| Concept | Description |
|---|---|
| Read Capacity Units (RCU) | One read capacity unit (RCU) represents one strongly consistent read per second, or two eventually consistent reads per second, for an item up to 4 KB in size. |
| Write Capacity Units (WCU) | One write capacity unit (WCU) represents one write per second for an item up to 1 KB in size. |
| Mode | On-Demand | Provisioned (default) | Provisioned with AutoScaling |
|---|---|---|---|
| Capacity Settings | ❌ None | Specify Read Capacity Units (RCU) and Write Capacity Units (WCU) | Define lower and upper capacity limits & target utilization percentage |
| Scaling Behaviour | Instantly handles up to double previous traffic peak | All Provisioned capacity is available | Scales capacity to handle traffic increases and decreases maintaining target utilization. |
| Throttling Behavior | Requests may be throttled if new peak is more than double previous within 30 minutes | Requests throttled if provisioned capacity is exceeded | Very short bursts may be throttled. Scales in response to changes in load testing in few mins. |
| Cost Consideration | Set amount for each read and write. Able to evaluate cost per transaction. | Set rate for provisioned capacity. - Overall costs may be lower if you have steady, consistent traffic. |
Same as Provisioned. |
| Use Case | Unknown workload, unpredictable application traffic, pay-per-use. | Predictable application traffic & capacity requirements, Consistent traffic. | Same as Provisioned. |