Database System Concepts: Chapter 2 Outline Quiz

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Questions and Answers

In a client/server architecture, what role does the server play?

Provides services such as file access, printing, archiving, or database access (correct)

Runs application programs and stores business rules

Provides the user with appropriate interfaces to utilize servers

Handles user interface programs and application programs

What is the main function of an application server or web server in a three-tier architecture for web applications?

Runs user interface programs and application programs

Adds an intermediate layer between the client and the database server to store business rules (correct)

Provides services such as file access, printing, archiving, or database access to client machines

Handles query and transaction functionality related to SQL processing

What is the purpose of an Open Database Connectivity (ODBC) in the context of client/server architectures for DBMSs?

Allows client-side programs to call the DBMS through an API (correct)

Adds an intermediate layer between the client and the database server

Handles query and transaction functionality related to SQL processing

Runs user interface programs and application programs

What distinguishes a three-tier architecture from a two-tier architecture in client/server systems?

Adds an intermediate layer between the client and the database server Signup and view all the answers

Which component in a client/server architecture provides the user interface capabilities and local processing?

Client machines Signup and view all the answers

What is the primary function of a printer server in a client/server architecture?

Forwards all print requests by clients to various printers Signup and view all the answers

What is the primary function of a file server in a client/server architecture?

Manages and stores files for client machines Signup and view all the answers

Which of the following correctly describes a centralized DBMS architecture?

Database management tasks are carried out on a single machine Signup and view all the answers

What is the main purpose of database storage reorganization in a DBMS?

Reorganize database files into different file organizations Signup and view all the answers

Which component of a DBMS is responsible for creating backup copies of the database?

Backup and recovery system Signup and view all the answers

In a client/server architecture, what function do communications software perform?

Establish and manage communication channels between clients and servers Signup and view all the answers

What role do CASE Tools play in database management?

Maintain design decisions, usage standards, and user information Signup and view all the answers

Which DBMS language is responsible for specifying user views or mappings to the conceptual schema?

View definition language (VDL) Signup and view all the answers

What is the primary function of a data dictionary system in database management?

Store design decisions, application descriptions, and standards Signup and view all the answers

What task is handled by performance monitoring in database systems?

Monitor database usage and provide statistics to the DBA Signup and view all the answers

Study Notes

Data Models, Schemas, and Instances

Data abstraction: suppression of details of data organization and storage, highlighting essential features for improved understanding of data.
Data model: a collection of concepts that describe the structure of a database, providing means to achieve data abstraction.
Basic operations: specify retrievals and updates on the database, allowing the database designer to specify a set of valid operations allowed on database objects.

Categories of Data Models

High-level or conceptual data models: close to the way many users perceive data.
Low-level or physical data models: describe the details of how data is stored on computer storage media.
Representational data models: easily understood by end users, similar to how data is organized in computer storage.
Entity: represents a real-world object or concept.
Attribute: represents some property of interest, further describing an entity.
Relationship: represents an association among entities.
Entity-Relationship model: describes entities and relationships.

Schemas, Instances, and Database State

Database schema: description of a database.
Schema diagram: displays selected aspects of the schema.
Schema construct: each object in the schema.
Database state or snapshot: data in the database at a particular moment in time.
Define a new database: specify the database schema to the DBMS, initial state, and valid state.
Schema evolution: changes applied to the schema as application requirements change.

Three-Schema Architecture and Data Independence

Internal level: describes the physical storage structure of the database.
Conceptual level: describes the structure of the whole database for a community of users.
External or view level: describes part of the database that a particular user group is interested in.
Data independence: capacity to change the schema at one level of a database system without having to change the schema at the next higher level.
Logical data independence: changes to the conceptual schema do not affect the external schema.
Physical data independence: changes to the internal schema do not affect the conceptual schema.

Database Languages

Data definition language (DDL): defines schemas.
Storage definition language (SDL): specifies the internal schema.
View definition language (VDL): specifies user views/mappings to conceptual schema.
Data manipulation language (DML): allows retrieval, insertion, deletion, and modification.
High-level or nonprocedural DML: can be used on its own to specify complex database operations concisely.
Low-level or procedural DML: must be embedded in a general-purpose programming language.

The Database System Environment

DBMS component modules: buffer management, stored data manager, DDL compiler, interactive query interface, query compiler, query optimizer, and precompiler.
Runtime database processor: executes queries and updating commands.
System catalog: stores metadata about the database.
Concurrency control system: manages concurrent access to the database.
Backup and recovery system: provides backup and recovery capabilities.

Database System Utilities

Loading: load existing data files into the database.
Backup: creates a backup copy of the database.
Database storage reorganization: reorganize a set of database files into different file organizations.
Performance monitoring: monitors database usage and provides statistics to the DBA.

Centralized and Client/Server Architectures for DBMSs

Centralized DBMSs architecture: all DBMS functionality, application program execution, and user interface processing carried out on one machine.
Client/Server architecture: separates the functionality into clients and servers.
Two-Tier Client/Server Architectures: client handles user interface programs and application programs, server handles query and transaction functionality related to SQL processing.
Three-Tier and n-Tier Architectures: adds intermediate layers between the client and the database server.

Classification of Database Management Systems

Data model: Relational, Object, Hierarchical and network (legacy), Native XML DBMS.
Number of users: Single-user, Multiuser.
Number of sites: Centralized, Distributed, Homogeneous, Heterogeneous.
Cost: Open source, Different types of licensing.
Access path options: general or special-purpose.

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Description

Test your knowledge on data models, schemas, database languages, system architectures and more based on Chapter 2 of Database System Concepts and Architecture. Explore topics like Three-Schema Architecture, Centralized and Client/Server Architectures, and Database Management Systems Classification.