Github user cloud-fan commented on a diff in the pull request:
https://github.com/apache/spark/pull/17630#discussion_r111535250
--- 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 {
--- End diff --
we should just return string in each cases of this pattern match.
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