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Posted to issues@spark.apache.org by "Jason Piper (JIRA)" <ji...@apache.org> on 2016/04/05 03:04:25 UTC

[jira] [Created] (SPARK-14393) monotonicallyIncreasingId not monotonically increasing with downstream coalesce

Jason Piper created SPARK-14393:
-----------------------------------

             Summary: 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

>>> 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|
+---------------------------+



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