3 files changed, 6 insertions, 1 deletions
diff --git a/changelog.d/14549.misc b/changelog.d/14549.misc
new file mode 100644
index 0000000000..d9d863dd20
--- /dev/null
+++ b/changelog.d/14549.misc
@@ -0,0 +1 @@
+Faster joins: use servers list approximation to send read receipts when in partial state instead of waiting for the full state of the room.
\ No newline at end of file
diff --git a/synapse/federation/sender/__init__.py b/synapse/federation/sender/__init__.py
index fc1d8c88a7..30ebd62883 100644
--- a/synapse/federation/sender/__init__.py
+++ b/synapse/federation/sender/__init__.py
@@ -647,7 +647,7 @@ class FederationSender(AbstractFederationSender):
         room_id = receipt.room_id
 
         # Work out which remote servers should be poked and poke them.
-        domains_set = await self._storage_controllers.state.get_current_hosts_in_room(
+        domains_set = await self._storage_controllers.state.get_current_hosts_in_room_or_partial_state_approximation(
             room_id
         )
         domains = [
diff --git a/tests/federation/test_federation_sender.py b/tests/federation/test_federation_sender.py
index 01f147418b..cbc99d30b9 100644
--- a/tests/federation/test_federation_sender.py
+++ b/tests/federation/test_federation_sender.py
@@ -38,6 +38,10 @@ class FederationSenderReceiptsTestCases(HomeserverTestCase):
             return_value=make_awaitable({"test", "host2"})
         )
 
+        hs.get_storage_controllers().state.get_current_hosts_in_room_or_partial_state_approximation = (
+            hs.get_storage_controllers().state.get_current_hosts_in_room
+        )
+
         return hs
 
     @override_config({"send_federation": True})