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.
Is this an implementation of JSON Patch RFC 6902?
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.
How is RU/s pricing calculated?
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.
Is there a limit to the number of partial document update operations?
There is a limit of 10 patch operations that can be added in a single patch specification.
Is partial document update supported for system-generated properties?
We do not support partial document update for system-generated properties like _id, _ts, _etag, _rid.
Can Time to Live (TTL) be patched?
Yes, it is possible to patch Time to Live (ttl) property of a document.
How does multi-region conflict resolution work for Arrays?
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.
Is partial document update supported for Analytical Store/Synapse Link enabled accounts?
Yes, partial document update works with Analytical Store/Synapse Link enabled accounts.
Next steps
- Learn more about Partial Document Update.