Currently, I utilize an AWS endpoint that returns a small JSON response based on my request.
I am considering updating all of my records (300,000+) daily.
My AWS counterparts can generate a JSON file of all records in S3 which I could then GET through a rest call at which point I am thinking I could parse the response with batch apex. However, I am concerned I will run into heap size, CPU processing, transaction or other governor limits.
The other approach I have considered is having a client access Salesforce through the Bulk API and upsert the records in this way.
What is the best practice for this many records?
I have read through the update mass records documentation: https://help.salesforce.com/articleView?id=000267082&language=en_US&type=1