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Posted to issues@quickstep.apache.org by "Zuyu Zhang (JIRA)" <ji...@apache.org> on 2018/04/21 21:00:01 UTC

[jira] [Created] (QUICKSTEP-118) Optimization Rule For Union of same subqueries

Zuyu Zhang created QUICKSTEP-118:
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             Summary: Optimization Rule For Union of same subqueries
                 Key: QUICKSTEP-118
                 URL: https://issues.apache.org/jira/browse/QUICKSTEP-118
             Project: Apache Quickstep
          Issue Type: Improvement
          Components: Query Optimizer
            Reporter: Zuyu Zhang


Currently, [the following query|https://github.com/apache/incubator-quickstep/blob/master/query_optimizer/tests/physical_generator/Select.test#L3156] is convert into a `UnionAll` followed by `Aggregate` for de-duplication.
{code:java}
SELECT int_col FROM test
UNION
SELECT int_col FROM test;
{code}
 

The optimizer should, however, transform such query into a simple select query:
{code:java}
SELECT int_col FROM test;
{code}



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