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Posted to issues@spark.apache.org by "Apache Spark (JIRA)" <ji...@apache.org> on 2017/03/27 03:29:41 UTC

[jira] [Commented] (SPARK-20104) Don't estimate IsNull or IsNotNull predicates for non-leaf node

    [ https://issues.apache.org/jira/browse/SPARK-20104?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15942583#comment-15942583 ] 

Apache Spark commented on SPARK-20104:
--------------------------------------

User 'wzhfy' has created a pull request for this issue:
https://github.com/apache/spark/pull/17438

> Don't estimate IsNull or IsNotNull predicates for non-leaf node
> ---------------------------------------------------------------
>
>                 Key: SPARK-20104
>                 URL: https://issues.apache.org/jira/browse/SPARK-20104
>             Project: Spark
>          Issue Type: Bug
>          Components: SQL
>    Affects Versions: 2.2.0
>            Reporter: Zhenhua Wang
>
> In current stage, we don't have advanced statistics such as sketches or histograms. As a result, some operator can't estimate `nullCount` accurately. E.g. left outer join estimation does not accurately update `nullCount` currently. So for IsNull and IsNotNull predicates, we only estimate them when the child is a leaf node, whose `nullCount` is accurate. 



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