Composite Primary Key

Question 1

DynamoDB - Composite Primary Key

Answer 1

How a Primary Key with a Partition and Sort Key Chooses Which Partition

Question 2

New Data Example

Answer 2

Alien: Romulan

Example sentence

Question 3

Primary Key Structure

Answer 3

Partition Key: Alien
• 1 to 255 characters, case sensitive
Sort Key: Name (optional)
• 1 to 255 characters, case sensitive

Question 4

Important Points

Answer 4

The combination of Partition Key and Sort Key must be unique.
DynamoDB’s Internal Hash Function is a secret, and we have no idea how the algorithm decides which partition to write data

Question 5

Partition Distribution

Answer 5

Partition A:
• Alien: Cardassian, Name: Dukat
• Alien: Cardassian, Name: Dumar
Partition B:
• Alien: Klingon, Name: Worf
• Alien: Klingon, Name: Kor
Partition C:
• Alien: Romulan, Name: Tomalok
• Alien: Romulan, Name: Toreth
• Alien: Romulan, Name: Valdore

Question 6

Key Concepts

Answer 6

When using a Sort Key, the records with the same Partition Key are kept together and sorted A-Z by the Sort Key

Key concept explanation