mustafasrepo commented on code in PR #9801:
URL: https://github.com/apache/arrow-datafusion/pull/9801#discussion_r1538921505
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datafusion/physical-expr/src/aggregate/first_last.rs:
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@@ -611,8 +634,20 @@ impl LastValueAccumulator {
}
})
.collect::<Vec<_>>();
- let indices = lexsort_to_indices(&sort_columns, Some(1))?;
- Ok((!indices.is_empty()).then_some(indices.value(0) as _))
+
+ if self.ignore_nulls {
+ let indices = lexsort_to_indices(&sort_columns, None)?;
+ // If ignoring nulls, find the last non-null value.
+ for index in indices.iter().flatten() {
+ if !value.is_null(index as usize) {
+ return Ok(Some(index as usize));
+ }
+ }
+ Ok(None)
+ } else {
+ let indices = lexsort_to_indices(&sort_columns, Some(1))?;
+ Ok((!indices.is_empty()).then_some(indices.value(0) as _))
Review Comment:
For `last_value` sort expressions are reversed. By this trick, we can get
the first expression in the sort to get last one.
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