EF Core Azure Cosmos DB Provider Limitations

The Cosmos provider has a number of limitations. Many of these limitations are a result of limitations in the underlying Cosmos database engine and are not specific to EF. But most simply haven't been implemented yet.

Temporary limitations

  • Even if there is only one entity type without inheritance mapped to a container it still has a discriminator property.
  • Entity types with partition keys don't work correctly in some scenarios
  • Include calls are not supported
  • Join calls are not supported

Azure Cosmos DB SDK limitations

  • Only async methods are provided


Since there are no sync versions of the low level methods EF Core relies on, the corresponding functionality is currently implemented by calling .Wait() on the returned Task. This means that using methods like SaveChanges, or ToList instead of their async counterparts could lead to a deadlock in your application

Azure Cosmos DB limitations

You can see the full overview of Azure Cosmos DB supported features, these are the most notable differences compared to a relational database:

  • Client-initiated transactions are not supported
  • Some cross-partition queries are either not supported or much slower depending on the operators involved