When developers experienced with relational databases first learn DynamoDB, they are shocked by two things. First, there is no JOIN. Second, you must decide how you will query the data first, then design the table accordingly — the exact opposite order from RDBMS. In this day, we understand why Amazon created Dynamo (the predecessor of DynamoDB) in 2007, how the core idea of partitioning and consistency model work internally. With this principle understood, DVA-C02 DynamoDB problems solve themselves without memorization.