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global |
Integration with Hive UDFs/UDAFs/UDTFs |
Integration with Hive UDFs/UDAFs/UDTFs |
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this work for additional information regarding copyright ownership.
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(the "License"); you may not use this file except in compliance with
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http://www.apache.org/licenses/LICENSE-2.0
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distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
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|
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.
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|
+--------------+
-- Register `UDFSubstr` and use it in Spark SQL.
-- Note that, it can achieve better performance if the return types and method parameters use Java primitives.
-- e.g., UDFSubstr. The data processing method is UTF8String <-> Text <-> String. we can avoid UTF8String <-> Text.
CREATE TEMPORARY FUNCTION hive_substr AS 'org.apache.hadoop.hive.ql.udf.UDFSubstr';
select hive_substr('Spark SQL', 1, 5) as value;
+-----+
|value|
+-----+
|Spark|
+-----+
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|
+---+---------------+