SQL vs NoSQL: Fetching All records in DynamoDB vs SQL Database

I am designing database for a project which requires frequent querying of all the records. The total number of records will be less than 500K. One of the databases I am considering is AWS DynamoDB where scan operation meant for this is very inefficient. What I fail to understand is whether it is inefficient in a SQL based database or there is one better than other for frequent calls for fetching all records.