PURPOSE: To reduce the frequency in write to a master file stored in a secondary storage device by writing out a transaction identifier and a flag to a record of a master log file at the time of the end of each transaction and newly generating the next record as an end record.

CONSTITUTION: At the time of a check point, the master log file consists of only records 1 and 2 where an end mark is written in the field of the transaction identifier and the flag is made ineffective. At the time of the end of a transaction the field of the transaction identifier of the record 1 and 2 is changed from the end mark to the transaction identifier and the flag of this record is made effective, and a new end record is added to the master log file. At the time of system down, transaction identifiers of records where flags are made effective are referred to perform the recovery processing. Thus, the frequency in write to the master file stored in the secondary storage device is reduced.