Patent ID: 8131679

Claim:
A control method for a computer system having a computer and a storage system connected to the computer, the computer having an input module for receiving transaction execution instructions, a processor for executing received transaction execution instructions, and a memory connected to the processor, the control method comprising: receiving, by the input module, a first transaction execution instruction designating an update to a set of data that is stored in the storage system; setting, by the processor, an attribute to indicate a locked state for a first data unit included in the set of data designated by the transaction execution instruction, the locked state for the first data unit indicating that operations on the first data unit by transaction execution instructions other than the first transaction execution instruction are restricted; storing, by the processor, an update log corresponding to execution of the first transaction execution instruction in a log buffer maintained in the memory connected to the processor; and upon the input module receiving a transaction completion instruction to complete the update designated by first transaction execution instruction, modifying, by the processor, the attribute from indicating the locked state to indicating a partial exclusive state for the first data unit, the partial exclusive state for the first data unit indicating that reference operations on the first data unit by transaction execution instructions are restricted and update operations on the first data unit by transaction execution instructions are not restricted, wherein modifying the attribute to indicate a partial exclusive state is performed by the processor upon a transaction completion log indicating completion of the first transaction execution instruction being stored in the log buffer; upon storage of the transaction completion log indicating completion of the first transaction execution instruction in the storage system, modifying, by the processor, the attribute to indicate an unlocked state for the first data unit, the unlocked state for the first data unit indicating that operations on the first data unit by any transaction execution instructions are not restricted; upon receiving a second transaction execution instruction designating a reference to the first data unit and a set of a reference permission attribute for the first data unit, executing, by the processor, the second transaction execution instruction without waiting until the attribute is modified from indicating the partial exclusive state for the first data unit to indicating the unlocked state for the first data unit.