[GitHub] [spark] wangyum commented on a change in pull request #29731: [WIP][SPARK-32706][SQL] Improve cast string to decimal type

[GitBox <gi...@apache.org>]

wangyum commented on a change in pull request #29731:
URL: https://github.com/apache/spark/pull/29731#discussion_r487111962



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File path: sql/catalyst/src/main/scala/org/apache/spark/sql/types/Decimal.scala
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@@ -143,8 +143,12 @@ final class Decimal extends Ordered[Decimal] with Serializable {
     } else if (decimal.scale < 0 && !SQLConf.get.allowNegativeScaleOfDecimalEnabled) {
       this._precision = decimal.precision - decimal.scale
       this._scale = 0
-      // set scale to 0 to correct unscaled value
-      this.decimalVal = decimal.setScale(0)
+      if (this._precision > 309) {

Review comment:
       `309` to support double. or it is should be `DecimalType.MAX_PRECISION`?




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