Lesson 5: Understanding Data Models and Schemas in Databases

Data Model

High-level constructs describing data storage.

Database Schema

Structure defining data organization in a database.

Relational Data Model

Most common database model based on relations.

Semantic Data Model

Abstract model focusing on data meaning and relationships.

Physical/Internal Schema

Actual storage structure and access paths of data.

Conceptual Schema

High-level structure representing data relationships.

External Schema

User-specific view of the database data.

Levels of Abstraction

Different perspectives on database structure.

Internal Schema Facts

Lowest abstraction level detailing data representation.

Stored Record

ANSI term for physical/internal schema representation.

Data Abstraction

Hiding low-level storage details from users.

DBMS

Database Management System for data manipulation.

File Organization

Method for storing data in a database.

Indexes

Auxiliary structures to speed data retrieval.

Physical Schema

Defines physical storage structure of a database.

Physical Database Design

Process of optimizing physical schema.

Entities

Objects or things stored in a database.

Attributes

Characteristics or properties of entities.

Relationships

Connections between different entities in a database.

Views

Virtual tables computed from database relations.

Data Manipulation Language (DML)

Language for querying and modifying database data.

Three Schema Architecture

Framework for separating database views and storage.

User Access

Customized data visibility for different users.

Database Administrator (DBA)

Responsible for managing database storage structure.

Data Abstraction Levels

Three levels: Physical, Conceptual, External.

Data Independence

Ability to change storage without user impact.

Security

Protection against unauthorized database access.

Performance Impact

Effect of tier separation on database efficiency.

Complexity

Challenges in understanding complete database schema.

Migration

Transitioning to new database environments.

Failure Resilience

Protection against data loss during tier failure.

Auxiliary Data Structures

Support data retrieval and storage efficiency.

Data Types

Classification of data stored in the database.

Storage Structures

Physical arrangement of data in a database.

User Groups

Categories of users with specific data needs.

Customization

Tailoring database access for individual users.