Spark SQL Guide

Integration with Hive UDFs/UDAFs/UDTFs

Description

Spark SQL supports integration of Hive UDFs, UDAFs and UDTFs. Similar to Spark UDFs and UDAFs, Hive UDFs work on a single row as input and generate a single row as output, while Hive UDAFs operate on multiple rows and return a single aggregated row as a result. In addition, Hive also supports UDTFs (User Defined Tabular Functions) that act on one row as input and return multiple rows as output. To use Hive UDFs/UDAFs/UTFs, the user should register them in Spark, and then use them in Spark SQL queries.

Examples

Hive has two UDF interfaces: UDF and GenericUDF. An example below uses GenericUDFAbs derived from GenericUDF.

-- Register `GenericUDFAbs` and use it in Spark SQL.
-- Note that, if you use your own programmed one, you need to add a JAR containing it
-- into a classpath,
-- e.g., ADD JAR yourHiveUDF.jar;
CREATE TEMPORARY FUNCTION testUDF AS 'org.apache.hadoop.hive.ql.udf.generic.GenericUDFAbs';

SELECT * FROM t;
+-----+
|value|
+-----+
| -1.0|
|  2.0|
| -3.0|
+-----+

SELECT testUDF(value) FROM t;
+--------------+
|testUDF(value)|
+--------------+
|           1.0|
|           2.0|
|           3.0|
+--------------+

An example below uses GenericUDTFExplode derived from GenericUDTF.

-- Register `GenericUDTFExplode` and use it in Spark SQL
CREATE TEMPORARY FUNCTION hiveUDTF
    AS 'org.apache.hadoop.hive.ql.udf.generic.GenericUDTFExplode';

SELECT * FROM t;
+------+
| value|
+------+
|[1, 2]|
|[3, 4]|
+------+

SELECT hiveUDTF(value) FROM t;
+---+
|col|
+---+
|  1|
|  2|
|  3|
|  4|
+---+

Hive has two UDAF interfaces: UDAF and GenericUDAFResolver. An example below uses GenericUDAFSum derived from GenericUDAFResolver.

-- Register `GenericUDAFSum` and use it in Spark SQL
CREATE TEMPORARY FUNCTION hiveUDAF
    AS 'org.apache.hadoop.hive.ql.udf.generic.GenericUDAFSum';

SELECT * FROM t;
+---+-----+
|key|value|
+---+-----+
|  a|    1|
|  a|    2|
|  b|    3|
+---+-----+

SELECT key, hiveUDAF(value) FROM t GROUP BY key;
+---+---------------+
|key|hiveUDAF(value)|
+---+---------------+
|  b|              3|
|  a|              3|
+---+---------------+