Hello,

We were wondering what the benefits are of setting hive.exec.parallel to
true. I know that this will execute any possible tasks in parallel. For
example MapReduce stages, sampling stages, merge stages, limit stages etc
will be executed in parallel allowing for the overall job to be completed
more quickly. However, my co worker and I decided to run a 400 line long
query in separate Tez sessions. I would set hive.exec.parallel=true and he
would set it to false. However, we see almost no improvement in speed. I am
assuming that is because the stages of my query is dependent on one another
(join a with b with c with d). Is this  the case? Can you give me examples
of queries where there would be improvement in speed (perhaps in TPC-DS)
when one sets hive.exec.parallel to true

Thanks

Yours Truly,
Varun Rao

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