Methods, apparatus, and system to provide access to a blockchain computer system as a service to a non-blockchain computer system through an application programming interface, wherein the application programming interface is configured through a portal computer and wherein application programming interface calls are implemented by an application programming interface processing computer.

A blockchain based data management method performed by a computing device according to an embodiment of the present disclosure includes recording a deletion event for off-chain data and time information of the deletion event in a blockchain network, and selectively deleting the off-chain data based on a validity verification result calculated for the time information, wherein the validity verification result is calculated using a time-consensus algorithm of the blockchain network.

Example implementations herein can be used to build, maintain, and access databases built database in multi-core computing systems with large VRAM and huge NVRAM. The database with optimistic concurrency control can be built on a transactional key-value data store that includes logically equivalent data pages stored in both VRAM and VRAM. Data records in volatile data pages in the VRAM represent the most recent version of the data. Data records in the NVRAM immutable and are organized in a stratified composite snapshot. A distributed log gleaner process is used to process entries corresponding to transactions on the volatile data pages and construct the snapshot. The log gleaner sorts the log entries by epoch, key range, and most recent use to partition the snapshot across multiple nodes.

Systems and methods are provided for leveraging blockchain technology in a swarm learning context, where nodes of a blockchain network that contribute data to training a machine learning model using their own local data can be rewarded. In order to conduct such data monetization in a fair and accurate manner, the systems and methods rely on various phases in which Merkle trees are used and corresponding Merkle roots are registered in a blockchain ledger. Moreover, any claims for a reward are challenged by peer nodes before the reward is distributed.

A system for memory synchronization of a multi-core system is provided, the system comprising: an assigning module which is configured to assign at least one memory partition to at least one core of the multi-core system; a mapping module which is configured to provide information for translation lookaside buffer shootdown for the multi-core system leveraged by sending an interrupt to the at least one core of the multi-core system, if a page table entry associated with the memory partition assigned to the at least one core is modified; and an interface module which is configured to provide an interface to the assigning module from user-space.

A concurrency control method of database transaction combining an optimistic lock and a pessimistic lock includes: integrating a lock in each fragment in a storage range, using a lock table globally, and recording a lock status of the each fragment in the lock table; before reading a data object of a fragment in the storage range, first querying in the lock table whether the data object of the fragment is locked by other reading-writing transactions; if the data object of the fragment is locked by other reading-writing transactions, blocking the current reading operation, and repeating the current reading operation, and if the current reading operation is blocked for more than a given time limit, since the pessimistic lock is invalid, intervening by the optimistic lock, and continuing reading the single row data of the current fragment.

A method of transferring data between database locations comprising: providing a location reference comprising location values of one or more data collections stored in a database; providing an indicator in association with at least one data collection of the one or more data collections, the indicator being provided in response to initiation of a transfer process of the at least one data collection from a first location of the database to a second location of the database; wherein the indicator is changeable between a first state and a second state, the first state being indicative of the initiation of the transfer process; and as part of the transfer process of the at least one data collection, selectively updating a location value of the at least one data collection in the location reference, in dependence on a determination of whether the indicator is in the first state or the second state.

A system and method for multi-master synchronous replication optimization, which comprises one device in a system is chosen as insert leader during insert. The insert leader allocates a range of rows (row_ids) to the incoming queries. If the query inserts more records than the range, it is rolled back. During the commit, the row_id range and the new records are sent to other masters for conflict checking. The present disclosure scalability and a throughput of the system is increased because of optimistic concurrency based replication.

A method includes: repeatedly executing a first processing configured to generate, in response to input of conversion examples of values set, a conversion program for converting values of records, convert the values of the records by executing the conversion program, and display a conversion result; and executing a second processing configured to select one or more second records from the records, each of the one or more records being a record on an upper side of a first record, the first record being a record for which a conversion example is added in second or subsequent input, determine whether a value of each second record is changed in a latest conversion result from a previous conversion result, and in response that a value of the second record is changed, cause the first processing to highlight a value of the second record in display of the latest conversion result.

Disclosed herein are methods, systems, and apparatus, including computer programs encoded on computer storage media, for enabling blockchain-based service of process. One method includes: receiving a request generated based on a blockchain-based application for delivering a notice associated with a legal action from a serving party to another party. The serving party is determined to be a registered user of the blockchain-based application. A time that the request is received is recorded on the blockchain. If the party to be served is determined to be a registered user of the blockchain-based application, identifying one or more manners of delivering the notice based on available communication methods included in the registration information of the serving party and registration information of the party to be served. The notice to the party to be served is determined based on at least one of the one or more manners.