Map-side join vs join

Map-side join vs join

What is map side joins and joins?

Create Two tables
1.prwatech_stu(prwatech_stu stored student information)
2.prwatech_emp(prwatech_emp employee information)

Input files are prwatech_stu and prwatech_emp stores as text files with this content

loading data into tables using text files stu,dept

Map-side join also helps in improving the performance of the task by decreasing the time to finish the task.

Map-side Join on the two tables to extract the list of departments in which each student belongs to department

when writing map reduce job no reduce task ,reducer is zero

While executing both the joins, you can find the two differences:

Map-reduce join has completed the job in less time when compared with the time taken in normal join.
Map-reduce join has completed its job without the help of any reducer whereas normal join executed this job with the help of one reducer.

Category: MAP REDUCE