What are the advantages of setting "hive.exec.parallel" to false in Hive ?

Question

I came to know that when hive.exec.parallel is set to true in hive i.e

set hive.exec.parallel=true; 

then independent tasks in a query can run in parallel.

Thanks to Qubole for this:

Are there any advantages of setting this parameter to false? I'll iterate myself here: Obviously, whenever possible, you would like to run things in parallel and have more throughput. Why would someone set this parameter to false - are there any disadvantages too?

Answer 1

It's simply a parameter because when it got introduced it wasn't clear how stable it would be and so you should be able to turn it off. Once enough people tried it and found it stable the default switched to true: https://issues.apache.org/jira/browse/HIVE-1033

There is no realistic disadvantage at this time.