Add logging on startup/shutdown (#8448)

This is so we can tell what is going on when things are taking a while to start up.

The main change here is to ensure that transactions that are created during startup get correctly logged like normal transactions.

21 files changed, 139 insertions, 107 deletions

diff --git a/synapse/app/_base.py b/synapse/app/_base.py
index 8bb0b142ca..f6f7b2bf42 100644
--- a/synapse/app/_base.py
+++ b/synapse/app/_base.py
@@ -272,6 +272,11 @@ def start(hs: "synapse.server.HomeServer", listeners: Iterable[ListenerConfig]):
         hs.get_datastore().db_pool.start_profiling()
         hs.get_pusherpool().start()
 
+        # Log when we start the shut down process.
+        hs.get_reactor().addSystemEventTrigger(
+            "before", "shutdown", logger.info, "Shutting down..."
+        )
+
         setup_sentry(hs)
         setup_sdnotify(hs)
 
diff --git a/synapse/storage/database.py b/synapse/storage/database.py
index 79ec8f119d..0d9d9b7cc0 100644
--- a/synapse/storage/database.py
+++ b/synapse/storage/database.py
@@ -32,6 +32,7 @@ from typing import (
     overload,
 )
 
+import attr
 from prometheus_client import Histogram
 from typing_extensions import Literal
 
@@ -90,13 +91,17 @@ def make_pool(
     return adbapi.ConnectionPool(
         db_config.config["name"],
         cp_reactor=reactor,
-        cp_openfun=engine.on_new_connection,
+        cp_openfun=lambda conn: engine.on_new_connection(
+            LoggingDatabaseConnection(conn, engine, "on_new_connection")
+        ),
         **db_config.config.get("args", {})
     )
 
 
 def make_conn(
-    db_config: DatabaseConnectionConfig, engine: BaseDatabaseEngine
+    db_config: DatabaseConnectionConfig,
+    engine: BaseDatabaseEngine,
+    default_txn_name: str,
 ) -> Connection:
     """Make a new connection to the database and return it.
 
@@ -109,11 +114,60 @@ def make_conn(
         for k, v in db_config.config.get("args", {}).items()
         if not k.startswith("cp_")
     }
-    db_conn = engine.module.connect(**db_params)
+    native_db_conn = engine.module.connect(**db_params)
+    db_conn = LoggingDatabaseConnection(native_db_conn, engine, default_txn_name)
+
     engine.on_new_connection(db_conn)
     return db_conn
 
 
+@attr.s(slots=True)
+class LoggingDatabaseConnection:
+    """A wrapper around a database connection that returns `LoggingTransaction`
+    as its cursor class.
+
+    This is mainly used on startup to ensure that queries get logged correctly
+    """
+
+    conn = attr.ib(type=Connection)
+    engine = attr.ib(type=BaseDatabaseEngine)
+    default_txn_name = attr.ib(type=str)
+
+    def cursor(
+        self, *, txn_name=None, after_callbacks=None, exception_callbacks=None
+    ) -> "LoggingTransaction":
+        if not txn_name:
+            txn_name = self.default_txn_name
+
+        return LoggingTransaction(
+            self.conn.cursor(),
+            name=txn_name,
+            database_engine=self.engine,
+            after_callbacks=after_callbacks,
+            exception_callbacks=exception_callbacks,
+        )
+
+    def close(self) -> None:
+        self.conn.close()
+
+    def commit(self) -> None:
+        self.conn.commit()
+
+    def rollback(self, *args, **kwargs) -> None:
+        self.conn.rollback(*args, **kwargs)
+
+    def __enter__(self) -> "Connection":
+        self.conn.__enter__()
+        return self
+
+    def __exit__(self, exc_type, exc_value, traceback) -> bool:
+        return self.conn.__exit__(exc_type, exc_value, traceback)
+
+    # Proxy through any unknown lookups to the DB conn class.
+    def __getattr__(self, name):
+        return getattr(self.conn, name)
+
+
 # The type of entry which goes on our after_callbacks and exception_callbacks lists.
 #
 # Python 3.5.2 doesn't support Callable with an ellipsis, so we wrap it in quotes so
@@ -247,6 +301,12 @@ class LoggingTransaction:
     def close(self) -> None:
         self.txn.close()
 
+    def __enter__(self) -> "LoggingTransaction":
+        return self
+
+    def __exit__(self, exc_type, exc_value, traceback):
+        self.close()
+
 
 class PerformanceCounters:
     def __init__(self):
@@ -395,7 +455,7 @@ class DatabasePool:
 
     def new_transaction(
         self,
-        conn: Connection,
+        conn: LoggingDatabaseConnection,
         desc: str,
         after_callbacks: List[_CallbackListEntry],
         exception_callbacks: List[_CallbackListEntry],
@@ -418,12 +478,10 @@ class DatabasePool:
             i = 0
             N = 5
             while True:
-                cursor = LoggingTransaction(
-                    conn.cursor(),
-                    name,
-                    self.engine,
-                    after_callbacks,
-                    exception_callbacks,
+                cursor = conn.cursor(
+                    txn_name=name,
+                    after_callbacks=after_callbacks,
+                    exception_callbacks=exception_callbacks,
                 )
                 try:
                     r = func(cursor, *args, **kwargs)
@@ -584,7 +642,10 @@ class DatabasePool:
                     logger.debug("Reconnecting closed database connection")
                     conn.reconnect()
 
-                return func(conn, *args, **kwargs)
+                db_conn = LoggingDatabaseConnection(
+                    conn, self.engine, "runWithConnection"
+                )
+                return func(db_conn, *args, **kwargs)
 
         return await make_deferred_yieldable(
             self._db_pool.runWithConnection(inner_func, *args, **kwargs)
@@ -1621,7 +1682,7 @@ class DatabasePool:
 
     def get_cache_dict(
         self,
-        db_conn: Connection,
+        db_conn: LoggingDatabaseConnection,
         table: str,
         entity_column: str,
         stream_column: str,
@@ -1642,9 +1703,7 @@ class DatabasePool:
             "limit": limit,
         }
 
-        sql = self.engine.convert_param_style(sql)
-
-        txn = db_conn.cursor()
+        txn = db_conn.cursor(txn_name="get_cache_dict")
         txn.execute(sql, (int(max_value),))
 
         cache = {row[0]: int(row[1]) for row in txn}
diff --git a/synapse/storage/databases/__init__.py b/synapse/storage/databases/__init__.py
index aa5d490624..0c24325011 100644
--- a/synapse/storage/databases/__init__.py
+++ b/synapse/storage/databases/__init__.py
@@ -46,7 +46,7 @@ class Databases:
             db_name = database_config.name
             engine = create_engine(database_config.config)
 
-            with make_conn(database_config, engine) as db_conn:
+            with make_conn(database_config, engine, "startup") as db_conn:
                 logger.info("[database config %r]: Checking database server", db_name)
                 engine.check_database(db_conn)
 
diff --git a/synapse/storage/databases/main/__init__.py b/synapse/storage/databases/main/__init__.py
index f823d66709..9b16f45f3e 100644
--- a/synapse/storage/databases/main/__init__.py
+++ b/synapse/storage/databases/main/__init__.py
@@ -284,7 +284,6 @@ class DataStore(
             " last_user_sync_ts, status_msg, currently_active FROM presence_stream"
             " WHERE state != ?"
         )
-        sql = self.database_engine.convert_param_style(sql)
 
         txn = db_conn.cursor()
         txn.execute(sql, (PresenceState.OFFLINE,))
diff --git a/synapse/storage/databases/main/event_push_actions.py b/synapse/storage/databases/main/event_push_actions.py
index 62f1738732..80f3b4d740 100644
--- a/synapse/storage/databases/main/event_push_actions.py
+++ b/synapse/storage/databases/main/event_push_actions.py
@@ -20,7 +20,7 @@ from typing import Dict, List, Optional, Tuple, Union
 import attr
 
 from synapse.metrics.background_process_metrics import run_as_background_process
-from synapse.storage._base import LoggingTransaction, SQLBaseStore, db_to_json
+from synapse.storage._base import SQLBaseStore, db_to_json
 from synapse.storage.database import DatabasePool
 from synapse.util import json_encoder
 from synapse.util.caches.descriptors import cached
@@ -74,11 +74,7 @@ class EventPushActionsWorkerStore(SQLBaseStore):
         self.stream_ordering_month_ago = None
         self.stream_ordering_day_ago = None
 
-        cur = LoggingTransaction(
-            db_conn.cursor(),
-            name="_find_stream_orderings_for_times_txn",
-            database_engine=self.database_engine,
-        )
+        cur = db_conn.cursor(txn_name="_find_stream_orderings_for_times_txn")
         self._find_stream_orderings_for_times_txn(cur)
         cur.close()
 
diff --git a/synapse/storage/databases/main/monthly_active_users.py b/synapse/storage/databases/main/monthly_active_users.py
index b2127598ef..c66f558567 100644
--- a/synapse/storage/databases/main/monthly_active_users.py
+++ b/synapse/storage/databases/main/monthly_active_users.py
@@ -214,7 +214,6 @@ class MonthlyActiveUsersStore(MonthlyActiveUsersWorkerStore):
         self._mau_stats_only = hs.config.mau_stats_only
 
         # Do not add more reserved users than the total allowable number
-        # cur = LoggingTransaction(
         self.db_pool.new_transaction(
             db_conn,
             "initialise_mau_threepids",
diff --git a/synapse/storage/databases/main/roommember.py b/synapse/storage/databases/main/roommember.py
index 86ffe2479e..bae1bd22d3 100644
--- a/synapse/storage/databases/main/roommember.py
+++ b/synapse/storage/databases/main/roommember.py
@@ -21,12 +21,7 @@ from synapse.events import EventBase
 from synapse.events.snapshot import EventContext
 from synapse.metrics import LaterGauge
 from synapse.metrics.background_process_metrics import run_as_background_process
-from synapse.storage._base import (
-    LoggingTransaction,
-    SQLBaseStore,
-    db_to_json,
-    make_in_list_sql_clause,
-)
+from synapse.storage._base import SQLBaseStore, db_to_json, make_in_list_sql_clause
 from synapse.storage.database import DatabasePool
 from synapse.storage.databases.main.events_worker import EventsWorkerStore
 from synapse.storage.engines import Sqlite3Engine
@@ -60,10 +55,8 @@ class RoomMemberWorkerStore(EventsWorkerStore):
         # background update still running?
         self._current_state_events_membership_up_to_date = False
 
-        txn = LoggingTransaction(
-            db_conn.cursor(),
-            name="_check_safe_current_state_events_membership_updated",
-            database_engine=self.database_engine,
+        txn = db_conn.cursor(
+            txn_name="_check_safe_current_state_events_membership_updated"
         )
         self._check_safe_current_state_events_membership_updated_txn(txn)
         txn.close()
diff --git a/synapse/storage/databases/main/schema/delta/20/pushers.py b/synapse/storage/databases/main/schema/delta/20/pushers.py
index 3edfcfd783..45b846e6a7 100644
--- a/synapse/storage/databases/main/schema/delta/20/pushers.py
+++ b/synapse/storage/databases/main/schema/delta/20/pushers.py
@@ -66,16 +66,15 @@ def run_create(cur, database_engine, *args, **kwargs):
         row[8] = bytes(row[8]).decode("utf-8")
         row[11] = bytes(row[11]).decode("utf-8")
         cur.execute(
-            database_engine.convert_param_style(
-                """
-            INSERT into pushers2 (
-            id, user_name, access_token, profile_tag, kind,
-            app_id, app_display_name, device_display_name,
-            pushkey, ts, lang, data, last_token, last_success,
-            failing_since
-            ) values (%s)"""
-                % (",".join(["?" for _ in range(len(row))]))
-            ),
+            """
+                INSERT into pushers2 (
+                id, user_name, access_token, profile_tag, kind,
+                app_id, app_display_name, device_display_name,
+                pushkey, ts, lang, data, last_token, last_success,
+                failing_since
+                ) values (%s)
+            """
+            % (",".join(["?" for _ in range(len(row))])),
             row,
         )
         count += 1
diff --git a/synapse/storage/databases/main/schema/delta/25/fts.py b/synapse/storage/databases/main/schema/delta/25/fts.py
index ee675e71ff..21f57825d4 100644
--- a/synapse/storage/databases/main/schema/delta/25/fts.py
+++ b/synapse/storage/databases/main/schema/delta/25/fts.py
@@ -71,8 +71,6 @@ def run_create(cur, database_engine, *args, **kwargs):
             " VALUES (?, ?)"
         )
 
-        sql = database_engine.convert_param_style(sql)
-
         cur.execute(sql, ("event_search", progress_json))
 
 
diff --git a/synapse/storage/databases/main/schema/delta/27/ts.py b/synapse/storage/databases/main/schema/delta/27/ts.py
index b7972cfa8e..1c6058063f 100644
--- a/synapse/storage/databases/main/schema/delta/27/ts.py
+++ b/synapse/storage/databases/main/schema/delta/27/ts.py
@@ -50,8 +50,6 @@ def run_create(cur, database_engine, *args, **kwargs):
             " VALUES (?, ?)"
         )
 
-        sql = database_engine.convert_param_style(sql)
-
         cur.execute(sql, ("event_origin_server_ts", progress_json))
 
 
diff --git a/synapse/storage/databases/main/schema/delta/30/as_users.py b/synapse/storage/databases/main/schema/delta/30/as_users.py
index b42c02710a..7f08fabe9f 100644
--- a/synapse/storage/databases/main/schema/delta/30/as_users.py
+++ b/synapse/storage/databases/main/schema/delta/30/as_users.py
@@ -59,9 +59,7 @@ def run_upgrade(cur, database_engine, config, *args, **kwargs):
         user_chunks = (user_ids[i : i + 100] for i in range(0, len(user_ids), n))
         for chunk in user_chunks:
             cur.execute(
-                database_engine.convert_param_style(
-                    "UPDATE users SET appservice_id = ? WHERE name IN (%s)"
-                    % (",".join("?" for _ in chunk),)
-                ),
+                "UPDATE users SET appservice_id = ? WHERE name IN (%s)"
+                % (",".join("?" for _ in chunk),),
                 [as_id] + chunk,
             )
diff --git a/synapse/storage/databases/main/schema/delta/31/pushers.py b/synapse/storage/databases/main/schema/delta/31/pushers.py
index 9bb504aad5..5be81c806a 100644
--- a/synapse/storage/databases/main/schema/delta/31/pushers.py
+++ b/synapse/storage/databases/main/schema/delta/31/pushers.py
@@ -65,16 +65,15 @@ def run_create(cur, database_engine, *args, **kwargs):
         row = list(row)
         row[12] = token_to_stream_ordering(row[12])
         cur.execute(
-            database_engine.convert_param_style(
-                """
-            INSERT into pushers2 (
-            id, user_name, access_token, profile_tag, kind,
-            app_id, app_display_name, device_display_name,
-            pushkey, ts, lang, data, last_stream_ordering, last_success,
-            failing_since
-            ) values (%s)"""
-                % (",".join(["?" for _ in range(len(row))]))
-            ),
+            """
+                INSERT into pushers2 (
+                id, user_name, access_token, profile_tag, kind,
+                app_id, app_display_name, device_display_name,
+                pushkey, ts, lang, data, last_stream_ordering, last_success,
+                failing_since
+                ) values (%s)
+            """
+            % (",".join(["?" for _ in range(len(row))])),
             row,
         )
         count += 1
diff --git a/synapse/storage/databases/main/schema/delta/31/search_update.py b/synapse/storage/databases/main/schema/delta/31/search_update.py
index 63b757ade6..b84c844e3a 100644
--- a/synapse/storage/databases/main/schema/delta/31/search_update.py
+++ b/synapse/storage/databases/main/schema/delta/31/search_update.py
@@ -55,8 +55,6 @@ def run_create(cur, database_engine, *args, **kwargs):
             " VALUES (?, ?)"
         )
 
-        sql = database_engine.convert_param_style(sql)
-
         cur.execute(sql, ("event_search_order", progress_json))
 
 
diff --git a/synapse/storage/databases/main/schema/delta/33/event_fields.py b/synapse/storage/databases/main/schema/delta/33/event_fields.py
index a3e81eeac7..e928c66a8f 100644
--- a/synapse/storage/databases/main/schema/delta/33/event_fields.py
+++ b/synapse/storage/databases/main/schema/delta/33/event_fields.py
@@ -50,8 +50,6 @@ def run_create(cur, database_engine, *args, **kwargs):
             " VALUES (?, ?)"
         )
 
-        sql = database_engine.convert_param_style(sql)
-
         cur.execute(sql, ("event_fields_sender_url", progress_json))
 
 
diff --git a/synapse/storage/databases/main/schema/delta/33/remote_media_ts.py b/synapse/storage/databases/main/schema/delta/33/remote_media_ts.py
index a26057dfb6..ad875c733a 100644
--- a/synapse/storage/databases/main/schema/delta/33/remote_media_ts.py
+++ b/synapse/storage/databases/main/schema/delta/33/remote_media_ts.py
@@ -23,8 +23,5 @@ def run_create(cur, database_engine, *args, **kwargs):
 
 def run_upgrade(cur, database_engine, *args, **kwargs):
     cur.execute(
-        database_engine.convert_param_style(
-            "UPDATE remote_media_cache SET last_access_ts = ?"
-        ),
-        (int(time.time() * 1000),),
+        "UPDATE remote_media_cache SET last_access_ts = ?", (int(time.time() * 1000),),
     )
diff --git a/synapse/storage/databases/main/schema/delta/56/unique_user_filter_index.py b/synapse/storage/databases/main/schema/delta/56/unique_user_filter_index.py
index 1de8b54961..bb7296852a 100644
--- a/synapse/storage/databases/main/schema/delta/56/unique_user_filter_index.py
+++ b/synapse/storage/databases/main/schema/delta/56/unique_user_filter_index.py
@@ -1,6 +1,8 @@
 import logging
+from io import StringIO
 
 from synapse.storage.engines import PostgresEngine
+from synapse.storage.prepare_database import execute_statements_from_stream
 
 logger = logging.getLogger(__name__)
 
@@ -46,7 +48,4 @@ def run_create(cur, database_engine, *args, **kwargs):
         select_clause,
     )
 
-    if isinstance(database_engine, PostgresEngine):
-        cur.execute(sql)
-    else:
-        cur.executescript(sql)
+    execute_statements_from_stream(cur, StringIO(sql))
diff --git a/synapse/storage/databases/main/schema/delta/57/local_current_membership.py b/synapse/storage/databases/main/schema/delta/57/local_current_membership.py
index 63b5acdcf7..44917f0a2e 100644
--- a/synapse/storage/databases/main/schema/delta/57/local_current_membership.py
+++ b/synapse/storage/databases/main/schema/delta/57/local_current_membership.py
@@ -68,7 +68,6 @@ def run_upgrade(cur, database_engine, config, *args, **kwargs):
                 INNER JOIN room_memberships AS r USING (event_id)
                 WHERE type = 'm.room.member' AND state_key LIKE ?
         """
-    sql = database_engine.convert_param_style(sql)
     cur.execute(sql, ("%:" + config.server_name,))
 
     cur.execute(
diff --git a/synapse/storage/prepare_database.py b/synapse/storage/prepare_database.py
index 4957e77f4c..459754feab 100644
--- a/synapse/storage/prepare_database.py
+++ b/synapse/storage/prepare_database.py
@@ -13,7 +13,6 @@
 # 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.
-
 import imp
 import logging
 import os
@@ -24,9 +23,10 @@ from typing import Optional, TextIO
 import attr
 
 from synapse.config.homeserver import HomeServerConfig
+from synapse.storage.database import LoggingDatabaseConnection
 from synapse.storage.engines import BaseDatabaseEngine
 from synapse.storage.engines.postgres import PostgresEngine
-from synapse.storage.types import Connection, Cursor
+from synapse.storage.types import Cursor
 from synapse.types import Collection
 
 logger = logging.getLogger(__name__)
@@ -67,7 +67,7 @@ UNAPPLIED_DELTA_ON_WORKER_ERROR = (
 
 
 def prepare_database(
-    db_conn: Connection,
+    db_conn: LoggingDatabaseConnection,
     database_engine: BaseDatabaseEngine,
     config: Optional[HomeServerConfig],
     databases: Collection[str] = ["main", "state"],
@@ -89,7 +89,7 @@ def prepare_database(
     """
 
     try:
-        cur = db_conn.cursor()
+        cur = db_conn.cursor(txn_name="prepare_database")
 
         # sqlite does not automatically start transactions for DDL / SELECT statements,
         # so we start one before running anything. This ensures that any upgrades
@@ -258,9 +258,7 @@ def _setup_new_database(cur, database_engine, databases):
             executescript(cur, entry.absolute_path)
 
     cur.execute(
-        database_engine.convert_param_style(
-            "INSERT INTO schema_version (version, upgraded) VALUES (?,?)"
-        ),
+        "INSERT INTO schema_version (version, upgraded) VALUES (?,?)",
         (max_current_ver, False),
     )
 
@@ -486,17 +484,13 @@ def _upgrade_existing_database(
 
             # Mark as done.
             cur.execute(
-                database_engine.convert_param_style(
-                    "INSERT INTO applied_schema_deltas (version, file) VALUES (?,?)"
-                ),
+                "INSERT INTO applied_schema_deltas (version, file) VALUES (?,?)",
                 (v, relative_path),
             )
 
             cur.execute("DELETE FROM schema_version")
             cur.execute(
-                database_engine.convert_param_style(
-                    "INSERT INTO schema_version (version, upgraded) VALUES (?,?)"
-                ),
+                "INSERT INTO schema_version (version, upgraded) VALUES (?,?)",
                 (v, True),
             )
 
@@ -532,10 +526,7 @@ def _apply_module_schema_files(cur, database_engine, modname, names_and_streams)
             schemas to be applied
     """
     cur.execute(
-        database_engine.convert_param_style(
-            "SELECT file FROM applied_module_schemas WHERE module_name = ?"
-        ),
-        (modname,),
+        "SELECT file FROM applied_module_schemas WHERE module_name = ?", (modname,),
     )
     applied_deltas = {d for d, in cur}
     for (name, stream) in names_and_streams:
@@ -553,9 +544,7 @@ def _apply_module_schema_files(cur, database_engine, modname, names_and_streams)
 
         # Mark as done.
         cur.execute(
-            database_engine.convert_param_style(
-                "INSERT INTO applied_module_schemas (module_name, file) VALUES (?,?)"
-            ),
+            "INSERT INTO applied_module_schemas (module_name, file) VALUES (?,?)",
             (modname, name),
         )
 
@@ -627,9 +616,7 @@ def _get_or_create_schema_state(txn, database_engine):
 
     if current_version:
         txn.execute(
-            database_engine.convert_param_style(
-                "SELECT file FROM applied_schema_deltas WHERE version >= ?"
-            ),
+            "SELECT file FROM applied_schema_deltas WHERE version >= ?",
             (current_version,),
         )
         applied_deltas = [d for d, in txn]
diff --git a/synapse/storage/types.py b/synapse/storage/types.py
index 2d2b560e74..970bb1b9da 100644
--- a/synapse/storage/types.py
+++ b/synapse/storage/types.py
@@ -61,3 +61,9 @@ class Connection(Protocol):
 
     def rollback(self, *args, **kwargs) -> None:
         ...
+
+    def __enter__(self) -> "Connection":
+        ...
+
+    def __exit__(self, exc_type, exc_value, traceback) -> bool:
+        ...
diff --git a/synapse/storage/util/id_generators.py b/synapse/storage/util/id_generators.py
index c92cd4a6ba..51f680d05d 100644
--- a/synapse/storage/util/id_generators.py
+++ b/synapse/storage/util/id_generators.py
@@ -54,7 +54,7 @@ def _load_current_id(db_conn, table, column, step=1):
     """
     # debug logging for https://github.com/matrix-org/synapse/issues/7968
     logger.info("initialising stream generator for %s(%s)", table, column)
-    cur = db_conn.cursor()
+    cur = db_conn.cursor(txn_name="_load_current_id")
     if step == 1:
         cur.execute("SELECT MAX(%s) FROM %s" % (column, table))
     else:
@@ -269,7 +269,7 @@ class MultiWriterIdGenerator:
     def _load_current_ids(
         self, db_conn, table: str, instance_column: str, id_column: str
     ):
-        cur = db_conn.cursor()
+        cur = db_conn.cursor(txn_name="_load_current_ids")
 
         # Load the current positions of all writers for the stream.
         if self._writers:
@@ -283,15 +283,12 @@ class MultiWriterIdGenerator:
                     stream_name = ?
                     AND instance_name != ALL(?)
             """
-            sql = self._db.engine.convert_param_style(sql)
             cur.execute(sql, (self._stream_name, self._writers))
 
             sql = """
                 SELECT instance_name, stream_id FROM stream_positions
                 WHERE stream_name = ?
             """
-            sql = self._db.engine.convert_param_style(sql)
-
             cur.execute(sql, (self._stream_name,))
 
             self._current_positions = {
@@ -340,7 +337,6 @@ class MultiWriterIdGenerator:
                 "instance": instance_column,
                 "cmp": "<=" if self._positive else ">=",
             }
-            sql = self._db.engine.convert_param_style(sql)
             cur.execute(sql, (min_stream_id * self._return_factor,))
 
             self._persisted_upto_position = min_stream_id
diff --git a/synapse/storage/util/sequence.py b/synapse/storage/util/sequence.py
index 2dd95e2709..ff2d038ad2 100644
--- a/synapse/storage/util/sequence.py
+++ b/synapse/storage/util/sequence.py
@@ -17,6 +17,7 @@ import logging
 import threading
 from typing import Callable, List, Optional
 
+from synapse.storage.database import LoggingDatabaseConnection
 from synapse.storage.engines import (
     BaseDatabaseEngine,
     IncorrectDatabaseSetup,
@@ -53,7 +54,11 @@ class SequenceGenerator(metaclass=abc.ABCMeta):
 
     @abc.abstractmethod
     def check_consistency(
-        self, db_conn: Connection, table: str, id_column: str, positive: bool = True
+        self,
+        db_conn: LoggingDatabaseConnection,
+        table: str,
+        id_column: str,
+        positive: bool = True,
     ):
         """Should be called during start up to test that the current value of
         the sequence is greater than or equal to the maximum ID in the table.
@@ -82,9 +87,13 @@ class PostgresSequenceGenerator(SequenceGenerator):
         return [i for (i,) in txn]
 
     def check_consistency(
-        self, db_conn: Connection, table: str, id_column: str, positive: bool = True
+        self,
+        db_conn: LoggingDatabaseConnection,
+        table: str,
+        id_column: str,
+        positive: bool = True,
     ):
-        txn = db_conn.cursor()
+        txn = db_conn.cursor(txn_name="sequence.check_consistency")
 
         # First we get the current max ID from the table.
         table_sql = "SELECT GREATEST(%(agg)s(%(id)s), 0) FROM %(table)s" % {