Use java.math.BigDecimal for casting String to Decimal instead of using toDouble.

Author: viirya

sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/Cast.scala

@@ -323,7 +323,7 @@ case class Cast(child: Expression, dataType: DataType) extends UnaryExpression w
   private[this] def castToDecimal(from: DataType, target: DecimalType): Any => Any = from match {
     case StringType =>
       buildCast[UTF8String](_, s => try {
-        changePrecision(Decimal(s.toString.toDouble), target)
+        changePrecision(Decimal(new java.math.BigDecimal(s.toString)), target)
       } catch {
         case _: NumberFormatException => null
       })