diff options
Diffstat (limited to 'synapse/storage/util/sequence.py')
| -rw-r--r-- | synapse/storage/util/sequence.py | 56 |
1 files changed, 53 insertions, 3 deletions
diff --git a/synapse/storage/util/sequence.py b/synapse/storage/util/sequence.py index 412df6b8ef..c780ade077 100644 --- a/synapse/storage/util/sequence.py +++ b/synapse/storage/util/sequence.py @@ -45,6 +45,21 @@ and run the following SQL: See docs/postgres.md for more information. """ +_INCONSISTENT_STREAM_ERROR = """ +Postgres sequence '%(seq)s' is inconsistent with associated stream position +of '%(stream_name)s' in the 'stream_positions' table. + +This is likely a programming error and should be reported at +https://github.com/matrix-org/synapse. + +A temporary workaround to fix this error is to shut down Synapse (including +any and all workers) and run the following SQL: + + DELETE FROM stream_positions WHERE stream_name = '%(stream_name)s'; + +This will need to be done every time the server is restarted. +""" + class SequenceGenerator(metaclass=abc.ABCMeta): """A class which generates a unique sequence of integers""" @@ -60,14 +75,20 @@ class SequenceGenerator(metaclass=abc.ABCMeta): db_conn: "LoggingDatabaseConnection", table: str, id_column: str, + stream_name: Optional[str] = None, 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. - This is to handle various cases where the sequence value can get out - of sync with the table, e.g. if Synapse gets rolled back to a previous + This is to handle various cases where the sequence value can get out of + sync with the table, e.g. if Synapse gets rolled back to a previous version and the rolled forwards again. + + If a stream name is given then this will check that any value in the + `stream_positions` table is less than or equal to the current sequence + value. If it isn't then it's likely that streams have been crossed + somewhere (e.g. two ID generators have the same stream name). """ ... @@ -93,8 +114,12 @@ class PostgresSequenceGenerator(SequenceGenerator): db_conn: "LoggingDatabaseConnection", table: str, id_column: str, + stream_name: Optional[str] = None, positive: bool = True, ): + """See SequenceGenerator.check_consistency for docstring. + """ + txn = db_conn.cursor(txn_name="sequence.check_consistency") # First we get the current max ID from the table. @@ -118,6 +143,18 @@ class PostgresSequenceGenerator(SequenceGenerator): "SELECT last_value, is_called FROM %(seq)s" % {"seq": self._sequence_name} ) last_value, is_called = txn.fetchone() + + # If we have an associated stream check the stream_positions table. + max_in_stream_positions = None + if stream_name: + txn.execute( + "SELECT MAX(stream_id) FROM stream_positions WHERE stream_name = ?", + (stream_name,), + ) + row = txn.fetchone() + if row: + max_in_stream_positions = row[0] + txn.close() # If `is_called` is False then `last_value` is actually the value that @@ -138,6 +175,14 @@ class PostgresSequenceGenerator(SequenceGenerator): % {"seq": self._sequence_name, "table": table, "max_id_sql": table_sql} ) + # If we have values in the stream positions table then they have to be + # less than or equal to `last_value` + if max_in_stream_positions and max_in_stream_positions > last_value: + raise IncorrectDatabaseSetup( + _INCONSISTENT_STREAM_ERROR + % {"seq": self._sequence_name, "stream_name": stream_name} + ) + GetFirstCallbackType = Callable[[Cursor], int] @@ -175,7 +220,12 @@ class LocalSequenceGenerator(SequenceGenerator): return self._current_max_id def check_consistency( - self, db_conn: Connection, table: str, id_column: str, positive: bool = True + self, + db_conn: Connection, + table: str, + id_column: str, + stream_name: Optional[str] = None, + positive: bool = True, ): # There is nothing to do for in memory sequences pass |