Abstract: A plurality of computers dispersedly store pieces of data and pieces of depository information of the respective pieces of data. The depository information indicates a depository computer storing data of the pieces of data. A first computer of the plurality of computers stores, when depository information of first data is absent in a first storing unit of the first computer, first depository information in the first storing unit. The first depository information indicates the first computer as a first depository computer storing the first data. The first data is stored in a second storing unit of the first computer. The first computer identifies, by searching the first storing unit, a second computer as a second depository computer storing second data to be manipulated in association with third data stored in the second storing unit.

Abstract: A first node is assigned a first data group, and a second node is assigned a second data group. In addition, the second node manages a backup copy of the first data group. The second node receives, from the first node, a log indicating an instruction executed on a data record belonging to the first data group, and stores the received log in a memory of the second node. The second node writes logs for a plurality of instructions accumulated in the memory into a storage device of the second node different from the memory when a predetermined condition is satisfied.

Abstract: A disclosed method executed by a computer includes: receiving measurement data of one measurement device among plural measurement devices; calculating an indicator value that represents a relationship between the measurement data of the one measurement device and measurement data of the plural measurement devices; and transmitting data for changing a transmission frequency of measurement data to at least one of the plural measurement devices, based on the calculated indicator value.

Abstract: A clock determination method executed by a first one of apparatuses included in a system includes receiving a list including first definite clock values of respective apparatuses, the list being circulated among the apparatuses; determining the first clock value of the first apparatus at a point in time based on a smallest of logical clock values regarding corresponding commands on which processing is not completed, the commands being included in commands received by the first apparatus and the logical clock values being obtained at a time of receiving the corresponding commands and being stored, and updating the first clock value, the updated first clock value being included in the list, by using the determined first clock value; specifying, as a second clock value for the system, a smallest of the first clock values included in the updated list; and transmitting the updated list to a second one of the apparatuses.

Abstract: A first node apparatus included in a distributed data store acquires first operation information and a first timestamp corresponding to target data. The first operation information specifies a first operation to be executed on the target data. The first timestamp indicates a first receipt time of the first operation information. The first node apparatus determines whether the first receipt time is earlier than some of second receipt times on the basis of second timestamps and the acquired first timestamp. The second timestamp indicates the second receipt time of second operation information. The second operation information specifies a second operation executed on the target data. The first node apparatus re-executes the second operations together with the first operation on the target data in the order of the receipt time when it is determined that the first receipt time is earlier than some of the second receipt times.

Abstract: A first node apparatus included in a distributed data store acquires first operation information and a first timestamp corresponding to target data. The first operation information specifies a first operation to be executed on the target data. The first timestamp indicates a first receipt time of the first operation information. The first node apparatus determines whether the first receipt time is earlier than some of second receipt times on the basis of second timestamps and the acquired first timestamp. The second timestamp indicates the second receipt time of second operation information. The second operation information specifies a second operation executed on the target data. The first node apparatus re-executes the second operations together with the first operation on the target data in the order of the receipt time when it is determined that the first receipt time is earlier than some of the second receipt times.

Abstract: A disclosed information processing system includes a receiving node and a storing node, the receiving node includes an order information adding unit that adds first order information to operation instructions included in an operation instruction sequence, the first order information indicating an order among the operation instruction sequences and an operation instruction transmission unit that transmits the one or more operation instructions to the storing node, the storing node includes an operation instruction execution unit that executes the operation instructions. Further, upon a receipt of a second operation instruction having the first order information indicating that the second operation instruction is earlier than the one or more first operation instructions, which was already executed, in the first order relationship, the storing node re-executes the first operation instruction after the second operation instruction is executed.

Abstract: A clock determination method executed by a first one of apparatuses included in a system includes receiving a list including first definite clock values of respective apparatuses, the list being circulated among the apparatuses; determining the first clock value of the first apparatus at a point in time based on a smallest of logical clock values regarding corresponding commands on which processing is not completed, the commands being included in commands received by the first apparatus and the logical clock values being obtained at a time of receiving the corresponding commands and being stored, and updating the first clock value, the updated first clock value being included in the list, by using the determined first clock value; specifying, as a second clock value for the system, a smallest of the first clock values included in the updated list; and transmitting the updated list to a second one of the apparatuses.