Github user viirya commented on a diff in the pull request:
https://github.com/apache/spark/pull/21291#discussion_r189149095
--- Diff:
sql/core/src/test/scala/org/apache/spark/sql/ConfigBehaviorSuite.scala ---
@@ -39,7 +39,9 @@ class ConfigBehaviorSuite extends QueryTest with
SharedSQLContext {
def computeChiSquareTest(): Double = {
val n = 10000
// Trigger a sort
- val data = spark.range(0, n, 1, 1).sort('id.desc)
+ // Range has range partitioning in its output now. To have a range
shuffle, we
+ // need to run a repartition first.
+ val data = spark.range(0, n, 1, 1).repartition(10).sort('id.desc)
--- End diff --
By `spark.range(0, n, 1, 10).sort('id.desc)`, there is no 3 times liner
relation between `a` and `b`. As shown above, this is also evenly distribution,
the chi-sq value is also under `100`.
Here we need a redistribution on data to make sampling difficult.
Previously, a repartition is added automatically before `sort`. Now `range` has
correct output partition info, so the repattition must be added manually.
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