How to set the max number of concurrent Lambda executions?

[moltar]

https://github.com/cdk-patterns/serverless/blob/main/the-scalable-webhook/README.md

Now we have our messages in a queue but we need to subscribe to the queue and insert the records into the DB. To do this we create a throttled lambda where we set the max number of concurrent executions to whatever scale we are happy with. This should be less than the max connections on our DB and should take into account any other Lambdas running in this account.

How does one achieve that?

Thanks