END COMPRESSION METHOD FOR LOG STREAM USING SCRATCH PAD OF LOGICALLY ELIMINATED ENTRY

摘要

PROBLEM TO BE SOLVED: To eliminate an unrequired data record from a log file by identifying the entry of a log stream not to be eliminated from the log stream, logically eliminating the entry logical from the log stream and eliminating it when it can be eliminated. SOLUTION: At the time of judging that a block in the log stream 112 is not required any more, a resource manager 108 checks whether or not an unrequired oldest block is the block present at the end of the log stream 112. When the log entry is not present at the end, the resource manager 108 writes information corresponding to the log entry to a scratch pad 114, and thus, it is logically eliminated. On the other hand, when the log block to be eliminated is the log block present at the rear end of the log stream 112 and it is not the only log block in the log stream 112, the log block is physically eliminated.