[GitHub] [arrow-datafusion] ygf11 commented on a diff in pull request #5345: Refactor DecorrelateWhereExists and add back Distinct if needs

["ygf11 (via GitHub)" <gi...@apache.org>]

ygf11 commented on code in PR #5345:
URL: https://github.com/apache/arrow-datafusion/pull/5345#discussion_r1113983497


##########
datafusion/expr/src/logical_plan/plan.rs:
##########
@@ -1773,6 +1773,22 @@ impl Aggregate {
             _ => plan_err!("Could not coerce into Aggregate!"),
         }
     }
+
+    pub fn is_distinct(&self) -> datafusion_common::Result<bool> {
+        let group_expr_size = self.group_expr.len();
+        if !self.aggr_expr.is_empty() || group_expr_size != self.schema.fields().len() {
+            return Ok(false);
+        }
+
+        let expected_group_exprs = expand_wildcard(&self.schema, self.input.as_ref())?;
+        let expected_expr_set = expected_group_exprs.iter().collect::<HashSet<&Expr>>();
+        let group_expr_set = self.group_expr.iter().collect::<HashSet<&Expr>>();
+        Ok(group_expr_set
+            .intersection(&expected_expr_set)
+            .collect::<HashSet<_>>()
+            .len()
+            == group_expr_size)
+    }

Review Comment:
   A bool flag may be better.
   
   ```rust
   pub strct Aggregate {
       /// The incoming logical plan
       pub input: Arc<LogicalPlan>,
       /// Grouping expressions
       pub group_expr: Vec<Expr>,
       ...
       is_distinct: bool,
   }
   ```



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