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Diffstat (limited to 'lib/sqlalchemy/engine/__init__.py')
| -rw-r--r-- | lib/sqlalchemy/engine/__init__.py | 18 |
1 files changed, 18 insertions, 0 deletions
diff --git a/lib/sqlalchemy/engine/__init__.py b/lib/sqlalchemy/engine/__init__.py index 2a6c68d66..bd8b7e68a 100644 --- a/lib/sqlalchemy/engine/__init__.py +++ b/lib/sqlalchemy/engine/__init__.py @@ -192,6 +192,24 @@ def create_engine(*args, **kwargs): :ref:`dbengine_logging` for information on how to configure logging directly. + :param empty_in_strategy: The SQL compilation strategy to use when + rendering an IN or NOT IN expression for :meth:`.ColumnOperators.in_` + where the right-hand side + is an empty set. This is a string value that may be one of + ``static``, ``dynamic``, or ``dynamic_warn``. The ``static`` + strategy is the default, and an IN comparison to an empty set + will generate a simple false expression "1 != 1". The ``dynamic`` + strategy behaves like that of SQLAlchemy 1.1 and earlier, emitting + a false expression of the form "expr != expr", which has the effect + of evaluting to NULL in the case of a null expression. + ``dynamic_warn`` is the same as ``dynamic``, however also emits a + warning when an empty set is encountered; this because the "dynamic" + comparison is typically poorly performing on most databases. + + .. versionadded:: 1.2 Added the ``empty_in_strategy`` setting and + additionally defaulted the behavior for empty-set IN comparisons + to a static boolean expression. + :param encoding: Defaults to ``utf-8``. This is the string encoding used by SQLAlchemy for string encode/decode operations which occur within SQLAlchemy, **outside of |