Sorting in Apache Pig

Rearranging the rows returned from a query result set in ascending or descending order is the most commonly utilized function by analysts. Sorting can be done by date, particular integer or decimal column values, or textual column values.

Prerequisites:
1) Sample Data.
File Name: emp.csv
“7839, KING, PRESIDENT, 0,17/Nov/1981, 5000, 0, 10
“7698, BLAKE, MANAGER, 7839, 01/May/1981, 2850, 0, 30
“7782, CLARK, MANAGER, 7839, 06/Sep/1981, 2450, 0, 10
“7566, JONES, MANAGER, 7839, 04/Feb/1981, 2975, 0, 20
“7788, SCOTT, ANALYST, 7566, 13/Jul/87, 3000, 0, 20
“7902, FORD, ANALYST, 7566, 03/Dec/1981, 3000, 0, 20
“7369, SMITH, CLERK, 7902, 17/Dec/1980, 800, 0, 20
“7499, ALLEN, SALESMAN, 7698, 20/Feb/1981, 1600, 300, 30
“7521, WARD, SALESMAN, 7698, 22/Feb/1981, 1250, 500, 30
“7654, MARTIN, SALESMAN, 7698, 28/Sep/1981, 1250, 1400, 30
“7844, TURNER, SALESMAN, 7698, 09/Aug/1981, 1500, 0, 30
“7876, ADAMS, CLERK, 7788, 13/Jul/87, 1100, 0, 20
“7900, JAMES, CLERK, 7698, 03/Dec/1981, 950, 0, 30
“7934, MILLER, CLERK, 7782, 23/Jan/1982, 1300, 0, 10

2) Loading the data into a relation.
“Execute the below in a single line to avoid each line execution.
emp = LOAD ‘Desktop/Docs/emp.csv’ USING PigStorage(‘,’) AS
“““( empno:int,
“““ename:chararray,
“““job:chararray,
“““mgr:int,
“““hiredate:chararray,
“““sal:double,
“““comm:double,
“““deptno:int);

Sorting Example:
Sorted_Data = ORDER emp BY empno;
or
Sorted_Data = ORDER emp BY empno ASC, deptno ASC;
Dump Sorted_Data;

Result:
“`Fetch the data using “Dump” command and it will show all the rows from “emp”
“`sorted by empno.

“`The above command is equal to:
SELECT * FROM emp ORDER BY empno;