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From Frank Luo <j...@merkleinc.com>
Subject RE: how to get counts as a byproduct of a query
Date Wed, 02 Dec 2015 21:43:01 GMT
I might not illustrate the problem well. Let’s try on a sample.

Here is what I have:
Table_A, column X and Y
Table B, column X and Z

I want to do a join on both tables on column X, like
“select a.X, a.Y, b.Z
From A a
Join B b on A.X=B.X”

In the meaning time, I want to get counts for both Table A and B. I am not able to write a
query to do both.


From: Jörn Franke [mailto:jornfranke@gmail.com]
Sent: Wednesday, December 02, 2015 3:22 PM
To: user@hive.apache.org
Subject: Re: how to get counts as a byproduct of a query

I am  not sure if I understand, but why this should not be possible using SQL in hive?

On 02 Dec 2015, at 21:26, Frank Luo <jluo@merkleinc.com<mailto:jluo@merkleinc.com>>
wrote:
Didn’t get any response, so trying one more time. I cannot believe I am the only one facing
the problem.

From: Frank Luo
Sent: Tuesday, December 01, 2015 10:40 PM
To: user@hive.apache.org<mailto:user@hive.apache.org>
Subject: how to get counts as a byproduct of a query

Very often I need to run a query against a table(s), then collect some counts. I am wondering
if there is a way to kill two birds by scanning the table once. (I don’t mind to save the
counts as a separate file or something like that)

For example, I got a table A and B. I need to do an inner join to get some result. In the
meaning time, I need to know the table counts for both A and B. Is there a smart way to get
join result as well as the counts by reading the tables once?

Thanks in advance.

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