02 Apr: LLAP & CGroups: a marriage made in heaven

Hive LLAP (for Live Long and Process), also called Interactive Query on HDInsight, is a service whose promise is to provide performance below the second for queries on very large tables. To achieve interactive performance levels, LLAP relies on Hadoop by using the Tez execution engine and by adding LLAP daemons to cache data, manage JIT optimization, and eliminate most of the startup costs. Caching, pre-fetching, some query processing and access control are moved into the daemons….