- use a faster discard when loading

- don't do a bool on identity map since it calls __len__

1 files changed, 2 insertions, 2 deletions

diff --git a/lib/sqlalchemy/orm/session.py b/lib/sqlalchemy/orm/session.py
index 036045dba..52873eb34 100644
--- a/lib/sqlalchemy/orm/session.py
+++ b/lib/sqlalchemy/orm/session.py
@@ -1427,10 +1427,10 @@ class Session(_SessionClassMethods):
                 if state.key is None:
                     state.key = instance_key
                 elif state.key != instance_key:
-                    # primary key switch. use discard() in case another
+                    # primary key switch. use safe_discard() in case another
                     # state has already replaced this one in the identity
                     # map (see test/orm/test_naturalpks.py ReversePKsTest)
-                    self.identity_map.discard(state)
+                    self.identity_map.safe_discard(state)
                     if state in self.transaction._key_switches:
                         orig_key = self.transaction._key_switches[state][0]
                     else: