Serverless lambda rest api not updating database properly

Question

I am invoking my lambda REST api to update tables in dynamo db but it only updates the database after the second time its invoked. e.g - 1st call I post "some data" to lambda api it doesn't do anything but 2nd call I post "other data" it will process the first call I made("some data"). If I call lambda the third time then it will process "other data". If I wait between 1st and 2nd call the "some data" is lost and never processed. 
Everything works fine when I run the server locally. I am using api-gateway, lambda and express serverless-http packages. I have tried logging before and after the db calls are made looks like the code is executing but the database is not updating. What am I doing wrong?

Accepted Answer

As you are using node.js I think the issue is that the function returns before the function finished updating the database. Once the function returns, the Lambda execution environment is frozen and it will be unfrozen when the next request is received.

You should either update the DB using a synchronous mode, i.e., use `await` when updating the DB, or make sure that the `context.callbackWaitsForEmptyEventLoop` is set to `true`. See more information [here](https://docs.aws.amazon.com/lambda/latest/dg/nodejs-handler.html).

Serverless lambda rest api not updating database properly

Relevant questions

Return a custom header from lambda authorizer in API-gateway (HTTP api)

How to use postgres rest api in AWS

ApiGateway REST not respecting Lambda alias