[GitHub] [arrow-datafusion] Dandandan commented on a diff in pull request #5408: refactor count_distinct to not to have update and merge

["Dandandan (via GitHub)" <gi...@apache.org>]

Dandandan commented on code in PR #5408:
URL: https://github.com/apache/arrow-datafusion/pull/5408#discussion_r1118194128


##########
datafusion/physical-expr/src/aggregate/count_distinct.rs:
##########
@@ -205,6 +146,52 @@ impl Accumulator for DistinctCountAccumulator {
 
         Ok(cols_out.into_iter().collect())
     }
+    fn update_batch(&mut self, values: &[ArrayRef]) -> Result<()> {
+        if values.is_empty() {
+            return Ok(());
+        }
+        let arr = &values[0];
+        (0..arr.len()).try_for_each(|index| {
+            let scalar = ScalarValue::try_from_array(arr, index)?;
+            let scalar = vec![scalar];

Review Comment:
   We can avoid creating a `Vec` here 



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