One of the benefits of storing data in a structured container such as a table is to have index structures to make data lookup faster.
Index DDL Statements
The following are the supported operations on indexes:
Index_DDL_Statement := Create_Index_Statement.
U-SQL at the moment supports only clustered indexes that are used to cluster the associated U-SQL tables according to the index keys. Since the table then is physically stored as that index, there can only be one clustered index per table and one cannot delete a clustered index. Instead one drops the table.
Alternative indexes such as column store indexes and secondary indexes that give you support for secondary access patterns are planned for future releases.