METHOD AND DEVICE FOR EXECUTING CONNECTION QUESTION IN DATA BASE SYSTEM

摘要

PROBLEM TO BE SOLVED: To generate a response to a connection by using a map for erasing a segment which can not satisfy a connected predicate. SOLUTION: A connection has a connected predicate between a 1st table having plural 1st fragments and a 2nd table having plural 2nd fragments and concerning the respective correspondent fragments from the 1st table, a retrieved connection fragment identifies a fragment from the 2nd table including a record satisfying the connected predicate with a record from a correspondent fragment from the 1st table. In order to delete the other fragments, a data base system generates or accesses a connection fragment map 36 in a data base 30. The connection fragment map 36 does not include any record indicating which fragment from two tables can satisfy the connected predicate but shows the unnecessity of retrieval during the execution of question and is used for deleting fragments which can not satisfy the connected predicate.