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In our work, we need to use the custom UDF function:

1. You can create persistent functions

two。 You can also compile it in the source code

This document is used in source code compilation. Here are the compilation steps

Download the source package

Wget http://archive.cloudera.com/cdh6/cdh/5/hive-1.1.0-cdh6.7.0-src.tar.gztar xf hive-1.1.0-cdh6.7.0-src.tar.gzcd hive-1.1.0-cdh6.7.0/

Enter the directory of the UDF code

Cd ql/src/java/org/apache/hadoop/hive/ql/udf/- We can see a lot of UDF code here, starting with UDFXXX.java

Put the UDF code in the directory above

HelloUDF.javapackage com.ruozedata.hadoop.udf;import org.apache.hadoop.hive.ql.exec.UDF;public class HelloUDF extends UDF {public String evaluate (String input) {/ / TODO... Here is the return "Hello:" + input;} / / the following is the test code public static void main (String [] args) {HelloUDF udf = new HelloUDF (); String output = udf.evaluate ("test data"); System.out.println (output);}}

Register a custom UDF function in the source code

Cd ql/src/java/org/apache/hadoop/hive/ql/exec/#vim FunctionRegistry.javaimport org.apache.hadoop.hive.ql.udf.HelloUDF

Add the following to line 176

System.registerUDF ("HelloUDF", HelloUDF.class,false)

Compile hive

[root@hadoop001 exec] # pwd/opt/sourcecode/hive-1.1.0-cdh6.7.0 [root@hadoop001 hive-1.1.0-cdh6.7.0] # mvn clean package-DskipTests-Phadoop-2-Pdist

The compiled file is:

1.packaging/target/apache-hive-1.1.0-cdh6.7.0-bin.tar.gz

2.. / lib/hive-exec-1.1.0-cdh6.7.0.jar

Mode of use

Method 1: redeploy apache-hive-1.1.0-cdh6.7.0-bin.tar.gz

Method 2: copy the compiled / lib/hive-exec-1.1.0-cdh6.7.0.jar to the ${HIVE_HOME} / lib/ directory

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