Next-generation database software maker MongoDB (MDB 1.77%) is already a fantastic performer in my personal stock portfolio. Share prices have more than tripled since I opened my MongoDB position in the spring of 2020.

At the same time, the stock is coming back from a recent plunge, and I really want to boost my MongoDB position before the discount fades away. This disruptive tech stock has miles and miles of untouched growth ahead of it, and the stock strikes me as a fantastic buy at these prices.

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Price swings

This growth stock is sensitive to the progression of the COVID-19 pandemic. Many investors have caught on to the idea that MongoDB can thrive during lockdowns and remote-work policies, so the stock often moves up when the virus spikes and down when virus-fighting efforts are successful.

Therefore, MongoDB's chart took a southward detour when vaccination efforts increased in the spring. The stalled rocket engines fired up again in May due to the arrival of the delta variant. All told, the stock is trading 13% below February's all-time highs, including a 52% rebound from the recent lows.

I found myself thinking about hitting the buy button for MongoDB in early May. Now I'm kicking myself for not taking action back then. The stock has gained 45% since I posted my bullish musings.

It's not too late to take action, though.

The business case for MongoDB

MongoDB is a leader in the market for NoSQL database systems, which threatens to disrupt the more traditional sector of relational databases. The long-term opportunity is huge, and MongoDB has only just begun to exploit it.

In the last four quarters, MongoDB generated $642 million of top-line sales. In the same period, relational database giant Oracle (ORCL 1.41%) scraped together revenues of $40.5 billion. In other words, MongoDB's trailing sales amounted to less than 1.6% of Oracle's revenues. The company is barely scratching the surface of an enormous market.

That is changing in a hurry, though. MongoDB's cloud-based Atlas database is growing by leaps and bounds, delivering 73% year-over-year sales growth in the recently reported first quarter of fiscal year 2022. Oracle is tight-lipped about the precise growth rates of specific software solutions, but the veteran's revenue growth stopped at 8% in the fourth quarter of 2021.

MongoDB is running circles around the traditional database names in terms of sales growth. The company reinvests every spare penny into further product development and marketing campaigns in order to keep the growth engines roaring.

This is classic high-growth planning 101, and I expect MongoDB's fantastic business development to continue for many years to come. That massive market pie won't look so untouched in a few years, given MongoDB's sector-smashing growth trajectory.

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Image source: Getty Images.

Buy MongoDB now or regret it later

According to master investor Warren Buffett, it's better to invest in a great business at a fair price than a fair company at a great price. MongoDB was recently a wonderful company whose stock was trading at a wonderful price. Right now, you can still grab shares of this amazing company at a reasonable price. However, I'm not sure how much longer these relatively low prices will last.

That's why I want to boost my MongoDB position while the stock is trading at a discount. The Fool's ironclad disclosure policy forces me to hold off for a couple of days after mentioning the stock in an article, so it will have to wait until next week. In the meantime, nothing's stopping you from at least taking a closer look at MongoDB.