1 files changed, 25 insertions, 5 deletions
diff --git a/synapse/storage/devices.py b/synapse/storage/devices.py
index bd56ba2515..53e36791d5 100644
--- a/synapse/storage/devices.py
+++ b/synapse/storage/devices.py
@@ -108,6 +108,23 @@ class DeviceStore(SQLBaseStore):
             desc="delete_device",
         )
 
+    def delete_devices(self, user_id, device_ids):
+        """Deletes several devices.
+
+        Args:
+            user_id (str): The ID of the user which owns the devices
+            device_ids (list): The IDs of the devices to delete
+        Returns:
+            defer.Deferred
+        """
+        return self._simple_delete_many(
+            table="devices",
+            column="device_id",
+            iterable=device_ids,
+            keyvalues={"user_id": user_id},
+            desc="delete_devices",
+        )
+
     def update_device(self, user_id, device_id, new_display_name=None):
         """Update a device.
 
@@ -291,7 +308,7 @@ class DeviceStore(SQLBaseStore):
         """Get stream of updates to send to remote servers
 
         Returns:
-            (now_stream_id, [ { updates }, .. ])
+            (int, list[dict]): current stream id and list of updates
         """
         now_stream_id = self._device_list_id_gen.get_current_token()
 
@@ -312,17 +329,20 @@ class DeviceStore(SQLBaseStore):
             SELECT user_id, device_id, max(stream_id) FROM device_lists_outbound_pokes
             WHERE destination = ? AND ? < stream_id AND stream_id <= ? AND sent = ?
             GROUP BY user_id, device_id
+            LIMIT 20
         """
         txn.execute(
             sql, (destination, from_stream_id, now_stream_id, False)
         )
-        rows = txn.fetchall()
 
-        if not rows:
+        # maps (user_id, device_id) -> stream_id
+        query_map = {(r[0], r[1]): r[2] for r in txn}
+        if not query_map:
             return (now_stream_id, [])
 
-        # maps (user_id, device_id) -> stream_id
-        query_map = {(r[0], r[1]): r[2] for r in rows}
+        if len(query_map) >= 20:
+            now_stream_id = max(stream_id for stream_id in query_map.itervalues())
+
         devices = self._get_e2e_device_keys_txn(
             txn, query_map.keys(), include_all_devices=True
         )