Chapter 2: Database System Concepts and Architecture - VOCABULARY flashcards

Vocabulary flashcards covering key terms from the lecture notes on database system concepts, architecture, data models, schemas, independence, languages, and architectures.

Database approach

A centralized repository of data defined once and shared by multiple users through queries and application programs; emphasizes self-describing DBMS, data abstraction, and multiuser access.

Traditional file processing

An approach where each application defines and uses its own files, leading to data redundancy and duplicated maintenance.

Self-describing nature of a DBMS

The database system stores metadata that describes the data structure, enabling the DBMS to interpret the data.

Insulation between programs and data

Separation of application programs from data storage to protect data from changes in programs and to enable data abstraction.

Data abstraction

Hiding details of data organization and storage to highlight essential features, allowing different users to view data at different levels of detail.

Multiple views

The ability to present different perspectives of the same data to different users or applications.

Sharing of data

Concurrent access to data by multiple users and programs from a common repository.

Multiuser transaction processing

Support for concurrent transactions by multiple users while preserving data consistency and integrity.

Data model

A collection of concepts that describe the structure of a database and its basic operations.

Schema

Description of a database’s structure, including its objects and associations; often represented by a schema diagram.

Instance

A particular state of the database; the data currently stored in the database.

Database state

The data in the database at a specific moment in time; essentially a snapshot of the instance.

Schema diagram

A visual representation of a database schema showing entities, attributes, and relationships.

Schema evolution

Changes applied to the schema as application requirements change.

Three-Schema Architecture

An architecture with Internal (physical), Conceptual (global logical), and External (user view) levels, plus mappings between levels.

Internal level

Describes the physical storage structure of the database and access paths.

Conceptual level

Describes the overall logical structure of the database for a community of users.

External level (view level)

Describes the portion of the database relevant to a particular user or group.

External view

The user-specific perspective or subset of the database provided to a user or group.

External/Conceptual mapping

Mapping from external views to the conceptual schema.

Conceptual/Internal mapping

Mapping from the conceptual schema to the internal storage schema.

Data independence

Ability to change one level of a database system without requiring changes at higher levels.

Logical data independence

Ability to change the conceptual schema without changing external schemas or applications.

Physical data independence

Ability to change the internal storage without changing the conceptual or external schemas.

DBMS languages

Languages used to define, manipulate, and control data in a DBMS (e.g., DDL, DML, DCL, TCL, SDL, VDL, QDL).

DDL (Data Definition Language)

Language used to define data and storage schemas.

SDL (Storage Definition Language)

Language that specifies the internal schema and how data is stored on disk.

DML (Data Manipulation Language)

Language that allows retrieval, insertion, deletion, and modification of data.

DCL (Data Control Language)

Language used to control access to data and enforce permissions.

TCL (Transaction Control)

Language used to manage transactions (commit, rollback, etc.).

VDL (View Definition Language)

Language that defines user views and their mappings to the conceptual schema.

QDL (Query Definition Language)

Language that defines queries or query operations.

SQL

Structured Query Language; a master language that integrates many DBMS subsystems.

SQL Injection (SQL Insertion Hack)

Attack exploiting unsanitized inputs to inject or alter SQL commands, potentially causing data loss or leakage.

ODBC (Open Database Connectivity)

API enabling client applications to call a DBMS; requires software on both client and server.

JDBC (Java Database Connectivity)

Java API that allows Java programs to access DBMSs through a standard interface.

Two-tier client/server architecture

Server handles SQL processing; client provides user interface and application programs.

Three-tier and n-tier architectures

Architecture with an application server between client and database server, often including a web server and multiple layers.

Centralized DBMS

DBMS architecture where all processing runs on a single machine (mainframe model).

Client/server architecture

Architecture where clients request services from dedicated servers; servers host DBMS and data services.