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Hive, mail # user - Same tablename in DESTINATION and FROM clause


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RE: Same tablename in DESTINATION and FROM clause
Steven Wong 2012-03-16, 21:08
What I've observed is: "yes" if the table is HDFS-backed; "it depends" if otherwise.
From: Mohit Gupta [mailto:[EMAIL PROTECTED]]
Sent: Thursday, March 15, 2012 9:23 PM
To: [EMAIL PROTECTED]; Ramkumar
Subject: Re: Same tablename in DESTINATION and FROM clause

No. First write the result in a temp table, then load it into the original table.
On Thu, Mar 15, 2012 at 4:53 PM, Ramkumar <[EMAIL PROTECTED]<mailto:[EMAIL PROTECTED]>> wrote:
Hi,

Does the MR jobs of a hive query write directly to the destination or are the results of the MR jobs moved to the destination at the end?
To be more precise, is it safe to write query in the following way,

insert overwrite table X
select do_something from X join Y  on (some key)

Was little reluctant to go by the experimental results and wanted to confirm.

Thanks,
Ram
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Best Regards,

Mohit Gupta