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Posted to issues@spark.apache.org by "Zhenhua Wang (JIRA)" <ji...@apache.org> on 2017/10/12 15:14:02 UTC

[jira] [Closed] (SPARK-22164) support histogram in estimating the cardinality of aggregate (or group-by) operator

     [ https://issues.apache.org/jira/browse/SPARK-22164?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Zhenhua Wang closed SPARK-22164.
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> support histogram in estimating the cardinality of aggregate (or group-by) operator
> -----------------------------------------------------------------------------------
>
>                 Key: SPARK-22164
>                 URL: https://issues.apache.org/jira/browse/SPARK-22164
>             Project: Spark
>          Issue Type: Sub-task
>          Components: SQL
>    Affects Versions: 2.2.0
>            Reporter: Ron Hu
>
> Histogram is effective in dealing with skewed distribution. After we generate histogram information for column statistics, we need to adjust aggregate (or group-by) cardinality estimation based on equi-height histogram information.



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