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Posted to issues@spark.apache.org by "Kevin Ushey (JIRA)" <ji...@apache.org> on 2016/10/10 17:27:21 UTC
[jira] [Comment Edited] (SPARK-14393) monotonicallyIncreasingId not
monotonically increasing with downstream coalesce
[ https://issues.apache.org/jira/browse/SPARK-14393?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15562887#comment-15562887 ]
Kevin Ushey edited comment on SPARK-14393 at 10/10/16 5:27 PM:
---------------------------------------------------------------
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 use this function safely?
was (Author: kevinushey):
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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