| 摘要 |
In a data base system including a data base section for memorizing a plurality of data blocks and a buffer memory for memorizing a selected one of the data blocks as a buffered data block. The data base section includes a first memory unit for a first selected one of the data blocks as a first data block. Supplied with a search request signal which specifies a specific data block, a control unit transfers the first data block to the buffer memory when the specific data block is not present in the buffer memory but is present in the first memory unit. When the specific data block is also not present in the first memory unit, a reading unit reads the specific data block from the data base section and transfers the specific data block to the first memory unit under control of the control section. A copying unit transfers the specific data block to the buffer memory also under control of the control unit. Furthermore, the specific data block may be renewed into a renewal data block which is memorized in the buffer memory. The copying unit transfers the renewal data block to a second memory unit under control of the control unit. The control unit exchanges the specific data block for the renewal data block. Thereafter, the renewal and the specific data blocks are stored in the first and the second memory units, respectively.
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