- optimize collection of cols we insert as none

1 files changed, 9 insertions, 9 deletions

diff --git a/lib/sqlalchemy/orm/mapper.py b/lib/sqlalchemy/orm/mapper.py
index 14dc5d7f8..89c092b58 100644
--- a/lib/sqlalchemy/orm/mapper.py
+++ b/lib/sqlalchemy/orm/mapper.py
@@ -1894,27 +1894,27 @@ class Mapper(InspectionAttr):
     """
 
     @_memoized_configured_property
-    def _propkey_to_col(self):
+    def _insert_cols_as_none(self):
         return dict(
             (
                 table,
-                dict(
-                    (self._columntoproperty[col].key, col)
-                    for col in columns
-                )
+                frozenset(
+                    col.key for col in columns
+                    if not col.primary_key and
+                    not col.server_default and not col.default)
             )
             for table, columns in self._cols_by_table.items()
         )
 
     @_memoized_configured_property
-    def _col_to_propkey(self):
+    def _propkey_to_col(self):
         return dict(
             (
                 table,
-                [
-                    (col, self._columntoproperty[col].key)
+                dict(
+                    (self._columntoproperty[col].key, col)
                     for col in columns
-                ]
+                )
             )
             for table, columns in self._cols_by_table.items()
         )