问题
I can't seem to find the documentation on what kinds of events DynamoDB is able to trigger a lambda function based on. All I can find is mentions of when a new record is added to a table or a record is updated. Are those the two "only" actions/events available? Or could I also trigger a lambda function when I request a records that does not exists (which is what I need in my case, where I will be using DynamoDB as a cache)?
回答1:
Triggering a Lambda function automatically because somebody queried for a key that doesn't exist is not supported by DynamoDB. You would have to handle that in your querying code.
回答2:
Triggering AWS Lambda through events happening in DynamoDB is done by utilizing DynamoDB Streams.
As stated in the documentation:
DynamoDB Streams captures a time-ordered sequence of item-level modifications in any DynamoDB table, and stores this information in a log for up to 24 hours.
So they only capture operations which modify data, which isn't the case for read operations.
来源：https://stackoverflow.com/questions/46936182/what-event-can-be-triggered-to-fire-a-lambda-function-in-dynamodb