I am trying to retrieve a document from Azure Cosmos DB without a partition key using this code

Container container = cosmosClient.Value.GetContainer(databaseId, containerId);
var retrieved = await container.ReadItemAsync<Doc>(id, PartitionKey.None);

This always gives a 404 not found error. If I pass the partition key

var retrieved = await container.ReadItemAsync<Doc>(id, new PartitionKey("1234"));

Then it works ok. I don't know the partition though, so how can I make this work?

I am trying to retrieve a document from Azure Cosmos DB without a partition key using this code

Container container = cosmosClient.Value.GetContainer(databaseId, containerId);
var retrieved = await container.ReadItemAsync<Doc>(id, PartitionKey.None);

This always gives a 404 not found error. If I pass the partition key

var retrieved = await container.ReadItemAsync<Doc>(id, new PartitionKey("1234"));

Then it works ok. I don't know the partition though, so how can I make this work?

• c#
• azure
• azure-cosmosdb

• The reason the Partition Key is needed is because the identity of a document is both the id + Partition Key. You can have documents with the same id but different Partition Key, but there cannot be documents with the same id AND Partition Key, any attempt to create duplicates results in HTTP 409 responses. – Matias Quaranta Commented Mar 25 at 14:42

1 Answer 1

You would need to perform a cross-partition query. This is however an expensive operation.

var query = new QueryDefinition("SELECT * FROM c WHERE c.id = @id")
    .WithParameter("@id", id);
var iterator = container.GetItemQueryIterator<Doc>(query);
var results = new List<Doc>();
while (iterator.HasMoreResults)
{
    var response = await iterator.ReadNextAsync();
    results.AddRange(response);
}
var retrieved = results.FirstOrDefault(); // If you know the ID is unique.