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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