DynamoDB
Efficiency considerations: + FilterExpressions are executed one the items are returned.
Example Code: Complete example, stackoverflow
Building a Mars Rover Application with DynamoDB
Two videos, you will find some solutions there if you really want to make it right [source]: https://www.youtube.com/watch?v=HaEPXoXVf2k https://www.youtube.com/watch?v=DIQVJqiSUkE