If you go back about a decade, Hadoop was hot and getting hotter. It was a platform for processing big data, just as big data was emerging from the domain of a few web-scale companies to one where every company was suddenly concerned about processing huge amounts of data. The future was bright, an open source project with a bunch of startups emerging to fulfill that big data promise in the enterprise. Three companies in particular emerged out of that early scrum — Cloudera, Hortonworks and MapR — and between them raised more than $1.5 billion.