Distributed And Parallel Database System Dpsql Consistency Mechanism

Database is the state and progress of some phenomena in the real world.The data in database must be consistent for its right reflection of the realworld. Any interruption in the updating process or any other wrong proceduremay cause data inconsistency. The key element to ensure the data consistencyis to make the updating sequence clear, its called transation.So, any accessing and updating operation to the database can beconsidered as an atomic operation called transaction. Transaction applies all-or-nothing principle. When customers order an operation to database,transaction must ensure that it can lock the related data for its own operation.When transaction is running, it must log running states which will be usedwhen the database need a recovery. Using transaction, it also needs to apply"two-phrase-commit"protocol for any database update to guarantee theconsistency of database.DPSQL is a distributed and parallel database system which is being self-developed by 8010 Lab, UESTC. There are two problems about dataconsistency in the implementation of DPSQL.If DPSQL use double-log mechanism, the transaction log of InnoDB and SQL log of DPSQL might be inconsistent.If DPSQL use the standard two-phrase-commit protocol, it might cause inconsistency because of the rocking problems of transaction commit.The conception of consistency used in this paper is only refered to theabove two problems.Based on hard research work, this paper first analyses the transactionmechanism of InnoDB, then it introduces the distributed transactionmechanism of DPSQL, especially the implementation of distributedtransaction log. DPSQL system applies an adapt two-phrase-commit (2PC)...