Azure Cosmos DB shares some optimization tips in this short video.

A well-planned partitioning strategy will optimize database reads and writes, enabling you to achieve great speed at any scale with Azure Cosmos DB. In under two minutes, you’ll gain an understanding of how partitioning works, why it’s critical to performance as your database scales, and how to select the best key for your database. 

Learn more about partitioning strategy:

Do you need to change a partition key you’ve already defined in a collection (or collections)?

Program manager Theo van Kraay shows how an account with Azure Cosmos DB Core (SQL) API can change partition keys using change feed.

If you’re new to partitioning, watch this video first: https://youtu.be/oqk41KY6rhA.

For more about partitioning with Azure Cosmos DB, visit: https://docs.microsoft.com/en-us/azure/cosmos-db/partition-data