T-M-L-C/hive-udf

UDF, GenericUDF, UDTF, UDAF

hive_udf

UDF, GenericUDF, UDTF, UDAF #Create a table Create a table named employee:

CREATE TABLE employee(
	name			STRING,
	salary			FLOAT,
	subordinates	ARRAY<STRING>,
	deductions		MAP<STRING, FLOAT>,
	address			STRUCT<street:STRING, city:STRING, state:STRING, zip:INT>
)
ROW FORMAT DELIMITED
FIELDS TERMINATED BY '\001'
COLLECTION ITEMS TERMINATED BY '\002'
MAP KEYS TERMINATED BY '\003'
LINES TERMINATED BY '\n'

Load the data that is in data directory.

hadoop fs -put employee.txt /hive

LOAD DATA INPATH '/hive/employees.txt'
OVERWRITE INTO TABLE employee

#Compile and package Compile and package the source codes by maven.First of all, enter the project's root directory, then execute the follow commands in shell:

$ mvn clean
$ mvn clean compile
$ mvn clean package

#Run the examples If we successfully installed Hadoop and Hive before, we are able to run the examples now. Firstly, we should add the jar into CLASSPATH:

hive> ADD jar /root/experiment/hive/hive-0.0.1-SNAPSHOT.jar;

Secondly, create the temporary functions:

hive> CREATE TEMPORARY FUNCTION hello 
    > AS 'edu.wzm.hive.HelloUDF';
hive> CREATE TEMPORARY FUNCTION contains 
    > AS 'edu.wzm.hive.ComplexUDFExample';
hive> CREATE TEMPORARY FUNCTION collect 
    > AS 'edu.wzm.hive.udaf.GenericUDAFCollect';
hive> CREATE TEMPORARY FUNCTION explode_name 
    > AS 'edu.wzm.hive.udtf.ExplodeNameUDTF';

finally, test the example:

hive> SELECT hell(name)
    > FROM employee;
hive> SELECT contains(subordinates, subordinates[0]), subordinates
    > FROM employee;
hive> SELECT collect(name)
    > FROM employee;
hive> SELECT salary, concat_ws(',', collect(name))
    > FROM employee;    
hive> SELECT explode_name(name)
    > FROM employee;