Choosing a Data Store

The decision the exam asks most often. Access pattern before product: S3 and the lake, Redshift and the warehouse, DynamoDB for key-value at scale, RDS and Aurora for relational workloads, and the specialised stores — with the constraints (latency, query shape, cardinality, cost at rest) that eliminate the wrong three.

Content current as of 2026-10.

Lessons

  1. Access pattern decides the store
  2. S3 as the data lake
  3. Redshift and the warehouse
  4. DynamoDB, RDS, and Aurora
  5. The specialised stores

Sources