将功能参数传递给Pig

Question

Here is my problem with Apache Pig, I run Pig script in a Python script. There is a field called priority in Pig, whose value is either a random number, or just null. Each record of input should have a different random number. Python code would determine between random number and null before call Pig script.

Scenario one: pig -param param1="" -f my_pig_script.pig

scenario two(just guess): pig -function param1=random() -f my_pig_script.pig

How two write right Pig script under scenario two?

Thanks

Answer 1

One thing is for sure - you do not need to (actually should not) pass random() as param, as it would pass ONLY 1 RANDOM NUMBER as param, which you do not want. The question is how to convey your PIG script to use null or random. Go ahead and pass null or non-null value to param1, pass non-null when you want pig script to use random instead of null.

Inside PIG script, you can use ternary operator as below:

A = FOREACH B GENERATE param1 IS NULL ? NULL : RANDOM();

Hope this helps!