[GitHub] spark pull request #16594: [SPARK-17078] [SQL] Show stats when explain

[gatorsmile <gi...@git.apache.org>]

Github user gatorsmile commented on a diff in the pull request:

    https://github.com/apache/spark/pull/16594#discussion_r102137142
  
    --- Diff: sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/plans/logical/Statistics.scala ---
    @@ -54,11 +57,29 @@ case class Statistics(
     
       /** Readable string representation for the Statistics. */
       def simpleString: String = {
    -    Seq(s"sizeInBytes=$sizeInBytes",
    -      if (rowCount.isDefined) s"rowCount=${rowCount.get}" else "",
    +    Seq(s"sizeInBytes=${format(sizeInBytes, isSize = true)}",
    +      if (rowCount.isDefined) s"rowCount=${format(rowCount.get, isSize = false)}" else "",
           s"isBroadcastable=$isBroadcastable"
         ).filter(_.nonEmpty).mkString(", ")
       }
    +
    +  /** Show the given number in a readable format. */
    +  def format(number: BigInt, isSize: Boolean): String = {
    +    val decimalValue = BigDecimal(number, new MathContext(3, RoundingMode.HALF_UP))
    +    if (isSize) {
    +      // The largest unit in Utils.bytesToString is TB
    +      val PB = 1L << 50
    +      if (number < 2 * PB) {
    +        // The number is not very large, so we can use Utils.bytesToString to show it.
    +        Utils.bytesToString(number.toLong)
    +      } else {
    +        // The number is too large, show it in scientific notation.
    +        decimalValue.toString() + " B"
    +      }
    +    } else {
    +      decimalValue.toString()
    --- End diff --
    
    Always represent it using scientific notation? Or only do it when the number is too large?


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