switch back from GIST to GIN indexes

synapse/storage/schema/delta/38/postgres_fts_gist.sql

@@ -13,5 +13,7 @@
  * limitations under the License.
  */
 
- INSERT into background_updates (update_name, progress_json)
-     VALUES ('event_search_postgres_gist', '{}');
+-- We no longer do this given we back it out again in schema 46
+
+-- INSERT into background_updates (update_name, progress_json)
+--     VALUES ('event_search_postgres_gist', '{}');

synapse/storage/schema/delta/46/postgres_fts_gin.sql

@@ -0,0 +1,17 @@
+/* Copyright 2018 New Vector Ltd
+ *
+ * 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.
+ */
+
+INSERT into background_updates (update_name, progress_json)
+    VALUES ('event_search_postgres_gin', '{}');

synapse/storage/search.py

@@ -31,7 +31,7 @@ class SearchStore(BackgroundUpdateStore):
 
     EVENT_SEARCH_UPDATE_NAME = "event_search"
     EVENT_SEARCH_ORDER_UPDATE_NAME = "event_search_order"
-    EVENT_SEARCH_USE_GIST_POSTGRES_NAME = "event_search_postgres_gist"
+    EVENT_SEARCH_USE_GIN_POSTGRES_NAME = "event_search_postgres_gin"
 
     def __init__(self, db_conn, hs):
         super(SearchStore, self).__init__(db_conn, hs)
@@ -43,8 +43,8 @@ def __init__(self, db_conn, hs):
             self._background_reindex_search_order
         )
         self.register_background_update_handler(
-            self.EVENT_SEARCH_USE_GIST_POSTGRES_NAME,
-            self._background_reindex_gist_search
+            self.EVENT_SEARCH_USE_GIN_POSTGRES_NAME,
+            self._background_reindex_gin_search
         )
 
     @defer.inlineCallbacks
@@ -145,25 +145,34 @@ def reindex_search_txn(txn):
         defer.returnValue(result)
 
     @defer.inlineCallbacks
-    def _background_reindex_gist_search(self, progress, batch_size):
+    def _background_reindex_gin_search(self, progress, batch_size):
+        '''This handles old synapses which used GIST indexes, if any;
+        converting them back to be GIN as per the actual schema.
+        '''
+
         def create_index(conn):
-            conn.rollback()
-            conn.set_session(autocommit=True)
-            c = conn.cursor()
+            try:
+                conn.rollback()
+                conn.set_session(autocommit=True)
+                c = conn.cursor()
 
-            c.execute(
-                "CREATE INDEX CONCURRENTLY event_search_fts_idx_gist"
-                " ON event_search USING GIST (vector)"
-            )
+                c.execute(
+                    "CREATE INDEX CONCURRENTLY event_search_fts_idx"
+                    " ON event_search USING GIN (vector)"
+                )
 
-            c.execute("DROP INDEX event_search_fts_idx")
+                c.execute("DROP INDEX event_search_fts_idx_gist")
 
-            conn.set_session(autocommit=False)
+                conn.set_session(autocommit=False)
+            except e:
+                logger.warn(
+                    "Ignoring error %s when trying to switch from GIST to GIN" % (e,)
+                )
 
         if isinstance(self.database_engine, PostgresEngine):
             yield self.runWithConnection(create_index)
 
-        yield self._end_background_update(self.EVENT_SEARCH_USE_GIST_POSTGRES_NAME)
+        yield self._end_background_update(self.EVENT_SEARCH_USE_GIN_POSTGRES_NAME)
         defer.returnValue(1)
 
     @defer.inlineCallbacks