2 files changed, 30 insertions, 1 deletions
diff --git a/synapse/rest/admin/__init__.py b/synapse/rest/admin/__init__.py
index 79f22a59f1..770df261ce 100644
--- a/synapse/rest/admin/__init__.py
+++ b/synapse/rest/admin/__init__.py
@@ -68,7 +68,10 @@ from synapse.rest.admin.rooms import (
     RoomTimestampToEventRestServlet,
 )
 from synapse.rest.admin.server_notice_servlet import SendServerNoticeServlet
-from synapse.rest.admin.statistics import UserMediaStatisticsRestServlet
+from synapse.rest.admin.statistics import (
+    LargestRoomsStatistics,
+    UserMediaStatisticsRestServlet,
+)
 from synapse.rest.admin.username_available import UsernameAvailableRestServlet
 from synapse.rest.admin.users import (
     AccountDataRestServlet,
@@ -259,6 +262,7 @@ def register_servlets(hs: "HomeServer", http_server: HttpServer) -> None:
     UserRestServletV2(hs).register(http_server)
     UsersRestServletV2(hs).register(http_server)
     UserMediaStatisticsRestServlet(hs).register(http_server)
+    LargestRoomsStatistics(hs).register(http_server)
     EventReportDetailRestServlet(hs).register(http_server)
     EventReportsRestServlet(hs).register(http_server)
     AccountDataRestServlet(hs).register(http_server)
diff --git a/synapse/rest/admin/statistics.py b/synapse/rest/admin/statistics.py
index 9c45f4650d..19780e4b4c 100644
--- a/synapse/rest/admin/statistics.py
+++ b/synapse/rest/admin/statistics.py
@@ -113,3 +113,28 @@ class UserMediaStatisticsRestServlet(RestServlet):
             ret["next_token"] = start + len(users_media)
 
         return HTTPStatus.OK, ret
+
+
+class LargestRoomsStatistics(RestServlet):
+    """Get the largest rooms by database size.
+
+    Only works when using PostgreSQL.
+    """
+
+    PATTERNS = admin_patterns("/statistics/database/rooms$")
+
+    def __init__(self, hs: "HomeServer"):
+        self.auth = hs.get_auth()
+        self.stats_controller = hs.get_storage_controllers().stats
+
+    async def on_GET(self, request: SynapseRequest) -> Tuple[int, JsonDict]:
+        await assert_requester_is_admin(self.auth, request)
+
+        room_sizes = await self.stats_controller.get_room_db_size_estimate()
+
+        return HTTPStatus.OK, {
+            "rooms": [
+                {"room_id": room_id, "estimated_size": size}
+                for room_id, size in room_sizes
+            ]
+        }