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Posted to issues@spark.apache.org by "Apache Spark (JIRA)" <ji...@apache.org> on 2016/11/03 05:26:58 UTC

[jira] [Commented] (SPARK-14393) values generated by non-deterministic functions shouldn't change after coalesce or union

    [ https://issues.apache.org/jira/browse/SPARK-14393?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15631653#comment-15631653 ] 

Apache Spark commented on SPARK-14393:
--------------------------------------

User 'felixcheung' has created a pull request for this issue:
https://github.com/apache/spark/pull/15747

> values generated by non-deterministic functions shouldn't change after coalesce or union
> ----------------------------------------------------------------------------------------
>
>                 Key: SPARK-14393
>                 URL: https://issues.apache.org/jira/browse/SPARK-14393
>             Project: Spark
>          Issue Type: Bug
>          Components: SQL
>    Affects Versions: 1.6.0, 2.0.0, 2.0.1
>            Reporter: Jason Piper
>            Assignee: Xiangrui Meng
>            Priority: Blocker
>              Labels: correctness, releasenotes
>             Fix For: 2.1.0
>
>
> When utilising monotonicallyIncreasingId with a coalesce, it appears that every partition uses the same offset (0) leading to non-monotonically increasing IDs.
> See examples below
> {code}
> >>> sqlContext.range(10).select(monotonicallyIncreasingId()).show()
> +---------------------------+
> |monotonicallyincreasingid()|
> +---------------------------+
> |                25769803776|
> |                51539607552|
> |                77309411328|
> |               103079215104|
> |               128849018880|
> |               163208757248|
> |               188978561024|
> |               214748364800|
> |               240518168576|
> |               266287972352|
> +---------------------------+
> >>> sqlContext.range(10).select(monotonicallyIncreasingId()).coalesce(1).show()
> +---------------------------+
> |monotonicallyincreasingid()|
> +---------------------------+
> |                          0|
> |                          0|
> |                          0|
> |                          0|
> |                          0|
> |                          0|
> |                          0|
> |                          0|
> |                          0|
> |                          0|
> +---------------------------+
> >>> sqlContext.range(10).repartition(5).select(monotonicallyIncreasingId()).coalesce(1).show()
> +---------------------------+
> |monotonicallyincreasingid()|
> +---------------------------+
> |                          0|
> |                          1|
> |                          0|
> |                          0|
> |                          1|
> |                          2|
> |                          3|
> |                          0|
> |                          1|
> |                          2|
> +---------------------------+
> {code}



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