Primary Keys

Option 1: Partition key only

• partition key must be unique for each item

• partition key must be "diverse" so that the data is distributed

• Example: user_id for a users table

  

Option 2: Partition key + Sort Key

• the combination must be unique
• data is grouped by partition key
• sort key == range key
• Example: users-games table

  • user_id for the partition key

  • game_id for the sort key

    

Provisioned Throughput

• Read Capacity Units (RCU): throughput for reads
• Write Capacity Units (WCU): throughput for writes
• Throughput can be exceeded temporarily using "burst credit"
• If burst credit are empty, you'll get a "ProvisionedThroughputException"
• exponential back-off retry

Write Capacity Units

• 1 WCU = 1 write/second for 1 item up to 1 KB
• Example:
  • write 10 objects per seconds of 2 KB each ⇒ 2 * 10 = 20 WCU
  • write 6 objects per second of 4.5 KB each ⇒ 6 * 5 = 30 WCU (4.5KB rounded ⇒ 5KB)
  • write 120 objects per minute of 2KB each ⇒ 120 / 6 * 2 = 4 WCU