Impala is a SQL query system for Hadoop from Cloudera. It is currently in beta; and it has been opensource and it's source can be downloaded from Gitap. It supports the same SQL syntax, the ODBC driver and the user interface (which is Beeswax) as Apache Hive.We can use it to query data, whether it is stored in ADFS or Apache H-base. And we can do selects, joins and aggregate functions.