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From Gopal Vijayaraghavan <>
Subject Re: Wrong column is picked in HIVE 2.0.0 + TEZ 0.8.2 left join
Date Tue, 01 Mar 2016 18:28:07 GMT
(Bcc: Tez, Cross-post to hive)

> I added ³set hive.execution.engine=mr;² at top of the script, seems the
>result is correctŠ

Pretty sure it's due to the same table aliases for both dummy tables
(they're both called _dummy_table) auto join conversion.

hive> set;

Should go back to using slower tagged joins even in Tez, which will add a
table-tag i.e first table will be (<table-key>, 0) amd 2nd table will be
(<table-key>, 1).

I suspect the difference between the MR and Tez runs are lookup between
the table-name + expr (both equal for _dummy_table.11).

> per Jeff Zhang's thinking if you were to set the exec engine to 'mr'
>would it still fail?   if so, then its not Tez . :)

Hive has a a whole set of join algorithms which can only work on Tez, so
it's not always that easy.

Considering this is on hive-2.0.0, I recommend filing a JIRA on 2.0.0 and
marking it with 2.0.1 as a target version.




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