Design And Implementation Of The Data Migration System For GBase

The development of database with independent intellectualproperty is an important step for our information industry. There isurgent requirement of it in national defence and e-government.TheGBase system is a homemade database with independent intellectualproperty ,which nanda general company and a graduate schoolupgrade by their database product archetype. The data migrationsystem(DMS) that this paper introduces is one of basic peripheraltools of GBase database system,which has important meaning ofupdating the information systems and popularizing the wholedatabase product. Most database manufacturer has afforded their data migrationtools.for example the InfoMover of Informix,the data transfer system ofMicrosoft SQL Server,the Oracle Warehouse Builder and so on;In thethird party's product,the DataStage of Ascential Software companyand the SwisSQL of AdventNet company have offerded data migrationin the various mainstream database.And the migrations offerded bythese products applies to their self-database produce or themainstream database in the world.So there is great requirement todesign the data migration system that fit the property of GBase. This DMS of GBase has consulted the functions of the populardata migration tools in the market,such as the DMS of Microsoft SQLServer and DB2.This paper has analyzed various data types of thosedatabase,and contrasts those types with the data types of GBase.Thesystem uses object oriented programming method,and have muchefficiency with lowest error rate.While migrating a million rows,There isno error took place in the system which provide the credible log.Thesystem is friendly,flexible, practical and.same with migration demandof various databases. The migration system uses the middle-database model,whichdescribes various data types of database with middle language(eg.Java).The information of database will be transmitted into themiddle-database from the source database,and the data structure willbe established in the aim database with the information of themiddle-database.The middle-database just transmit and save theinformation of the database,and data dictionary only contain therelation define and field define except the real data.The system is programmed with Java and can steadily run inmany platforms.The migration system includes five importantmodules:Interface module provides the interface and controls the workflow;JDBC drive module tests the usability of JDBC drivers;Userconnection module tests the connection of the migration system anddatabase syatem.Mapping module automatically maps the databasetypes and JDBC types .Structural extracted module transfers theinformation from the source database to the middle-database.SQLsentence prepared module provides the SQL sertences that othermodules need.Data transfer module gets the data from the sourcedatabase and inserts the data to the aim database.One feature of the system is automatically maps the data types forany database that provides the JDBC driver.The system can map thedatabase types and JDBC types,diminish differences of them,andautomatically work out various range of the database types andparticular information of precision.The automatically mapping willprovide the reference for users.User can modify the mapping for theirparticular demands, and form the most suitable mappings formigration.Using the automatically mapping can decrease the error rateand easily find the problem.Another feature of the system is making choice in various SQLsertences.There are lots of defferences of SQL syntax in the databasewith which dealt in the migration.Since the whole SQL syntax is toocomplex to input by user,the system has contrasted the SQL syntax inthe database in the demand and reference the standard SQL syntax tofind the least intersection.So the system will be more current andfriendly.The migration system has been tested in detail in many platformand compared with other native system.The results of test andcomparison verified that the system can successfully migrateschemas,tables,columns,views and data.The validity and efficiency ofthe system can achieve the level of the native system.There is some work remained to improve and implement,for thatsystem is just the first version and time is restricted.In the function,themigration system can not migrate the stored produce/function betweenthe different databases.And that problems need a lot of workload andhave too much technical difficulty.The native migration systems do nothave successful solution on those cases. The system also has otherproblem,such as can not transfer some restricts of table andview.Those problems will be improved in the next version.In theperformance,the system programs with Java,which make less efficientthan that with C++.Some optimize arithmetic will be added in thesystem to enhance the efficiency of the migration system.