DynamoDB Atomic Counters

Greetings!

I have an application that utilizes a DynamoDB table to manage counters. When we update the value of the counter, we consume the returned value - this returned value is the old value of the counter. This counter is then used to retrieve a value in an array, it is effectively an index.

I currently increment these counters with Lambda functions - it's highly likely that many Lambdas may attempt to update the value of a given counter at the same time. It's important that each Lambda function receives a different value of the counter.

Utilizing DynamoDB atomic counters, can I expect that each Lambda function will receive a different value for the counter?

Example:

• 10 Lambdas attempt to update value of a counter where its current value is 0
• The Update Expression is "ADD count :incr" where ":incr" is 1
• Each Lambdas update is processed
• The returned value from each update is unique per Lambda and the values are 0 - 9
• The final value of the counter is 10