DBMS Components and Functions

Questions and Answers

What is the term for the independence of data structures and storage organization from DBMS access programs?

Physical data independence

Logical data independence

Program-data independence (correct)

Data abstraction

What is the capacity to change the physical schema without having to change the conceptual or logical schema?

Program-data independence

Physical data independence (correct)

Data abstraction

Logical data independence

What is the primary function of a recovery subsystem in a DBMS?

Transaction execution

Data abstraction

Concurrency control

Ensuring each completed transaction has its effect permanently recorded (correct)

What allows hundreds of concurrent transactions to execute per second in OLTP?

Concurrency control Signup and view all the answers

What is the term for presenting users with a conceptual view of the database, hiding storage details?

Data abstraction Signup and view all the answers

What is the result of using a data model to hide storage details?

Programs refer to data model constructs Signup and view all the answers

What is the benefit of supporting multiple views of the data?

Each user sees a different view of the database, describing only the data of interest to that user Signup and view all the answers

What is the primary function of the DBMS in supporting multiple views of the data?

To present users with a conceptual view of the database Signup and view all the answers

What is the term for allowing a set of concurrent users to retrieve from and update the database?

Multi-user transaction processing Signup and view all the answers

What is the primary characteristic of OLTP?

Allowing hundreds of concurrent transactions to execute per second Signup and view all the answers

Study Notes

DBMS Components

A DBMS consists of several subsystems, each responsible for a specific function.
It interacts with the operating system to manage and access data.

Functions of DBMS

Defines a database in terms of its data types, structures, and constraints.
Constructs or loads the initial database contents on a secondary storage device.
Manipulates the database through retrieval (querying, reporting, and accessing through Web applications) and update (insertions, deletions, and modifications).
Processes and shares data among concurrent users and application programs while maintaining data validity and consistency.
Provides security measures to prevent unauthorized access.
Presents and visualizes data.
Performs system and software maintenance of the database and associated programs.

Users Interaction with Databases

Users interact with databases through their applications, which are programs that utilize the data stored in a database.
Applications generate queries (retrieval) and update transactions (insert, delete, modify) that access different parts of the data.

Database Applications

Applications must not allow unauthorized users to access data and must keep up with changing user requirements.
Applications interact with a database by generating queries and update transactions.

Advantages of Using the Database Approach

Controls redundancy in data storage and development and maintenance efforts.
Represents complex relationships among data and provides storage structures for efficient query processing.
Provides backup and recovery services.
Restricts unauthorized access to data.
Shares data among multiple users.
Optimizes queries for efficient processing.
Enforces integrity constraints on the database.
Provides multiple interfaces to different classes of users.

Additional Implications of Using the Database Approach

Enforces standards.
Reduces application development time.
Provides economies of scale across applications and departments.
Offers flexibility to change data structures.
Makes current information available.

Database Users

Database Administrators (DBA): authorize access, coordinate, control, and monitor database use, acquire software and hardware resources, and monitor efficiency.
Database Analysts and Designers: define content, structure, constraints, and functions or transactions against the database and communicate with end-users.
Database Application Developers: write application programs, including system analysts, application programmers, and business analysts.
Database End-users: use data for queries, reports, and updates.

Database Characteristics

Insulation between programs and data: allows changing data structures and storage organization without changing DBMS access programs.
Logical data independence: allows changing conceptual or logical schemas without changing requirements representations and associated application programs.
Physical data independence: allows changing physical schema without changing conceptual or logical schema.

The Three-Levels Mapping

Main Characteristics of the Database Approach
Data Abstraction: a data model is used to hide storage details and present a conceptual view of the database.
Support of multiple views of the data: each user sees a different view of the database, which describes only the data of interest to that user.