Functions of DBMS Data Definition and storage management; Data Manipulation, Data Access; Data Security and integrity; Transaction management, Data recovery and concurrency; Data dictionary; Schema:描述数据库中的数据结构(逻辑设计) Instance:某一时刻对数据库照的一张相(该时刻具体的数据) Data Models(重点...
Since relational DBMSs are wide-spread, providing a relational global view for users who are only familiar with the relational model to access data in a multidatabase system is significant. However, the prior work on schema integration can not efficiently capture the relationships among relations ...
Thedata object number identifies the segment (data objectAAAPecinExample 12-1). A data object number is assigned to every database segment. Schema objects in the same segment, such as atable cluster, have the same data object number.(前五位指向object numer。) FFF The tablespace-relativedata ...
We provide a clear separation of the type and class hierarchies of the external schema from those of the conceptual schema. This approach allows for better and cleaner modularization of information systems built on top of object-oriented databases. In this paper, we concentrate on the mechanisms ...
What is a Relation Schema?A relation schema describes the structure of the relation, with the name of the relation(name of table), its attributes and their names and type.What is a Relation Key?A relation key is an attribute which can uniquely identify a particular tuple(row) in a ...
Meng et al., “A Theory of Translation From Relational Queries to Hierarchical Queries,” IEEE Transactions on Knowledge and Data Engineering, Apr. 1995, vol. 7(2): pp. 228-245. Halevy et al., “Schema Mediation in Peer Data Management Systems,” IEEE Proceedings of the 19th International...
(shown in storage226). The database227is representative of any collection of data regardless of the particular physical representation. By way of illustration, the database227may be organized according to a relational schema (accessible by SQL queries) or according to an XML schema (accessible by...
there was an enormous growth in Business Intelligence databases. Now the Third Normal Form design had to include Star Schema design. Then there came the data warehouse appliances – proprietary boxes like Greenplum (now part of EMC) and Netezza (now part of IBM). They had their own nuances....
With correctly designed metaclasses, it is possible to let the developer manage the reengineering of a relational schema inside an object-oriented database =-=[5]-=-. Now, a system like Pclos [12, 13] provides to the developer transparent and systematic links between the two worlds. It ...
User view means a view of part or all of the contents of a database specified to facilitate a particular purpose or user activity. It is a partial and/or redefined description of the logical schema of the database [22]. The PPI definition is based on the user view of the monitoring sy...