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Creating Custom UDFs

First, you need to create a new class that extends UDF, with one or more methods named evaluate.

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For a more involved example, see this page.

As of Hive 0.13, you can register your function as a permanent UDF either in the current database or in a specified database, as described in Permanent Functions. For example:

create function my_db.my_lower as 'com.example.hive.udf.Lower';

Deploying Jars for User Defined Functions and User Defined SerDes

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hive> list jars;
my_jar.jar

See Hive CLI for full syntax and more examples.

As of Hive 0.13, UDFs also have the option of of being able to specify required jars in the CREATE FUNCTION statement:

CREATE FUNCTION myfunc AS 'myclass' USING JAR 'hdfs:///path/to/jar';

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