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From "Kevin Ushey (JIRA)" <j...@apache.org>
Subject [jira] [Issue Comment Deleted] (SPARK-14393) monotonicallyIncreasingId not monotonically increasing with downstream coalesce
Date Mon, 10 Oct 2016 17:26:20 GMT

     [ https://issues.apache.org/jira/browse/SPARK-14393?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Kevin Ushey updated SPARK-14393:
--------------------------------
    Comment: was deleted

(was: Am I correct to understand that I should simply expect `monotonicallyIncreasingId()`
to _not_ produce monotonically increasing ids, sometimes?

If this is the case, then how can one expect to use this function safely?)

> monotonicallyIncreasingId not monotonically increasing with downstream coalesce
> -------------------------------------------------------------------------------
>
>                 Key: SPARK-14393
>                 URL: https://issues.apache.org/jira/browse/SPARK-14393
>             Project: Spark
>          Issue Type: Bug
>          Components: SQL
>    Affects Versions: 1.6.0
>            Reporter: Jason Piper
>
> 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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