From fee8bdf641d56a7ead670acf2ec52ebe135730cf Mon Sep 17 00:00:00 2001
From: Emil Ejbyfeldt <emil.ejbyfeldt@gmail.com>
Date: Wed, 25 Sep 2024 20:09:18 +0200
Subject: [PATCH] PR suggestion comment

---
 datafusion/physical-plan/src/aggregates/mod.rs | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/datafusion/physical-plan/src/aggregates/mod.rs b/datafusion/physical-plan/src/aggregates/mod.rs
index 1e6880748f2c..124dcdc8d171 100644
--- a/datafusion/physical-plan/src/aggregates/mod.rs
+++ b/datafusion/physical-plan/src/aggregates/mod.rs
@@ -261,6 +261,9 @@ impl PhysicalGroupBy {
     }
 
     /// Returns the data type of the grouping id.
+    /// The grouping ID value is a bitmask where each set bit
+    /// indicates that the corresponding grouping expression is
+    /// null
     fn grouping_id_type(&self) -> DataType {
         if self.expr.len() <= 8 {
             DataType::UInt8