Optimize getting current user session

We get all user session when logging in, this isn't necessary and does
show up in a memray trace. I don't think it's a leak, but this is going
to be more efficient.

lib/galaxy/model/__init__.py

@@ -10736,6 +10736,20 @@ WorkflowInvocationStep.subworkflow_invocation_id = column_property(
 # <user_obj>.preferences[pref_name] = pref_value
 User.preferences = association_proxy("_preferences", "value", creator=UserPreference)
 
+# Optimized version of getting the current Galaxy session.
+# See https://github.com/sqlalchemy/sqlalchemy/discussions/7638 for approach
+session_partition = select(
+    GalaxySession,
+    func.row_number().over(order_by=GalaxySession.update_time, partition_by=GalaxySession.user_id).label("index"),
+).alias()
+partitioned_session = aliased(GalaxySession, session_partition)
+User.current_galaxy_session = relationship(
+    partitioned_session,
+    primaryjoin=and_(partitioned_session.user_id == User.id, session_partition.c.index < 2),
+    uselist=False,
+    viewonly=True,
+)
+
 
 @event.listens_for(HistoryDatasetCollectionAssociation, "init")
 def receive_init(target, args, kwargs):

lib/galaxy/webapps/base/webapp.py

@@ -835,7 +835,7 @@ class GalaxyWebTransaction(base.DefaultWebTransaction, context.ProvidesHistoryCo
         history = None
         set_permissions = False
         try:
-            users_last_session = user.galaxy_sessions[0]
+            users_last_session = user.current_galaxy_session
         except Exception:
             users_last_session = None
         if (

lib/galaxy/webapps/galaxy/controllers/admin.py

@@ -77,7 +77,7 @@ class UserListGrid(grids.Grid):
     class LastLoginColumn(grids.GridColumn):
         def get_value(self, trans, grid, user):
             if user.galaxy_sessions:
-                return self.format(user.galaxy_sessions[0].update_time)
+                return self.format(user.current_galaxy_session.update_time)
             return "never"
 
         def sort(self, trans, query, ascending, column_name=None):

lib/galaxy/webapps/reports/controllers/users.py

@@ -164,8 +164,9 @@ class Users(BaseUIController, ReportQueryBuilder):
             .filter(galaxy.model.User.table.c.deleted == false())
             .order_by(galaxy.model.User.table.c.email)
         ):
-            if user.galaxy_sessions:
-                last_galaxy_session = user.galaxy_sessions[0]
+            current_galaxy_session = user.current_galaxy_session
+            if current_galaxy_session:
+                last_galaxy_session = current_galaxy_session
                 if last_galaxy_session.update_time < cutoff_time:
                     users.append((user.email, last_galaxy_session.update_time.strftime("%Y-%m-%d")))
             else:

lib/tool_shed/grids/admin_grids.py

@@ -46,8 +46,8 @@ class UserGrid(grids.Grid):
 
     class LastLoginColumn(grids.GridColumn):
         def get_value(self, trans, grid, user):
-            if user.galaxy_sessions:
-                return self.format(user.galaxy_sessions[0].update_time)
+            if user.current_galaxy_session:
+                return self.format(user.current_galaxy_session.update_time)
             return "never"
 
     class StatusColumn(grids.GridColumn):