Research On User-typed Type And Object-Relation Technology In Dameng Database System

With the change of application, Traditional relational database management system in the face the great challenge of the "non-classical" areas appeared to be inadequate. To meet the need, the function of UDT is added to DM5 which is the practical database system researched and developed by ourselves. Meanwhile , we do research of the Complex Object which is the core concept of the object-relational technology , so that we gradually make DM5 extend to object-relational database.The overall strategy of DM5 expansion of object-relational database is the integration of two strategies. As the result of the two strategies integrated, on one hand, one packaging layer put on the kernel of DBMS server is used to deal with the usual object data. On the other hand, some special functions such as supporting Complex Objects are implemented by extending the kernel of system.The design and realization of UDT is as below. We implement the single UDT based on the built-in data type and the structured UDT, even the reference to the UDT, and the structured UDT can be inherited or nested by the other structured UDT. The logical information of UDT is inserted into the new dictionary table, and the object identifier make up of identifier of one table and identifier of one item.The search of Complex Object is as below. Above the analysis of the component information of the complex object, we design and implement the forms and manifestations of complex object in all . In these manifestations, we target the expression of the links precisely and clearly. The strategy of object management is object buffer and object gathered. In order to manage the object buffer, we use the object buffer group. We make the application of hierarchical complex object aggregation strategy to DM5, so that we scan effectively the layers of the tables.