Minor - P4 This query success compile and run. But, result is not right!
Example:
var cursor = from uc in usersCollection.AsQueryable()
join cc in candlesCollection.AsQueryable() on uc.Pairs.First(p=>p.Name == "CAD_HKD").Id equals cc.UserPairId into joined
select new { uc.FirstName, uc.LastName, Count = joined.Count()};
This code return 50 records, but every propery "Count" = 0! It is not right, because data exist in the collection!