title: DynamoDB and computed columns: Run Lambda on GetItem / Query request but before data is returned to caller
body: <p>Is it possible to run a Lambda function as part of a <code>GetItem</code> / <code>Query</code> request? I plan to use some kind of computed colum that I would like to update before the value is returned to the caller. The current idea is to do this with a Lambda function and DynamoDB Streams. Up to know, I kind of missed the part in the docs where I can specify the exact moment when the Lambda is executed (before, after fetching data). Of course, I am open for better ideas!</p>