Cheat sheetAWS-04

Databases

AWS SAA / Databases

Separate availability (Multi-AZ) from scalability (read replicas), and match the workload to the right engine.

MAZ
RDS Multi-AZSynchronous standby for automatic failover; does NOT serve reads.
RR
Read replicaAsync copy to scale reads; not an automatic failover target.
DDB
DynamoDBServerless NoSQL, single-digit-ms latency, massive scale.
EC
ElastiCacheIn-memory Redis/Memcached fronting a DB for hot reads.
⚑

Use read replicas to offload reporting; use Multi-AZ purely for failover.

Read-heavy reportsPoint analytics at read replicas so the primary handles writes.
Cart at scaleDynamoDB for millisecond latency and a flexible schema at any volume.
Multi-AZ: sync standby, auto-failover, no reads
Read replica: async, scale reads, promote manually
ElastiCache: cache-aside for repeated hot queries
rdsauroradynamodbelasticachemulti-azread-replica
review in 6d