Summary: https://www.udemy.com/course/aws-certified-cloud-practitioner-new/learn/lecture/20260728

• Contents:

Databases 101

Ref: https://www.udemy.com/course/aws-certified-cloud-practitioner-new/learn/lecture/20118314

• DBs allow you to give some structure to your stored data, making it easily searchable/queryable
  • Define schemas, indexes, and relationships in your dataset
  • 💡 Like taking a raw text and creating a table of contents, numbered pages, highlighting sections, marking pages, taking notes… makes it easier to find stuff!

Relational Databases = SQL Databases = Relational DB Management Systems (RDBMS)

• 🔧 Rigid schemas and tables, defined rows (items) and columns (attributes)
  • Can use SQL (Structured Query Language) to query tables
• Relational tables are very similar to Excel spreadsheets, with links between them!
• Examples
  • Open source: MySQL, PostgreSQL, MariaDB…
  • Proprietary: Oracle SQL, Microsoft SQL Server…
• Two main optimization types
  • Row-based = OLTP (OnLine Transactional Processing) → optimized for transactions
    • e.g. Amazon RDS, Amazon Aurora
  • Column-based = OLAP (OnLine Analytical Processing) → optimized for analytics
    • e.g. Amazon Redshift

Non-relational Databases = NoSQL Databases

• 🔧 Less rigid, more flexible schemas
  • ‼️ Can NOT use pure SQL!! (some NoSQL DBs can use SQL-like languages)
  • ❗ Scale better than SQL DBs (but have less consistency)
• Examples
  • Document DBs (e.g. MongoDB)
    • Can for example store documents in JSON format
  • Graph DBs (e.g. Amazon Neptune)
  • key-value DBs (e.g. Amazon DynamoDB)
    • Example of DDB table (Primary Key + Attributes)
  • …

Databases in AWS

• Can always run DB programs/SW inside an EC2 instance…
  • ❗ But you have to manage that instance! It's usually a lot of admin overhead!
• Recommended: use AWS-managed DB services
  • 👍 Quick provisioning, HA, vertical/horizontal scaling
  • 👍 Automated backups/restores
  • 👍 Patches & updates handled by AWS
  • 👍 Easy integrations with monitoring, alerting, and other AWS services
  • 👎 Less control than your own, managed DB

AWS SQL Database Services

• Amazon RDS (Relational Database Service):
  • Row-based, OLTP, free-tier eligible
  • Private service → deploys RDS instances in your VPC, which host a SQL engine of your choice (PostgreSQL, MariaDB…)
  • Optional features:
    • Read Replicas (RRs) → allow for Read scalability (can read from more than one instance, distributes Read operations across many instances)
    • Multi-AZ deployments → allow quick failover to a different AZ → HA