Parallel database processing system and retrieval method using secondary

Abstract

A parallel database processing system a global database processing unit, a plurality of local database processing units, and a network interconnecting the global database processing unit and a plurality of local database processing units, wherein one table containing a number of records is partitioned into local tables, each local table being provided in a corresponding one of the local database processing units, secondary key indexes representing correspondence between the values of secondary keys for all records in the table and access information to the records corresponding to the secondary keys, are partitioned on the basis of the values into local secondary key indexes, each set of the local secondary key indexes being provided in a corresponding one of the local database processing units, and an identifying unit is provided in the global database processing unit, the identifying unit responsive to a retrieval request with the secondary key identifying the local database processing unit having the local secondary key index corresponding to the secondary key. At the global database processing unit, the retrieval request with the secondary key is received, the identifying unit identifies the local database processing unit having the local secondary key index corresponding to the secondary key, and the retrieval request with the secondary key is transferred to the identified local database processing unit. At the identified local database processing unit, its own local secondary key indexes are referred to obtain access information corresponding to the transferred retrieval request with the secondary key, and the retrieval request with the secondary key is processed by using the access information so that the local table corresponding to the retrieval request with the secondary key is accessed.