不过它需要用java来编写,而不是用传统的SQL来完成
实现一个UDF的步骤如下:
- 实现一个Java Class,继承自UDF
- 打成jar包,并加入到Hive的ClassPath中
- 生成自定义函数,执行select
- 删除刚才创建的临时函数
用来判断array中是否包含某个值,hive的标准函数中并没有此功能函数
package com.sohu.hadoop.hive.udf; import java.util.*; import org.apache.hadoop.hive.ql.exec.UDF; import org.apache.hadoop.io.Text; import org.apache.hadoop.io.BooleanWritable; import org.apache.hadoop.io.Text; public final class ArrayContains extends UDF { public BooleanWritable evaluate(ArrayList
然后执行编译打包:
javac -classpath /opt/hadoop_client/hadoop/hadoop-0.20.2+228-core.jar:/opt/hadoop_client/hive/lib/hive-exec-0.5.0.jar src/com/sohu/hadoop/hive/udf/ArrayContains.java -d build最后执行Hive QL查询:
jar -cvf hadooop-mc-udf.jar -C build .
hive -e "add jar /opt/ysz/udf/hadooop-mc-udf.jar;drop temporary function array_contains;create temporary function array_contains as 'com.sohu.hadoop.hive.udf.ArrayContains';select suv,channelid from pvlog_pre where array_contains(channelid,'2')"
http://www.tech126.com/hive-udf/
最新评论