What are UDF, UDTF, and UDAF in Hive?

In Hive, UDF (User Defined Function) refers to user-defined functions that enable users to create custom functions to extend Hive’s functionality. UDFs can process individual input records and return an output value.

UDTF (User Defined Table Function) is a user-defined table function that allows users to write a function that can return multiple output values and return the results as a table.

UDAFF(User Defined Aggregation Function) is a user-defined aggregation function that allows users to write a function that can aggregate a group of input records and return an aggregated result.

These three types of user-defined functions can be written and used in Hive according to users’ needs, helping them extend Hive’s functionality and facilitate more complex data processing operations.