Streams with initial state

Question

I would like to expose something like a subscription or a "sticky query": the goal is to query DynamoDB and return the results via the WebSockets API in API Gateway. Well, whenever DynamoDB changes in a way the query would be affected (I guess I could use Streams for that) I would like to notify the client(s). How can I make sure the client gets the initial list and all updates? I would like to make sure the client doesn't miss any updates right after the subscription is created and before the initial list of results is returned to it...

Answer 1

To inform your clients about changes in your DynamoDB, DynamoDB Streams could be used. However, the information is only available for 24 hours. Even if you write your updates to a Kinesis Stream , your information will be available for a maximum of 7 days (according to the FAQ )

I suggest splitting your use-case in two:

• Create a service where you return the initial state of your "sticky query"
• Create a stream which will notify your clients about updates to the "sticky query"