diff options
Diffstat (limited to 'lib/sqlalchemy/engine')
| -rw-r--r-- | lib/sqlalchemy/engine/create.py | 25 | ||||
| -rw-r--r-- | lib/sqlalchemy/engine/default.py | 38 |
2 files changed, 57 insertions, 6 deletions
diff --git a/lib/sqlalchemy/engine/create.py b/lib/sqlalchemy/engine/create.py index 43378f24e..ed3d452e0 100644 --- a/lib/sqlalchemy/engine/create.py +++ b/lib/sqlalchemy/engine/create.py @@ -260,7 +260,15 @@ def create_engine(url, **kwargs): the size of dynamically generated column labels to that many characters. If less than 6, labels are generated as "_(counter)". If ``None``, the value of - ``dialect.max_identifier_length`` is used instead. + ``dialect.max_identifier_length``, which may be affected via the + :paramref:`.create_engine.max_identifier_length` parameter, + is used instead. The value of :paramref:`.create_engine.label_length` + may not be larger than that of + :paramref:`.create_engine.max_identfier_length`. + + .. seealso:: + + :paramref:`.create_engine.max_identifier_length` :param listeners: A list of one or more :class:`~sqlalchemy.interfaces.PoolListener` objects which will @@ -271,6 +279,21 @@ def create_engine(url, **kwargs): "sqlalchemy.engine" logger. Defaults to a hexstring of the object's id. + :param max_identifier_length: integer; override the max_identifier_length + determined by the dialect. if ``None`` or zero, has no effect. This + is the database's configured maximum number of characters that may be + used in a SQL identifier such as a table name, column name, or label + name. All dialects determine this value automatically, however in the + case of a new database version for which this value has changed but + SQLAlchemy's dialect has not been adjusted, the value may be passed + here. + + .. versionadded:: 1.3.9 + + .. seealso:: + + :paramref:`.create_engine.label_length` + :param max_overflow=10: the number of connections to allow in connection pool "overflow", that is connections that can be opened above and beyond the pool_size setting, which defaults diff --git a/lib/sqlalchemy/engine/default.py b/lib/sqlalchemy/engine/default.py index eac593125..8d9962c59 100644 --- a/lib/sqlalchemy/engine/default.py +++ b/lib/sqlalchemy/engine/default.py @@ -109,6 +109,7 @@ class DefaultDialect(interfaces.Dialect): # length at which to truncate # any identifier. max_identifier_length = 9999 + _user_defined_max_identifier_length = None # length at which to truncate # the name of an index. @@ -204,6 +205,7 @@ class DefaultDialect(interfaces.Dialect): case_sensitive=True, supports_native_boolean=None, empty_in_strategy="static", + max_identifier_length=None, label_length=None, **kwargs ): @@ -248,11 +250,10 @@ class DefaultDialect(interfaces.Dialect): "'dynamic', or 'dynamic_warn'" ) - if label_length and label_length > self.max_identifier_length: - raise exc.ArgumentError( - "Label length of %d is greater than this dialect's" - " maximum identifier length of %d" - % (label_length, self.max_identifier_length) + self._user_defined_max_identifier_length = max_identifier_length + if self._user_defined_max_identifier_length: + self.max_identifier_length = ( + self._user_defined_max_identifier_length ) self.label_length = label_length @@ -312,6 +313,21 @@ class DefaultDialect(interfaces.Dialect): ): self._description_decoder = self.description_encoding = None + if not self._user_defined_max_identifier_length: + max_ident_length = self._check_max_identifier_length(connection) + if max_ident_length: + self.max_identifier_length = max_ident_length + + if ( + self.label_length + and self.label_length > self.max_identifier_length + ): + raise exc.ArgumentError( + "Label length of %d is greater than this dialect's" + " maximum identifier length of %d" + % (self.label_length, self.max_identifier_length) + ) + def on_connect(self): """return a callable which sets up a newly created DBAPI connection. @@ -326,6 +342,18 @@ class DefaultDialect(interfaces.Dialect): """ return None + def _check_max_identifier_length(self, connection): + """Perform a connection / server version specific check to determine + the max_identifier_length. + + If the dialect's class level max_identifier_length should be used, + can return None. + + .. versionadded:: 1.3.9 + + """ + return None + def _check_unicode_returns(self, connection, additional_tests=None): if util.py2k and not self.supports_unicode_statements: cast_to = util.binary_type |