The Key Technology Research Of Data Synchronization On Heterogeneous Database

With the development of information technology, the application of database is more and more extensive. But due to the constant expansion of the enterprise and the differences between the chosen development environment and database software which cause the heterogeneity of data storage. In order to ensure the consistency of the data among all the nodes, it is necessary to integrate heterogeneous databases. Because of the continuous changes of data, it is necessary to synchronize the heterogeneous database. How to realize the data exchange between these heterogeneous databases and finally to achieve the data synchronization between heterogeneous databases has great significance.The synchronization process of heterogeneous database mainly includes capture of changeable data, data transformation and data synchronization.Firstly, it analyses the advantages and disadvantages of the current changeable data capture methods, and presents an improved method- the combinations of triggers, control tables and timestamps. It needn?t to require any alteration in the original database table, and it only needs to create CRUD triggers for each synchronization table, and to create a containing timestamp control table in the database. This method has utility. The control table stores the primary key values of changeable table and some control information, it greatly saves the storage space. Because all the DML operations on the table will activate the corresponding trigger, “oscillation” will arise in the process of synchronizing data updates. Therefore, the design of the trigger is required to determine whether the current operation is synchronous data update operation. If it is, the trigger is executed; otherwise, the trigger is not executed.Then, analyzing the existing data transformation technology of heterogeneous data determine the use of XML technology to achieve heterogeneous data transformation. XML technology can be performed in many incompatible systems and databases for data transformation which greatly reduce the complexity of the data exchange. When the relational data is converted into a XML document, the data needs to be preprocessed. The purpose of preprocessing is to remove redundant data, generate the smallest set of data and reduce the transmission of data.Finally, the converted XML document is transmitted to the target database through the Web Services in order to achieve synchronization. Web Services has the characteristics of platform independence and loose coupling, which is suitable for the different applications.