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Posted to issues@tajo.apache.org by "Hyoungjun Kim (JIRA)" <ji...@apache.org> on 2014/07/22 13:24:38 UTC

[jira] [Created] (TAJO-973) DISTINCT should support SortAggregation in first stage.

Hyoungjun Kim created TAJO-973:
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             Summary: DISTINCT should support SortAggregation in first stage.
                 Key: TAJO-973
                 URL: https://issues.apache.org/jira/browse/TAJO-973
             Project: Tajo
          Issue Type: Improvement
            Reporter: Hyoungjun Kim
            Assignee: Hyoungjun Kim
            Priority: Minor


Currently Tajo only support HashAggregation in first stage in the case of DISTINCT. If a task for first stage has many records, OutOfMemory occurs. Tajo should support SortAggregation.
Tajo does not know what the algorithm should choose in the first stage. And Tajo does not support query hint clause. So I will add "tajo-distinct-first-stage-algorithm" property in the TajoConf. After TAJO-928 that property can be set in session variable.
 



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