pg does not know the insert_id in advance, so super will never return true

activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb

@@ -441,10 +441,8 @@ def insert_sql(sql, name = nil, pk = nil, id_value = nil, sequence_name = nil)
           return id
         end
 
-        # Otherwise, insert then grab last_insert_id.
-        if insert_id = super
-          insert_id
-        else
+        super
+
         # If neither pk nor sequence name is given, look them up.
         unless pk || sequence_name
           pk, sequence_name = *pk_and_sequence_for(table)
@@ -456,7 +454,6 @@ def insert_sql(sql, name = nil, pk = nil, id_value = nil, sequence_name = nil)
           last_insert_id(sequence_name)
         end
       end
-      end
       alias :create :insert
 
       # create a 2D array representing the result set