How fast is DynamoDB?

Fast. DynamoDB delivers consistent single-digit-millisecond read and write latency at any scale. Adding DynamoDB Accelerator (DAX), an in-memory cache, cuts eventually consistent reads to microseconds. Performance stays flat as tables grow because reads target a partition key directly rather than scanning, so latency does not degrade with data volume.

Why it stays fast at scale

A GetItem or Query hashes the partition key and goes straight to the right physical partition. It never scans the whole table, so response time is roughly constant whether the table has thousands or billions of items.

Microsecond reads with DAX

DAX is a fully managed, write-through in-memory cache that fronts your table. It returns eventually consistent reads in microseconds — up to a 10x improvement — with no cache-invalidation code to write.

What can slow you down

• Scans and filters — reading the whole table is slow and costly; design key-based access instead.
• Hot partitions — an uneven key distribution throttles one partition while the rest sit idle.

Good key design, not more hardware, is what keeps DynamoDB fast.

Go deeper

Read query vs scan and avoid a hot partition. Download DynoTable to see which reads run as Query vs Scan.