tweak

homeassistant/components/recorder/core.py

@@ -164,6 +164,7 @@ class EventTypeManager:
         """Initialize the event manager."""
         self._id_map: dict[str, int] = LRU(EVENT_DATA_ID_CACHE_SIZE)
         self._pending: dict[str, EventTypes] = {}
+        self.active = False
 
     def load(self, events: list[Event], session: Session) -> None:
         """Load the event types into memory."""
@@ -222,6 +223,11 @@ class EventTypeManager:
         self._id_map.clear()
         self._pending.clear()
 
+    def evict_purged(self, event_types: Iterable[str]) -> None:
+        """Evict purged event types."""
+        for event_type in event_types:
+            self._id_map.pop(event_type, None)
+
 
 class Recorder(threading.Thread):
     """A threaded recorder class."""

homeassistant/components/recorder/migration.py

@@ -1341,6 +1341,7 @@ def migrate_event_type_ids(instance: Recorder) -> bool:
         _drop_index(
             session_maker, "events", "ix_events_event_type_timed_fired_ts", quiet=True
         )
+        instance.event_type_manager.active = True
 
     _LOGGER.debug("Migrating event_types done=%s", is_done)
     return is_done

homeassistant/components/recorder/purge.py

@@ -24,12 +24,14 @@ from .queries import (
     data_ids_exist_in_events_with_fast_in_distinct,
     delete_event_data_rows,
     delete_event_rows,
+    delete_event_types_rows,
     delete_recorder_runs_rows,
     delete_states_attributes_rows,
     delete_states_rows,
     delete_statistics_runs_rows,
     delete_statistics_short_term_rows,
     disconnect_states_rows,
+    find_event_types_to_purge,
     find_events_to_purge,
     find_latest_statistics_runs_run_id,
     find_legacy_event_state_and_attributes_and_data_ids_to_purge,
@@ -110,6 +112,7 @@ def purge_old_data(
             return False
 
         _purge_old_recorder_runs(instance, session, purge_before)
+        _purge_old_event_types(instance, session)
     if repack:
         repack_database(instance)
     return True
@@ -564,6 +567,22 @@ def _purge_old_recorder_runs(
     _LOGGER.debug("Deleted %s recorder_runs", deleted_rows)
 
 
+def _purge_old_event_types(instance: Recorder, session: Session) -> None:
+    """Purge all old event types."""
+    # Event types is small, no need to batch run it
+    purged_event_types = set()
+    event_type_ids = set()
+    for event_type_id, event_type in session.execute(find_event_types_to_purge()):
+        purged_event_types.add(event_type)
+        event_type_ids.add(event_type_id)
+
+    deleted_rows = session.execute(delete_event_types_rows(event_type_ids))
+    _LOGGER.debug("Deleted %s event types", deleted_rows)
+
+    # Evict any entries in the event_type cache referring to a purged state
+    instance.event_type_manager.evict_purged(purged_event_types)
+
+
 def _purge_filtered_data(instance: Recorder, session: Session) -> bool:
     """Remove filtered states and events that shouldn't be in the database."""
     _LOGGER.debug("Cleanup filtered data")

homeassistant/components/recorder/queries.py

@@ -737,3 +737,26 @@ def find_states_context_ids_to_migrate() -> StatementLambdaElement:
         .filter(States.context_id_bin.is_(None))
         .limit(SQLITE_MAX_BIND_VARS)
     )
+
+
+def find_event_types_to_purge() -> StatementLambdaElement:
+    """Find event_type_ids to purge."""
+    return lambda_stmt(
+        lambda: select(EventTypes.event_type_id, EventTypes.event_type).where(
+            EventTypes.event_type_id
+            == (
+                select(
+                    distinct(Events.event_type_id).label("unused_event_type_id")
+                ).filter(Events.event_type_id.not_in(select(EventTypes.event_type_id)))
+            ).c.unused_event_type_id
+        )
+    )
+
+
+def delete_event_types_rows(event_type_ids: Iterable[int]) -> StatementLambdaElement:
+    """Delete EventTypes rows."""
+    return lambda_stmt(
+        lambda: delete(EventTypes)
+        .where(EventTypes.event_type_id.in_(event_type_ids))
+        .execution_options(synchronize_session=False)
+    )