Can lambda know the specific attribute which changed in the dynamo db table update, when a lambda is triggered by dynamo db table update item??


My client has an architecture to trigger a lambda whenever the dynamo db table is updated. However, my client needs to perform a check on the specific attribute which changed. The lambda payload gives the new and old image. However the lambda should compare and check what changed between the old and new image in order to proceed to the next step. In this case, is there any way the lambda can know which specific attribute changed when an item is updated in a dynamo db ?

asked 9 months ago294 views
1 Answer

Yes, if you configure your DynamoDB Stream to emit NEW_AND_OLD_IMAGES then the Lambda can see the before and after of the update. You will then have to decide in your application logic which values where changed by comparing the OLD_IMAGE to the NEW_IMAGE

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answered 9 months ago
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reviewed 9 months ago
  • To maybe add to that: the way we do this comparison is by using jsonpatch which is a standardized way of representing the diff between two JSON objects. It is also available in a lot of languages.

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