| 摘要 |
PROBLEM TO BE SOLVED: To provide the technology of extracting higher-order N keys with respect to designated items by means of a memory with a small size and estimating the cardinality with respect to the keys. SOLUTION: A traffic acquisition section 101 acquires traffic data, and a monitoring key, cardinality count object item designation section 102 designates an object item from which keys and cardinality being monitoring objects are counted. A cardinality information calculation section 103 stores cardinality information by each division key resulting from dividing key information and updates the cardinality information with respect to a division key resulting from dividing key information of a concerned packet by each acquired packet. A higher-order N-key information calculation section 104 stores higher-order N keys and cardinality estimated from the cardinality information stored in the cardinality information calculation section 103 and associated with the keys, and discriminates the object item to be a new cardinality count object designation item when the cardinality information is changed as a result of the cardinality information calculation section 103 updating the cardinality information at packet acquisition, and updates a cardinality estimate value and the higher-order key information of the key. COPYRIGHT: (C)2007,JPO&INPIT
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