Which side join is taken by default by hive Map-side or Reduce-side

Question

I want to know that when I run join task in Hive, does it take Map-side join or Reduce-side join by default?

Answer 1

The syntax for Map-side join and Reduce-side join are different. So, there would not be conflicts running the join. 

The example for Map-side join is:

SELECT /*+ MAPJOIN(dataset2) */ dataset1.name, dataset1.eid,dataset2.eid FROM dataset1 JOIN dataset2 ON dataset1.first_name = dataset2.first_name;

The exmaple for Reduce-side join is:

select emp.name, dept.deptname from emp join dept on emp.deptid=dept.deptid;