Merge pull request #5294 from matrix-org/erikj/speed_up_room_stats

Speed up room stats background update

synapse/storage/schema/delta/54/stats2.sql

@@ -0,0 +1,28 @@
+/* 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.
+ */
+
+-- This delta file gets run after `54/stats.sql` delta.
+
+-- We want to add some indices to the temporary stats table, so we re-insert
+-- 'populate_stats_createtables' if we are still processing the rooms update.
+INSERT INTO background_updates (update_name, progress_json)
+    SELECT 'populate_stats_createtables', '{}'
+    WHERE
+        'populate_stats_process_rooms' IN (
+            SELECT update_name FROM background_updates
+        )
+        AND 'populate_stats_createtables' NOT IN (  -- don't insert if already exists
+            SELECT update_name FROM background_updates
+        );