[jira] [Updated] (SPARK-17959) spark.sql.join.preferSortMergeJoin has no effect for simple join due to calculated size of LogicalRdd

["Stavros Kontopoulos (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/SPARK-17959?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Stavros Kontopoulos updated SPARK-17959:
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    Summary: spark.sql.join.preferSortMergeJoin has no effect for simple join due to calculated size of LogicalRdd  (was: spark.sql.join.preferSortMergeJoin has no effect for simple join)

> spark.sql.join.preferSortMergeJoin has no effect for simple join due to calculated size of LogicalRdd
> -----------------------------------------------------------------------------------------------------
>
>                 Key: SPARK-17959
>                 URL: https://issues.apache.org/jira/browse/SPARK-17959
>             Project: Spark
>          Issue Type: Bug
>          Components: SQL
>    Affects Versions: 2.0.1
>            Reporter: Stavros Kontopoulos
>
> Example code:   
> val df = spark.sparkContext.parallelize(List(("A", 10, "dss@s1"), ("A", 20, "dss@s2"),
>       ("B", 1, "dss@qqa"), ("B", 2, "dss@qqb"))).toDF("Group", "Amount", "Email")
>     df.as("a").join(df.as("b"))
>       .where($"a.Group" === $"b.Group")
>       .explain()
> I always get the SortMerge strategy (never shuffle hash join) even if i set spark.sql.join.preferSortMergeJoin to false since:
> sinzeInBytes = 2^63-1
> https://github.com/apache/spark/blob/master/sql/core/src/main/scala/org/apache/spark/sql/execution/ExistingRDD.scala#L101
> and thus:
> condition here: https://github.com/apache/spark/blob/master/sql/core/src/main/scala/org/apache/spark/sql/execution/SparkStrategies.scala#L127
> is always false...
> I think this shouldnt be the case my df has a specifc size and number of partitions (200 which is btw far from optimal)...



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