1 files changed, 51 insertions, 0 deletions
diff --git a/synapse/storage/schema/main/delta/78/03event_extremities_constraints.py b/synapse/storage/schema/main/delta/78/03event_extremities_constraints.py
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+++ b/synapse/storage/schema/main/delta/78/03event_extremities_constraints.py
@@ -0,0 +1,51 @@
+# 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.
+
+
+"""
+This migration adds foreign key constraint to `event_forward_extremities` table.
+"""
+from synapse.storage.background_updates import (
+    ForeignKeyConstraint,
+    run_validate_constraint_and_delete_rows_schema_delta,
+)
+from synapse.storage.database import LoggingTransaction
+from synapse.storage.engines import BaseDatabaseEngine
+
+FORWARD_EXTREMITIES_TABLE_SCHEMA = """
+    CREATE TABLE event_forward_extremities2(
+        event_id TEXT NOT NULL,
+        room_id TEXT NOT NULL,
+        UNIQUE (event_id, room_id),
+        CONSTRAINT event_forward_extremities_event_id FOREIGN KEY (event_id) REFERENCES events (event_id)
+    )
+"""
+
+
+def run_create(cur: LoggingTransaction, database_engine: BaseDatabaseEngine) -> None:
+    run_validate_constraint_and_delete_rows_schema_delta(
+        cur,
+        ordering=7803,
+        update_name="event_forward_extremities_event_id_foreign_key_constraint_update",
+        table="event_forward_extremities",
+        constraint_name="event_forward_extremities_event_id",
+        constraint=ForeignKeyConstraint("events", [("event_id", "event_id")]),
+        sqlite_table_name="event_forward_extremities2",
+        sqlite_table_schema=FORWARD_EXTREMITIES_TABLE_SCHEMA,
+    )
+
+    # We can't add a similar constraint to `event_backward_extremities` as the
+    # events in there don't exist in the `events` table and `event_edges`
+    # doesn't have a unique constraint on `prev_event_id` (so we can't make a
+    # foreign key point to it).