From 0a1d5c85ad29f386e4bc23f79666d5acd3dcf436 Mon Sep 17 00:00:00 2001
From: "J. Nick Koston" <nick@koston.org>
Date: Tue, 7 Feb 2023 07:50:44 -0600
Subject: [PATCH] Optimize history.get_last_state_changes query (#87554)

fixes undefined
---
 homeassistant/components/recorder/history.py  | 48 ++++++++++---------
 tests/components/recorder/test_history.py     |  2 +-
 .../recorder/test_history_db_schema_30.py     |  2 +-
 3 files changed, 28 insertions(+), 24 deletions(-)

diff --git a/homeassistant/components/recorder/history.py b/homeassistant/components/recorder/history.py
index 72ae57dde27..0f3db70f66a 100644
--- a/homeassistant/components/recorder/history.py
+++ b/homeassistant/components/recorder/history.py
@@ -518,48 +518,52 @@ def state_changes_during_period(
 
 
 def _get_last_state_changes_stmt(
-    schema_version: int, number_of_states: int, entity_id: str | None
+    schema_version: int, number_of_states: int, entity_id: str
 ) -> StatementLambdaElement:
     stmt, join_attributes = lambda_stmt_and_join_attributes(
         schema_version, False, include_last_changed=False
     )
     if schema_version >= 31:
-        stmt += lambda q: q.filter(
-            (States.last_changed_ts == States.last_updated_ts)
-            | States.last_changed_ts.is_(None)
+        stmt += lambda q: q.where(
+            States.state_id
+            == (
+                select(States.state_id)
+                .filter(States.entity_id == entity_id)
+                .order_by(States.last_updated_ts.desc())
+                .limit(number_of_states)
+                .subquery()
+            ).c.state_id
         )
     else:
-        stmt += lambda q: q.filter(
-            (States.last_changed == States.last_updated) | States.last_changed.is_(None)
+        stmt += lambda q: q.where(
+            States.state_id
+            == (
+                select(States.state_id)
+                .filter(States.entity_id == entity_id)
+                .order_by(States.last_updated.desc())
+                .limit(number_of_states)
+                .subquery()
+            ).c.state_id
         )
-    if entity_id:
-        stmt += lambda q: q.filter(States.entity_id == entity_id)
     if join_attributes:
         stmt += lambda q: q.outerjoin(
             StateAttributes, States.attributes_id == StateAttributes.attributes_id
         )
-    if schema_version >= 31:
-        stmt += lambda q: q.order_by(
-            States.entity_id, States.last_updated_ts.desc()
-        ).limit(number_of_states)
-    else:
-        stmt += lambda q: q.order_by(
-            States.entity_id, States.last_updated.desc()
-        ).limit(number_of_states)
+
+    stmt += lambda q: q.order_by(States.state_id.desc())
     return stmt
 
 
 def get_last_state_changes(
-    hass: HomeAssistant, number_of_states: int, entity_id: str | None
+    hass: HomeAssistant, number_of_states: int, entity_id: str
 ) -> MutableMapping[str, list[State]]:
     """Return the last number_of_states."""
-    start_time = dt_util.utcnow()
-    entity_id = entity_id.lower() if entity_id is not None else None
-    entity_ids = [entity_id] if entity_id is not None else None
+    entity_id_lower = entity_id.lower()
+    entity_ids = [entity_id_lower]
 
     with session_scope(hass=hass) as session:
         stmt = _get_last_state_changes_stmt(
-            _schema_version(hass), number_of_states, entity_id
+            _schema_version(hass), number_of_states, entity_id_lower
         )
         states = list(execute_stmt_lambda_element(session, stmt))
         return cast(
@@ -568,7 +572,7 @@ def get_last_state_changes(
                 hass,
                 session,
                 reversed(states),
-                start_time,
+                dt_util.utcnow(),
                 entity_ids,
                 include_start_time_state=False,
             ),
diff --git a/tests/components/recorder/test_history.py b/tests/components/recorder/test_history.py
index 83d55f978af..670b08f3e21 100644
--- a/tests/components/recorder/test_history.py
+++ b/tests/components/recorder/test_history.py
@@ -330,7 +330,7 @@ def test_get_last_state_changes(hass_recorder):
 
     start = dt_util.utcnow() - timedelta(minutes=2)
     point = start + timedelta(minutes=1)
-    point2 = point + timedelta(minutes=1)
+    point2 = point + timedelta(minutes=1, seconds=1)
 
     with patch(
         "homeassistant.components.recorder.core.dt_util.utcnow", return_value=start
diff --git a/tests/components/recorder/test_history_db_schema_30.py b/tests/components/recorder/test_history_db_schema_30.py
index 4384f284fe8..ee4bb7ab051 100644
--- a/tests/components/recorder/test_history_db_schema_30.py
+++ b/tests/components/recorder/test_history_db_schema_30.py
@@ -257,7 +257,7 @@ def test_get_last_state_changes(hass_recorder):
 
     start = dt_util.utcnow() - timedelta(minutes=2)
     point = start + timedelta(minutes=1)
-    point2 = point + timedelta(minutes=1)
+    point2 = point + timedelta(minutes=1, seconds=1)
 
     with patch(
         "homeassistant.components.recorder.core.dt_util.utcnow", return_value=start