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From "Ron Hu (JIRA)" <j...@apache.org>
Subject [jira] [Created] (SPARK-22164) support histogram in estimating the cardinality of aggregate (or group-by) operator
Date Fri, 29 Sep 2017 00:38:02 GMT
Ron Hu created SPARK-22164:
------------------------------

             Summary: 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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