Github user cloud-fan commented on a diff in the pull request: https://github.com/apache/spark/pull/17630#discussion_r111527728 --- Diff: sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/plans/logical/Statistics.scala --- @@ -104,22 +106,45 @@ case class ColumnStat( /** * Returns a map from string to string that can be used to serialize the column stats. * The key is the name of the field (e.g. "distinctCount" or "min"), and the value is the string - * representation for the value. The deserialization side is defined in [[ColumnStat.fromMap]]. + * representation for the value. min/max values are converted to the external data type. For + * example, for DateType we store java.sql.Date, and for TimestampType we store + * java.sql.Timestamp. The deserialization side is defined in [[ColumnStat.fromMap]]. * * As part of the protocol, the returned map always contains a key called "version". * In the case min/max values are null (None), they won't appear in the map. */ - def toMap: Map[String, String] = { + def toMap(colName: String, dataType: DataType): Map[String, String] = { val map = new scala.collection.mutable.HashMap[String, String] map.put(ColumnStat.KEY_VERSION, "1") map.put(ColumnStat.KEY_DISTINCT_COUNT, distinctCount.toString) map.put(ColumnStat.KEY_NULL_COUNT, nullCount.toString) map.put(ColumnStat.KEY_AVG_LEN, avgLen.toString) map.put(ColumnStat.KEY_MAX_LEN, maxLen.toString) - min.foreach { v => map.put(ColumnStat.KEY_MIN_VALUE, v.toString) } - max.foreach { v => map.put(ColumnStat.KEY_MAX_VALUE, v.toString) } + min.foreach { v => map.put(ColumnStat.KEY_MIN_VALUE, toExternalString(v, colName, dataType)) } + max.foreach { v => map.put(ColumnStat.KEY_MAX_VALUE, toExternalString(v, colName, dataType)) } map.toMap } + + /** + * Converts the given value from Catalyst data type to string representation of external + * data type. + */ + private def toExternalString(v: Any, colName: String, dataType: DataType): String = { + val externalValue = dataType match { + case BooleanType => v.asInstanceOf[Boolean] + case _: IntegralType => v.toString.toLong + case DateType => DateTimeUtils.toJavaDate(v.toString.toInt) --- End diff -- nit: `v.asInstanceOf[Int]`
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