Sliding sync: don't fetch room summary for named rooms. (#17683)

For rooms with a name we can skip fetching a full room summary, as we
don't need to calculate heroes, and instead just fetch the room counts
directly.

This also changes things to not return counts and heroes for non-joined
rooms. For left/banned rooms we were returning zero values anyway, and
for invite/knock rooms we don't really want to leak such information
(even if some of is included in the stripped state).

1 files changed, 19 insertions, 0 deletions

diff --git a/synapse/storage/schema/main/delta/87/03_current_state_index.sql b/synapse/storage/schema/main/delta/87/03_current_state_index.sql
new file mode 100644

index 0000000000..76b974271c
--- /dev/null
+++ b/synapse/storage/schema/main/delta/87/03_current_state_index.sql
@@ -0,0 +1,19 @@
+--
+-- This file is licensed under the Affero General Public License (AGPL) version 3.
+--
+-- Copyright (C) 2024 New Vector, Ltd
+--
+-- This program is free software: you can redistribute it and/or modify
+-- it under the terms of the GNU Affero General Public License as
+-- published by the Free Software Foundation, either version 3 of the
+-- License, or (at your option) any later version.
+--
+-- See the GNU Affero General Public License for more details:
+-- <https://www.gnu.org/licenses/agpl-3.0.html>.
+
+
+-- Add a background updates to add a new index:
+-- `current_state_events(room_id, membership) WHERE type = 'm.room.member'
+-- This makes counting membership in rooms (for syncs) much faster
+INSERT INTO background_updates (ordering, update_name, progress_json) VALUES
+  (8701, 'current_state_events_members_room_index', '{}');