Hive is not the only product providing SQL-on-Hadoop capability. The second most widely used is likely Impala, announced in late 2012 and released in spring 2013. Though originally developed internally within Cloudera, its source code is periodically pushed to an open source Git repository (https://github.com/cloudera/impala).

Impala was created out of the same perception of Hive's weaknesses that led to the Stinger initiative.

Impala also took some inspiration from Google Dremel (http://static.googleusercontent.com/media/research.google.com/en//pubs/archive/36632.pdf) which was first openly described by a paper published in 2009. Dremel was built at Google to address the gap between the need for very fast queries on very large datasets and the high latency inherent in the existing MapReduce model underpinning Hive at the time. Dremel was a sophisticated approach to this problem that, rather than building mitigations atop MapReduce such as implemented by Hive, instead created a new...