1. 1 Welcome : To the third learning sequence “ DB ACTORS “ Present learning: We shall explore the following topics: - DB limitations. - DB actors. - DB Administrator. Recap : In the previous learning sequence, we discussed the: - What is DB & DBMS. - Advantages of DBMS.

2. 2 DB limitations The decision to use a DBMS for company’s information needs as critical as decision to introduce computer in the first time. The commission to DBMS in costly because it represent a large commitment in term of money and human resources. The limitations are:

3. 3 DB limitations 1- Complexity : The DBMS is a complex piece of software, it requires DB experts both to look after it and also to design and develop the database. 2- Cost : comprehensive DBMS are expensive to purchase and give rise to additional overhead when in operation.

4. 4 DB limitations 3- Inefficiencies : By no means a database system is inefficient, but what is meant here that in large systems, whenever weakness appear even though it is simple, the maintenance of such weakness will take a considerable time. 4- Rigidity : The most current DBMS, where designed to manage a particular type data ( for example, fixed length record ).

5. 5 Database Actors A primary goal of a database system is to retrieve information from and store new information in the database. People who work with a database can be categorized as database actors ( users ).

6. 6 Database Actors 1- Database Administrators: - authorizing access to the database. - coordinating and monitoring its use. - acquiring software and hardware resources as needed - Schema definition.

7. 7 Database Actors 2- Database Designers: - identifying the data to be stored in the database. - choosing appropriate structures to represent and store this data undertaken before the database is actually implemented and populated with data. - communicate with all prospective database users. - develop a view of the database that meets the data and processing requirements for each group of users

8. 8 Database Actors 3- End Users: Access to the database for querying, updating, and generating reports. 3.1- Casual end users: - occasionally access the database. - need different information each time. - learn only a few facilities that they may use repeatedly. - use a sophisticated database query language to specify their requests - typically middle- or high-level managers or other occasional browsers

9. 9 Database Actors 3.2- Naive or parametric end users: - constantly querying and updating the database, using standard types of queries and updates called canned transactions that have been carefully programmed and tested. - need to learn very little about the facilities provided by the DBMS.

10. 10 Database Actors 3.3- Sophisticated end users: - Engineers, scientists, business analysts, and others who thoroughly familiarize themselves with the facilities of the DBMS so as to implement their applications to meet their complex requirements. - Try to learn most of the DBMS facilities in order to achieve their complex requirements.

11. 11 Database Actors 3.4- Stand-alone users: - Maintain personal databases by using ready-made program packages that provide easy-to-use menu or graphics-based interfaces. An example is the user of a tax package that stores a variety of personal financial data for tax purposes. - Typically become very proficient in using a specific software package.

12. 12 Database Actors 4- System Analysts and Application Programmers: - Determine the requirements of end users, especially naive and parametric end users, and develop specifications for canned transactions that meet these requirements. - Application programmers implement these specifications as programs; then they test, debug, document, and maintain these canned transactions

13. 13 Database Actors 5- Workers behind the Scene: - Typically do not use the database for their own purposes. - DBMS system designers and implementers. - design and implement the DBMS modules (for implementing the catalog, query language, interface processors, data access, concurrency control, recovery, and security. ) and interfaces as a software package.

14. 14 Database Actors 6- Tool developers: - Tools are optional packages that are often purchased separately. - include packages for database design, performance monitoring, natural language or graphical interfaces, prototyping, simulation, and test data generation.

15. 15 Database Actors 7- Operators and maintenance personnel: - system administration personnel who are responsible for the actual running and maintenance of the hardware and software environment for the database system.

16. 16 Database Actors The Data Base Administrator ( DBA ) is the person (or group of person) responsible for overall control of the database system. DBA will require a number of utility programs to help on this job such as: - Loading Routines ( to create the database ). - Reorganizing Routines (to rearrange space occupied by deleted data). - Journaling Routines ( to note each operation against the database, together with identification of the user performance ). - Recovery Routines ( to restore the database to an earlier state after hardware software failure). - Statistical Analysis Routines ( to assist in monitoring performance ). - Data Dictionary ( the most important tool used by DBA – it is data about data ).

17. 17 Summary : In this learning sequence, we discussed the following: - DB limitations. - DB actors. - DBA tools.

18. 18 END