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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