| 摘要 |
PURPOSE:To make it unnecessary to execute mapping at every file access by providing a mapping cell on a record definition and storage part, and executing the mapping only when dissidence of a pattern of a record has been detected at the time of access. CONSTITUTION:First of all, in a step 20, a record requested by a user is read out of a data base, and converted to a record defined body format. Subsequently, in a step 21, the bit map length of the converted record, and a bit map are compared with an access pattern of the previous time, and when they coincide with each other, the processing is shifted to item access of a step 24 as it is. When they do not coincide with each other, in a step 22, the mapping processing such as an addition of an item, its deletion, attribute conversion, etc. is performed for the converted record, and in a step 23, the generated bit map length and the bit map part are stored in a mapping cell as an access pattern together with a record address, and thereafter, item access of a step 24 is executed.
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