| 摘要 |
PURPOSE:To improve the retrieving performance for emerging frequency conditions by storing the address of a higher level record of a hierarchical structure as the pointer value of an index record and producing an index where the emerging frequency of the key value is added to a pointer part. CONSTITUTION:When the conditions are retrieved with correspondence secured between a single key value and the unfixed number of pieces of value, the field value of a lower level record is defined as the key value. Then an index record is produced with the address of a higher level record storing the key value defined as the pointer value. While another index record where the emerging frequency of the key value in a lower level record group connected to the higher level record shown by the pointer value is added to the pointer part is produced and stored in an index file against the first index record. When the emerging frequency of the specific value is designated as the conditional value, the key value which satisfies the conditions is retrieved with reference to said index file. In such a way, the retrieving performance is improved for the emerging frequency conditions.
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