Lesson 2: Understanding Database Systems and Their Types

Single-user database

Supports only one user at a time; a single-user database that runs on a personal computer is called a desktop database.

Multiuser database

Supports multiple users at the same time.

Workgroup database

A multiuser database that supports a relatively small number of users (usually fewer than 50) or a specific department within an organization.

Enterprise database

Used by the entire organization and supports many users (more than 50, usually hundreds) across many departments.

Centralized database

A database that supports data located at a single site.

Client/server architecture

Systems that use one or more client nodes directly connected to a central server.

Global clock

A clock of the central node that all client nodes sync up with.

Central node

One single central unit which serves/coordinates all the other nodes in the system.

Dependent failure of components

Central node failure causes the entire system to fail.

Components of Centralized System

Includes Node (Computer, Mobile, etc.), Server, and Communication link (Cables, Wi-Fi, etc.).

Client-Server architecture

The central node that serves the other nodes in the system is the server node and all the other nodes are the client nodes.

Centralized System

Single server node manages all data and requests.

Decentralized Database

Each node independently decides, aggregating overall behavior.

Hot Updates

Updates applied without taking the server offline.

Vertical Scaling

Adding resources to a single node for performance.

Peer-to-Peer Architecture

All nodes are equal, with no central authority.

Master-Slave Architecture

One node coordinates others without supreme control.

High Availability

Multiple nodes ensure continuous system operation.

Performance Bottlenecks

Reduced by distributing load across multiple nodes.

Concurrency of Components

Nodes reach consensus on transactions and commands.

Independent Failure

Nodes fail without affecting overall system functionality.

Distributed Database

Data stored across multiple sites for redundancy.

Google Search System

Multiple computers collaborate to return search results.

Cluster Computing

Multiple computers work together as a single entity.

Grid Computing

Pooling resources to create a powerful supercomputer.

Organisations Using Centralized Systems

National Informatics Center, IBM.

Organisations Using Decentralized Systems

Bitcoin, Tor network.

Data Analysis

Simplified when data is centralized.

Operational Database

Supports daily operations; also called transactional database.

Data Warehouse

Stores data for tactical and strategic decision-making.

Data Massaging

Data manipulation to extract useful information.

Unstructured Data

Data in original raw format, not organized.

Structured Data

Formatted data for storage and information generation.

Semistructured Data

Processed data presented in a prearranged format.

XML (Extensible Markup Language)

Language for representing and manipulating data elements.

Database Design

Activities focused on structuring a database.

Manual File Systems

Paper-based systems organized for data use.

Computerized File Systems

Digital files requiring programming for data retrieval.

Data

Raw facts with little meaning until organized.

Field

Character group with specific meaning in data.

Record

Set of fields describing a person, place, or thing.

File

Collection of related records.

ACID Properties

Ensures reliable database transactions.

Atomicity

All operations in a transaction must succeed.

Consistency

Database rules maintain stability before and after transactions.

Isolation

Transactions operate independently without interference.

Durability

Changes persist after transaction completion.