Big Data platform ThoughtSpot has raised $30 million in an oversubscribed Series B financing round led by Khosla Ventures, with participation from existing investor Lightspeed Venture Partners. As part of the funding, Khosla's Keith Rabois will join the company's Board of Directors. ThoughtSpot's Data Search Appliance is a plug-and-play solution that provides a search-based user experience for business data access and analysis. The company, which previously raised $10.7 million of Series A funding at a valuation of $31 million in 2012, will use the new capital to hire additional talent. In fact, it's offering a $20,000 referral bonus to anyone connected to its employees on LinkedIn that refers a candidate who gets hired.