[Backend Dependencies Update] Update sqlalchemy to 1.4.15

[pyup-bot]

This PR updates SQLAlchemy from 1.3.10 to 1.4.15.

Changelog

1.4.15

:released: May 11, 2021

 .. change::
     :tags: bug, documentation, mysql
     :tickets: 5397

     Added support for the ``ssl_check_hostname=`` parameter in mysql connection
     URIs and updated the mysql dialect documentation regarding secure
     connections. Original pull request courtesy of Jerry Zhao.

 .. change::
     :tags: bug, orm, regression
     :tickets: 6449

     Fixed additional regression caused by "eager loaders run on unexpire"
     feature :ticket:`1763` where the feature would run for a
     ``contains_eager()`` eagerload option in the case that the
     ``contains_eager()`` were chained to an additional eager loader option,
     which would then produce an incorrect query as the original query-bound
     join criteria were no longer present.

 .. change::
     :tags: feature, general
     :tickets: 6241

     A new approach has been applied to the warnings system in SQLAlchemy to
     accurately predict the appropriate stack level for each warning
     dynamically. This allows evaluating the source of SQLAlchemy-generated
     warnings and deprecation warnings to be more straightforward as the warning
     will indicate the source line within end-user code, rather than from an
     arbitrary level within SQLAlchemy's own source code.

 .. change::
     :tags: bug, orm
     :tickets: 6459

     Fixed issue in subquery loader strategy which prevented caching from
     working correctly. This would have been seen in the logs as a "generated"
     message instead of "cached" for all subqueryload SQL emitted, which by
     saturating the cache with new keys would degrade overall performance; it
     also would produce "LRU size alert" warnings.


 .. change::
     :tags: bug, sql
     :tickets: 6460

     Adjusted the logic added as part of :ticket:`6397` in 1.4.12 so that
     internal mutation of the :class:`.BindParameter` object occurs within the
     clause construction phase as it did before, rather than in the compilation
     phase. In the latter case, the mutation still produced side effects against
     the incoming construct and additionally could potentially interfere with
     other internal mutation routines.

.. changelog::

1.4.14

:released: May 6, 2021

 .. change::
     :tags: bug, regression, orm
     :tickets: 6426

     Fixed regression involving ``lazy='dynamic'`` loader in conjunction with a
     detached object. The previous behavior was that the dynamic loader upon
     calling methods like ``.all()`` returns empty lists for detached objects
     without error, this has been restored; however a warning is now emitted as
     this is not the correct result. Other dynamic loader scenarios correctly
     raise ``DetachedInstanceError``.

 .. change::
     :tags: bug, regression, sql
     :tickets: 6428

     Fixed regression caused by the "empty in" change just made in
     :ticket:`6397` 1.4.12 where the expression needs to be parenthesized for
     the "not in" use case, otherwise the condition will interfere with the
     other filtering criteria.


 .. change::
     :tags: bug, sql, regression
     :tickets: 6436

     The :class:`.TypeDecorator` class will now emit a warning when used in SQL
     compilation with caching unless the ``.cache_ok`` flag is set to ``True``
     or ``False``. A new class-level attribute :attr:`.TypeDecorator.cache_ok`
     may be set which will be used as an indication that all the parameters
     passed to the object are safe to be used as a cache key if set to ``True``,
     ``False`` means they are not.

 .. change::
     :tags: engine, bug, regression
     :tickets: 6427

     Established a deprecation path for calling upon the
     :meth:`_cursor.CursorResult.keys` method for a statement that returns no
     rows to provide support for legacy patterns used by the "records" package
     as well as any other non-migrated applications. Previously, this would
     raise :class:`.ResourceClosedException` unconditionally in the same way as
     it does when attempting to fetch rows. While this is the correct behavior
     going forward, the :class:`_cursor.LegacyCursorResult` object will now in
     this case return an empty list for ``.keys()`` as it did in 1.3, while also
     emitting a 2.0 deprecation warning. The :class:`_cursor.CursorResult`, used
     when using a 2.0-style "future" engine, will continue to raise as it does
     now.

 .. change::
     :tags: usecase, engine, orm
     :tickets: 6288

     Applied consistent behavior to the use case of
     calling ``.commit()`` or ``.rollback()`` inside of an existing
     ``.begin()`` context manager, with the addition of potentially
     emitting SQL within the block subsequent to the commit or rollback.
     This change continues upon the change first added in
     :ticket:`6155` where the use case of calling "rollback" inside of
     a ``.begin()`` contextmanager block was proposed:

     * calling ``.commit()`` or ``.rollback()`` will now be allowed
       without error or warning within all scopes, including
       that of legacy and future :class:`_engine.Engine`, ORM
       :class:`_orm.Session`, asyncio :class:`.AsyncEngine`.  Previously,
       the :class:`_orm.Session` disallowed this.

     * The remaining scope of the context manager is then closed;
       when the block ends, a check is emitted to see if the transaction
       was already ended, and if so the block returns without action.

     * It will now raise **an error** if subsequent SQL of any kind
       is emitted within the block, **after** ``.commit()`` or
       ``.rollback()`` is called.   The block should be closed as
       the state of the executable object would otherwise be undefined
       in this state.

.. changelog::

1.4.13

:released: May 3, 2021

 .. change::
     :tags: bug, regression, orm
     :tickets: 6410

     Fixed regression in ``selectinload`` loader strategy that would cause it to
     cache its internal state incorrectly when handling relationships that join
     across more than one column, such as when using a composite foreign key.
     The invalid caching would then cause other unrelated loader operations to
     fail.


 .. change::
     :tags: bug, orm, regression
     :tickets: 6414

     Fixed regression where :meth:`_orm.Query.filter_by` would not work if the
     lead entity were a SQL function or other expression derived from the
     primary entity in question, rather than a simple entity or column of that
     entity. Additionally, improved the behavior of
     :meth:`_sql.Select.filter_by` overall to work with column expressions even
     in a non-ORM context.

 .. change::
     :tags: bug, engine, regression
     :tickets: 6408

     Restored a legacy transactional behavior that was inadvertently removed
     from the :class:`_engine.Connection` as it was never tested as a known use
     case in previous versions, where calling upon the
     :meth:`_engine.Connection.begin_nested` method, when no transaction is
     present, does not create a SAVEPOINT at all and instead starts an outer
     transaction, returning a :class:`.RootTransaction` object instead of a
     :class:`.NestedTransaction` object.  This :class:`.RootTransaction` then
     will emit a real COMMIT on the database connection when committed.
     Previously, the 2.0 style behavior was present in all cases that would
     autobegin a transaction but not commit it, which is a behavioral change.

     When using a :term:`2.0 style` connection object, the behavior is unchanged
     from previous 1.4 versions; calling :meth:`_future.Connection.begin_nested`
     will "autobegin" the outer transaction if not already present, and then as
     instructed emit a SAVEPOINT, returning the :class:`.NestedTransaction`
     object. The outer transaction is committed by calling upon
     :meth:`_future.Connection.commit`, as is "commit-as-you-go" style usage.

     In non-"future" mode, while the old behavior is restored, it also
     emits a 2.0 deprecation warning as this is a legacy behavior.


 .. change::
     :tags: bug, asyncio, regression
     :tickets: 6409

     Fixed a regression introduced by :ticket:`6337` that would create an
     ``asyncio.Lock`` which could be attached to the wrong loop when
     instantiating the async engine before any asyncio loop was started, leading
     to an asyncio error message when attempting to use the engine under certain
     circumstances.

 .. change::
     :tags: bug, orm, regression
     :tickets: 6419

     Fixed regression where using :func:`_orm.selectinload` and
     :func:`_orm.subqueryload` to load a two-level-deep path would lead to an
     attribute error.

 .. change::
     :tags: bug, orm, regression
     :tickets: 6420

     Fixed regression where using the :func:`_orm.noload` loader strategy in
     conjunction with a "dynamic" relationship would lead to an attribute error
     as the noload strategy would attempt to apply itself to the dynamic loader.

 .. change::
     :tags: usecase, postgresql
     :tickets: 6198

     Add support for server side cursors in the pg8000 dialect for PostgreSQL.
     This allows use of the
     :paramref:`.Connection.execution_options.stream_results` option.

.. changelog::

1.4.12

:released: April 29, 2021

 .. change::
     :tags: bug, orm, regression, caching
     :tickets: 6391

     Fixed critical regression where bound parameter tracking as used in the SQL
     caching system could fail to track all parameters for the case where the
     same SQL expression containing a parameter were used in an ORM-related
     query using a feature such as class inheritance, which was then embedded in
     an enclosing expression which would make use of that same expression
     multiple times, such as a UNION. The ORM would individually copy the
     individual SELECT statements as part of compilation with class inheritance,
     which then embedded in the enclosing statement would fail to accommodate
     for all parameters. The logic that tracks this condition has been adjusted
     to work for multiple copies of a parameter.

 .. change::
     :tags: bug, sql
     :tickets: 6258, 6397

     Revised the "EMPTY IN" expression to no longer rely upon using a subquery,
     as this was causing some compatibility and performance problems. The new
     approach for selected databases takes advantage of using a NULL-returning
     IN expression combined with the usual "1 != 1" or "1 = 1" expression
     appended by AND or OR. The expression is now the default for all backends
     other than SQLite, which still had some compatibility issues regarding
     tuple "IN" for older SQLite versions.

     Third party dialects can still override how the "empty set" expression
     renders by implementing a new compiler method
     ``def visit_empty_set_op_expr(self, type_, expand_op)``, which takes
     precedence over the existing
     ``def visit_empty_set_expr(self, element_types)`` which remains in place.


 .. change::
     :tags: bug, orm
     :tickets: 6350

     Fixed two distinct issues mostly affecting
     :class:`_hybrid.hybrid_property`, which would come into play under common
     mis-configuration scenarios that were silently ignored in 1.3, and now
     failed in 1.4, where the "expression" implementation would return a non
     :class:`_sql.ClauseElement` such as a boolean value. For both issues, 1.3's
     behavior was to silently ignore the mis-configuration and ultimately
     attempt to interpret the value as a SQL expression, which would lead to an
     incorrect query.

     * Fixed issue regarding interaction of the attribute system with
       hybrid_property, where if the ``__clause_element__()`` method of the
       attribute returned a non-:class:`_sql.ClauseElement` object, an internal
       ``AttributeError`` would lead the attribute to return the ``expression``
       function on the hybrid_property itself, as the attribute error was
       against the name ``.expression`` which would invoke the ``__getattr__()``
       method as a fallback. This now raises explicitly. In 1.3 the
       non-:class:`_sql.ClauseElement` was returned directly.

     * Fixed issue in SQL argument coercions system where passing the wrong
       kind of object to methods that expect column expressions would fail if
       the object were altogether not a SQLAlchemy object, such as a Python
       function, in cases where the object were not just coerced into a bound
       value. Again 1.3 did not have a comprehensive argument coercion system
       so this case would also pass silently.


 .. change::
     :tags: bug, orm
     :tickets: 6378

     Fixed issue where using a :class:`_sql.Select` as a subquery in an ORM
     context would modify the :class:`_sql.Select` in place to disable
     eagerloads on that object, which would then cause that same
     :class:`_sql.Select` to not eagerload if it were then re-used in a
     top-level execution context.


 .. change::
     :tags: bug, regression, sql
     :tickets: 6343

     Fixed regression where usage of the :func:`_sql.text` construct inside the
     columns clause of a :class:`_sql.Select` construct, which is better handled
     by using a :func:`_sql.literal_column` construct, would nonetheless prevent
     constructs like :func:`_sql.union` from working correctly. Other use cases,
     such as constructing subuqeries, continue to work the same as in prior
     versions where the :func:`_sql.text` construct is silently omitted from the
     collection of exported columns.   Also repairs similar use within the
     ORM.


 .. change::
     :tags: bug, regression, sql
     :tickets: 6261

     Fixed regression involving legacy methods such as
     :meth:`_sql.Select.append_column` where internal assertions would fail.

 .. change::
     :tags: usecase, sqlite
     :tickets: 6379

     Default to using ``SingletonThreadPool`` for in-memory SQLite databases
     created using URI filenames. Previously the default pool used was the
     ``NullPool`` that precented sharing the same database between multiple
     engines.

 .. change::
     :tags: bug, regression, sql
     :tickets: 6300

     Fixed regression caused by :ticket:`5395` where tuning back the check for
     sequences in :func:`_sql.select` now caused failures when doing 2.0-style
     querying with a mapped class that also happens to have an ``__iter__()``
     method. Tuned the check some more to accommodate this as well as some other
     interesting ``__iter__()`` scenarios.


 .. change::
     :tags: bug, mssql, schema
     :tickets: 6345

     Add :meth:`_types.TypeEngine.as_generic` support for
     :class:`sqlalchemy.dialects.mysql.BIT` columns, mapping
     them to :class:`_sql.sqltypes.Boolean`.

 .. change::
     :tags: bug, orm, regression
     :tickets: 6360, 6359

     Fixed issue where the new :ref:`autobegin <session_autobegin>` behavior
     failed to "autobegin" in the case where an existing persistent object has
     an attribute change, which would then impact the behavior of
     :meth:`_orm.Session.rollback` in that no snapshot was created to be rolled
     back. The "attribute modify" mechanics have been updated to ensure
     "autobegin", which does not perform any database work, does occur when
     persistent attributes change in the same manner as when
     :meth:`_orm.Session.add` is called. This is a regression as in 1.3, the
     rollback() method always had a transaction to roll back and would expire
     every time.

 .. change::
     :tags: bug, mssql, regression
     :tickets: 6366

     Fixed regression caused by :ticket:`6306` which added support for
     ``DateTime(timezone=True)``, where the previous behavior of the pyodbc
     driver of implicitly dropping the tzinfo from a timezone-aware date when
     INSERTing into a timezone-naive DATETIME column were lost, leading to a SQL
     Server error when inserting timezone-aware datetime objects into
     timezone-native database columns.

 .. change::
     :tags: orm, bug, regression
     :tickets: 6386

     Fixed regression in ORM where using hybrid property to indicate an
     expression from a different entity would confuse the column-labeling logic
     in the ORM and attempt to derive the name of the hybrid from that other
     class, leading to an attribute error. The owning class of the hybrid
     attribute is now tracked along with the name.

 .. change::
     :tags: orm, bug, regression
     :tickets: 6401

     Fixed regression in hybrid_property where a hybrid against a SQL function
     would generate an ``AttributeError`` when attempting to generate an entry
     for the ``.c`` collection of a subquery in some cases; among other things
     this would impact its use in cases like that of ``Query.count()``.


 .. change::
     :tags: bug, postgresql
     :tickets: 6373

     Fixed very old issue where the :class:`_types.Enum` datatype would not
     inherit the :paramref:`_schema.MetaData.schema` parameter of a
     :class:`_schema.MetaData` object when that object were passed to the
     :class:`_types.Enum` using :paramref:`_types.Enum.metadata`.

 .. change::
     :tags: bug, orm, dataclasses
     :tickets: 6346

     Adjusted the declarative scan for dataclasses so that the inheritance
     behavior of :func:`_orm.declared_attr` established on a mixin, when using
     the new form of having it inside of a ``dataclasses.field()`` construct and
     not actually a descriptor attribute on the class, correctly accommodates
     the case when the target class to be mapped is a subclass of an existing
     mapped class which has already mapped that :func:`_orm.declared_attr`, and
     therefore should not be re-applied to this class.


 .. change::
     :tags: bug, schema, mysql, mariadb, oracle, postgresql
     :tickets: 6338

     Ensure that the MySQL and MariaDB dialect ignore the
     :class:`_sql.Identity` construct while rendering the ``AUTO_INCREMENT``
     keyword in a create table.

     The Oracle and PostgreSQL compiler was updated to not render
     :class:`_sql.Identity` if the database version does not support it
     (Oracle < 12 and PostgreSQL < 10). Previously it was rendered regardless
     of the database version.

 .. change::
     :tags: bug, orm
     :tickets: 6353

     Fixed an issue with the (deprecated in 1.4)
     :meth:`_schema.ForeignKeyConstraint.copy` method that caused an error when
     invoked with the ``schema`` argument.

 .. change::
     :tags: bug, engine
     :tickets: 6361

     Fixed issue where usage of an explicit :class:`.Sequence` would produce
     inconsistent "inline" behavior for an :class:`.Insert` construct that
     includes multiple values phrases; the first seq would be inline but
     subsequent ones would be "pre-execute", leading to inconsistent sequence
     ordering. The sequence expressions are now fully inline.

.. changelog::

1.4.11

:released: April 21, 2021

 .. change::
     :tags: bug, engine, regression
     :tickets: 6337

     Fixed critical regression caused by the change in :ticket:`5497` where the
     connection pool "init" phase no longer occurred within mutexed isolation,
     allowing other threads to proceed with the dialect uninitialized, which
     could then impact the compilation of SQL statements.


 .. change::
     :tags: bug, orm, regression, declarative
     :tickets: 6331

     Fixed regression where recent changes to support Python dataclasses had the
     inadvertent effect that an ORM mapped class could not successfully override
     the ``__new__()`` method.

.. changelog::

1.4.10

:released: April 20, 2021

 .. change::
     :tags: bug, declarative, regression
     :tickets: 6291

     Fixed :func:`_declarative.instrument_declarative` that called
     a non existing registry method.

 .. change::
     :tags: bug, orm
     :tickets: 6320

     Fixed bug in new :func:`_orm.with_loader_criteria` feature where using a
     mixin class with :func:`_orm.declared_attr` on an attribute that were
     accessed inside the custom lambda would emit a warning regarding using an
     unmapped declared attr, when the lambda callable were first initialized.
     This warning is now prevented using special instrumentation for this
     lambda initialization step.


 .. change::
     :tags: usecase, mssql
     :tickets: 6306

     The :paramref:`_types.DateTime.timezone` parameter when set to ``True``
     will now make use of the ``DATETIMEOFFSET`` column type with SQL Server
     when used to emit DDL, rather than ``DATETIME`` where the flag was silently
     ignored.

 .. change::
     :tags: orm, bug, regression
     :tickets: 6326

     Fixed additional regression caused by the "eagerloaders on refresh" feature
     added in :ticket:`1763` where the refresh operation historically would set
     ``populate_existing``, which given the new feature now overwrites pending
     changes on eagerly loaded objects when autoflush is false. The
     populate_existing flag has been turned off for this case and a more
     specific method used to ensure the correct attributes refreshed.

 .. change::
     :tags: bug, orm, result
     :tickets: 6299

     Fixed an issue when using 2.0 style execution that prevented using
     :meth:`_result.Result.scalar_one` or
     :meth:`_result.Result.scalar_one_or_none` after calling
     :meth:`_result.Result.unique`, for the case where the ORM is returning a
     single-element row in any case.

 .. change::
     :tags: bug, sql
     :tickets: 6327

     Fixed issue in SQL compiler where the bound parameters set up for a
     :class:`.Values` construct wouldn't be positionally tracked correctly if
     inside of a :class:`_sql.CTE`, affecting database drivers that support
     VALUES + ctes and use positional parameters such as SQL Server in
     particular as well as asyncpg.   The fix also repairs support for
     compiler flags such as ``literal_binds``.

 .. change::
     :tags: bug, schema
     :tickets: 6287

     Fixed issue where :func:`_functions.next_value` was not deriving its type
     from the corresponding :class:`_schema.Sequence`, instead hardcoded to
     :class:`_types.Integer`. The specific numeric type is now used.

 .. change::
     :tags: bug, mypy
     :tickets: 6255

     Fixed issue where mypy plugin would not correctly interpret an explicit
     :class:`_orm.Mapped` annotation in conjunction with a
     :func:`_orm.relationship` that refers to a class by string name; the
     correct annotation would be downgraded to a less specific one leading to
     typing errors.

 .. change::
     :tags: bug, sql
     :tickets: 6256

     Repaired and solidified issues regarding custom functions and other
     arbitrary expression constructs which within SQLAlchemy's column labeling
     mechanics would seek to use ``str(obj)`` to get a string representation to
     use as an anonymous column name in the ``.c`` collection of a subquery.
     This is a very legacy behavior that performs poorly and leads to lots of
     issues, so has been revised to no longer perform any compilation by
     establishing specific methods on :class:`.FunctionElement` to handle this
     case, as SQL functions are the only use case that it came into play. An
     effect of this behavior is that an unlabeled column expression with no
     derivable name will be given an arbitrary label starting with the prefix
     ``"_no_label"`` in the ``.c`` collection of a subquery; these were
     previously being represented either as the generic stringification of that
     expression, or as an internal symbol.

 .. change::
     :tags: usecase, orm
     :ticketS: 6301

     Altered some of the behavior repaired in :ticket:`6232` where the
     ``immediateload`` loader strategy no longer goes into recursive loops; the
     modification is that an eager load (joinedload, selectinload, or
     subqueryload) from A->bs->B which then states ``immediateload`` for a
     simple manytoone B->a->A that's in the identity map will populate the B->A,
     so that this attribute is back-populated when the collection of A/A.bs are
     loaded. This allows the objects to be functional when detached.


.. changelog::

1.4.9

:released: April 17, 2021

 .. change::
     :tags: bug, sql, regression
     :tickets: 6290

     Fixed regression where an empty in statement on a tuple would result
     in an error when compiled with the option ``literal_binds=True``.

 .. change::
     :tags: bug, regression, orm, performance, sql
     :tickets: 6304

     Fixed a critical performance issue where the traversal of a
     :func:`_sql.select` construct would traverse a repetitive product of the
     represented FROM clauses as they were each referred towards by columns in
     the columns clause; for a series of nested subqueries with lots of columns
     this could cause a large delay and significant memory growth. This
     traversal is used by a wide variety of SQL and ORM functions, including by
     the ORM :class:`_orm.Session` when it's configured to have
     "table-per-bind", which while this is not a common use case, it seems to be
     what Flask-SQLAlchemy is hardcoded as using, so the issue impacts
     Flask-SQLAlchemy users. The traversal has been repaired to uniqify on FROM
     clauses which was effectively what would happen implicitly with the pre-1.4
     architecture.

 .. change::
     :tags: bug, postgresql, sql, regression
     :tickets: 6303

     Fixed an argument error in the default and PostgreSQL compilers that
     would interfere with an UPDATE..FROM or DELETE..FROM..USING statement
     that was then SELECTed from as a CTE.

 .. change::
     :tags: bug, orm, regression
     :tickets: 6272

     Fixed regression where an attribute that is mapped to a
     :func:`_orm.synonym` could not be used in column loader options such as
     :func:`_orm.load_only`.

 .. change::
     :tags: usecase, orm
     :tickets: 6267

     Established support for :func:`_orm.synoynm` in conjunction with
     hybrid property, assocaitionproxy is set up completely, including that
     synonyms can be established linking to these constructs which work
     fully.   This is a behavior that was semi-explicitly disallowed previously,
     however since it did not fail in every scenario, explicit support
     for assoc proxy and hybrids has been added.


.. changelog::

1.4.8

:released: April 15, 2021

 .. change::
     :tags: change, mypy

     Updated Mypy plugin to only use the public plugin interface of the
     semantic analyzer.

 .. change::
     :tags: bug, mssql, regression
     :tickets: 6265

     Fixed an additional regression in the same area as that of :ticket:`6173`,
     :ticket:`6184`, where using a value of 0 for OFFSET in conjunction with
     LIMIT with SQL Server would create a statement using "TOP", as was the
     behavior in 1.3, however due to caching would then fail to respond
     accordingly to other values of OFFSET. If the "0" wasn't first, then it
     would be fine. For the fix, the "TOP" syntax is now only emitted if the
     OFFSET value is omitted entirely, that is, :meth:`_sql.Select.offset` is
     not used. Note that this change now requires that if the "with_ties" or
     "percent" modifiers are used, the statement can't specify an OFFSET of
     zero, it now needs to be omitted entirely.

 .. change::
     :tags: bug, engine

     The :meth:`_engine.Dialect.has_table` method now raises an informative
     exception if a non-Connection is passed to it, as this incorrect behavior
     seems to be common.  This method is not intended for external use outside
     of a dialect.  Please use the :meth:`.Inspector.has_table` method
     or for cross-compatibility with older SQLAlchemy versions, the
     :meth:`_engine.Engine.has_table` method.


 .. change::
     :tags: bug, regression, sql
     :tickets: 6249

     Fixed regression where the :class:`_sql.BindParameter` object would not
     properly render for an IN expression (i.e. using the "post compile" feature
     in 1.4) if the object were copied from either an internal cloning
     operation, or from a pickle operation, and the parameter name contained
     spaces or other special characters.

 .. change::
     :tags: bug, mypy
     :tickets: 6205

     Revised the fix for ``OrderingList`` from version 1.4.7 which was testing
     against the incorrect API.

 .. change::
     :tags: bug, asyncio
     :tickets: 6220

     Fix typo that prevented setting the ``bind`` attribute of an
     :class:`_asyncio.AsyncSession` to the correct value.

 .. change::
     :tags: feature, sql
     :tickets: 3314

     The tuple returned by :attr:`.CursorResult.inserted_primary_key` is now a
     :class:`_result.Row` object with a named tuple interface on top of the
     existing tuple interface.




 .. change::
     :tags: bug, regression, sql, sqlite
     :tickets: 6254

     Fixed regression where the introduction of the INSERT syntax "INSERT...
     VALUES (DEFAULT)" was not supported on some backends that do however
     support "INSERT..DEFAULT VALUES", including SQLite. The two syntaxes are
     now each individually supported or non-supported for each dialect, for
     example MySQL supports "VALUES (DEFAULT)" but not "DEFAULT VALUES".
     Support for Oracle has also been enabled.

 .. change::
     :tags: bug, regression, orm
     :tickets: 6259

     Fixed a cache leak involving the :func:`_orm.with_expression` loader
     option, where the given SQL expression would not be correctly considered as
     part of the cache key.

     Additionally, fixed regression involving the corresponding
     :func:`_orm.query_expression` feature. While the bug technically exists in
     1.3 as well, it was not exposed until 1.4. The "default expr" value of
     ``null()`` would be rendered when not needed, and additionally was also not
     adapted correctly when the ORM rewrites statements such as when using
     joined eager loading. The fix ensures "singleton" expressions like ``NULL``
     and ``true`` aren't "adapted" to refer to columns in ORM statements, and
     additionally ensures that a :func:`_orm.query_expression` with no default
     expression doesn't render in the statement if a
     :func:`_orm.with_expression` isn't used.

 .. change::
     :tags: bug, orm
     :tickets: 6252

     Fixed issue in the new feature of :meth:`_orm.Session.refresh` introduced
     by :ticket:`1763` where eagerly loaded relationships are also refreshed,
     where the ``lazy="raise"`` and ``lazy="raise_on_sql"`` loader strategies
     would interfere with the :func:`_orm.immediateload` loader strategy, thus
     breaking the feature for relationships that were loaded with
     :func:`_orm.selectinload`, :func:`_orm.subqueryload` as well.

.. changelog::

1.4.7

:released: April 9, 2021

 .. change::
     :tags: bug, sql, regression
     :tickets: 6222

     Enhanced the "expanding" feature used for :meth:`_sql.ColumnOperators.in_`
     operations to infer the type of expression from the right hand list of
     elements, if the left hand side does not have any explicit type set up.
     This allows the expression to support stringification among other things.
     In 1.3, "expanding" was not automatically used for
     :meth:`_sql.ColumnOperators.in_` expressions, so in that sense this change
     fixes a behavioral regression.


 .. change::
     :tags: bug, mypy

     Fixed issue in Mypy plugin where the plugin wasn’t inferring the correct
     type for columns of subclasses that don’t directly descend from
     ``TypeEngine``, in particular that of  ``TypeDecorator`` and
     ``UserDefinedType``.

 .. change::
     :tags: bug, orm, regression
     :tickets: 6221

     Fixed regression where the :func:`_orm.subqueryload` loader strategy would
     fail to correctly accommodate sub-options, such as a :func:`_orm.defer`
     option on a column, if the "path" of the subqueryload were more than one
     level deep.


 .. change::
     :tags: bug, sql

     Fixed the "stringify" compiler to support a basic stringification
     of a "multirow" INSERT statement, i.e. one with multiple tuples
     following the VALUES keyword.


 .. change::
     :tags: bug, orm, regression
     :tickets: 6211

     Fixed regression where the :func:`_orm.merge_frozen_result` function relied
     upon by the dogpile.caching example was not included in tests and began
     failing due to incorrect internal arguments.

 .. change::
     :tags: bug, engine, regression
     :tickets: 6218

     Fixed up the behavior of the :class:`_result.Row` object when dictionary
     access is used upon it, meaning converting to a dict via ``dict(row)`` or
     accessing members using strings or other objects i.e. ``row["some_key"]``
     works as it would with a dictionary, rather than raising ``TypeError`` as
     would be the case with a tuple, whether or not the C extensions are in
     place. This was originally supposed to emit a 2.0 deprecation warning for
     the "non-future" case using :class:`_result.LegacyRow`, and was to raise
     ``TypeError`` for the "future" :class:`_result.Row` class. However, the C
     version of :class:`_result.Row` was failing to raise this ``TypeError``,
     and to complicate matters, the :meth:`_orm.Session.execute` method now
     returns :class:`_result.Row` in all cases to maintain consistency with the
     ORM result case, so users who didn't have C extensions installed would
     see different behavior in this one case for existing pre-1.4 style
     code.

     Therefore, in order to soften the overall upgrade scheme as most users have
     not been exposed to the more strict behavior of :class:`_result.Row` up
     through 1.4.6, :class:`_result.LegacyRow` and :class:`_result.Row` both
     provide for string-key access as well as support for ``dict(row)``, in all
     cases emitting the 2.0 deprecation warning when ``SQLALCHEMY_WARN_20`` is
     enabled. The :class:`_result.Row` object still uses tuple-like behavior for
     ``__contains__``, which is probably the only noticeable behavioral change
     compared to :class:`_result.LegacyRow`, other than the removal of
     dictionary-style methods ``values()`` and ``items()``.

 .. change::
     :tags: bug, regression, orm
     :tickets: 6233

     Fixed critical regression where the :class:`_orm.Session` could fail to
     "autobegin" a new transaction when a flush occurred without an existing
     transaction in place, implicitly placing the :class:`_orm.Session` into
     legacy autocommit mode which commit the transaction. The
     :class:`_orm.Session` now has a check that will prevent this condition from
     occurring, in addition to repairing the flush issue.

     Additionally, scaled back part of the change made as part of :ticket:`5226`
     which can run autoflush during an unexpire operation, to not actually
     do this in the case of a :class:`_orm.Session` using legacy
     :paramref:`_orm.Session.autocommit` mode, as this incurs a commit within
     a refresh operation.

 .. change::
     :tags: change, tests

     Added a new flag to :class:`.DefaultDialect` called ``supports_schemas``;
     third party dialects may set this flag to ``False`` to disable SQLAlchemy's
     schema-level tests when running the test suite for a third party dialect.

 .. change::
     :tags: bug, regression, schema
     :tickets: 6216

     Fixed regression where usage of a token in the
     :paramref:`_engine.Connection.execution_options.schema_translate_map`
     dictionary which contained special characters such as braces would fail to
     be substituted properly. Use of square bracket characters ``[]`` is now
     explicitly disallowed as these are used as a delimiter character in the
     current implementation.

 .. change::
     :tags: bug, regression, orm
     :tickets: 6215

     Fixed regression where the ORM compilation scheme would assume the function
     name of a hybrid property would be the same as the attribute name in such a
     way that an ``AttributeError`` would be raised, when it would attempt to
     determine the correct name for each element in a result tuple. A similar
     issue exists in 1.3 but only impacts the names of tuple rows. The fix here
     adds a check that the hybrid's function name is actually present in the
     ``__dict__`` of the class or its superclasses before assigning this name;
     otherwise, the hybrid is considered to be "unnamed" and ORM result tuples
     will use the naming scheme of the underlying expression.

 .. change::
     :tags: bug, orm, regression
     :tickets: 6232

     Fixed critical regression caused by the new feature added as part of
     :ticket:`1763`, eager loaders are invoked on unexpire operations. The new
     feature makes use of the "immediateload" eager loader strategy as a
     substitute for a collection loading strategy, which unlike the other
     "post-load" strategies was not accommodating for recursive invocations
     between mutually-dependent relationships, leading to recursion overflow
     errors.


.. changelog::

1.4.6

:released: April 6, 2021

 .. change::
     :tags: bug, sql, regression, oracle, mssql
     :tickets: 6202

     Fixed further regressions in the same area as that of :ticket:`6173` released in
     1.4.5, where a "postcompile" parameter, again most typically those used for
     LIMIT/OFFSET rendering in Oracle and SQL Server, would fail to be processed
     correctly if the same parameter rendered in multiple places in the
     statement.



 .. change::
     :tags: bug, orm, regression
     :tickets: 6203

     Fixed regression where a deprecated form of :meth:`_orm.Query.join` were
     used, passing a series of entities to join from without any ON clause in a
     single :meth:`_orm.Query.join` call, would fail to function correctly.

 .. change::
     :tags: bug, mypy
     :tickets: 6147

     Applied a series of refactorings and fixes to accommodate for Mypy
     "incremental" mode across multiple files, which previously was not taken
     into account. In this mode the Mypy plugin has to accommodate Python
     datatypes expressed in other files coming in with less information than
     they have on a direct run.

     Additionally, a new decorator :func:`_orm.declarative_mixin` is added,
     which is necessary for the Mypy plugin to be able to definifitely identify
     a Declarative mixin class that is otherwise not used inside a particular
     Python file.

     .. seealso::

         :ref:`mypy_declarative_mixins`


 .. change::
     :tags: bug, mypy
     :tickets: 6205

     Fixed issue where the Mypy plugin would fail to interpret the
     "collection_class" of a relationship if it were a callable and not a class.
     Also improved type matching and error reporting for collection-oriented
     relationships.


 .. change::
     :tags: bug, sql
     :tickets: 6204

     Executing a :class:`_sql.Subquery` using :meth:`_engine.Connection.execute`
     is deprecated and will emit a deprecation warning; this use case was an
     oversight that should have been removed from 1.4. The operation will now
     execute the underlying :class:`_sql.Select` object directly for backwards
     compatibility. Similarly, the :class:`_sql.CTE` class is also not
     appropriate for execution. In 1.3, attempting to execute a CTE would result
     in an invalid "blank" SQL statement being executed; since this use case was
     not working it now raises :class:`_exc.ObjectNotExecutableError`.
     Previously, 1.4 was attempting to execute the CTE as a statement however it
     was working only erratically.

 .. change::
     :tags: bug, regression, orm
     :tickets: 6206

     Fixed critical regression where the :meth:`_orm.Query.yield_per` method in
     the ORM would set up the internal :class:`_engine.Result` to yield chunks
     at a time, however made use of the new :meth:`_engine.Result.unique` method
     which uniques across the entire result. This would lead to lost rows since
     the ORM is using ``id(obj)`` as the uniquing function, which leads to
     repeated identifiers for new objects as already-seen objects are garbage
     collected. 1.3's behavior here was to "unique" across each chunk, which
     does not actually produce "uniqued" results when results are yielded in
     chunks. As the :meth:`_orm.Query.yield_per` method is already explicitly
     disallowed when joined eager loading is in place, which is the primary
     rationale for the "uniquing" feature, the "uniquing" feature is now turned
     off entirely when :meth:`_orm.Query.yield_per` is used.

     This regression only applies to the legacy :class:`_orm.Query` object; when
     using :term:`2.0 style` execution, "uniquing" is not automatically applied.
     To prevent the issue from arising from explicit use of
     :meth:`_engine.Result.unique`, an error is now raised if rows are fetched
     from a "uniqued" ORM-level :class:`_engine.Result` if any
     :ref:`yield per <orm_queryguide_yield_per>` API is also in use, as the
     purpose of ``yield_per`` is to allow for arbitrarily large numbers of rows,
     which cannot be uniqued in memory without growing the number of entries to
     fit the complete result size.


 .. change::
     :tags: usecase, asyncio, postgresql
     :tickets: 6199

     Added accessors ``.sqlstate`` and synonym ``.pgcode`` to the ``.orig``
     attribute of the SQLAlchemy exception class raised by the asyncpg DBAPI
     adapter, that is, the intermediary exception object that wraps on top of
     that raised by the asyncpg library itself, but below the level of the
     SQLAlchemy dialect.

.. changelog::

1.4.5

:released: April 2, 2021

 .. change::
     :tags: bug, sql, postgresql
     :tickets: 6183

     Fixed bug in new :meth:`_functions.FunctionElement.render_derived` feature
     where column names rendered out explicitly in the alias SQL would not have
     proper quoting applied for case sensitive names and other non-alphanumeric
     names.

 .. change::
     :tags: bug, regression, orm
     :tickets: 6172

     Fixed regression where the :func:`_orm.joinedload` loader strategy would
     not successfully joinedload to a mapper that is mapper against a
     :class:`.CTE` construct.

 .. change::
     :tags: bug, regression, sql
     :tickets: 6181

     Fixed regression where use of the :meth:`.Operators.in_` method with a
     :class:`_sql.Select` object against a non-table-bound column would produce
     an ``AttributeError``, or more generally using a :class:`_sql.ScalarSelect`
     that has no datatype in a binary expression would produce invalid state.


 .. change::
     :tags: bug, mypy
     :tickets: sqlalchemy/sqlalchemy2-stubs/14

     Fixed issue in mypy plugin where newly added support for
     :func:`_orm.as_declarative` needed to more fully add the
     ``DeclarativeMeta`` class to the mypy interpreter's state so that it does
     not result in a name not found error; additionally improves how global
     names are setup for the plugin including the ``Mapped`` name.


 .. change::
     :tags: bug, mysql, regression
     :tickets: 6163

     Fixed regression in the MySQL dialect where the reflection query used to
     detect if a table exists would fail on very old MySQL 5.0 and 5.1 versions.

 .. change::
     :tags: bug, sql
     :tickets: 6184

     Added a new flag to the :class:`_engine.Dialect` class called
     :attr:`_engine.Dialect.supports_statement_cache`. This flag now needs to be present
     directly on a dialect class in order for SQLAlchemy's
     :ref:`query cache <sql_caching>` to take effect for that dialect. The
     rationale is based on discovered issues such as :ticket:`6173` revealing
     that dialects which hardcode literal values from the compiled statement,
     often the numerical parameters used for LIMIT / OFFSET, will not be
     compatible with caching until these dialects are revised to use the
     parameters present in the statement only. For third party dialects where
     this flag is not applied, the SQL logging will show the message "dialect
     does not support caching", indicating the dialect should seek to apply this
     flag once they have verified that no per-statement literal values are being
     rendered within the compilation phase.

     .. seealso::

       :ref:`engine_thirdparty_caching`

 .. change::
     :tags: bug, postgresql
     :tickets: 6099

     Fixed typo in the fix for :ticket:`6099` released in 1.4.4 that completely
     prevented this change from working correctly, i.e. the error message did not match
     what was actually emitted by pg8000.

 .. change::
     :tags: bug, orm, regression
     :tickets: 6171

     Scaled back the warning message added in :ticket:`5171` to not warn for
     overlapping columns in an inheritance scenario where a particular
     relationship is local to a subclass and therefore does not represent an
     overlap.

 .. change::
     :tags: bug, regression, oracle
     :tickets: 6173

     Fixed critical regression where the Oracle compiler would not maintain the
     correct parameter values in the LIMIT/OFFSET for a select due to a caching
     issue.


 .. change::
     :tags: bug, postgresql
     :tickets: 6170

     Fixed issue where the PostgreSQL :class:`.PGInspector`, when generated
     against an :class:`_engine.Engine`, would fail for ``.get_enums()``,
     ``.get_view_names()``, ``.get_foreign_table_names()`` and
     ``.get_table_oid()`` when used against a "future" style engine and not the
     connection directly.

 .. change::
     :tags: bug, schema
     :tickets: 6146

     Introduce a new parameter :paramref:`_types.Enum.omit_aliases` in
     :class:`_types.Enum` type allow filtering aliases when using a pep435 Enum.
     Previous versions of SQLAlchemy kept aliases in all cases, creating
     database enum type with additional states, meaning that they were treated
     as different values in the db. For backward compatibility this flag
     defaults to ``False`` in the 1.4 series, but will be switched to ``True``
     in a future version. A deprecation warning is raise if this flag is not
     specified and the passed enum contains aliases.

 .. change::
     :tags: bug, mssql
     :tickets: 6163

     Fixed a regression in MSSQL 2012+ that prevented the order by clause
     to be rendered when ``offset=0`` is used in a subquery.

 .. change::
     :tags: bug, asyncio
     :tickets: 6166


     Fixed issue where the asyncio extension could not be loaded
     if running Python 3.6 with the backport library of
     ``contextvars`` installed.

.. changelog::

1.4.4

:released: March 30, 2021

 .. change::
     :tags: bug, misc

     Adjusted the usage of the ``importlib_metadata`` library for loading
     setuptools entrypoints in order to accommodate for some deprecation
     changes.


 .. change::
     :tags: bug, postgresql
     :tickets: 6099

     Modified the ``is_disconnect()`` handler for the pg8000 dialect, which now
     accommodates for a new ``InterfaceError`` emitted by pg8000 1.19.0. Pull
     request courtesy Hamdi Burak Usul.


 .. change::
     :tags: bug, orm
     :tickets: 6139

     Fixed critical issue in the new :meth:`_orm.PropComparator.and_` feature
     where loader strategies that emit secondary SELECT statements such as
     :func:`_orm.selectinload` and :func:`_orm.lazyload` would fail to
     accommodate for bound parameters in the user-defined criteria in terms of
     the current statement being executed, as opposed to the cached statement,
     causing stale bound values to be used.

     This also adds a warning for the case where an object that uses
     :func:`_orm.lazyload` in conjunction with :meth:`_orm.PropComparator.and_`
     is attempted to be serialized; the loader criteria cannot reliably
     be serialized and deserialized and eager loading should be used for this
     case.


 .. change::
     :tags: bug, engine
     :tickets: 6138

     Repair wrong arguments to exception handling method
     in CursorResult.

 .. change::
     :tags: bug, regression, orm
     :tickets: 6144

     Fixed missing method :meth:`_orm.Session.get` from the
     :class:`_orm.ScopedSession` interface.


 .. change::
     :tags: usecase, engine
     :tickets: 6155

     Modified the context manager used by :class:`_engine.Transaction` so that
     an "already detached" warning is not emitted by the ending of the context
     manager itself, if the transaction were already manually rolled back inside
     the block. This applies to regular transactions, savepoint transactions,
     and legacy "marker" transactions. A warning is still emitted if the
     ``.rollback()`` method is called explicitly more than once.

.. changelog::

1.4.3

:released: March 25, 2021

 .. change::
     :tags: bug, orm
     :tickets: 6069

     Fixed a bug where python 2.7.5 (default on CentOS 7) wasn't able to import
     sqlalchemy, because on this version of Python ``exec "statement"`` and
     ``exec("statement")`` do not behave the same way.  The compatibility
     ``exec_()`` function was used instead.

 .. change::
     :tags: sqlite, feature, asyncio
     :tickets: 5920

     Added support for the aiosqlite database driver for use with the
     SQLAlchemy asyncio extension.

     .. seealso::

       :ref:`aiosqlite`

 .. change::
     :tags: bug, regression, orm, declarative
     :tickets: 6128

     Fixed regression where the ``.metadata`` attribute on a per class level
     would not be honored, breaking the use case of per-class-hierarchy
     :class:`.schema.MetaData` for abstract declarative classes and mixins.


     .. seealso::

       :ref:`declarative_metadata`

 .. change::
     :tags: bug, mypy

     Added support for the Mypy extension to correctly interpret a declarative
     base class that's generated using the :func:`_orm.as_declarative` function
     as well as the :meth:`_orm.registry.as_declarative_base` method.

 .. change::
     :tags: bug, mypy
     :tickets: 6109

     Fixed bug in Mypy plugin where the Python type detection
     for the :class:`_types.Boolean` column type would produce
     an exception; additionally implemented support for :class:`_types.Enum`,
     including detection of a string-based enum vs. use of Python ``enum.Enum``.

 .. change::
     :tags: bug, reflection, postgresql
     :tickets: 6129

     Fixed reflection of identity columns in tables with mixed case names
     in PostgreSQL.

 .. change::
     :tags: bug, sqlite, regression
     :tickets: 5848

     Repaired the ``pysqlcipher`` dialect to connect correctly which had
     regressed in 1.4, and added test + CI support to maintain the driver
     in working condition.  The dialect now imports the ``sqlcipher3`` module
     for Python 3 by default before falling back to ``pysqlcipher3`` which
     is documented as now being unmaintained.

     .. seealso::

       :ref:`pysqlcipher`


 .. change::
     :tags: bug, orm
     :tickets: 6060

     Fixed bug where ORM queries using a correlated subquery in conjunction with
     :func:`_orm.column_property` would fail to correlate correctly to an
     enclosing subquery or to a CTE when :meth:`_sql.Select.correlate_except`
     were used in the property to control correlation, in cases where the
     subquery contained the same selectables as ones within the correlated
     subquery that were intended to not be correlated.

 .. change::
     :tags: bug, orm
     :tickets: 6131

     Fixed bug where combinations of the new "relationship with criteria"
     feature could fail in conjunction with features that make use of the new
     "lambda SQL" feature, including loader strategies such as selectinload and
     lazyload, for more complicated scenarios such as polymorphic loading.

 .. change::
     :tags: bug, orm
     :tickets: 6124

     Repaired support so that the :meth:`_sql.ClauseElement.params` method can
     work correctly with a :class:`_sql.Select` object that includes joins
     across ORM relationship structures, which is a new feature in 1.4.


 .. change::
     :tags: bug, engine, regression
     :tickets: 6119

     Restored the :class:`_engine.ResultProxy` name back to the
     ``sqlalchemy.engine`` namespace. This name refers to the
     :class:`_engine.LegacyCursorResult` object.

 .. change::
     :tags: bug, orm
     :tickets: 6115

     Fixed issue where a "removed in 2.0" warning were generated internally by
     the relationship loader mechanics.


.. changelog::

1.4.2

:released: March 19, 2021

 .. change::
     :tags: bug, orm, dataclasses
     :tickets: 6093

     Fixed issue in new ORM dataclasses functionality where dataclass fields on
     an abstract base or mixin that contained column or other mapping constructs
     would not be mapped if they also included a "default" key within the
     dataclasses.field() object.


 .. change::
     :tags: bug, regression, orm
     :tickets: 6088

     Fixed regression where the :attr:`_orm.Query.selectable` accessor, which is
     a synonym for :meth:`_orm.Query.__clause_element__`, got removed, it's now
     restored.

 .. change::
     :tags: bug, engine, regression

     Restored top level import for ``sqlalchemy.engine.reflection``. This
     ensures that the base :class:`_reflection.Inspector` class is properly
     registered so that :func:`_sa.inspect` works for third party dialects that
     don't otherwise import this package.


 .. change::
     :tags: bug, regression, orm
     :tickets: 6086

     Fixed regression where use of an unnamed SQL expression such as a SQL
     function would raise a column targeting error if the query itself were
     using joinedload for an entity and was also being wrapped in a subquery by
     the joinedload eager loading process.


 .. change::
     :tags: bug, orm, regression
     :tickets: 6092

     Fixed regression where the :meth:`_orm.Query.filter_by` method would fail
     to locate the correct source entity if the :meth:`_orm.Query.join` method
     had been used targeting an entity without any kind of ON clause.


 .. change::
     :tags: postgresql, usecase
     :tickets: 6982

     Rename the column name used by a reflection query that used
     a reserved word in some postgresql compatible databases.

 .. change::
     :tags: usecase, orm, dataclasses
     :tickets: 6100

     Added support for the :class:`_orm.declared_attr` object to work in the
     context of dataclass fields.

     .. seealso::

         :ref:`orm_declarative_dataclasses_mixin`

 .. change::
     :tags: bug, sql, regression
     :tickets: 6101

     Fixed issue where using a ``func`` that includes dotted packagenames would
     fail to be cacheable by the SQL caching system due to a Python list of
     names that needed to be a tuple.


 .. change::
     :tags: bug, regression, orm
     :tickets: 6095

     Fixed regression where the SQL compilation of a :class:`.Function` would
     not work correctly if the object had been "annotated", which is an internal
     memoization process used mostly by the ORM. In particular it could affect
     ORM lazy loads which make greater use of this feature in 1.4.

 .. change::
     :tags: bug, sql, regression
     :tickets: 6097

     Fixed regression in the :func:`_sql.case` construct, where the "dictionary"
     form of argument specification failed to work correctly if it were passed
     positionally, rather than as a "whens" keyword argument.

 .. change::
     :tags: bug, orm
     :tickets: 6090

     Fixed regression where the :class:`.ConcreteBase` would fail to map at all
     when a mapped column name overlapped with the discriminator column name,
     producing an assertion error. The use case here did not function correctly
     in 1.3 as the polymorphic union would produce a query that ignored the
     discriminator column entirely, while emitting duplicate column warnings. As
     1.4's architecture cannot easily reproduce this essentially broken behavior
     of 1.3 at the ``select()`` level right now, the use case now raises an
     informative error message instructing the user to use the
     ``.ConcreteBase._concrete_discriminator_name`` attribute to resolve the
     conflict. To assist with this configuration,
     ``.ConcreteBase._concrete_discriminator_name`` may be placed on the base
     class only where it will be automatically used by subclasses; previously
     this was not the case.


 .. change::
     :tags: bug, mypy
     :tickets: sqlalchemy/sqlalchemy2-stubs/2

     Fixed issue in MyPy extension which crashed on detecting the type of a
     :class:`.Column` if the type were given with a module prefix like
     ``sa.Integer()``.


.. changelog::

1.4.1

:released: March 17, 2021

 .. change::
     :tags: bug, orm, regression
     :tickets: 6066

     Fixed regression where producing a Core expression construct such as
     :func:`_sql.select` using ORM entities would eagerly configure the mappers,
     in an effort to maintain compatibility with the :class:`_orm.Query` object
     which necessarily does this to support many backref-related legacy cases.
     However, core :func:`_sql.select` constructs are also used in mapper
     configurations and such, and to that degree this eager configuration is
     more of an inconvenience, so eager configure has been disabled for the
     :func:`_sql.select` and other Core constructs in the absence of ORM loading
     types of functions such as :class:`_orm.Load`.

     The change maintains the behavior of :class:`_orm.Query` so that backwards
     compatibility is maintained. However, when using a :func:`_sql.select` in
     conjunction with ORM entities, a "backref" that isn't explicitly placed on
     one of the classes until mapper configure time won't be available unless
     :func:`_orm.configure_mappers` or the newer :func:`_orm.registry.configure`
     has been called elsewhere. Prefer using
     :paramref:`_orm.relationship.back_populates` for more explicit relationship
     configuration which does not have the eager configure requirement.


 .. change::
     :tags: bug, mssql, regression
     :tickets: 6058

     Fixed regression where a new setinputsizes() API that's available for
     pyodbc was enabled, which is apparently incompatible with pyodbc's
     fast_executemany() mode in the absence of more accurate typing information,
     which as of yet is not fully implemented or tested. The pyodbc dialect and
     connector has been modified so that setinputsizes() is not used at all
     unless the parameter ``use_setinputsizes`` is passed to the dialect, e.g.
     via :func:`_sa.create_engine`, at which point its behavior can be
     customized using the :meth:`.DialectEvents.do_setinputsizes` hook.

     .. seealso::

       :ref:`mssql_pyodbc_setinputsizes`

 .. change::
     :tags: bug, orm, regression
     :tickets: 6055

     Fixed a critical regression in the relationship lazy loader where the SQL
     criteria used to fetch a related many-to-one object could go stale in
     relation to other memoized structures within the loader if the mapper had
     configuration changes, such as can occur when mappers are late configured
     or configured on demand, producing a comparison to None and returning no
     object. Huge thanks to Alan Hamlett for their help tracking this down late
     into the night.



 .. change::
     :tags: bug, regression
     :tickets: 6068

     Added back ``items`` and ``values`` to ``ColumnCollection`` class.
     The regression was introduced while adding support for duplicate
     columns in from clauses and selectable in ticket 4753.


 .. change::
     :tags: bug, engine, regression
     :tickets: 6074

     The Python ``namedtuple()`` has the behavior such that the names ``count``
     and ``index`` will be served as tuple values if the named tuple includes
     those names; if they are absent, then their behavior as methods of
     ``collections.abc.Sequence`` is maintained. Therefore the
     :class:`_result.Row` and :class:`_result.LegacyRow` classes have been fixed
     so that they work in this same way, maintaining the expected behavior for
     database rows that have columns named "index" or "count".

 .. change::
     :tags: bug, orm, regression
     :tickets: 6076

     Fixed regression where the :meth:`_orm.Query.exists` m