Azure Cosmos DB SQL API UPDATE statement - don't replace whole document

Can I write an UPDATE statement for Azure Cosmos DB? The SQL API supports queries, but what about updates?

In particular, I am looking to update documents without having to retrieve the whole document. I have the ID for the document and I know the exact path I want to update within the document. For example, say that my document is

{
  "id": "9e576f8b-146f-4e7f-a68f-14ef816e0e50",
  "name": "Fido",
  "weight": 35,
  "breed": "pomeranian",
  "diet": {
    "scoops": 3,
    "timesPerDay": 2
  }
}

and I want to update diet.timesPerDay to 1 where the ID is "9e576f8b-146f-4e7f-a68f-14ef816e0e50". Can I do that using the Azure SQL API without completely replacing the document?

Upvotes: 28

Answers (5)

Nick Chapsas

Reputation: 7200

Original Answer, as of 2019

The Cosmos DB SQL language only supports the Select statement.

Partially updating a document isn't supported via the sql language or the SQL API.

People have made it clear that that's a feature they want so there is a highly upvoted request for it that can be found here: https://feedback.azure.com/forums/263030-azure-cosmos-db/suggestions/6693091-be-able-to-do-partial-updates-on-document

Microsoft has already started to work on that so the only thing you can do is wait.

2024 Update

Yes, you can "patch" your item to only update a single field. Note that there are six operations in the patch API: add, set, replace, remove, increment and move

This is official known as a Partial Document Update

The Docs

Upvotes: 27

Nalin Jayasuriya

Reputation: 407

I know it's been a while since the original question was posed, but this entry is the primary search result.

We can now use the following operation to update only part of the record.

Container.PatchItemAsync

https://learn.microsoft.com/en-us/dotnet/api/microsoft.azure.cosmos.container.patchitemasync?view=azure-dotnet

Upvotes: 3

Sajeetharan

Reputation: 222720

To elaborate more on this, Updating partially a document in CosmosDb on the server isn’t possible, instead you can do whatever you need to do in the memory.In order to literally UPDATE the document, you will have to to retrieve the entire document from the CosmosDb, update the property/properties that you need to update and then call the ‘Replace’ method in the CosmosDb SDK to replace the document in question. Alternatively you can also use ‘Upsert’ which checks if the document already exists and performs an ‘Insert’ if true or ‘Replace’ if false.

NOTE : Make sure you have the latest version of the document before you commit an update!

UPDATE :

CosmosDB support for Partial Update is GAed. You can read more from here

Upvotes: 8