Github user srowen commented on a diff in the pull request:
https://github.com/apache/spark/pull/5974#discussion_r29844326
--- Diff: core/src/main/scala/org/apache/spark/rdd/RDD.scala ---
@@ -1177,8 +1177,9 @@ abstract class RDD[T: ClassTag](
* It must be greater than 0.000017.
*/
def countApproxDistinct(relativeSD: Double = 0.05): Long = withScope {
+ require(relativeSD > 0.000017, s"accuracy ($relativeSD) must be
greater than 0.000017")
val p = math.ceil(2.0 * math.log(1.054 / relativeSD) /
math.log(2)).toInt
- countApproxDistinct(p, 0)
+ countApproxDistinct(if (p < 4) 4 else p, 0)
--- End diff --
Seems OK, in that it enforces the contract in the docs, and then avoids an
error in a case that does not seem to be an error. @rxin do you have any
thoughts on this one?
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