HPL/SQL is included to Apache Hive since version 2.0
HPL/SQL is an open source tool (Apache License 2.0) that implements procedural SQL language for Apache Hive, SparkSQL, Impala as well as any other SQL-on-Hadoop implementation, any NoSQL and any RDBMS.
HPL/SQL is a hybrid and heterogeneous language that understands syntaxes and semantics of almost any existing procedural SQL dialect, and you can use with any database, for example, running existing Oracle PL/SQL code on Apache Hive and Microsoft SQL Server, or running Transact-SQL on Oracle, Cloudera Impala or Amazon Redshift.
HPL/SQL language is compatible to a large extent with Oracle PL/SQL, ANSI/ISO SQL/PSM (IBM DB2, MySQL, Teradata i.e), Teradata BTEQ, PostgreSQL PL/pgSQL (Netezza), Transact-SQL (Microsoft SQL Server and Sybase) that allows you leveraging existing SQL/DWH skills and familiar approach to implement data warehouse solutions on Hadoop. It also facilitates migration of existing business logic to Hadoop.
HPL/SQL is an efficient way to implement ETL processes in Hadoop.