Azure Cosmos DB: Unique index constraint violation using UpsertDocumentAsync

Question

I have defined a UniqueKey policy in my Azure Cosmos DB Container, for field UniqueName

The below function is being called on a timer.

I'm attempting to Upsert documents in Azure Cosmos DB using Azure Functions bindings, like so:

public async Task ManageItems([ActivityTrigger] string records,
        [CosmosDB(
        databaseName: "mydatabase",
        collectionName: "items",
        ConnectionStringSetting = "CosmosDbConnectionString")] DocumentClient client,
        ILogger log)
        {
             var collectionUri = UriFactory.CreateDocumentCollectionUri("mydatabase", "items");


            
            foreach (var record in records)
            {
                log.LogDebug($"Upserting itemNumber={record.UniqueName}");
                await client.UpsertDocumentAsync(collectionUri, record);
            }
         }

During the first execution in a blank "items" container, the Upsert for each record works splendidly, inserting each record as a specific document.

However when doing a test of the same data as the first execution, but now expecting an "Update" as opposed to an "Insert" attempt, I get an exception:

Unique index constraint violation after UpsertDocumentAsync method runs.

What am I missing here?

To my understanding, an Upsert is either an update or insert, depending on whether the object exists or not, via it's unique identifier.

The check of whether the outgoing object unique id from the method matches the existing document unique id is supposed to be happening at the Cosmos DB container level.

What I expect to happen is the call notices that the document with that unique ID already exists, and it performs an update, not throw an exception. I would expect it to throw an exception if the method was Insert only.

score -1 · Answer 1 · answered Nov 30 '21 at 16:39

This issue was fixed by specifying an explicit "id" field in the class where the "records" came from.

The "id" was set to the unique "recordNumber" that I wanted to use as a unique value.

For good measure I set the disableAutomaticIdGeneration to true in the UpsertDocumentAsync method

UpsertDocumentAsync(collectionUri, record, disableAutomaticIdGeneration:true);

No more unique index violation, and no duplicates either.

Worth noting the solution is similar to this one: How can I insert/update data in CosmosDB in an Azure function

Azure Cosmos DB: Unique index constraint violation using UpsertDocumentAsync

1 Answers1