Experimental support for MSC3970: per-device transaction IDs (#15318)

1 files changed, 53 insertions, 0 deletions

diff --git a/synapse/storage/schema/main/delta/74/05_events_txn_id_device_id.sql b/synapse/storage/schema/main/delta/74/05_events_txn_id_device_id.sql
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index 0000000000..517a821a56
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+++ b/synapse/storage/schema/main/delta/74/05_events_txn_id_device_id.sql
@@ -0,0 +1,53 @@
+/* Copyright 2023 The Matrix.org Foundation C.I.C
+ *
+ * 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.
+ */
+
+-- For MSC3970, in addition to the (room_id, user_id, token_id, txn_id) -> event_id mapping for each local event,
+-- we also store the (room_id, user_id, device_id, txn_id) -> event_id mapping.
+--
+-- This adds a new event_txn_id_device_id table.
+
+-- A map of recent events persisted with transaction IDs. Used to deduplicate
+-- send event requests with the same transaction ID.
+--
+-- Note: with MSC3970, transaction IDs are scoped to the 
+-- room ID/user ID/device ID that was used to make the request.
+--
+-- Note: The foreign key constraints are ON DELETE CASCADE, as if we delete the
+-- event or device we don't want to try and de-duplicate the event.
+CREATE TABLE IF NOT EXISTS event_txn_id_device_id (
+    event_id TEXT NOT NULL,
+    room_id TEXT NOT NULL,
+    user_id TEXT NOT NULL,
+    device_id TEXT NOT NULL,
+    txn_id TEXT NOT NULL,
+    inserted_ts BIGINT NOT NULL,
+    FOREIGN KEY (event_id)
+        REFERENCES events (event_id) ON DELETE CASCADE,
+    FOREIGN KEY (user_id, device_id)
+        REFERENCES devices (user_id, device_id) ON DELETE CASCADE
+);
+
+-- This ensures that there is only one mapping per event_id.
+CREATE UNIQUE INDEX IF NOT EXISTS event_txn_id_device_id_event_id
+    ON event_txn_id_device_id(event_id);
+
+-- This ensures that there is only one mapping per (room_id, user_id, device_id, txn_id) tuple.
+-- Events are usually looked up using this index.
+CREATE UNIQUE INDEX IF NOT EXISTS event_txn_id_device_id_txn_id 
+    ON event_txn_id_device_id(room_id, user_id, device_id, txn_id);
+
+-- This table is cleaned up regularly, removing the oldest entries, hence this index.
+CREATE INDEX IF NOT EXISTS event_txn_id_device_id_ts
+    ON event_txn_id_device_id(inserted_ts);