MongoDB (MDB 1.77%) is due to report fourth-quarter earnings after close of trading on Thursday -- and Wall Street is nervous. Analysts following the database are expecting strong sales growth for the quarter -- more than 20% -- but a steep falloff in earnings, which could plunge 17% to $0.47 per share. Or perhaps I should say most analysts are nervous. On Wednesday morning, before earnings even come out, Citigroup analyst Tyler Radke decided to double down on his "buy" rating on MongoDB stock -- and raise ...