Problem:
1) I create IMongoQuery myQuery = some stuff.
2) I create IQueryable expresion = myCollection.Find(myQuery).AsQueryable
3) Apply some additional condition: expresion.Where(x => x.SomeProperty=someValue)
4) Execute it.

Execution:
1) MongoCursor executed myQuery part.
2) Via Linq-to-Object "Where" condition applied to MongoCursor result in memory
So I got two queries - first on the server and the second in memory

Expected:
All expression must be executed like a single query on the server side.