diff --git a/synapse/storage/schema/delta/53/user_share.sql b/synapse/storage/schema/delta/53/user_share.sql
new file mode 100644
index 0000000000..5831b1a6f8
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+++ b/synapse/storage/schema/delta/53/user_share.sql
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+/* Copyright 2017 Vector Creations Ltd, 2019 New Vector Ltd
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+-- Old disused version of the tables below.
+DROP TABLE IF EXISTS users_who_share_rooms;
+
+-- Tables keeping track of what users share rooms. This is a map of local users
+-- to local or remote users, per room. Remote users cannot be in the user_id
+-- column, only the other_user_id column. There are two tables, one for public
+-- rooms and those for private rooms.
+CREATE TABLE IF NOT EXISTS users_who_share_public_rooms (
+ user_id TEXT NOT NULL,
+ other_user_id TEXT NOT NULL,
+ room_id TEXT NOT NULL
+);
+
+CREATE TABLE IF NOT EXISTS users_who_share_private_rooms (
+ user_id TEXT NOT NULL,
+ other_user_id TEXT NOT NULL,
+ room_id TEXT NOT NULL
+);
+
+CREATE UNIQUE INDEX users_who_share_public_rooms_u_idx ON users_who_share_public_rooms(user_id, other_user_id, room_id);
+CREATE INDEX users_who_share_public_rooms_r_idx ON users_who_share_public_rooms(room_id);
+CREATE INDEX users_who_share_public_rooms_o_idx ON users_who_share_public_rooms(other_user_id);
+
+CREATE UNIQUE INDEX users_who_share_private_rooms_u_idx ON users_who_share_private_rooms(user_id, other_user_id, room_id);
+CREATE INDEX users_who_share_private_rooms_r_idx ON users_who_share_private_rooms(room_id);
+CREATE INDEX users_who_share_private_rooms_o_idx ON users_who_share_private_rooms(other_user_id);
+
+-- Make sure that we populate the tables initially by resetting the stream ID
+UPDATE user_directory_stream_pos SET stream_id = NULL;
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