restore comments

apache · Jan 19, 2022 · c065f05 · c065f05
1 parent cdda360
commit c065f05
Showing 1 changed file with 5 additions and 1 deletion.
diff --git a/datafusion/src/physical_plan/coercion_rule/binary_rule.rs b/datafusion/src/physical_plan/coercion_rule/binary_rule.rs
@@ -432,8 +432,10 @@ fn numerical_coercion(lhs_type: &DataType, rhs_type: &DataType) -> Option<DataTy
         return None;
     };
 
-    // same type => all good
+    // can't compare dictionaries directly due to
+    // https://github.com/apache/arrow-rs/issues/1201
     if lhs_type == rhs_type && !is_dictionary(lhs_type) {
+        // same type => all good
         return Some(lhs_type.clone());
     }
 
@@ -456,6 +458,8 @@ fn numerical_coercion(lhs_type: &DataType, rhs_type: &DataType) -> Option<DataTy
 
 /// coercion rules for equality operations. This is a superset of all numerical coercion rules.
 fn eq_coercion(lhs_type: &DataType, rhs_type: &DataType) -> Option<DataType> {
+    // can't compare dictionaries directly due to
+    // https://github.com/apache/arrow-rs/issues/1201
     if lhs_type == rhs_type && !is_dictionary(lhs_type) {
         // same type => equality is possible
         return Some(lhs_type.clone());