 24 which retrieves whether or not a specified data file or the update log file is present in the storage device 3, and a data-file-before- update restoring means 25 which restores the contents of the specified data file before update by referring to the data file after update and update log file.
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