MongoDB (MDB 4.83%) 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 his target price to $550 per share, implying 34% upside in MongoDB stock.

Is MongoDB stock a buy?

This is not to say that Radke has zero qualms about MongoDB. Writing in a note covered by TheFly.com on Wednesday, the analyst notes that peer tech stocks Elastic and Snowflake both disappointed with their guidance last week, which didn't live up to (perhaps irrationally exuberant) expectations, leading Citi to "temper" its optimism. Deal sizes being recorded in the sector, noted Radke, are still "healthy," albeit trending smaller in January.

So why raise the price target if Citi isn't 100% certain that MongoDB is going to wow us? Honestly, I'm not sure. Despite raising its price target (implying it thinks the stock is worth more than its current $411 share price), Radke advised investors to wait for even steeper "pullbacks" in the shares before buying -- which sounds kind of contradictory.

It also might be the right call.

Consider: With negative profit by generally accepted accounting principles (GAAP) and only $89 million in trailing free cash flow (FCF), MongoDB stock costs well over 320 times FCF going into earnings. Granted, investors have high hopes that this growth stock will grow into its pricey valuation. (Long-term growth rates are estimated at 50%.) But like Radke said, these are high hopes ... that might need to be tempered.

If MongoDB misses on earnings Thursday, or even just disappoints on guidance, that might be exactly what happens: MongoDB stock could get "tempered" ... with a vengeance.