diff options
| -rw-r--r-- | changelog.d/6135.bugfix | 1 | ||||
| -rw-r--r-- | synapse/storage/client_ips.py | 46 | ||||
| -rw-r--r-- | synapse/storage/engines/postgres.py | 7 | ||||
| -rw-r--r-- | synapse/storage/engines/sqlite.py | 8 |
4 files changed, 55 insertions, 7 deletions
diff --git a/changelog.d/6135.bugfix b/changelog.d/6135.bugfix new file mode 100644 index 0000000000..5f9f010cb1 --- /dev/null +++ b/changelog.d/6135.bugfix @@ -0,0 +1 @@ +Fix bug in background update that adds last seen information to the `devices` table, and improve its performance on Postgres. diff --git a/synapse/storage/client_ips.py b/synapse/storage/client_ips.py index 539584288d..bb135166ce 100644 --- a/synapse/storage/client_ips.py +++ b/synapse/storage/client_ips.py @@ -463,14 +463,46 @@ class ClientIpStore(background_updates.BackgroundUpdateStore): last_device_id = progress.get("last_device_id", "") def _devices_last_seen_update_txn(txn): + # This consists of two queries: + # + # 1. The sub-query searches for the next N devices and joins + # against user_ips to find the max last_seen associated with + # that device. + # 2. The outer query then joins again against user_ips on + # user/device/last_seen. This *should* hopefully only + # return one row, but if it does return more than one then + # we'll just end up updating the same device row multiple + # times, which is fine. + + if self.database_engine.supports_tuple_comparison: + where_clause = "(user_id, device_id) > (?, ?)" + where_args = [last_user_id, last_device_id] + else: + # We explicitly do a `user_id >= ? AND (...)` here to ensure + # that an index is used, as doing `user_id > ? OR (user_id = ? AND ...)` + # makes it hard for query optimiser to tell that it can use the + # index on user_id + where_clause = "user_id >= ? AND (user_id > ? OR device_id > ?)" + where_args = [last_user_id, last_user_id, last_device_id] + sql = """ - SELECT u.last_seen, u.ip, u.user_agent, user_id, device_id FROM devices - INNER JOIN user_ips AS u USING (user_id, device_id) - WHERE user_id > ? OR (user_id = ? AND device_id > ?) - ORDER BY user_id ASC, device_id ASC - LIMIT ? - """ - txn.execute(sql, (last_user_id, last_user_id, last_device_id, batch_size)) + SELECT + last_seen, ip, user_agent, user_id, device_id + FROM ( + SELECT + user_id, device_id, MAX(u.last_seen) AS last_seen + FROM devices + INNER JOIN user_ips AS u USING (user_id, device_id) + WHERE %(where_clause)s + GROUP BY user_id, device_id + ORDER BY user_id ASC, device_id ASC + LIMIT ? + ) c + INNER JOIN user_ips AS u USING (user_id, device_id, last_seen) + """ % { + "where_clause": where_clause + } + txn.execute(sql, where_args + [batch_size]) rows = txn.fetchall() if not rows: diff --git a/synapse/storage/engines/postgres.py b/synapse/storage/engines/postgres.py index 289b6bc281..601617b21e 100644 --- a/synapse/storage/engines/postgres.py +++ b/synapse/storage/engines/postgres.py @@ -72,6 +72,13 @@ class PostgresEngine(object): """ return True + @property + def supports_tuple_comparison(self): + """ + Do we support comparing tuples, i.e. `(a, b) > (c, d)`? + """ + return True + def is_deadlock(self, error): if isinstance(error, self.module.DatabaseError): # https://www.postgresql.org/docs/current/static/errcodes-appendix.html diff --git a/synapse/storage/engines/sqlite.py b/synapse/storage/engines/sqlite.py index e9b9caa49a..ac92109366 100644 --- a/synapse/storage/engines/sqlite.py +++ b/synapse/storage/engines/sqlite.py @@ -38,6 +38,14 @@ class Sqlite3Engine(object): """ return self.module.sqlite_version_info >= (3, 24, 0) + @property + def supports_tuple_comparison(self): + """ + Do we support comparing tuples, i.e. `(a, b) > (c, d)`? This requires + SQLite 3.15+. + """ + return self.module.sqlite_version_info >= (3, 15, 0) + def check_database(self, txn): pass |