Fundamentals of Database _Assignment

Questions: 1. Which account is designated as the owner of a relation? What privileges does the owner of a relation have?2. How is the view mechanism used as an authorization mechanism?3. Discuss the types of privileges at the account level and those at the relation level.4. What are the main reasons for and potential advantages of distributed databases?5. What additional functions does a DDBMS have over a centralized DBMS? Answers: 1. With respect to some specific relation, an owner account is the user account that have all controls over that relation. Owner can have maximum privileges on the relation. An owner of the relation can have the following privileges, Selection Modification Referencing With respect to that relation. 2. With respect to a database, a view is a set of records from a query and is represented as a virtual relation. It is not a part of the physical schema of the database, rather it is a virtually calculated set of records those are processed dynamically from the database. Views can also be used in access control mechanism. These can be used to grant access limits on some relation for multiple users. For example, in an office, there will be payroll information of all employees. Now, the accountant have access to the payroll relation. CEO is an employee, so the payroll information of the CEO will also be in the payroll relation. But an account should not have access control to all payroll information of the CEO. Thus, view will be used to separate the access control on the same physical relation payroll. It will give different level of access control on the data of the payroll relation. 3. Granting privilege is related to the concept of authorization of the identifier for some user account. A user will have some set of access restrictions to some relations of the database. When the user will need to access some relation, the system will check for the set of relations and access controls that have been granted previously to that user, if it matches, then the user will have access to the requested information from some relation. Assignment of privileges to some user can be any of the two types. Those are, Account level The DBA of the database will set the privileges in this level. The privileges will be effective independently to each of the relations of the database. Relation level Again the DBA will set the privileges to relations or views of the database. 4. Distributed databases works based on some network. The potential advantages of distributed databases are, It is easier and more flexible for development of applications. It performs better. It is scalable. 5. The additional features of distributed database over the same in centralized database are, It keeps track of distribution, replication and fragmentation of data. It supports distributed query processing over a network. It supports distributed transaction management, data replication management, distributed recovery management. There is distributed catalog management. The overall complexities of the above features is lesser in distributed database compared to centralized databases. References Cellary, W., T. Morzy, E. G. (2014). Concurrency Control in Distributed Database Systems. Elsevier. Elmasri, R., Navathe, S. B. (2013). Fundamentals of Database Systems. Pearson . Mullins, C. S. (2013). Database Administration: The Complete Guide to DBA Practices and Procedures. Addison-Wesley Professional. zsu, M. T., Valduriez, P. (2011). Principles of Distributed Database Systems. Springer. Rahimi, S. K., Haug, F. S. (2010). Distributed Database Management Systems. John Wiley Sons. Silberschatz, A., Korth, H. F., Sudarshan, S. (2011). Database System Concepts (6th ed.). McGraw-Hill.