Update sqlalchemy to 1.3.23

[pyup-bot]

This PR updates SQLAlchemy from 1.2.12 to 1.3.23.

Changelog

1.3.23

:released: February 1, 2021

 .. change::
     :tags: bug, ext
     :tickets: 5836

     Fixed issue where the stringification that is sometimes called when
     attempting to generate the "key" for the ``.c`` collection on a selectable
     would fail if the column were an unlabeled custom SQL construct using the
     ``sqlalchemy.ext.compiler`` extension, and did not provide a default
     compilation form; while this seems like an unusual case, it can get invoked
     for some ORM scenarios such as when the expression is used in an "order by"
     in combination with joined eager loading.  The issue is that the lack of a
     default compiler function was raising :class:`.CompileError` and not
     :class:`.UnsupportedCompilationError`.

 .. change::
     :tags: bug, postgresql
     :tickets: 5645

     For SQLAlchemy 1.3 only, setup.py pins pg8000 to a version lower than
     1.16.6. Version 1.16.6 and above is supported by SQLAlchemy 1.4. Pull
     request courtesy Giuseppe Lumia.

 .. change::
     :tags: bug, postgresql
     :tickets: 5850

     Fixed issue where using :meth:`_schema.Table.to_metadata` (called
     :meth:`_schema.Table.tometadata` in 1.3) in conjunction with a PostgreSQL
     :class:`_postgresql.ExcludeConstraint` that made use of ad-hoc column
     expressions would fail to copy correctly.

 .. change::
     :tags: bug, sql
     :tickets: 5816

     Fixed bug where making use of the :meth:`.TypeEngine.with_variant` method
     on a :class:`.TypeDecorator` type would fail to take into account the
     dialect-specific mappings in use, due to a rule in :class:`.TypeDecorator`
     that was instead attempting to check for chains of :class:`.TypeDecorator`
     instances.


 .. change::
     :tags: bug, mysql, reflection
     :tickets: 5860

     Fixed bug where MySQL server default reflection would fail for numeric
     values with a negation symbol present.


 .. change::
     :tags: bug, oracle
     :tickets: 5813

     Fixed regression in Oracle dialect introduced by :ticket:`4894` in
     SQLAlchemy 1.3.11 where use of a SQL expression in RETURNING for an UPDATE
     would fail to compile, due to a check for "server_default" when an
     arbitrary SQL expression is not a column.


 .. change::
     :tags: usecase, mysql
     :tickets: 5808

     Casting to ``FLOAT`` is now supported in MySQL >= (8, 0, 17) and
     MariaDb >= (10, 4, 5).

 .. change::
     :tags: bug, mysql
     :tickets: 5898

     Fixed long-lived bug in MySQL dialect where the maximum identifier length
     of 255 was too long for names of all types of constraints, not just
     indexes, all of which have a size limit of 64. As metadata naming
     conventions can create too-long names in this area, apply the limit to the
     identifier generator within the DDL compiler.

 .. change::
     :tags: bug, oracle
     :tickets: 5812

     Fixed bug in Oracle dialect where retriving a CLOB/BLOB column via
     :meth:`_dml.Insert.returning` would fail as the LOB value would need to be
     read when returned; additionally, repaired support for retrieval of Unicode
     values via RETURNING under Python 2.

 .. change::
     :tags: bug, mysql
     :tickets: 5821

     Fixed deprecation warnings that arose as a result of the release of PyMySQL
     1.0, including deprecation warnings for the "db" and "passwd" parameters
     now replaced with "database" and "password".


 .. change::
     :tags: bug, mysql
     :tickets: 5800

     Fixed regression from SQLAlchemy 1.3.20 caused by the fix for
     :ticket:`5462` which adds double-parenthesis for MySQL functional
     expressions in indexes, as is required by the backend, this inadvertently
     extended to include arbitrary :func:`_sql.text` expressions as well as
     Alembic's internal textual component,  which are required by Alembic for
     arbitrary index expressions which don't imply double parenthesis.  The
     check has been narrowed to include only binary/ unary/functional
     expressions directly.

.. changelog::

1.3.22

:released: December 18, 2020

 .. change::
     :tags: bug, oracle
     :tickets: 5784
     :versions: 1.4.0b2

     Fixed regression which occured due to :ticket:`5755` which implemented
     isolation level support for Oracle.   It has been reported that many Oracle
     accounts don't actually have permission to query the ``v$transaction``
     view so this feature has been altered to gracefully fallback when it fails
     upon database connect, where the dialect will assume "READ COMMITTED" is
     the default isolation level as was the case prior to SQLAlchemy 1.3.21.
     However, explicit use of the :meth:`_engine.Connection.get_isolation_level`
     method must now necessarily raise an exception, as Oracle databases with
     this restriction explicitly disallow the user from reading the current
     isolation level.

.. changelog::

1.3.21

:released: December 17, 2020

 .. change::
     :tags: bug, orm
     :tickets: 5774
     :versions: 1.4.0b2

     Added a comprehensive check and an informative error message for the case
     where a mapped class, or a string mapped class name, is passed to
     :paramref:`_orm.relationship.secondary`.  This is an extremely common error
     which warrants a clear message.

     Additionally, added a new rule to the class registry resolution such that
     with regards to the :paramref:`_orm.relationship.secondary` parameter, if a
     mapped class and its table are of the identical string name, the
     :class:`.Table` will be favored when resolving this parameter.   In all
     other cases, the class continues to be favored if a class and table
     share the identical name.

 .. change::
     :tags: sqlite, usecase
     :tickets: 5685

     Added ``sqlite_with_rowid=False`` dialect keyword to enable creating
     tables as ``CREATE TABLE … WITHOUT ROWID``. Patch courtesy Sean Anderson.

 .. change::
     :tags: bug, sql
     :tickets: 5691

     A warning is emmitted if a returning() method such as
     :meth:`_sql.Insert.returning` is called multiple times, as this does not
     yet support additive operation.  Version 1.4 will support additive
     operation for this.  Additionally, any combination of the
     :meth:`_sql.Insert.returning` and :meth:`_sql.ValuesBase.return_defaults`
     methods now raises an error as these methods are mutually exclusive;
     previously the operation would fail silently.


 .. change::
     :tags: bug, mssql
     :tickets: 5751

     Fixed bug where a CREATE INDEX statement was rendered incorrectly when
     both ``mssql-include`` and ``mssql_where`` were specified. Pull request
     courtesy Adiorz.

 .. change::
     :tags: bug, postgresql, mysql
     :tickets: 5729
     :versions: 1.4.0b2

     Fixed regression introduced in 1.3.2 for the PostgreSQL dialect, also
     copied out to the MySQL dialect's feature in 1.3.18, where usage of a non
     :class:`_schema.Table` construct such as :func:`_sql.text` as the argument
     to :paramref:`_sql.Select.with_for_update.of` would fail to be accommodated
     correctly within the PostgreSQL or MySQL compilers.


 .. change::
     :tags: bug, mssql
     :tickets: 5646

     Added SQL Server code "01000" to the list of disconnect codes.


 .. change::
     :tags: usecase, postgresql
     :tickets: 5604
     :versions: 1.4.0b2

     Added new parameter :paramref:`_postgresql.ExcludeConstraint.ops` to the
     :class:`_postgresql.ExcludeConstraint` object, to support operator class
     specification with this constraint.  Pull request courtesy Alon Menczer.

 .. change::
     :tags: bug, mysql, reflection
     :tickets: 5744
     :versions: 1.4.0b2

     Fixed issue where reflecting a server default on MariaDB only that
     contained a decimal point in the value would fail to be reflected
     correctly, leading towards a reflected table that lacked any server
     default.


 .. change::
     :tags: bug, orm
     :tickets: 5664

     Fixed bug in :meth:`_query.Query.update` where objects in the
     :class:`_ormsession.Session` that were already expired would be
     unnecessarily SELECTed individually when they were refreshed by the
     "evaluate"synchronize strategy.

 .. change::
     :tags: usecase, oracle
     :tickets: 5755

     Implemented support for the SERIALIZABLE isolation level for Oracle
     databases, as well as a real implementation for
     :meth:`_engine.Connection.get_isolation_level`.

     .. seealso::

         :ref:`oracle_isolation_level`

 .. change::
     :tags: mysql, sql
     :tickets: 5696

     Added missing keywords to the ``RESERVED_WORDS`` list for the MySQL
     dialect: ``action``, ``level``, ``mode``, ``status``, ``text``, ``time``.
     Pull request courtesy Oscar Batori.

 .. change::
     :tags: bug, orm
     :tickets: 5737
     :versions: 1.4.0b2

     Fixed bug involving the ``restore_load_context`` option of ORM events such
     as :meth:`_ormevent.InstanceEvents.load` such that the flag would not be
     carried along to subclasses which were mapped after the event handler were
     first established.



 .. change::
     :tags: bug, sql
     :tickets: 5656

     Fixed structural compiler issue where some constructs such as MySQL /
     PostgreSQL "on conflict / on duplicate key" would rely upon the state of
     the :class:`_sql.Compiler` object being fixed against their statement as
     the top level statement, which would fail in cases where those statements
     are branched from a different context, such as a DDL construct linked to a
     SQL statement.


 .. change::
     :tags: mssql, sqlite, reflection
     :tickets: 5661

     Fixed issue with composite primary key columns not being reported
     in the correct order. Patch courtesy fulpm.

.. changelog::

1.3.20

:released: October 12, 2020

 .. change::
     :tags: bug, orm
     :tickets: 4428

     An :class:`.ArgumentError` with more detail is now raised if the target
     parameter for :meth:`_query.Query.join` is set to an unmapped object.
     Prior to this change a less detailed ``AttributeError`` was raised.
     Pull request courtesy Ramon Williams.

 .. change::
     :tags: bug, mysql
     :tickets: 5568

     The "skip_locked" keyword used with ``with_for_update()`` will emit a
     warning when used on MariaDB backends, and will then be ignored.   This is
     a deprecated behavior that will raise in SQLAlchemy 1.4, as an application
     that requests "skip locked" is looking for a non-blocking operation which
     is not available on those backends.



 .. change::
     :tags: bug, engine
     :tickets: 5599

     Fixed issue where a non-string object sent to
     :class:`_exc.SQLAlchemyError` or a subclass, as occurs with some third
     party dialects, would fail to stringify correctly. Pull request
     courtesy Andrzej Bartosiński.

 .. change::
     :tags: bug, sql
     :tickets: 5644

     Fixed issue where the ``pickle.dumps()`` operation against
     :class:`_expression.Over` construct would produce a recursion overflow.

 .. change::
     :tags: postgresql, usecase
     :tickets: 4392

     The psycopg2 dialect now support PostgreSQL multiple host connections, by
     passing host/port combinations to the query string. Pull request courtesy
     Ramon Williams.

     .. seealso::

         :ref:`psycopg2_multi_host`

 .. change::
     :tags: bug, mysql
     :tickets: 5617

     Fixed bug where an UPDATE statement against a JOIN using MySQL multi-table
     format would fail to include the table prefix for the target table if the
     statement had no WHERE clause, as only the WHERE clause were scanned to
     detect a "multi table update" at that particular point.  The target
     is now also scanned if it's a JOIN to get the leftmost table as the
     primary table and the additional entries as additional FROM entries.


 .. change::
     :tags: bug, postgresql
     :tickets: 5518

     Adjusted the :meth:`_types.ARRAY.Comparator.any` and
     :meth:`_types.ARRAY.Comparator.all` methods to implement a straight "NOT"
     operation for negation, rather than negating the comparison operator.

 .. change::
     :tags: bug, pool
     :tickets: 5582

     Fixed issue where the following pool parameters were not being propagated
     to the new pool created when :meth:`_engine.Engine.dispose` were called:
     ``pre_ping``, ``use_lifo``.  Additionally the ``recycle`` and
     ``reset_on_return`` parameter is now propagated for the
     :class:`_engine.AssertionPool` class.

 .. change::
     :tags: bug, ext, associationproxy
     :tickets: 5541, 5542

     An informative error is now raised when attempting to use an association
     proxy element as a plain column expression to be SELECTed from or used in a
     SQL function; this use case is not currently supported.


 .. change::
     :tags: bug, sql
     :tickets: 5618

     Fixed bug where an error was not raised in the case where a
     :func:`_sql.column` were added to more than one :func:`_sql.table` at a
     time.  This raised correctly for the :class:`_schema.Column` and
     :class:`_schema.Table` objects. An :class:`_exc.ArgumentError` is now
     raised when this occurs.

 .. change::
     :tags: bug, orm
     :tickets: 4589

     Fixed issue where using a loader option against a string attribute name
     that is not actually a mapped attribute, such as a plain Python descriptor,
     would raise an uninformative AttributeError;  a descriptive error is now
     raised.



 .. change::
     :tags: mysql, usecase
     :tickets: 5462

     Adjusted the MySQL dialect to correctly parenthesize functional index
     expressions as accepted by MySQL 8. Pull request courtesy Ramon Williams.

 .. change::
     :tags: bug, engine
     :tickets: 5632

     Repaired a function-level import that was not using SQLAlchemy's standard
     late-import system within the sqlalchemy.exc module.


 .. change::
     :tags: change, mysql
     :tickets: 5539

     Add new MySQL reserved words: ``cube``, ``lateral`` added in MySQL 8.0.1
     and 8.0.14, respectively; this indicates that these terms will be quoted if
     used as table or column identifier names.

 .. change::
     :tags: bug, mssql
     :tickets: 5592

     Fixed issue where a SQLAlchemy connection URI for Azure DW with
     ``authentication=ActiveDirectoryIntegrated`` (and no username+password)
     was not constructing the ODBC connection string in a way that was
     acceptable to the Azure DW instance.

 .. change::
     :tags: bug, postgresql
     :tickets: 5520

     Fixed issue where the :class:`_postgresql.ENUM` type would not consult the
     schema translate map when emitting a CREATE TYPE or DROP TYPE during the
     test to see if the type exists or not.  Additionally, repaired an issue
     where if the same enum were encountered multiple times in a single DDL
     sequence, the "check" query would run repeatedly rather than relying upon a
     cached value.


 .. change::
     :tags: bug, tests
     :tickets: 5635

     Fixed incompatibilities in the test suite when running against Pytest 6.x.


.. changelog::

1.3.19

:released: August 17, 2020

 .. change::
     :tags: usecase, py3k
     :tickets: 5357

     Added a ``**kw`` argument to the :meth:`.DeclarativeMeta.__init__` method.
     This allows a class to support the :pep:`487` metaclass hook
     ``__init_subclass__``.  Pull request courtesy Ewen Gillies.


 .. change::
     :tags: bug, sql
     :tickets: 5470

     Repaired an issue where the "ORDER BY" clause rendering a label name rather
     than a complete expression, which is particularly important for SQL Server,
     would fail to occur if the expression were enclosed in a parenthesized
     grouping in some cases.   This case has been added to test support. The
     change additionally adjusts the "automatically add ORDER BY columns when
     DISTINCT is present" behavior of ORM query, deprecated in 1.4, to more
     accurately detect column expressions that are already present.

 .. change::
     :tags: usecase, mysql
     :tickets: 5481

     The MySQL dialect will render FROM DUAL for a SELECT statement that has no
     FROM clause but has a WHERE clause. This allows things like "SELECT 1 WHERE
     EXISTS (subquery)" kinds of queries to be used as well as other use cases.


 .. change::
     :tags: bug, mssql, sql
     :tickets: 5467

     Fixed bug where the mssql dialect incorrectly escaped object names that
     contained ']' character(s).

 .. change::
     :tags: bug, reflection, sqlite, mssql
     :tickets: 5456

     Applied a sweep through all included dialects to ensure names that contain
     single or double quotes are properly escaped when querying system tables,
     for all :class:`.Inspector` methods that accept object names as an argument
     (e.g. table names, view names, etc).   SQLite and MSSQL contained two
     quoting issues that were repaired.

 .. change::
     :tags: bug, mysql
     :tickets: 5411

     Fixed an issue where CREATE TABLE statements were not specifying the
     COLLATE keyword correctly.

 .. change::
     :tags: bug, datatypes, sql
     :tickets: 4733

     The ``LookupError`` message will now provide the user with up to four
     possible values that a column is constrained to via the :class:`.Enum`.
     Values longer than 11 characters will be truncated and replaced with
     ellipses. Pull request courtesy Ramon Williams.

 .. change::
     :tags: bug, postgresql
     :tickets: 5476

     Fixed issue where the return type for the various RANGE comparison
     operators would itself be the same RANGE type rather than BOOLEAN, which
     would cause an undesirable result in the case that a
     :class:`.TypeDecorator` that defined result-processing behavior were in
     use.  Pull request courtesy Jim Bosch.



 .. change::
     :tags: bug, mysql
     :tickets: 5493

     Added MariaDB code 1927 to the list of "disconnect" codes, as recent
     MariaDB versions apparently use this code when the database server was
     stopped.

 .. change::
     :tags: usecase, declarative, orm
     :tickets: 5513

     The name of the virtual column used when using the
     :class:`_declarative.AbstractConcreteBase` and
     :class:`_declarative.ConcreteBase` classes can now be customized, to allow
     for models that have a column that is actually named ``type``.  Pull
     request courtesy Jesse-Bakker.

 .. change::
     :tags: usecase, orm
     :tickets: 5494

     Adjusted the workings of the :meth:`_orm.Mapper.all_orm_descriptors`
     accessor to represent the attributes in the order that they are located in
     a deterministic way, assuming the use of Python 3.6 or higher which
     maintains the sorting order of class attributes based on how they were
     declared.   This sorting is not guaranteed to match the declared order of
     attributes in all cases however; see the method documentation for the exact
     scheme.



 .. change::
     :tags: bug, sql
     :tickets: 5500

     Fixed issue where the
     :paramref:`_engine.Connection.execution_options.schema_translate_map`
     feature would not take effect when the :meth:`_schema.Sequence.next_value`
     function function for a :class:`_schema.Sequence` were used in the
     :paramref:`_schema.Column.server_default` parameter and the create table
     DDL were emitted.

.. changelog::

1.3.18

:released: June 25, 2020

 .. change::
     :tags: bug, sqlite
     :tickets: 5395

     Added "exists" to the list of reserved words for SQLite so that this word
     will be quoted when used as a label or column name. Pull request courtesy
     Thodoris Sotiropoulos.

 .. change::
     :tags: bug, mssql
     :tickets: 5366, 5364

     Refined the logic used by the SQL Server dialect to interpret multi-part
     schema names that contain many dots, to not actually lose any dots if the
     name does not have bracking or quoting used, and additionally to support a
     "dbname" token that has many parts including that it may have multiple,
     independently-bracketed sections.



 .. change::
     :tags: bug, mssql, pyodbc
     :tickets: 5346

     Fixed an issue in the pyodbc connector such that a warning about pyodbc
     "drivername" would be emitted when using a totally empty URL.  Empty URLs
     are normal when producing a non-connected dialect object or when using the
     "creator" argument to create_engine(). The warning now only emits if the
     driver name is missing but other parameters are still present.

 .. change::
     :tags: bug, mssql
     :tickets: 5373

     Fixed issue with assembling the ODBC connection string for the pyodbc
     DBAPI. Tokens containing semicolons and/or braces "{}" were not being
     correctly escaped, causing the ODBC driver to misinterpret the
     connection string attributes.

 .. change::
     :tags: usecase, orm
     :tickets: 5326

     Improve error message when using :meth:`_query.Query.filter_by` in
     a query where the first entity is not a mapped class.

 .. change::
     :tags: sql, schema
     :tickets: 5324

     Introduce :class:`.IdentityOptions` to store common parameters for
     sequences and identity columns.

 .. change::
     :tags: usecase, sql
     :tickets: 5309

     Added a ".schema" parameter to the :func:`_expression.table` construct,
     allowing ad-hoc table expressions to also include a schema name.
     Pull request courtesy Dylan Modesitt.

 .. change::
     :tags: bug, mssql
     :tickets: 5339

     Fixed issue where ``datetime.time`` parameters were being converted to
     ``datetime.datetime``, making them incompatible with comparisons like
     ``>=`` against an actual :class:`_mssql.TIME` column.

 .. change::
     :tags: bug, mssql
     :tickets: 5359

     Fixed an issue where the ``is_disconnect`` function in the SQL Server
     pyodbc dialect was incorrectly reporting the disconnect state when the
     exception messsage had a substring that matched a SQL Server ODBC error
     code.

 .. change::
     :tags: bug, engine
     :tickets: 5326

     Further refinements to the fixes to the "reset" agent fixed in
     :ticket:`5326`, which now emits a warning when it is not being correctly
     invoked and corrects for the behavior.  Additional scenarios have been
     identified and fixed where this warning was being emitted.


 .. change::
     :tags: usecase, sqlite
     :tickets: 5297

     SQLite 3.31 added support for computed column. This change
     enables their support in SQLAlchemy when targeting SQLite.

 .. change::
     :tags: bug, schema
     :tickets: 5276

     Fixed issue where ``dialect_options`` were omitted when a
     database object (e.g., :class:`.Table`) was copied using
     :func:`.tometadata`.

 .. change::
     :tags: bug, sql
     :tickets: 5344

     Correctly apply self_group in type_coerce element.

     The type coerce element did not correctly apply grouping rules when using
     in an expression

 .. change::
     :tags: bug, oracle, reflection
     :tickets: 5421

     Fixed bug in Oracle dialect where indexes that contain the full set of
     primary key columns would be mistaken as the primary key index itself,
     which is omitted, even if there were multiples.  The check has been refined
     to compare the name of the primary key constraint against the index name
     itself, rather than trying to guess based on the columns present in the
     index.

 .. change::
     :tags: change, sql, sybase
     :tickets: 5294

     Added ``.offset`` support to sybase dialect.
     Pull request courtesy Alan D. Snow.

 .. change::
     :tags: bug, engine
     :tickets: 5341

     Fixed issue in :class:`.URL` object where stringifying the object
     would not URL encode special characters, preventing the URL from being
     re-consumable as a real URL.  Pull request courtesy Miguel Grinberg.

 .. change::
     :tags: usecase, mysql
     :tickets: 4860

     Implemented row-level locking support for mysql.  Pull request courtesy
     Quentin Somerville.

 .. change::
     :tags: change, mssql
     :tickets: 5321

     Moved the ``supports_sane_rowcount_returning = False`` requirement from
     the ``PyODBCConnector`` level to the ``MSDialect_pyodbc`` since pyodbc
     does work properly in some circumstances.

 .. change::
     :tags: change, examples

     Added new option ``--raw`` to the examples.performance suite
     which will dump the raw profile test for consumption by any
     number of profiling visualizer tools.   Removed the "runsnake"
     option as runsnake is very hard to build at this point;

 .. change::
     :tags: bug, sql
     :tickets: 5353

     Added :meth:`.Select.with_hint` output to the generic SQL string that is
     produced when calling ``str()`` on a statement.  Previously, this clause
     would be omitted under the assumption that it was dialect specific.
     The hint text is presented within brackets to indicate the rendering
     of such hints varies among backends.


 .. change::
     :tags: usecase, orm
     :tickets: 5198

     Added a new parameter :paramref:`_orm.query_expression.default_expr` to the
     :func:`_orm.query_expression` construct, which will be appled to queries
     automatically if the :func:`_orm.with_expression` option is not used. Pull
     request courtesy Haoyu Sun.

.. changelog::

1.3.17

:released: May 13, 2020

 .. change::
     :tags: bug, oracle
     :tickets: 5246

     Some modifications to how the cx_oracle dialect sets up per-column
     outputtype handlers for LOB and numeric datatypes to adjust for potential
     changes coming in cx_Oracle 8.


 .. change::
     :tags: bug, orm
     :tickets: 5288

     Fixed bug where using :func:`.with_polymorphic` as the target of a join via
     :meth:`.RelationshipComparator.of_type` on a mapper that already has a
     subquery-based with_polymorphic setting that's equivalent to the one
     requested would not correctly alias the ON clause in the join.

 .. change::
     :tags: bug, oracle, performance
     :tickets: 5314

     Changed the implementation of fetching CLOB and BLOB objects to use
     cx_Oracle's native implementation which fetches CLOB/BLOB objects inline
     with other result columns, rather than performing a separate fetch. As
     always, this can be disabled by setting auto_convert_lobs to False.

     As part of this change, the behavior of a CLOB that was given a blank
     string on INSERT now returns None on SELECT, which is now consistent with
     that of VARCHAR on Oracle.


 .. change::
     :tags: usecase, postgresql
     :tickets: 5265

     Added support for columns or type :class:`.ARRAY` of :class:`.Enum`,
     :class:`.JSON` or :class:`_postgresql.JSONB` in PostgreSQL.
     Previously a workaround was required in these use cases.


 .. change::
     :tags: schema
     :tickets: 4138

     Add ``comment`` attribute to :class:`_schema.Column` ``__repr__`` method.

 .. change::
     :tags: bug, orm
     :tickets: 5303

     Fixed issue in the area of where loader options such as selectinload()
     interact with the baked query system, such that the caching of a query is
     not supposed to occur if the loader options themselves have elements such
     as with_polymorphic() objects in them that currently are not
     cache-compatible.  The baked loader could sometimes not fully invalidate
     itself in these some of these scenarios leading to missed eager loads.


 .. change::
     :tags: bug, engine
     :tickets: 5326

     Fixed fairly critical issue where the DBAPI connection could be returned to
     the connection pool while still in an un-rolled-back state. The reset agent
     responsible for rolling back the connection could be corrupted in the case
     that the transaction was "closed" without being rolled back or committed,
     which can occur in some scenarios when using ORM sessions and emitting
     .close() in a certain pattern involving savepoints.   The fix ensures that
     the reset agent is always active.


 .. change::
     :tags: bug, orm
     :tickets: 5304

     Modified the internal "identity set" implementation, which is a set that
     hashes objects on their id() rather than their hash values, to not actually
     call the ``__hash__()`` method of the objects, which are typically
     user-mapped objects.  Some methods were calling this method as a side
     effect of the implementation.


 .. change::
     :tags: usecase, postgresql
     :tickets: 5266

     Raise an explicit :class:`.exc.CompileError` when adding a table with a
     column of type :class:`.ARRAY` of :class:`.Enum` configured with
     :paramref:`.Enum.native_enum` set to ``False`` when
     :paramref:`.Enum.create_constraint` is not set to ``False``

 .. change::
     :tags: bug, schema
     :tickets: 5298

     Fixed issue where an :class:`.Index` that is deferred in being associated
     with a table, such as as when it contains a :class:`.Column` that is not
     associated with any :class:`.Table` yet,  would fail to attach correctly if
     it also contained a non table-oriented expression.


 .. change::
     :tags: change, firebird
     :tickets: 5278

     Adjusted dialect loading for ``firebird://`` URIs so the external
     sqlalchemy-firebird dialect will be used if it has been installed,
     otherwise fall back to the (now deprecated) internal Firebird dialect.

 .. change::
     :tags: bug, mssql, reflection
     :tickets: 5255

     Fix a regression introduced by the reflection of computed column in
     MSSQL when using the legacy TDS version 4.2. The dialect will try
     to detect the protocol version of first connect and run in compatibility
     mode if it cannot detect it.

 .. change::
     :tags: bug, mssql, reflection
     :tickets: 5271

     Fix a regression introduced by the reflection of computed column in
     MSSQL when using SQL server versions before 2012, which does not support
     the ``concat`` function.

 .. change::
     :tags: bug, orm
     :tickets: 5269

     An informative error message is raised when an ORM many-to-one comparison
     is attempted against an object that is not an actual mapped instance.
     Comparisons such as those to scalar subqueries aren't supported;
     generalized comparison with subqueries is better achieved using
     :meth:`~.RelationshipProperty.Comparator.has`.


 .. change::
     :tags: usecase, orm
     :tickets: 5262

     Added an accessor :attr:`.ColumnProperty.Comparator.expressions` which
     provides access to the group of columns mapped under a multi-column
     :class:`.ColumnProperty` attribute.


 .. change::
     :tags: bug, schema
     :tickets: 5316

     A warning is emitted when making use of the :attr:`.MetaData.sorted_tables`
     attribute as well as the :func:`_schema.sort_tables` function, and the
     given tables cannot be correctly sorted due to a cyclic dependency between
     foreign key constraints. In this case, the functions will no longer sort
     the involved tables by foreign key, and a warning will be emitted. Other
     tables that are not part of the cycle will still be returned in dependency
     order. Previously, the sorted_table routines would return a collection that
     would unconditionally omit all foreign keys when a cycle was detected, and
     no warning was emitted.


 .. change::
     :tags: orm, usecase
     :tickets: 5237

     Introduce :paramref:`_orm.relationship.sync_backref` flag in a relationship
     to control if the synchronization events that mutate the in-Python
     attributes are added. This supersedes the previous change :ticket:`5149`,
     which warned that ``viewonly=True`` relationship target of a
     back_populates or backref configuration would be disallowed.

.. changelog::

1.3.16

:released: April 7, 2020

 .. change::
     :tags: oracle, usecase
     :tickets: 5200

     Implemented AUTOCOMMIT isolation level for Oracle when using cx_Oracle.
     Also added a fixed default isolation level of READ COMMITTED for Oracle.


 .. change::
     :tags: bug, mysql
     :tickets: 5239

     Fixed issue in MySQL dialect when connecting to a pseudo-MySQL database
     such as that provided by ProxySQL, the up front check for isolation level
     when it returns no row will not prevent the dialect from continuing to
     connect. A warning is emitted that the isolation level could not be
     detected.


 .. change::
     :tags: bug, tests
     :tickets: 5201

     Fixed an issue that prevented the test suite from running with the
     recently released py.test 5.4.0.


 .. change::
     :tags: bug, oracle, reflection
     :tickets: 5146

     Fixed regression / incorrect fix caused by fix for :ticket:`5146` where the
     Oracle dialect reads from the "all_tab_comments" view to get table comments
     but fails to accommodate for the current owner of the table being
     requested, causing it to read the wrong comment if multiple tables of the
     same name exist in multiple schemas.


 .. change::
     :tags: types, enum
     :tickets: 5183

     The :class:`.Enum` type now supports the parameter :paramref:`.Enum.length`
     to specify the length of the VARCHAR column to create when using
     non native enums by setting :paramref:`.Enum.native_enum` to ``False``

 .. change::
     :tags: bug, orm
     :tickets: 5228

     Fixed bug in :func:`_orm.selectinload` loading option where two or more
     loaders that represent different relationships with the same string key
     name as referenced from a single :func:`_orm.with_polymorphic` construct
     with multiple subclass mappers would fail to invoke each subqueryload
     separately, instead making use of a single string-based slot that would
     prevent the other loaders from being invoked.


 .. change::
     :tags: schema, reflection
     :tickets: 5063

     Added support for reflection of "computed" columns, which are now returned
     as part of the structure returned by :meth:`_reflection.Inspector.get_columns`.
     When reflecting full :class:`_schema.Table` objects, computed columns will
     be represented using the :class:`.Computed` construct.

 .. change::
     :tags: orm, performance
     :tickets: 5162

     Modified the queries used by subqueryload and selectinload to no longer
     ORDER BY the primary key of the parent entity;  this ordering was there to
     allow the rows as they come in to be copied into lists directly with a
     minimal level of Python-side collation.   However, these ORDER BY clauses
     can negatively impact the performance of the query as in many scenarios
     these columns are derived from a subquery or are otherwise not actual
     primary key columns such that SQL planners cannot make use of indexes. The
     Python-side collation uses the native itertools.group_by() to collate the
     incoming rows, and has been modified to allow multiple
     row-groups-per-parent to be assembled together using list.extend(), which
     should still allow for relatively fast Python-side performance.  There will
     still be an ORDER BY present for a relationship that includes an explicit
     order_by parameter, however this is the only ORDER BY that will be added to
     the query for both kinds of loading.

 .. change::
     :tags: mssql, mysql, oracle, usecase
     :tickets: 5137

     Added support for :meth:`.ColumnOperators.is_distinct_from` and
     :meth:`.ColumnOperators.isnot_distinct_from` to SQL Server,
     MySQL, and Oracle.

 .. change::
     :tags: sqlite, usecase
     :tickets: 5164

     Implemented AUTOCOMMIT isolation level for SQLite when using pysqlite.

 .. change::
     :tags: bug, postgresql
     :tickets: 5205

     Fixed issue where a "covering" index, e.g. those which have an  INCLUDE
     clause, would be reflected including all the columns in INCLUDE clause as
     regular columns.  A warning is now emitted if these additional columns are
     detected indicating that they are currently ignored.  Note that full
     support for "covering" indexes is part of :ticket:`4458`.  Pull request
     courtesy Marat Sharafutdinov.

 .. change::
     :tags: sql, types
     :tickets: 5052

     Add ability to literal compile a :class:`DateTime`, :class:`Date`
     or :class:`Time` when using the string dialect for debugging purposes.
     This change does not impact real dialect implementation that retain
     their current behavior.

 .. change::
     :tags: installer
     :tickets: 5207

     Ensured that the "pyproject.toml" file is not included in builds, as the
     presence of this file indicates to pip that a pep-517 installation process
     should be used.  As this mode of operation appears to be not well supported
     by current tools / distros, these problems are avoided within the scope
     of SQLAlchemy installation by omitting the file.


 .. change::
     :tags: bug, orm
     :tickets: 5210

     Fixed issue where a lazyload that uses session-local "get" against a target
     many-to-one relationship where an object with the correct primary key is
     present, however it's an instance of a sibling class, does not correctly
     return None as is the case when the lazy loader actually emits a load for
     that row.

 .. change::
     :tags: bug, orm, declarative
     :tickets: 5238

     The string argument accepted as the first positional argument by the
     :func:`_orm.relationship` function when using the Declarative API is no longer
     interpreted using the Python ``eval()`` function; instead, the name is dot
     separated and the names are looked up directly in the name resolution
     dictionary without treating the value as a Python expression.  However,
     passing a string argument to the other :func:`_orm.relationship` parameters
     that necessarily must accept Python expressions will still use ``eval()``;
     the documentation has been clarified to ensure that there is no ambiguity
     that this is in use.

     .. seealso::

         :ref:`declarative_relationship_eval` - details on string evaluation

.. changelog::

1.3.15

:released: March 11, 2020

 .. change::
     :tags: bug, orm
     :tickets: 5194

     Adjusted the error message emitted by :meth:`_query.Query.join` when a left hand
     side can't be located that the :meth:`_query.Query.select_from` method is the
     best way to resolve the issue.  Also, within the 1.3 series, used a
     deterministic ordering when determining the FROM clause from a given column
     entity passed to :class:`_query.Query` so that the same expression is determined
     each time.


 .. change::
     :tags: orm, bug
     :tickets: 5196

     Fixed regression in 1.3.14 due to :ticket:`4849` where a sys.exc_info()
     call failed to be invoked correctly when a flush error would occur. Test
     coverage has been added for this exception case.


.. changelog::

1.3.14

:released: March 10, 2020

 .. change::
     :tags: bug, sql, postgresql
     :tickets: 5181

     Fixed bug where a CTE of an INSERT/UPDATE/DELETE that also uses RETURNING
     could then not be SELECTed from directly, as the internal state of the
     compiler would try to treat the outer SELECT as a DELETE statement itself
     and access nonexistent state.


 .. change::
     :tags: bug, orm
     :tickets: 5110

     Fixed regression caused in 1.3.13 by :ticket:`5056` where a refactor of the
     ORM path registry system made it such that a path could no longer be
     compared to an empty tuple, which can occur in a particular kind of joined
     eager loading path.   The "empty tuple" use case has been resolved so that
     the path registry is compared to a path registry in all cases;  the
     :class:`.PathRegistry` object itself now implements ``__eq__()`` and
     ``__ne__()`` methods which will take place for all equality comparisons and
     continue to succeed in the not anticipated case that a non-
     :class:`.PathRegistry` object is compared, while emitting a warning that
     this object should not be the subject of the comparison.



 .. change::
     :tags: bug, orm
     :tickets: 5149

     Setting a relationship to viewonly=True which is also the target of a
     back_populates or backref configuration will now emit a warning and
     eventually be disallowed. back_populates refers specifically to mutation
     of an attribute or collection, which is disallowed when the attribute is
     subject to viewonly=True.   The viewonly attribute is not subject to
     persistence behaviors which means it will not reflect correct results
     when it is locally mutated.

 .. change::
     :tags: bug, oracle
     :tickets: 5146

     Fixed a reflection bug where table comments could only be retrieved for
     tables actually owned by the user but not for tables visible to the user
     but owned by someone else.  Pull request courtesy Dave Hirschfeld.

 .. change::
     :tags: bug, performance
     :tickets: 5180

     Revised an internal change to the test system added as a result of
     :ticket:`5085` where a testing-related module per dialect would be loaded
     unconditionally upon making use of that dialect, pulling in SQLAlchemy's
     testing framework as well as the ORM into the module import space.   This
     would only impact initial startup time and memory to a modest extent,
     however it's best that these additional modules aren't reverse-dependent on
     straight Core usage.

 .. change::
     :tags: bug, installation
     :tickets: 5138

     Vendored the ``inspect.formatannotation`` function inside of
     ``sqlalchemy.util.compat``, which is needed for the vendored version of
     ``inspect.formatargspec``.  The function is not documented in cPython and
     is not guaranteed to be available in future Python versions.


 .. change::
     :tags: bug, mssql
     :tickets: 5132

     Fixed issue where the :class:`_mssql.DATETIMEOFFSET` type would not
     accommodate for the ``None`` value, introduced as part of the series of
     fixes for this type first introduced in :ticket:`4983`, :ticket:`5045`.
     Additionally, added support for passing a backend-specific date formatted
     string through this type, as is typically allowed for date/time types on
     most other DBAPIs.

 .. change::
     :tags: bug, engine
     :tickets: 5182

     Expanded the scope of cursor/connection cleanup when a statement is
     executed to include when the result object fails to be constructed, or an
     after_cursor_execute() event raises an error, or autocommit / autoclose
     fails.  This allows the DBAPI cursor to be cleaned up on failure and for
     connectionless execution allows the connection to be closed out and
     returned to the connection pool, where previously it waiting until garbage
     collection would trigger a pool return.

 .. change::
     :tags: bug, postgresql
     :tickets: 5158

     Fixed issue where the "schema_translate_map" feature would not work with a
     PostgreSQL native enumeration type (i.e. :class:`.Enum`,
     :class:`_postgresql.ENUM`) in that while the "CREATE TYPE" statement would
     be emitted with the correct schema, the schema would not be rendered in
     the CREATE TABLE statement at the point at which the enumeration was
     referenced.


 .. change::
     :tags: usecase, ext
     :tickets: 5114

     Added keyword arguments to the :meth:`.MutableList.sort` function so that a
     key function as well as the "reverse" keyword argument can be provided.


 .. change::
     :tags: bug, general, py3k
     :tickets: 4849

     Applied an explicit "cause" to most if not all internally raised exceptions
     that are raised from within an internal exception catch, to avoid
     misleading stacktraces that suggest an error within the handling of an
     exception.  While it would be preferable to suppress the internally caught
     exception in the way that the ``__suppress_context__`` attribute would,
     there does not as yet seem to be a way to do this without suppressing an
     enclosing user constructed context, so for now it exposes the internally
     caught exception as the cause so that full information about the context
     of the error is maintained.

 .. change::
     :tags: orm, bug
     :tickets: 5121

     Fixed an additional regression in the same area as that of :ticket:`5080`
     introduced in 1.3.0b3 via :ticket:`4468` where the ability to create a
     joined option across a :func:`.with_polymorphic` into a relationship
     against the base class of that with_polymorphic, and then further into
     regular mapped relationships would fail as the base class component would
     not add itself to the load path in a way that could be located by the
     loader strategy. The changes applied in :ticket:`5080` have been further
     refined to also accommodate this scenario.

 .. change::
     :tags: bug, postgresql, reflection
     :tickets: 5170

     Fixed bug where PostgreSQL reflection of CHECK constraints would fail to
     parse the constraint if the SQL text contained newline characters. The
     regular expression has been adjusted to accommodate for this case. Pull
     request courtesy Eric Borczuk.

 .. change::
     :tags: usecase, orm
     :tickets: 5129

     Added a new flag :paramref:`.InstanceEvents.restore_load_context` and
     :paramref:`.SessionEvents.restore_load_context` which apply to the
     :meth:`.InstanceEvents.load`, :meth:`.InstanceEvents.refresh`, and
     :meth:`.SessionEvents.loaded_as_persistent` events, which when set will
     restore the "load context" of the object after the event hook has been
     called.  This ensures that the object remains within the "loader context"
     of the load operation that is already ongoing, rather than the object being
     transferred to a new load context due to refresh operations which may have
     occurred in the event. A warning is now emitted when this condition occurs,
     which recommends use of the flag to resolve this case.  The flag is
     "opt-in" so that there is no risk introduced to existing applications.

     The change additionally adds support for the ``raw=True`` flag to
     session lifecycle events.

 .. change::
     :tags: bug, mysql
     :tickets: 5173

     Fixed issue in MySQL :meth:`.mysql.Insert.on_duplicate_key_update` construct
     where using a SQL function or other composed expression for a column argument
     would not properly render the ``VALUES`` keyword surrounding the column
     itself.

.. changelog::

1.3.13

:released: January 22, 2020

 .. change::
     :tags: bug, postgresql
     :tickets: 5039

     Fixed issue where the PostgreSQL dialect would fail to parse a reflected
     CHECK constraint that was a boolean-valued function (as opposed to a
     boolean-valued expression).

 .. change::
     :tags: bug, ext
     :tickets: 5086

     Fixed bug in sqlalchemy.ext.serializer where a unique
     :class:`.BindParameter` object could conflict with itself if it were
     present in the mapping itself, as well as the filter condition of the
     query, as one side would be used against the non-deserialized version and
     the other side would use the deserialized version.  Logic is added to
     :class:`.BindParameter` similar to its "clone" method which will uniquify
     the parameter name upon deserialize so that it doesn't conflict with its
     original.


 .. change::
     :tags: usecase, sql
     :tickets: 5079

     A function created using :class:`.GenericFunction` can now specify that the
     name of the function should be rendered with or without quotes by assigning
     the :class:`.quoted_name` construct to the .name element of the object.
     Prior to 1.3.4, quoting was never applied to function names, and some
     quoting was introduced in :ticket:`4467` but no means to force quoting for
     a mixed case name was available.  Additionally, the :class:`.quoted_name`
     construct when used as the name will properly register its lowercase name
     in the function registry so that the name continues to be available via the
     ``func.`` registry.

     .. seealso::

         :class:`.GenericFunction`


 .. change::
     :tags: bug, engine
     :tickets: 5048

     Fixed issue where the collection of value processors on a
     :class:`.Compiled` object would be mutated when "expanding IN" parameters
     were used with a datatype that has bind value processors; in particular,
     this would mean that when using statement caching and/or baked queries, the
     same compiled._bind_processors collection would be mutated concurrently.
     Since these processors are the same function for a given bind parameter
     namespace every time, there was no actual negative effect of this issue,
     however, the execution of a :class:`.Compiled` object should never be
     causing any changes in its state, especially given that they are intended
     to be thread-safe and reusable once fully constructed.


 .. change::
     :tags: tests, postgresql
     :tickets: 5057

     Improved detection of two phase transactions requirement for the PostgreSQL
     database by testing that max_prepared_transactions is set to a value
     greater than 0.  Pull request courtesy Federico Caselli.


 .. change::
     :tags: bug, orm, engine
     :tickets: 5056, 5050, 5071

     Added test support and repaired a wide variety of unnecessary reference
     cycles created for short-lived objects, mostly in the area of ORM queries.
     Thanks much to Carson Ip for the help on this.


 .. change::
     :tags: orm, bug
     :tickets: 5107

     Fixed regression in loader options introduced in 1.3.0b3 via :ticket:`4468`
     where the ability to create a loader option using
     :meth:`.PropComparator.of_type` targeting an aliased entity that is an
     inheriting subclass of the entity which the preceding relationship refers
     to would fail to produce a matching path.   See also :ticket:`5082` fixed
     in this same release which involves a similar kind of issue.

 .. change::
     :tags: bug, tests
     :tickets: 4946

     Fixed a few test failures which would occur on Windows due to SQLite file
     locking issues, as well as some timing issues in connection pool related
     tests; pull request courtesy Federico Caselli.


 .. change::
     :tags: orm, bug
     :tickets: 5082

     Fixed regression in joined eager loading introduced in 1.3.0b3 via
     :ticket:`4468` where the ability to create a joined option across a
     :func:`.with_polymorphic` into a polymorphic subclass using
     :meth:`.RelationshipProperty.of_type` and then further along regular mapped
     relationships would fail as the polymorphic subclass would not add itself
     to the load path in a way that could be located by the loader strategy.  A
     tweak has been made to resolve this scenario.


 .. change::
     :tags: performance, orm

     Identified a performance issue in the system by which a join is constructed
     based on a mapped relationship.   The clause adaption system would be used
     for the majority of join expressions including in the common case where no
     adaptation is needed.   The conditions under which this adaptation occur
     have been refined so that average non-aliased joins along a simple
     relationship without a "secondary" table use about 70% less function calls.


 .. change::
     :tags: usecase, postgresql
     :tickets: 5040

     Added support for prefixes to the :class:`_expression.CTE` construct, to allow
     support for Postgresql 12 "MATERIALIZED" and "NOT MATERIALIZED" phrases.
     Pull request courtesy Marat Sharafutdinov.

     .. seealso::

         :meth:`_expression.HasCTE.cte`

 .. change::
     :tags: bug, mssql
     :tickets: 5045

     Fixed issue where a timezone-aware ``datetime`` value being converted to
     string for use as a parameter value of a :class:`_mssql.DATETIMEOFFSET`
     column was omitting the fractional seconds.

 .. change::
     :tags: bug, orm
     :tickets: 5068

     Repaired a warning in the ORM flush process that was not covered by  test
     coverage when deleting objects that use the "version_id" feature. This
     warning is generally unreachable unless using a dialect that sets the
     "supports_sane_rowcount" flag to False, which  is not typically the case
     however is possible for some MySQL configurations as well as older Firebird
     drivers, and likely some third party dialects.

 .. change::
     :tags: bug, orm
     :tickets: 5065

     Fixed bug where usage of joined eager loading would not properly wrap the
     query inside of a subquery when :meth:`_query.Query.group_by` were used against
     the query.   When any kind of result-limiting approach is used, such as
     DISTINCT, LIMIT, OFFSET, joined eager loading embeds the row-limited query
     inside of a subquery so that the collection results are not impacted.   For
     some reason, the presence of GROUP BY was never included in this criterion,
     even though it has a similar effect as using DISTINCT.   Additionally, the
     bug would prevent using GROUP BY at all for a joined eager load query for
     most database platforms which forbid non-aggregated, non-grouped columns
     from being in the query, as the additional columns for the joined eager
     load would not be accepted by the database.



.. changelog::

1.3.12

:released: December 16, 2019

 .. change::
     :tags: bug, sql
     :tickets: 5028

     Fixed bug where "distinct" keyword passed to :func:`_expression.select` would not
     treat a string value as a "label reference" in the same way that the
     :meth:`_expression.select.distinct` does; it would instead raise unconditionally. This
     keyword argument and the others passed to :func:`_expression.select` will ultimately
     be deprecated for SQLAlchemy 2.0.


 .. change::
     :tags: bug, orm
     :tickets: 4997

     Fixed issue involving ``lazy="raise"`` strategy where an ORM delete of an
     object would raise for a simple "use-get" style many-to-one relationship
     that had lazy="raise" configured.  This is inconsistent vs. the change
     introduced in 1.3 as part of :ticket:`4353`, where it was established that
     a history operation that does not expect emit SQL should bypass the
     ``lazy="raise"`` check, and instead effectively treat it as
     ``lazy="raise_on_sql"`` for this case.  The fix adjusts the lazy loader
     strategy to not raise for the case where the lazy load was instructed that
     it should not emit SQL if the object were not present.

 .. change::
     :tags: bug, sql

     Changed the text of the exception for "Can't resolve label reference" to
     include other kinds of label coercions, namely that "DISTINCT" is also in
     this category under the PostgreSQL dialect.


 .. change::
     :tags: bug, orm
     :tickets: 5000

     Fixed regression introduced in 1.3.0 related to the association proxy
     refactor in :ticket:`4351` that prevented :func:`.composite` attributes
     from working in terms of an association proxy that references them.

 .. change::
     :tags: bug, mssql
     :tickets: 4983

     Repaired support for the :class:`_mssql.DATETIMEOFFSET` datatype on PyODBC,
     by adding PyODBC-level result handlers as it does not include native
     support for this datatype.  This includes usage of the Python 3 "timezone"
     tzinfo subclass in order to set up a timezone, which on Python 2 makes
     use of a minimal backport of "timezone" in sqlalchemy.util.


 .. change::
     :tags: bug, orm
     :tickets: 4993

     Setting persistence-related flags on :func:`_orm.relationship` while also
     setting viewonly=True will now emit a regular warning, as these flags do
     not make sense for a viewonly=True relationship.   In particular, the
     "cascade" settings have their own warning that is generated based on the
     individual values, such as "delete, delete-orphan", that should not apply
     to a viewonly relationship.   Note however that in the case of "cascade",
     these settings are still erroneously taking effect even though the
     relationship is set up as "viewonly".   In 1.4, all persistence-related
     cascade settings will be disallowed on a viewonly=True relationship in
     order to resolve this issue.

 .. change::
     :tags: bug, sqlite
     :tickets: 5014

     Fixed issue to workaround SQLite's behavior of assigning "numeric" affinity
     to JSON datatypes, first described at :ref:`change_3850`, which returns
     scalar numeric JSON values as a number and not as a string that can be JSON
     deserialized.  The SQLite-specific JSON deserializer now gracefully
     degrades for this case as an exception and bypasses deserialization for
     single numeric values, as from a JSON perspective they are already
     deserialized.



 .. change::
     :tags: bug, orm, py3k
     :tickets: 4990

     Fixed issue where when assigning a collection to itself as a slice, the
     mutation operation would fail as it would first erase the assigned
     collection inadvertently.   As an assignment that does not change  the
     contents should not generate events, the operation is now a no-op. Note
     that the fix only applies to Python 3; in Python 2, the ``__setitem__``
     hook isn't called in this case; ``__setslice__`` is used instead which
     recreates the list item-by-item in all cases.

 .. change::
     :tags: bug, orm
     :tickets: 5034

     Fixed issue where by if the "begin" of a transaction failed at the Core
     engine/connection level, such as due to network error or database is locked
     for some transactional recipes, within the context of the :class:`.Session`
     procuring that connection from the connection pool and then immediately
     returning it, the ORM :class:`.Session` would not close the connection
     despite this connection not being stored within the state of that
     :class:`.Session`.  This would lead to the connection being cleaned out by
     the connection pool weakref handler within garbage collection which is an
     unpreferred codepath that in some special configurations can emit errors in
     standard error.

.. changelog::

1.3.11

:released: November 11, 2019

 .. change::
     :tags: bug, mssql
     :tickets: 4973

     Fixed issue in MSSQL dialect where an expression-based OFFSET value in a
     SELECT would be rejected, even though the dialect can render this
     expression inside of a ROW NUMBER-oriented LIMIT/OFFSET construct.


 .. change::
     :tags: orm, usecase
     :tickets: 4934

     Added accessor :meth:`_query.Query.is_single_entity` to :class:`_query.Query`, which
     will indicate if the results returned by this :class:`_query.Query` will be a
     list of ORM entities, or a tuple of entities or column expressions.
     SQLAlchemy hopes to improve upon the behavior of single entity / tuples in
     future releases such that the behavior would be explicit up front, however
     this attribute should be helpful with the current behavior.  Pull request
     courtesy Patrick Hayes.

 .. change::
     :tags: bug, mysql
     :tickets: 4945

     Added "Connection was killed" message interpreted from the base
     pymysql.Error class in order to detect closed connection, based on reports
     that this message is arriving via a pymysql.InternalError() object which
     indicates pymysql is not handling it correctly.

 .. change::
     :tags: bug, orm
     :tickets: 4954

     The :paramref:`_orm.relationship.omit_join` flag was not intended to be
     manually set to True, and will now emit a warning when this occurs.  The
     omit_join optimization is detected automatically, and the ``omit_join``
     flag was only intended to disable the optimization in the hypothetical case
     that the optimization may have interfered with correct results, which has
     not been observed with the modern version of this feature.   Setting the
     flag to True when it is not automatically detected may cause the selectin
     load feature to not work correctly when a non-default primary join
     condition is in use.


 .. change::
     :tags: bug, orm
     :tickets: 4915

     A warning is emitted if a primary key value is passed to :meth:`_query.Query.get`
     that consists of None for all primary key column positions.   Previously,
     passing a single None outside of a tuple would raise a ``TypeError`` and
     passing a composite None (tuple of None values) wo

[codecov]

Codecov Report

❗ No coverage uploaded for pull request base (master@97e3944). Click here to learn what that means.
The diff coverage is n/a.

@@            Coverage Diff            @@
##             master      #95   +/-   ##
=========================================
  Coverage          ?   43.66%           
=========================================
  Files             ?        7           
  Lines             ?      687           
  Branches          ?      139           
=========================================
  Hits              ?      300           
  Misses            ?      378           
  Partials          ?        9           

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[coveralls]

Coverage decreased (-0.2%) to 38.997% when pulling 6d57d9c on pyup-update-sqlalchemy-1.2.12-to-1.3.23 into 97e3944 on master.

[pyup-bot]

Closing this in favor of #96