Which of the following is an example of a good DynamoDB hash key?

Answer options:

A.Book Title
B.International Standard Book Number (ISBN)
C.Book Author
D.Book Language

Answer: B
DynamoDB best practice states that a hash key should have high cardinality to avoid hot partitions.
Option A is incorrect because there could be many books with the same title. ISBN is a better choice.
Option B is CORRECT because ISBN is a high cardinality attribute as it uniquely identifies each book.
Option C is incorrect because an author can have many books published. Therefore, this is a low cardinality attribute resulting in a hot partition.
Option D is incorrect because there are many books published in any single language. This is a low cardinality attribute resulting in a hot partition.
Reference:
https://docs.aws.amazon.com/amazondynamodb/latest/developerguide/bp-partition-key-uniform-load.html