APPLIES TO: 
NoSQL
Partial Document Update allows you to modify specific properties or fields on an item without the need to perform a full document replace operation. This article answers commonly asked questions about Azure Cosmos DB Partial Document Update.
Azure Cosmos DB partial document update is inspired by JSON Patch RFC 6902. There are other features such as Conditional Patch while some of the features of JSON Patch RFC 6902 such as (Copy, Test) have not been implemented.
Is partial document update compatible with serverless, provisioned throughput and autoscale modes of billing?
Yes, partial document update is available across serverless, provisioned throughput and autoscale modes.
Partial Document Update is normalized into request unit billing in the same way as other database operations. Users should not expect a significant reduction in RU.
There is a limit of 10 patch operations that can be added in a single patch specification.
We do not support partial document update for system-generated properties like _id, _ts, _etag, _rid.
Yes, it is possible to patch Time to Live (ttl) property of a document.
Arrays are treated as an atomic unit. If the same property in an array is concurrently updated in different regions (thereby resulting in a conflict), only one of the changes will persist.
Yes, partial document update works with Analytical Store/Synapse Link enabled accounts.
- Learn more about Partial Document Update.