Database Management System Course Material
- 1. Course Code – Course name Unit – 1 : Session – 6 : SLO -1 SRM Institute of Science and Technology 1
- 2. DBMS Architecture • 2-tier DBMS Architecture • 2-tier DBMS architecture includes an Application layer between the user and the DBMS, which is responsible to communicate the user's request to the DBMS and then send the response to the user from the DBMS. • An application interface known as ODBC(Open Database Connectivity) provides an API that allow client side program to call the DBMS. • Client application – on which remote database users work. • Server application – on which the database system runs.
- 3. DBMS Architecture • 3-tier DBMS Architecture • The objective of the three level architecture is to separate each user's view of the database from the Way the database is physically represented. • In a 3-tier architecture, the client machine acts as a front end application and does not contain any direct database calls. • Instead, the client end communicates with an application server, usually through a forms interface.
- 5. DBMS System Structure • A primary goal of a database system is to retrieve information from database and store information into the database. • People who work with a database can be categorized as database users or database administrators. • Different types of user interfaces have been designed for the different types of users. • There are four different types of database- system users can be classified.
- 6. DBMS System Structure • Naive users Any user who does not have any knowledge about database. There task is to just use the developed application and get the desired results. • Application programmers are computer professionals who write application programs. They can choose many tools to develop user interfaces. • Sophisticated users interact with the system without writing programs. Instead, they form their requests either using a database query language or by using tools.
- 7. DBMS System Structure • DBA (Database Administrator) • DBA can be a single person or it can be a group of person. • Database Administrator is responsible for everything that is related to database. • He makes the policies, strategies and provides technical supports.
- 8. DBMS System Structure • Query Processor Components • DML Compiler • It translates DML statements into low level instructions(Binary language) that query evaluation engine understands. • Embedded DML Pre-compiler • It converts DML statements to normal procedure calls. The Pre-compiler must interact with the DML compiler to generate the appropriate code(host language).
- 9. DBMS System Structure • DDL Interpreter • It interprets the DDL statements and records them in a set of tables containing meta data or data dictionary. • Query Evaluation Engine • It executes low-level instructions generated by the DML compiler. • Storage Manager Components • They provide the interface between the disk storage and query processor. • Authorization and Integrity Manager • It tests for the satisfaction of integrity constraints checks the authority of users to access data.
- 10. DBMS System Structure • Transaction Manager • It ensures that the database remains in a consistent state despite the system failures and that concurrent transaction execution proceeds without conflicting. • File Manager • It manages the allocation of space on disk storage. • Buffer Manager • It is responsible for fetching data from disk storage into main memory and deciding what data to cache in memory.
- 11. DBMS System Structure • Disk Storage • Data Files • It stores the database files(Binary format) • Data Dictionary • It stores meta data (data about data) about the structure of the database. • Indices • Provide fast access to data items that hold particular values. • Statistical Data • It stores statistical information about the data in the database. This information is used by query processor to select efficient ways to execute query.
- 12. Database Administrator • Coordinates all the activities of the database system; the database administrator has a good understanding of the enterprise’s information resources and needs. • Database administrator's duties include: – Schema definition – Storage structure and access method definition – Schema and physical organization modification – Granting user authority to access the database – Specifying integrity constraints – Acting as liaison with users – Monitoring performance and responding to changes in requirements