DynamoDB Provisioned

• Provisioned the following
  • RCU (Read capacity units): throughput for read
    • Because of read replicas, we have 3 mode:
      • Strongly Consistent Read
        • we will get consistent read all the time
        • set ConsistentRead parameter to True in API calls (GetItem, BatchGetItem, Query, Scan)
        • Will consume 2 RCU per read
      • Eventually Consistent Read (default):
        • possible we get outdated data if we read right after write
      • Transactional: See DynamoDB Transactions
    • 1 RCU = 1 strongly consistent read or 2 eventually consistent read and can read 4KB
      • For example:
        • 10 strongly consistent reads per second 4 KB : 10 RCUs
        • 16 Evetually consistent reads per seconds with item size 12KB:
          • 8 * 3 = 24 RCU
        • 10 strongly consistent reads with 6 KB per item:
          • 10 * 2 = 20 RCU
          • We round 6KB to 8KB per item
  • WCU (Write capacity units): throughput for writes
    • 1 write per request for an item up to 1 KB in size
    • Have 2 modes:
      • Standard
      • Transactional: DynamoDB Transactions that is single or nothing
      • Example:
        • if have 6 items per second with 4.5KB per item:
          • 6 * 5 = 30 WCU
• Option to setup auto-scaling of RCU and WCU to meet demand by providing
  • min, max, target utility (%)
• Throughput can be exceeded temporarily using Burst Capacity
  • If Burst Capacity is exhausted, you will get ProvisionedThroughputExceededException
  • See DynamoDB Throttling