[jira] [Created] (HIVE-17041) Aggregate elimination with UNIQUE and NOT NULL column

["Jesus Camacho Rodriguez (JIRA)" <ji...@apache.org>]

Jesus Camacho Rodriguez created HIVE-17041:
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             Summary: Aggregate elimination with UNIQUE and NOT NULL column
                 Key: HIVE-17041
                 URL: https://issues.apache.org/jira/browse/HIVE-17041
             Project: Hive
          Issue Type: Sub-task
          Components: Logical Optimizer
    Affects Versions: 3.0.0
            Reporter: Jesus Camacho Rodriguez


If columns are part of a GROUP BY expression and they are UNIQUE and do not accept NULL values, i.e. PK or UK+NOTNULL, the _Aggregate_ operator can be transformed into a Project operator, as each row will end up in a different group.

For instance, given that _pk_ is the PRIMARY KEY for the table, the GROUP BY could be removed from grouping columns for following query:
{code:sql}
SELECT pk, value1
FROM table_1
GROUP BY value1, pk, value2;
{code}




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