public class TestObject
        {
            [BsonId]
            public string DeviceID { get; set; }
            public List<string> Sessions = new List<string>();
        }

 async private void demo(theTestModel model)
        {
            var id = "heavy";
            var test = model.Database.GetCollection<TestObject>("test");
            model.Database.DropCollection(test.CollectionNamespace.CollectionName);
            var heavy = new TestObject() { DeviceID = "heavy" };
            var lite = new TestObject() { DeviceID = "light" };
            for (int i = 0; i < 260000; i++) heavy.Sessions.Add(Guid.NewGuid().ToString());
            for (int i = 0; i < 1000; i++) lite.Sessions.Add(Guid.NewGuid().ToString());
            test.InsertOne(heavy);
            test.InsertOne(lite);

            
            var test1heavy = await test.Find(x => x.DeviceID == id).FirstOrDefaultAsync();
            // test1heavy contains the expected results

            var test2heavy = await test.AsQueryable().FirstOrDefaultAsync(x => x.DeviceID == id);
            // test2heavy is null
            id = "light";

            // test1light contains the expected results
            var test1light = await test.Find(x => x.DeviceID == id).FirstOrDefaultAsync();
            // test2light contains the expected results
            var test2light = await test.AsQueryable().FirstOrDefaultAsync(x => x.DeviceID == id);

            
        }