Abstract: By corresponding the external databases to the predicates used in query processing according to a predetermined ontology, it is allowed to issue a query through the ontology. The query thrown into the integrated database is expanded into the set of approximate queries according to approximation rules provided in the ontology. The optimization module refers to the query capability of the external databases to perform the query optimizing in which these approximate queries can be executed efficiently as a whole.

Abstract: The present invention aims to dynamically re-configure hosts and storage in a shared-nothing database. In the shared-nothing database, processes 24 to 29 executed in the hosts 11 to 14 access data of a storage device 30. A system manager 70 and a database manager 10 manage the hosts 11 to 14 and the storage device 30. The processes 24 to 29 access one or more disks 51 to 54 of the storage device. To add or reduce the number of the hosts, the processes 24 to 29 are reassigned among the hosts 11 to 14.

Abstract: By introducing the concept of negation into an association rule, the number of combinations of items, serving as candidates of the association rule containing negative items, becomes enormous for mining. The invention sorts out frequent itemsets to be included in an association rule in advance by ensuing its upper bound of confidence satisfying conditions of a confidence and a confidence increment input by an user. Also, by checking a logic product for each bit of a bit string reflecting the presence of each item in the itemset, the combinations of items as candidates are pruned. The pruning of unnecessary combinations is effectively carried out. The number of combinations of the items for compiling association rules is reduced.

Abstract: By introducing the concept of negation into an association rule, the number of combinations of items, serving as candidates of the association rule containing negative items, becomes enormous for mining. The invention sorts out frequent itemsets to be included in an association rule in advance by ensuing its upper bound of confidence satisfying conditions of a confidence and a confidence increment input by an user. Also, by checking a logic product for each bit of a bit string reflecting the presence of each item in the itemset, the combinations of items as candidates are pruned. The pruning of unnecessary combinations is effectively carried out. The number of combinations of the items for compiling association rules is reduced.

Abstract: By corresponding the external databases to the predicates used in query processing according to a predetermined ontology, it is allowed to issue a query through the ontology. The query thrown into the integrated database is expanded into the set of approximate queries according to approximation rules provided in the ontology. The optimization module refers to the query capability of the external databases to perform the query optimizing in which these approximate queries can be executed efficiently as a whole.

Abstract: A data relay server connected between a client computer and a database server produces a query message obtained by encrypting a retrieval condition designated by the client computer, and transmits the query message to the database server. The database server encrypts a specific data item which is designated by the retrieval condition and read out from the database, retrieves service information matched with the retrieval condition by encrypted data matching, and replies the service information as a retrieval result to the data relay server.

Abstract: In order to realize high speed process for grouping the records having the identical values of one or more columns of the input list, the input list is canned, a hash value is generated using a hash function in which a value of the column as the non-vacant partial aggregation of the columns for the grouping is used as the argument, and it is determined whether two or more records having the hash values exist or not. The input list is scanned again and the calculating process of the aggregation columns is immediately executed for the records having the hash value for which it is determined by the first scanning that there is only one record having the identical hash value, the result of such calculating process is output and the records are defined as the input of the ordinary grouping process for the records which are determined to exist as the two or more records.

Abstract: A method, system and computer program for picking up and simultaneously executing common processings among a plurality of retrieval processings present in a series of queries so as to retrieve data from a database. The invention also provides a method, system and computer program for performing a query compiling. The invention performs a common scanning processing of data in the database while performing a judging operation according to retrieval conditions included in the retrieval processings of a query. Data judged to satisfy the retrieval conditions are set in output buffers and are transferred to the next processing nodes. Query-compiling is performed by detecting common processings from a query execution tree and transforming the common processings into a common scanning processing.

Abstract: A query issue processing method, a query conversion processing method, and a data control processing method are provided for enhancing the efficiency of random sampling processing for use in a database processing system. In query issue processing 2, a query including random sampling processing is issued. In query conversion processing 8, application sequences of random sampling processing and another query processing are exchanged by considering a sampling unit of the random sampling processing. Further, in record control processing 4, random access to a secondary storage device is reduced, thereby enhancing random sampling processing efficiency. Unlike the conventional query conversion processing not considering the sampling unit, the issuance of the query including random sampling processing and performing query conversion by considering the sampling unit allow random sampling to be applied also to a query including aggregation processing, thereby enhancing the efficiency of queries in a wider range.