We ummed and ahhed for a while over this. We definitely wanted a tight structure and relatability between tables which points towards SQL. The Aurora Serverless was a strong contender as it allows easy access from node via the aws-sdk. However we liked the very easy scalability of DDB, and most of the persistence work was executing on single entries containing a lot of fields which lends itself well to DDB. There are very few cases where we need to select a large list of items, and any complex queries are neatly scriptable in AppSync resolvers in Velocity. Going for Document over SQL was a very fundamental decision which has shaped how a lot of the API, and therefore the product, functions.