Add membership column to current_state_events table.

It turns out that doing a join is surprisingly expensive for the DB to
do when room_membership table is larger than the disk cache.

1 files changed, 19 insertions, 0 deletions

diff --git a/synapse/storage/schema/delta/56/current_state_events_membership.sql b/synapse/storage/schema/delta/56/current_state_events_membership.sql
new file mode 100644
index 0000000000..5c754651cb
--- /dev/null
+++ b/synapse/storage/schema/delta/56/current_state_events_membership.sql
@@ -0,0 +1,19 @@
+/* Copyright 2019 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.
+ */
+
+-- We add membership to current state so that we don't need to join against
+-- room_memberships, which can be surprisingly costly (we do such queries
+-- very frequently).
+ALTER TABLE current_state_events ADD membership TEXT;