RDS vs DynamoDB: when do you choose each?
Options
- RDS is managed SQL; DynamoDB is serverless NoSQL for simple, huge access (Correct option)
- They are identical services that differ only in their price
- RDS is a NoSQL store; DynamoDB is a relational SQL database
- DynamoDB supports joins and complex SQL queries like RDS does
Answer
RDS: managed relational databases (PostgreSQL, MySQL...) with SQL and joins. DynamoDB: serverless key-value/document NoSQL with very high scale and simple access patterns
Why
RDS runs engines like PostgreSQL, MySQL, SQL Server or Oracle for you (backups, patching, failover) while you keep SQL, transactions and joins. Choose it for most business apps.
DynamoDB is a fully managed NoSQL store that scales to huge traffic with single-digit millisecond reads, but you design tables around known access patterns (partition key) and have no joins.
Azure equivalents: Azure SQL / Azure Database for PostgreSQL, and Cosmos DB.
Remember
Relational and flexible queries: RDS. Massive simple key lookups: DynamoDB.