DynamoDB guarantees durability and reliability. When a write operation has been made, it has already been replicated in three AZs in less than a second. DynamoDB provides customers with the full control of the consistency model when reading data.

If your application can tolerate inconsistent state you can perform queries with eventually consistent reads, which can return stale data under high concurrency scenarios.

For applications that need to be consistent at all times, you can configure queries to be strongly consistent. As a result, every user will have the same view of data under any circumstance.

This applies for GetItem, Query, and Scan operations, take into account that eventually consistent reads cost half of a strong consistent read.