Support ScannedCount on DynamoDb Document Model

[ithielnor]

Describe the feature

Expose ScannedCount on Amazon.DynamoDBv2.DocumentModel.Search

Use Case

I need to query a dataset to obtain a count of records that match a specific filter, and additionally execute another query to count all those records that do not match the same filter. This is supported with Count and ScannedCount on the low-level QueryResponse but the document-model and object-model do not expose ScannedCount at all.

Proposed Solution

Add a new read-only property ScannedCount to the Search class. Get should return GetScannedCount() which can be functionally similar to the existing GetCount(). Both GetCount() and GetScannedCount() should cache the Count and ScannedCount to avoid duplicate requests when both are needed.

Other Information

No response

Acknowledgements

• I may be able to implement this feature request
• This feature might incur a breaking change

AWS .NET SDK and/or Package version used

AWSSDK.Core 3.7.10.13
AWSSDK.DynamoDBv2 3.7.3.28

Targeted .NET Platform

.NET Framework 4.7.2

Operating System and version

Windows 10

[ithielnor]

I've made a quick stab at implementing the proposed solution above.

I'm somewhat confused by CollectResults which appears to be an internal property for disabling the caching of results on Matches. I've refactored the GetNextSet and GetCount to no longer consider CollectResults for caching the count.

[ashishdhingra]

ScannedCount appears to be supported in response by Query and Scan service API operations. This needs review with the team.