Answer: When it's a database-less appliance. Unlike some competing products, Dataupia's data warehouse appliance doesn't have its own database management system. Instead, Dataupia's appliance, called Satori Server, performs analysis on data stored in existing databases.

I first wrote about Dataupia last July. That post was headlined "The Promise Of Data Warehousing Made Easy" based on the company's assertion that customers could use its system to deploy a multiterabyte data warehouse in less than an hour.

One of the reasons that's theoretically so easy is that Dataupia loads data from existing databases -- DB2, Oracle, SQL Server -- to create a virtual data store, against which customers can run analysis and generate reports. Dataupia calls it "omniversal transparency."

Since I last wrote about the company, Dataupia has been adding new capabilities to Satori Server -- including data visualization through a partnership with Tableau Software -- and named a few new customers. In November, Dataupia closed $16 million in Series B funding.

I met with Dataupia CTO John O'Brien recently in InformationWeek's San Francisco office. You can check out the interview below.