Lecture Notes: Introduction to Databases and Database Management Systems (DBMS)

Overview

• Introduction to databases and the role of Database Administrators (DBAs).
• Cloud Engineers and Architects often suggest databases rather than working in-depth with them.
• Importance of performance testing to switch databases if needed.

Definition of a Database

• Database: An organized collection of structured information stored electronically.
• Data is refined and stored in a database by organizations.

Database Management System (DBMS)

• DBMS: Software providing an interface for users/applications to interact with stored data.
  • Functions include retrieving, updating, managing, and organizing data.

Types of DBMS

• Relational DBMS (RDBMS): Known as SQL databases.
• Non-relational DBMS: Known as NoSQL databases.
• Examples:
  • Relational: MySQL, PostgreSQL, Oracle.
  • Non-relational: Cassandra, MongoDB, DynamoDB (AWS).

Characteristics of Relational Databases

• Data is stored in tables; relationships between different data attributes.
• Schema: Structure of data storage defined before data entry.
  • Altering the schema post-data entry is complex.
• Primary Key: Uniquely identifies each data entry, usually set before data entry.

SQL and NoSQL Databases

• SQL: Used for relational databases, involves structured query language.
• NoSQL: Stores unstructured/semi-structured data, often in key-value pairs or JSON format.

AWS Relational Database Service (RDS)

• RDS: AWS service to manage databases, reducing administrative overhead.
• Offers easy scaling, backup, recovery, and disaster recovery.
• Supports both relational (SQL) and non-relational (NoSQL) databases.

RDS Deployment Strategies

• Multi-AZ Instance Deployment: Provides active-passive setup for backup and disaster recovery.
• Multi-AZ Cluster Deployment: Provides active-active setup with multiple reader instances to split the load and improve performance.

Backups and Read Replicas

• Automatic and Manual Backups: AWS manages lifecycle of automatic backups; manual backups stay until deleted.
• Read Replicas: Used to scale read-heavy workloads and for disaster recovery.
  • Data replication to read replicas is asynchronous.

Hands-On Demo

• Creating a Database with AWS RDS: Use of MySQL in a private subnet.
• Bastion Host: Used to access the RDS instance securely.
• DB Management Tool: Usage of DBeaver for database operations.

Key Points to Remember

• Always define schema before data entry in relational databases.
• The importance of primary keys for data integrity.
• The use of bastion host for secure database access.
• Practice SQL commands for effective database management.

Additional Recommendations

• Study basic SQL for better understanding of database operations.
• Explore AWS documentation for deeper insights into RDS and DBMS functionalities.