DynamdoDb M payload latency anomaly

The tests were performed on Heroku private-l dyno running in Virginia, United States, Heroku region against a DynamoDb table in us-east-1 AWS region. The DynamoDb table had 10_000 RCU/WCU provisioned read/write capacity. For each request body "shape", the test was performed 1000 times. Rate of requests was limited at 2 per second to avoid server-side request throttling. The test measured time to execute HTTPS POST request, i.e. time to construct payload body is not part of the reported average execution time.

Test results test-2022-02-18.log (times are UTC)

Payload shape	Average time, ms	Payload description
payload_m_100wcu_277kb.json	63.586	map, 100 WCUs, 277 KB body size
payload_b_100wcu_136kb.json	14.094	binary, 100 WCUs, 136 KB body size
payload_b_204wcu_277kb.json	19.685	binary, 204 WCUs, 277 KB body size

CloudWatch Put latency during the test execution:

Test sources (as of 2022-02-18)

• Test loop testPutItem
• HTTPS POST dynamoRest
• Payload payloadM_100_WCU