Is DynamoDB still following CAP theorem with its "Strong Consistency" promises?

amazon amazon-dynamodb key-value consistency availability
Neeraj Gupta picture Neeraj Gupta · Sep 6, 2015 · Viewed 7k times · Source

Previously, DynamoDB was providing "eventual consistency" only, obeying "Availability" and "Partition Tolerance" portion of CAP theorem.

But now, DynamoDB provides "strong consistency" option apart from the "eventual consistency". Does that mean DynamoDB is not following CAP theorem?

Answer

Charles Duffy picture Charles Duffy · Sep 6, 2015

DynamoDB, in strongly consistent mode, trades against availability:

When you issue a strongly consistent read request, DynamoDB returns a response with the most up-to-date data that reflects updates by all prior related write operations to which DynamoDB returned a successful response. A strongly consistent read might be less available in the case of a network delay or outage. For the GetItem, Query or Scan operations, you can request a strongly consistent read result by specifying optional parameters in your request.

Thus, it violates no theoretical constraints.

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