diff options
Diffstat (limited to 'Doc/library')
| -rw-r--r-- | Doc/library/sqlite3.rst | 36 |
1 files changed, 22 insertions, 14 deletions
diff --git a/Doc/library/sqlite3.rst b/Doc/library/sqlite3.rst index 37d2a4f..9e3c56b 100644 --- a/Doc/library/sqlite3.rst +++ b/Doc/library/sqlite3.rst @@ -281,7 +281,7 @@ Connection Objects .. attribute:: isolation_level - Get or set the current isolation level. :const:`None` for autocommit mode or + Get or set the current default isolation level. :const:`None` for autocommit mode or one of "DEFERRED", "IMMEDIATE" or "EXCLUSIVE". See section :ref:`sqlite3-controlling-transactions` for a more detailed explanation. @@ -1010,22 +1010,30 @@ timestamp converter. Controlling Transactions ------------------------ -By default, the :mod:`sqlite3` module opens transactions implicitly before a -Data Modification Language (DML) statement (i.e. -``INSERT``/``UPDATE``/``DELETE``/``REPLACE``). - -You can control which kind of ``BEGIN`` statements sqlite3 implicitly executes -(or none at all) via the *isolation_level* parameter to the :func:`connect` -call, or via the :attr:`isolation_level` property of connections. +The underlying ``sqlite3`` library operates in ``autocommit`` mode by default, +but the Python :mod:`sqlite3` module by default does not. -If you want **autocommit mode**, then set :attr:`isolation_level` to ``None``. +``autocommit`` mode means that statements that modify the database take effect +immediately. A ``BEGIN`` or ``SAVEPOINT`` statement disables ``autocommit`` +mode, and a ``COMMIT``, a ``ROLLBACK``, or a ``RELEASE`` that ends the +outermost transaction, turns ``autocommit`` mode back on. -Otherwise leave it at its default, which will result in a plain "BEGIN" -statement, or set it to one of SQLite's supported isolation levels: "DEFERRED", -"IMMEDIATE" or "EXCLUSIVE". +The Python :mod:`sqlite3` module by default issues a ``BEGIN`` statement +implicitly before a Data Modification Language (DML) statement (i.e. +``INSERT``/``UPDATE``/``DELETE``/``REPLACE``). -The current transaction state is exposed through the -:attr:`Connection.in_transaction` attribute of the connection object. +You can control which kind of ``BEGIN`` statements :mod:`sqlite3` implicitly +executes via the *isolation_level* parameter to the :func:`connect` +call, or via the :attr:`isolation_level` property of connections. +If you specify no *isolation_level*, a plain ``BEGIN`` is used, which is +equivalent to specifying ``DEFERRED``. Other possible values are ``IMMEDIATE`` +and ``EXCLUSIVE``. + +You can disable the :mod:`sqlite3` module's implicit transaction management by +setting :attr:`isolation_level` to ``None``. This will leave the underlying +``sqlite3`` library operating in ``autocommit`` mode. You can then completely +control the transaction state by explicitly issuing ``BEGIN``, ``ROLLBACK``, +``SAVEPOINT``, and ``RELEASE`` statements in your code. .. versionchanged:: 3.6 :mod:`sqlite3` used to implicitly commit an open transaction before DDL |