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