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From Jayesh Lalwani <jayesh.lalw...@capitalone.com>
Subject Does row_number over a window cause a shuffle?
Date Fri, 03 Aug 2018 15:15:25 GMT
I have some code that adds a column that contains a row_number over a
window. It looks somewhat like this

val sortColumns: List[Column] = r.sortFields.map(sf =>
sf.map(col(_))).getOrElse(List(col(s"defaultSortCol")))
val partitionWindow = Window.partitionBy(s"groupByCol")
val window = partitionWindow.orderBy(sortColumns:_*)
df.withColumn(s"MyRank", row_number().over(window))

Will this cause a shuffle because I am partitioning by groupByCol? What
happens if groupByCol is a boolean? Will this cause the dataframe to be
partition into 2?

Or does Spark do something like using an accumulator to assign the row
numbers?
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