Order By clause helps to sort data.
hive> select * from person;
OK
1 John 23 15000.0 IT
2 Harry 30 42000.0 HR
3 Royen 45 85000.0 PR
4 Tim 48 52000.0 IT
5 Rony 28 35000.0 HR
hive> select * from person order by salary;
Output:-
1 John 23 15000.0
5 Rony 28 35000.0
2 Harry 30 42000.0
4 Tim 48 52000.0
3 Royen 45 85000.0
Order By uses one reducer because it does the global ordering. When a large data set and data are being sent to one reducer, there will be memory issues. So the solution to this is SORT BY.
