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Posted to issues@spark.apache.org by "Xiao Li (JIRA)" <ji...@apache.org> on 2016/10/08 20:57:20 UTC
[jira] [Commented] (SPARK-11055) Use mixing hash-based and
sort-based aggregation in TungstenAggregationIterator
[ https://issues.apache.org/jira/browse/SPARK-11055?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15558706#comment-15558706 ]
Xiao Li commented on SPARK-11055:
---------------------------------
Based on the PR, Davies did a similar work. [SPARK-11425] [SPARK-11486] Improve hybrid aggregation
> 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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