Understanding Partitioning in Azure Cosmos DB

If you thinking of using Azure Cosmos DB for your applications, you’ll need to understand how partitioning works to ensure that you don’t suffer from performance issues such as throttling. By having an effective partitioning strategy, we can ensure that our Cosmos databases can meet the performance requirements of that our applications demand. But how does partitioning work in Cosmos DB?

In order to scale containers within a database that meets the performance requirements that our applications needs, Cosmos DB uses partitioning. Items in our containers are divided into logical partitions which are based on partition keys that we associate with each item in a container.

Say if we have a story container that holds individual news stories and we have a partition key for news category and there are 10 unique values for a news categories, there will be 10 logical partitions created for story container.

Along with a partition key, each item in a container has a item ID with is unique within a logical partition. The item index is this value combined with the partition key.

As you can probably guess from our introduction, choosing a partition key is vital to our application’s performance. So let’s have a look at some strategies that we can employ to ensure that we pick an effective partition key:

• As I mentioned in my previous blog post about throughput in Cosmos DB, requests to the same partition key can’t exceed the amount of throughput…