Declare a comma seperated string constant

问题

Objective : Declare a comma seperated string constant

    test.csv
    =========
    a
    b
    c
    d
    e
    f

Pig Script :

  %declare ACTIVE_VALUES 'a', 'b','c' ; 

  -- Declaring constant like this using "" (double quotes) or even using escape characters (\) is resulting in a WARN message as below 
  -- WARN  org.apache.pig.tools.parameters.PreprocessorContext - Warning : Multiple values found for ACTIVE_VALUES

  A = LOAD 'test.csv' using PigStorage(',') AS (value:chararray);
  B = FILTER A BY value in ($ACTIVE_VALUES);
  dump B;

Expected Output :

 a
 b
 c

Any inputs on declaring a comma separated string constant in Pig.

-- Declaring constant like this using "" (double quotes) or even using escape characters (\) is resulting in a WARN message as below

-- WARN org.apache.pig.tools.parameters.PreprocessorContext - Warning : Multiple values found for ACTIVE_VALUES

回答1:

You can use a single comma delimited string ('a,b,c') and use STRSPLIT (https://pig.apache.org/docs/r0.9.1/func.html#strsplit) function on ACTIVE_VALUES to get bag of characters, which can be FLATTEN'd to create multiple records. This data can be INNER JOIN'ed with data from test file to get the desired results.

来源：https://stackoverflow.com/questions/29779866/declare-a-comma-seperated-string-constant