MongoDB Inc., the most well-funded startup in the NoSQL database world, has climbed higher still on the venture capital chart with a $80 million round that brings its total raised to nearly double that of itsnearest competitor. The funding round is a landmark for the segment as enterprises continue to shift spending away from traditional relational systems and NoSQL becomes a popular choice for new businesses.

MongoDB hadn’t sought so much investment when it first started courting investors sometime after acquiring WiredTiger Inc. in December for its high-performance storage engine and engineering talent. New CEO Dev Ittycheria told trade press that he hoped to cover the bill for the buyout without having to take away from expansion efforts, but that goal was quickly met.

Investors wanted more, however. The former venture capitalist said that resulted in MongoDB raising about three times as much as had been originally planned. Besides providing a fairly solid hint as to how much it paid for WiredTiger, the funding also sheds some valuable light on the startup’s plans for the next few quarters.

The capital left over after the WiredTiger deal adds to a sizable pile of working capital from previous rounds that affords MongoDB the flexibility to push out a public offering until after 2015, according to comments made by Ittycheria in a separate interview with Bloomberg. That would enable the startup to continue focusing on growing the top line and building out its business without worrying about too much about financial performance.

There are also other considerations, such as the need to build up a sufficiently attractive balance sheet before starting to pitch the stock to public investors. Lack of profits didn’t stop Hortonworks, Inc. from rocketing pass the billion-dollar valuation mark on its first day of trading, a fact that Ittycheria told Gigaom validates investor interest in “loosely, ‘big data’ companies.

“MongoDB is well capitalized with this latest round to grow the business, but it remains to be seen if the company has developed a sustainable business model,” said Wikibon analyst Jeff Kelly. “The challenge for MongoDB, as with competing NoSQL database companies, is to turn open source users into paying customers.This latest round buys MongoDB more time to crack that nut before opening its books.”

The investment saw an unmanned sovereign wealth fund join as an investor alongside Goldman Sachs Group Inc., with existing backers Altimeter Capital, New Enterprise Associates (NEA), Sequoia Capital and T. Rowe Price Associates, Inc. taking the opportunity to grow their stakes.