diff options
Diffstat (limited to 'lib/sqlalchemy/engine/create.py')
| -rw-r--r-- | lib/sqlalchemy/engine/create.py | 50 |
1 files changed, 26 insertions, 24 deletions
diff --git a/lib/sqlalchemy/engine/create.py b/lib/sqlalchemy/engine/create.py index e6da1d8e6..5932bfb9b 100644 --- a/lib/sqlalchemy/engine/create.py +++ b/lib/sqlalchemy/engine/create.py @@ -201,34 +201,32 @@ def create_engine(url, **kwargs): should **always be set to True**. Some SQLAlchemy features will fail to function properly if this flag is set to ``False``. - :param isolation_level: this string parameter is interpreted by various - dialects in order to affect the transaction isolation level of the - database connection. The parameter essentially accepts some subset of - these string arguments: ``"SERIALIZABLE"``, ``"REPEATABLE READ"``, - ``"READ COMMITTED"``, ``"READ UNCOMMITTED"`` and ``"AUTOCOMMIT"``. - Behavior here varies per backend, and - individual dialects should be consulted directly. - - Note that the isolation level can also be set on a - per-:class:`_engine.Connection` basis as well, using the + :param isolation_level: optional string name of an isolation level + which will be set on all new connections unconditionally. + Isolation levels are typically some subset of the string names + ``"SERIALIZABLE"``, ``"REPEATABLE READ"``, + ``"READ COMMITTED"``, ``"READ UNCOMMITTED"`` and ``"AUTOCOMMIT"`` + based on backend. + + The :paramref:`_sa.create_engine.isolation_level` parameter is + in contrast to the :paramref:`.Connection.execution_options.isolation_level` - feature. + execution option, which may be set on an individual + :class:`.Connection`, as well as the same parameter passed to + :meth:`.Engine.execution_options`, where it may be used to create + multiple engines with different isolation levels that share a common + connection pool and dialect. + + .. versionchanged:: 2.0 The + :paramref:`_sa.create_engine.isolation_level` + parameter has been generalized to work on all dialects which support + the concept of isolation level, and is provided as a more succinct, + up front configuration switch in contrast to the execution option + which is more of an ad-hoc programmatic option. .. seealso:: - :attr:`_engine.Connection.default_isolation_level` - - view default level - - :paramref:`.Connection.execution_options.isolation_level` - - set per :class:`_engine.Connection` isolation level - - :ref:`SQLite Transaction Isolation <sqlite_isolation_level>` - - :ref:`PostgreSQL Transaction Isolation <postgresql_isolation_level>` - - :ref:`MySQL Transaction Isolation <mysql_isolation_level>` - - :ref:`session_transaction_isolation` - for the ORM + :ref:`dbapi_autocommit` :param json_deserializer: for dialects that support the :class:`_types.JSON` @@ -594,6 +592,10 @@ def create_engine(url, **kwargs): event.listen(pool, "connect", on_connect) + builtin_on_connect = dialect._builtin_onconnect() + if builtin_on_connect: + event.listen(pool, "connect", builtin_on_connect) + def first_connect(dbapi_connection, connection_record): c = base.Connection( engine, |