liamzwbao commented on code in PR #17061:
URL: https://github.com/apache/datafusion/pull/17061#discussion_r2274741254


##########
datafusion/physical-plan/src/repartition/mod.rs:
##########
@@ -755,10 +756,43 @@ impl ExecutionPlan for RepartitionExec {
     }
 
     fn partition_statistics(&self, partition: Option<usize>) -> 
Result<Statistics> {
-        if partition.is_none() {
-            self.input.partition_statistics(None)
+        if let Some(partition) = partition {
+            let partition_count = self.partitioning().partition_count();
+            if partition >= partition_count {
+                return internal_err!(
+                    "RepartitionExec invalid partition {} (expected less than 
{})",
+                    partition,
+                    self.partitioning().partition_count()
+                );
+            }
+
+            let mut stats = self.input.partition_statistics(None)?;
+
+            // Distribute statistics across partitions
+            stats.num_rows = stats
+                .num_rows
+                .get_value()
+                .map(|rows| Precision::Inexact(rows / partition_count))
+                .unwrap_or(Precision::Absent);
+            stats.total_byte_size = stats
+                .total_byte_size
+                .get_value()
+                .map(|bytes| Precision::Inexact(bytes / partition_count))
+                .unwrap_or(Precision::Absent);
+
+            // Handle column statistics: keep min/max values, make others 
absent
+            for col_stats in &mut stats.column_statistics {
+                // Keep min_value and max_value as they represent data range

Review Comment:
   Makes sense, I'm wondering if there's benefit of setting them as `Inexact`, 
because we can still know that upper/lower limit of the data roughly.



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