In putSessionItem and in blob service we use a different approach

request.AddItem(
      DeviceSessionItem::FIELD_CHECKPOINT_TIME,
      Aws::DynamoDB::Model::AttributeValue(
          std::to_string(item.getCheckpointTime()))

We call AttributeValue instead of calling SetN method. Could you clarify which approach is correct and make sure to be consistent?

Is it safe to save uint64_t by using this method? In the documentation you linked I can't see that this method has this (or long long) variant. So it looks like we're going to cast the value to int - we should definitely fix that.

Is it safe to save uint64_t by using this method? In the documentation you linked I can't see that this method has this (or long long) variant. So it looks like we're going to cast the value to int - we should definitely fix that.

What's wrong with storing it in the dynamo as a string?

I think we should always work with strings when dealing with dynamo DB, even GetN returns a string.

The first thing is what Tomek mentioned about numeric data types - doesn't look safe.
Another thing is: is there a method that would return a number when fetching from the database?

I thought that the point why we have SetS and SetN while the function returns and gets string: it's because of how DynamoDB stores it. If we call SetN it will cast and store the value as a 64-bit integer.

But when I dig into it I've found that SetN is a simple helper to convert the numbers to the string... And this comment confirms this too.

That's why there is no any point to use SetN anywhere.
I've switched to the default AttributeValue which is SetS inside....