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Posted to issues@spark.apache.org by "Apache Spark (JIRA)" <ji...@apache.org> on 2017/01/25 02:58:27 UTC
[jira] [Assigned] (SPARK-19350) Cardinality estimation of Limit and
Sample
[ https://issues.apache.org/jira/browse/SPARK-19350?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Apache Spark reassigned SPARK-19350:
------------------------------------
Assignee: Apache Spark
> Cardinality estimation of Limit and Sample
> ------------------------------------------
>
> Key: SPARK-19350
> URL: https://issues.apache.org/jira/browse/SPARK-19350
> Project: Spark
> Issue Type: Sub-task
> Components: SQL
> Reporter: Zhenhua Wang
> Assignee: Apache Spark
>
> Currently, LocalLimit/GlobalLimit/Sample propagates the same row count and column stats from its child, which is incorrect.
> We can get the correct rowCount in Statistics for Limit/Sample whether cbo is enabled or not. And column stats should not be propagated because we don't know the distribution of columns after Limit or Sample.
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