Add user_filters.full_user_id column

Signed-off-by: Sean Quah <seanq@matrix.org>

synapse/storage/schema/main/delta/75/02_add_user_filters_full_user_id_column.sql

@@ -0,0 +1,23 @@
+/* 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.
+ */
+
+ALTER TABLE user_filters ADD COLUMN full_user_id TEXT;
+
+-- Add a unique index on the new column, mirroring the `user_filters_unique` unique
+-- index.
+CREATE UNIQUE INDEX full_user_filters_unique ON user_filters (full_user_id, filter_id);
+-- NB: This will lock the table for writes while the index is being built.
+--     There are around 4,000,000 user_filters on matrix.org so we expect this to take
+--     a couple of seconds at most.