Reference: https://docs.microsoft.com/en-us/azure/cosmos-db/provision-account-continuous-backup

Explanation:

Explanation:

Based on the characteristics of the application and the provided document structure, the most suitable partition key value for coll1 in the given scenario would be the customerId, Option B.
The application frequently creates new orders by different customers and customers often view their past order history. Using customerId as the partition key would ensure that all orders associated with a particular customer are stored in the same partition. This enables efficient querying of past order history for a specific customer and reduces cross-partition queries, resulting in lower costs and improved performance.
a partition key is a JSON property (or path) within your documents that is used by Azure Cosmos DB to distribute data among multiple partitions 3 . A partition key should have a high cardinali ty, which means it should have many distinct values, such as hundreds or thousands 1 . A partition key should also align with the most co mmon query patterns of your application, so that you can efficiently retrieve data by using the partition key value 1 .
Based on these criteria, one possible partition key that you could use for coll1 is B. customerId .
This partition key has the following advantages:
* It has a high cardinality, as each customer will have a unique ID 3 .
* It aligns with the query patterns of the application, a s customers will often view their past order history
3 .
* It minimizes costs, as it reduces the number of cross-partition queries and optimizes the storage and throughput utilization 1 .
This partition key also has some limitations, such as:
* It may not be optimal for scenarios where orders need to be queried independently from customers or aggregated by date or other criteria 3 .
* It may result in hot partitions or throttling if som e customers create orders more frequently than others or have more data than others 1 .
* It may not support transactions a cross multiple customers, as transactions are scoped to a single logical partition 2 .
Depending on your specific use case and requirements, you may need to adjust this partition key or choose a different one. For example, you could use a synthetic partition key that conc atenates multiple properties of an item 2 , or you could use a partition key with a random or pre-calculated suffix to distribute the workload more evenly 2 .