DCIT 55 Advanced Database Management Systems Reviewer: Lecture 1

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Questions and Answers

What is the purpose of a database system?

Improve hardware performance

Secure data transmission

Run queries on data (correct)

Format data for the end user

What is the difference between data and information?

Data has meaning to the end user, information does not. (correct)

Data is unstructured facts, and information is structured facts.

Data is processed facts, and information is raw facts.

Data is useful facts, and information is raw facts.

What is one role of a Database Management System (DBMS)?

Improve Data Integration (correct)

Hinder Decision Making

Impair Data Sharing

Decrease Data Security

What is a Single User Database most likely to support?

One user at a time Signup and view all the answers

Which type of database is suitable for a specific department in an organization?

Workgroup Database Signup and view all the answers

How does a DBMS contribute to end-user productivity?

Empowers end users to make quick informed decisions Signup and view all the answers

What is a centralized database?

A database located at a single site Signup and view all the answers

What is the main characteristic of the Relational Model?

It consists of a collection of tables Signup and view all the answers

What is data modeling?

The process of creating a data model for a specific problem domain Signup and view all the answers

What is the 'Variety' dimension in Big Data?

The fact that data comes in multiple formats Signup and view all the answers

What is the primary characteristic of a Cloud Database?

It is created and maintained using cloud services Signup and view all the answers

What is the 'Velocity' dimension in Big Data?

The speed at which data grows and needs to be processed Signup and view all the answers

Which backup method involves saving only the data that has changed since the last backup?

Incremental backups Signup and view all the answers

What is the purpose of the checkpoint facility in a database system?

To permanently write updates to the database Signup and view all the answers

Which backup method involves saving only the data that has changed since the last full backup?

Differential backups Signup and view all the answers

What is the role of the transaction log in a database system?

To keep track of changes to the database Signup and view all the answers

What is the purpose of the checkpoint process in a database system?

To ensure that all changes are permanently written to the database Signup and view all the answers

Which component of a database system is responsible for restoring the database to a reliable and steady-state after any failure occurs?

Recovery manager Signup and view all the answers

What does the INSERT INTO command do in a database?

Inserts new data into a database Signup and view all the answers

Which SQL command creates a new index?

CREATE INDEX Signup and view all the answers

What is an Equijoin in a relational database?

A join based on a related column between them Signup and view all the answers

How does a Natural Join work?

By joining tables based on all columns with the same name Signup and view all the answers

Which SQL command deletes a table?

DROP TABLE Signup and view all the answers

What does ALTER DATABASE command do in a database?

Modifies a database Signup and view all the answers

What is the role of a recovery manager in a database system?

To perform point-in-time recovery and rollback/rollforward operations Signup and view all the answers

What happens when a system crash occurs in a database system?

The recovery manager initiates crash recovery procedures Signup and view all the answers

What is a temporary update problem in the context of database failures?

When a transaction makes temporary updates and then rolls back due to a transaction abort or failure Signup and view all the answers

What is a lost update problem in a database system?

A concurrency control issue in multi-user systems due to concurrent data modification Signup and view all the answers

What is an unrepeatable read problem in a database system?

A phenomenon that occurs due to concurrent transactions Signup and view all the answers

Which of the following is a common type of database failure?

All of the above Signup and view all the answers

Study Notes

Database System

A software system used to store, retrieve, and run queries on data
A systematic collection of data, which is raw facts or unprocessed data
The database system provides improved data sharing, data security, data integration, decision making, and end-user productivity

Types of Databases

Single User Database: supports only one user at a time
Multi-user Database: supports multiple concurrent users
Workgroup Database: a multiuser database that supports fewer than 50 users, used for a specific department
Enterprise Database: represents the overall company data, supporting present and expected future needs
Centralized Database: stored at a single site
Distributed Database: stored in two or more physically independent sites
Cloud Database: created and maintained using cloud services such as Microsoft Azure or Amazon AWS

Data Modeling and Data Model

Data Modeling: the process of creating a specific data model for a determined problem domain
Data Model: a representation (usually graphic) of a complex “real-world” data structure

Evolution of Data Models

Hierarchical Model: uses a hierarchical tree structure to organize the data
Network Model: a database model conceived as a flexible way of representing objects and their relationships
Relational Model (Edgar F. Codd): a relational database consists of a collection of tables, each assigned a unique name

Big Data

Volume: refers to the amounts of data being stored
Velocity: refers to the speed with which data grows and the need to process it quickly
Variety: refers to the fact that data is collected in multiple different formats

Database Backup and Recovery

Backup Facilities

Full Backups: backing up the entire database at a specific point in time
Incremental Backups: backing up only the data that has changed since the last backup
Differential Backups: backing up only the data that has changed since the last full backup

Checkpoint Facility

Allows updates to the database to be made permanent and secure from vulnerability
Transaction Logs: used to keep track of changes to the database

Recovery Manager

Allows the database system to restore the database to a reliable and steady-state after any failure
Point-in-Time Recovery: restoring the database to a specific point in time
Rollback and Rollforward Operations: undo or redo changes made by incomplete or partially committed transactions
Crash Recovery: initiates crash recovery procedures to bring the database back to a consistent state

Database Failures

File Corruption: data corruption in a database file
File System Damage: damage to the file system that stores the database
Software and Hardware Failure: failure of software or hardware components that support the database

Problems in Database Systems

Temporary Update Problem: a scenario where a transaction makes temporary updates to the database and then rolls back those updates
Incorrect Summary Problem: aggregated or summarized data becomes inaccurate due to updates, deletions, or insertions of individual records
Lost Update Problem: a concurrency control issue that occurs in multi-user database systems
Unrepeatable Read Problem: a phenomenon that occurs in database systems with concurrent transactions

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Description

This quiz covers the fundamentals of Data and Database Administration, including definitions of Database System, Database, Data, and Information. It also discusses the roles of DBMS in improving data sharing. A useful tool for reviewing key concepts before examinations.