| 摘要 |
PROBLEM TO BE SOLVED: To enable the equalization of data bases DB which are duplexed even if data is updated or reference to other data is contained in data. SOLUTION: The content of data as well as the generation time and update time of the data are recorded. At the time of copying data from DB 1 of a master-side to DB 2 of a slave side, the data identifier of the copied data is recorded in DB 2 on the slave-side with the content of data. A valid data take- out part 4 takes out data generated or updated after user-designated time from DB 2 of the slave-side, and takes out data which are generated or updated before designated time but have not been taken out from DB 2 of the slave-side from DB 1 of the master-side.
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