Speed up `get_unread_event_push_actions_by_room` (#13005)

Fixes #11887 hopefully.

The core change here is that `event_push_summary` now holds a summary of counts up until a much more recent point, meaning that the range of rows we need to count in `event_push_actions` is much smaller.

This needs two major changes:
1. When we get a receipt we need to recalculate `event_push_summary` rather than just delete it
2. The logic for deleting `event_push_actions` is now divorced from calculating `event_push_summary`.

In future it would be good to calculate `event_push_summary` while we persist a new event (it should just be a case of adding one to the relevant rows in `event_push_summary`), as that will further simplify the get counts logic and remove the need for us to periodically update `event_push_summary` in a background job.

1 files changed, 3 insertions, 7 deletions

diff --git a/synapse/handlers/sync.py b/synapse/handlers/sync.py
index af19c513be..6ad053f678 100644
--- a/synapse/handlers/sync.py
+++ b/synapse/handlers/sync.py
@@ -18,7 +18,7 @@ from typing import TYPE_CHECKING, Any, Dict, FrozenSet, List, Optional, Set, Tup
 import attr
 from prometheus_client import Counter
 
-from synapse.api.constants import EventTypes, Membership, ReceiptTypes
+from synapse.api.constants import EventTypes, Membership
 from synapse.api.filtering import FilterCollection
 from synapse.api.presence import UserPresenceState
 from synapse.api.room_versions import KNOWN_ROOM_VERSIONS
@@ -1054,14 +1054,10 @@ class SyncHandler:
         self, room_id: str, sync_config: SyncConfig
     ) -> NotifCounts:
         with Measure(self.clock, "unread_notifs_for_room_id"):
-            last_unread_event_id = await self.store.get_last_receipt_event_id_for_user(
-                user_id=sync_config.user.to_string(),
-                room_id=room_id,
-                receipt_types=(ReceiptTypes.READ, ReceiptTypes.READ_PRIVATE),
-            )
 
             return await self.store.get_unread_event_push_actions_by_room_for_user(
-                room_id, sync_config.user.to_string(), last_unread_event_id
+                room_id,
+                sync_config.user.to_string(),
             )
 
     async def generate_sync_result(