[jira] [Created] (HIVE-26671) Incorrect results for group by/order by/limit query with 2 aggregates

["Steve Carlin (Jira)" <ji...@apache.org>]

Steve Carlin created HIVE-26671:
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             Summary: Incorrect results for group by/order by/limit query with 2 aggregates
                 Key: HIVE-26671
                 URL: https://issues.apache.org/jira/browse/HIVE-26671
             Project: Hive
          Issue Type: Bug
          Components: Operators
            Reporter: Steve Carlin


Grabbed this query from the Impala test suite.  It is a query run off of tpcds tables, but it's not really super special.  You will need a lot of data to reproduce this, though.

select
l_orderkey,
min(l_shipdate) as flt,
count(distinct l_partkey) as cnl 
from lineitem
group by l_orderkey order by l_orderkey limit 2;

The issue is with the Top N Key operator optimizer. The Top N Key operator is the first operator after the Table Scan.  The sort key is on both the l_orderkey and l_partkey columns, but this means that the second sort key might not be forwarded.



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