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Posted to issues@spark.apache.org by "Takeshi Yamamuro (JIRA)" <ji...@apache.org> on 2016/04/06 04:09:25 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=15227551#comment-15227551 ]
Takeshi Yamamuro edited comment on SPARK-14393 at 4/6/16 2:08 AM:
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Seems different `MonotonicallyIncreasingID` instances share the same stage, that is the same partition id. However, I'm not 100% sure this is a wrong behaviour because we can easily break this monotonically-increasing semantics by using repartition/coalesce after select(monotonicallyIncreasingId()).
was (Author: maropu):
Seems different `MonotonicallyIncreasingID` instances wrongly shares the same stage, that is the same partition id.
> 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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