Today I Learned: Azure Cosmos Db: Query for Fields not defined
There are several ways: Using LINQ For anyone who wants a Linq solution, it’s: query.Where(d => !d.SomeField.IsDefined()) Note: To get the IsDefined extension method, you need to add Microsoft.Azure.Documents.SystemFunctions namespace Using SQL Query Grammar with built-in functions IS_DEFINED (expr) - returns a Boolean indicating if the property has been assigned a value. SELECT TOP {0} * FROM Telemetry t WHERE (is_defined(t.longitude) OR is_defined(t.latitude)) Thanks to Azure Feedback and Azure Cosmos DB SQL syntax reference