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Subject Re: parallel inserts ?
Date Wed, 15 Feb 2012 16:19:53 GMT
Hi John
       Yes Insert is parallel in default for hive. Hive QL gets transformed to mapreduce jobs
and hence definitely it is parallel. The only case it is not parallel is when you have just
1 reducer . It is just reading and processing the input files and in parallel using map reduce
jobs from the source table data dir and writes the desired output files to the destination
table dir.       
        Hive is just an abstraction over map reduce and can't be compared against a db in
terms of features. Almost every data processing operation is just some map reduce jobs. 
Bejoy K S

From handheld, Please excuse typos.

-----Original Message-----
From: John B <>
Date: Wed, 15 Feb 2012 10:59:09 
To: <>
Subject: parallel inserts ?

Other sql datbases typically can parallelize selects but are unable to
automatically parallelize inserts.

With the most recent stable hiveql will the following statement have
the --insert-- automatically parallelized ?

 SELECT pv_users.gender
 FROM pv_users

I understand there is now 'insert into from' syntax. Is the
insert part of that statement automatically parallelized ?

What is the highest insert speed anybody has seen - and I am not
talking about imports I mean inserts from one table to another ?

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