| 摘要 |
PROBLEM TO BE SOLVED: To provide a method capable of performing the comparison of key values without restoring original data while reducing an index file capacity by performing data compression. SOLUTION: In the new preparation processing of an index page, the maximum value and minimum value of the key value to be stored in a page are compared with each other and front part matching data are decided. At the time of storing an index entry in the page, the front part matching data are excluded from the key value. The front part matching data are set to page control information as compression data. In an entry addition processing to the index page, in the case that the key value to be added does not contain the front part matching data inside the page control information, it is stored without being compressed and the number of non-compressed entries is increased. In the case of comparing a compressed key inside the index page with the key of a retrieval object, by excluding the front part matching data inside the page control information from the key of the retrieval object, they are compared with each other without restoring the compressed key. COPYRIGHT: (C)2004,JPO
|
