Amazon suggests to not include big libraries/dependencies in lambda functions.
As far as I know, SQLAlchemy is quite a big python library. Do you think it is a good idea to use it in lambda functions? An option would be to include it as a Lambda Layer and use it across all related Lambda functions.
Anyways, what is the best practise?
Serverless functions are meant to be small self-contained functions. SQLAlchemy is an ORM, which allows you to manipulate database objects like objects in python. If you're just writing a few serverless functions that do you're average CRUD operations on a database you're better off writing the SQL by composing the strings and directly executing that through your database driver (which you'll have to install anyways, even if you're using sqlalchemy). If you're building your own framework on top of AWS Lambda then perhaps consider sqlalchemy.
Is it a good idea to use Python SQLAlchemy in AWS Lambda?