I am using AWS Lambda to host code which fetches data from dynamodb.
The request comes from a client and inturn, the lambda queries and gets the data and sends it back as response.
Does this serve as end of a transaction?
Do we also check about if the response we sent back is consumed or not by the requestor ? If yes, how to go about it in Lambda when its stateless. ( if we need to change the code, and add step function to lambda, i'm still confused if the requestor automatically will send a 200 OK or we should query ?)
That is correct. Lambda returns the response and shuts down (this is good because you save money). If you are concerned about "exactly once delivery", consider using a message queue (eg: SQS, Kafka). Lambda will then publish to a topic and the requestor of data will subscribe to the topic.