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Posted to issues@spark.apache.org by "Apache Spark (JIRA)" <ji...@apache.org> on 2017/03/24 20:55:41 UTC
[jira] [Commented] (SPARK-19408) cardinality estimation involving
two columns of the same table
[ https://issues.apache.org/jira/browse/SPARK-19408?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15941117#comment-15941117 ]
Apache Spark commented on SPARK-19408:
--------------------------------------
User 'ron8hu' has created a pull request for this issue:
https://github.com/apache/spark/pull/17415
> cardinality estimation involving two columns of the same table
> --------------------------------------------------------------
>
> Key: SPARK-19408
> URL: https://issues.apache.org/jira/browse/SPARK-19408
> Project: Spark
> Issue Type: Sub-task
> Components: Optimizer
> Affects Versions: 2.1.0
> Reporter: Ron Hu
>
> In SPARK-17075, we estimate cardinality of predicate expression "column (op) literal", where op is =, <, <=, >, or >=. In SQL queries, we also see predicate expressions involving two columns such as "column-1 (op) column-2" where column-1 and column-2 belong to same table. Note that, if column-1 and column-2 belong to different tables, then it is a join operator's work, NOT a filter operator's work.
> In this jira, we want to estimate the filter factor of predicate expressions involving two columns of same table.
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