AWS Database Services
Identify AWS database services
What you will learn
- Distinguish relational (SQL) databases from NoSQL in terms of data structure and use.
- Choose between RDS and DynamoDB based on data shape and query pattern.
- Explain Aurora's core advantage over standard RDS engines.
- Explain why a caching layer (ElastiCache) is added on top of an existing database.
Choosing a database isn't "which is better" but "which fits my data's shape and query pattern." Data with complex relationships (orders, customers, invoices) suits relational, while very large-scale data with simple, predictable access patterns (a user session, an event counter) suits NoSQL.
The core services
| Amazon RDS | Managed relational databases (MySQL, PostgreSQL, and others) — AWS manages patching and backups, the customer manages schema and queries. |
|---|---|
| Amazon Aurora | An engine AWS built itself, compatible with MySQL/PostgreSQL, with much higher performance and availability via distributed storage. |
| Amazon DynamoDB | A serverless NoSQL database with consistent, low-latency response regardless of data size or load volume. |
| Amazon ElastiCache | An in-memory caching layer (Redis or Memcached) added on top of any database to speed up repeated reads. |
RDS vs. DynamoDB
| Amazon RDS | Amazon DynamoDB | |
|---|---|---|
| Data structure | Tables, relations, and SQL | Key-value pairs or documents, no complex relations |
| Server management | An underlying database server the customer partly manages (schema, queries) | Fully serverless — no instance to manage at all |
| Scaling as data grows | Needs planning for larger capacity at significant growth | Scales out automatically with no manual intervention |
What matters on the exam
- "Complex relationships between tables" points to RDS/Aurora, and "consistent latency at massive scale" points to DynamoDB.
- Aurora is not an entirely new engine — it's compatible with MySQL/PostgreSQL interfaces, so an app written for either usually runs on it with no major change.
Caching complements a database, it doesn't replace it
ElastiCache does not store data durably and does not substitute for a real database — it's used to speed up repeated reads of the same data already stored in RDS or DynamoDB, and to offload the primary database.
Quick check
Answer in your head first, then reveal.
Which service suits data with complex relationships?Reveal the answer
Amazon RDS (or Aurora).
What is Aurora's core advantage?Reveal the answer
Much higher performance and availability with full MySQL/PostgreSQL compatibility.
Does ElastiCache replace the need for a durable database?Reveal the answer
No — it only complements it to speed up repeated reads.
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Sources
Used to verify the facts. The writing is original to Passuit.