DynamoDB partition splitting for high throughput table

Question

I am trying to understand DynamoDB partitioning behaviour in a specific circumstance. I'd like to know what will happen to my partitions if my read/write throughput exceeds 3000 RCU or 1000 WCU for a single partition (assuming I have very popular item(s) getting queried/written). Say on this partition, only a single partition key is present (with many values holding different sort keys). I'd like to know what Dynamo's behaviour is when my usage rises above 3000 / 1000. Will DDB automatically split the partitions into two smaller ones? Where can I find documentation about this specific circumstance?

Thanks

Answer 1

DynamoDB automatically supports your access patterns using the throughput you have provisioned, as long as the traffic against a given partition key does not exceed 3000 read capacity units or 1000 write capacity units. (Source)

It does not support more than 3000 RCU or 1000 WCU per partition key, so if you are exceeding that, some of your requests for that partition key will be throttled.

If you need to write more than 1000 WCU, you can use write sharding. If you need to read more than 3000 RCU, you can create a GSI that is an exact copy of the table to distribute your reads, or it’s a good use case for using DAX.