Research On Anomaly Transaction Isolation And Repair Technologies Of Database In Distributed Environment

As the development of distributed computing environments, the data storage security indistributed environments has become a key factor that can not be ignored. And the database systemhas become the first choice to store and process information for people, therefore, in distributedenvironment, the accuracy and completeness of database is of great importance. While, in distributedenvironment, a database can be damaged much easier by malicious transactions, as a result, researchon the security technology of database in distributed environment is very important. The main workand innovations of this thesis are as follows:Firstly, introduce and analysis the related research on the characteristics of distributed computingenvironment, database isolation technology, database repair technology and distributed databaserepair technology, then points out and discusses the existing problems and shortcomings of theseexisting methods.Secondly, in order to achieve efficient restoring of accuracy and consistency of the database afterit has been attacked by malicious transaction in the distributed environment, there presents a RelatedTransaction Graph (RTG) based parallel repair technology for database in distributed environment.First, a related transaction graph model is proposed based on the transaction dependency graph.Second, according to RTG model we present a RTG transaction sequence generating algorithm andparallel scheduling algorithm on master node and a repair algorithm on replica node and then provethe correctness of the technology. Finally, the time cost model of the repair mechanism is given. Theexperiment’s result shows that compared to existing database repair strategies, the operations of whichare serial, this technology has higher repair efficiency.Thirdly, according to the characteristics of distributed environment, a two-level suspicioustransaction isolation mechanism is addressed, which including SIDP, NIDP, STIP and STRP thesefour protocol in system layer and node layer. Then transaction operation execution algorithm andon-the-fly suspicious transaction repair algorithm are proposed after providing the correctness of thesuspicious transation protocol. And the results of the experiments have demonstrated that it has moreefficient suspicious data repair rate and higher data available rate.At last, based on the research on anomaly transaction isolation and repair technologies ofdatabase in distributed environment, a RTG based parallel repairing mechanism and two-levelsuspicious transaction isolation mechanisms are designed and implemented in Grid DBMS namedNHGridDB, which is developed by our researching team. In addition, the design of relevant data structure and specific implementation steps are also illustrated. More, in the suspious transactionisolation mechanism, SQL dynamic modification rule is also addressed.