[
https://issues.apache.org/jira/browse/SPARK-12616?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15081744#comment-15081744
]
Apache Spark commented on SPARK-12616:
--------------------------------------
User 'gatorsmile' has created a pull request for this issue:
https://github.com/apache/spark/pull/10577
> Union logical plan should support arbitrary number of children (rather than
> binary)
> -----------------------------------------------------------------------------------
>
> Key: SPARK-12616
> URL: https://issues.apache.org/jira/browse/SPARK-12616
> Project: Spark
> Issue Type: Improvement
> Components: SQL
> Reporter: Reynold Xin
>
> Union logical plan is a binary node. However, a typical use case for union is
> to union a very large number of input sources (DataFrames, RDDs, or files).
> It is not uncommon to union hundreds of thousands of files. In this case, our
> optimizer can become very slow due to the large number of logical unions. We
> should change the Union logical plan to support an arbitrary number of
> children, and add a single rule in the optimizer (or analyzer?) to collapse
> all adjacent Unions into one.
> Note that this problem doesn't exist in physical plan, because the physical
> Union already supports arbitrary number of children.
--
This message was sent by Atlassian JIRA
(v6.3.4#6332)
---------------------------------------------------------------------
To unsubscribe, e-mail: issues-unsubscr...@spark.apache.org
For additional commands, e-mail: issues-h...@spark.apache.org
