CODEWITHSUNDEEP
hadoopmapreducehivehiveqlhadoop2
Abhi
Abhi

Reputation: 6568

Hive queries executing as Map only jobs

I recently came across a question

Will all Hive queries be converted into map and reduce jobs?

I know Hive queries are converted into a series of Map Reduce jobs.I am not talking about invoking external scripts in Hive. Is there any case where a reduce job is not required and Hive can achive the result by Map job itself.

What are your thoughts ?

Upvotes: 0

Views: 962

Answers (1)

alekya reddy
alekya reddy

Reputation: 934

yes. It just depends on what type of job you are running.

For example if you have a employee table with schema (Name, id , department).

The following query runs a Map only job. The Mapper recieves (Name, id , department) from hive table as the value and it emits the Name , Nullwritable . Hence we dont need reducer for this scenario.

select Name from employee;

Upvotes: 3

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