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Posted to issues@spark.apache.org by "Liang-Chi Hsieh (JIRA)" <ji...@apache.org> on 2015/10/11 20:09:05 UTC

[jira] [Created] (SPARK-11055) Use mixing hash-based and sort-based aggregation in TungstenAggregationIterator

Liang-Chi Hsieh created SPARK-11055:
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             Summary: Use mixing hash-based and sort-based aggregation in TungstenAggregationIterator
                 Key: SPARK-11055
                 URL: https://issues.apache.org/jira/browse/SPARK-11055
             Project: Spark
          Issue Type: Improvement
          Components: SQL
            Reporter: Liang-Chi Hsieh


In TungstenAggregationIterator we switch to sort-based aggregation when we can't allocate more memory for hashmap.

However, using external sorter-based aggregation will write too much key-value pairs into disk. We should use mixing hash-based and sort-based aggregation to reduce the key-value pairs needed to write to disk.



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