@JingJing Gu Thank you for your interest in Azure Cosmos DB.
You can configure your Cosmos databases and containers with Autoscale provisioned throughput
This allows you to set a "autoscale maximum throughput" and Cosmos DB takes care of automatically and instantaneously scaling the RU's until this maximum limit.
The advantage here is that Cosmos DB also automatically scales down when your partitions start experiencing less load.
For example, if you provision a container with Max Throughput (Tmax) of 4000 RU's, Cosmos DB can automatically scale between 400 - 4000 RU/s (0.1*Tmax - Tmax)
You are billed by the hour only for the highest throughput within that hour, saving you significantly in costs.
Detailed documentation is here and FAQ's on Autoscale are here.
Please let us know if you have any further questions.
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