:released: July 29, 2025

.. change::

:tags: usecase, orm

:tickets: 10674

Added ``dataclass_metadata`` argument to all ORM attribute constructors

that accept dataclasses parameters, e.g. :paramref:`.mapped_column.dataclass_metadata`,

:paramref:`.relationship.dataclass_metadata`, etc.

It's passed to the underlying dataclass ``metadata`` attribute

of the dataclass field. Pull request courtesy Sigmund Lahn.

.. change::

:tags: usecase, postgresql

:tickets: 10927

Added support for PostgreSQL 14+ JSONB subscripting syntax. When connected

to PostgreSQL 14 or later, JSONB columns now automatically use the native

subscript notation ``jsonb_col['key']`` instead of the arrow operator

``jsonb_col -> 'key'`` for both read and write operations. This provides

better compatibility with PostgreSQL's native JSONB subscripting feature

while maintaining backward compatibility with older PostgreSQL versions.

JSON columns continue to use the traditional arrow syntax regardless of

PostgreSQL version.

.. change::

:tags: bug, orm

:tickets: 12593

Implemented the :func:`_orm.defer`, :func:`_orm.undefer` and

:func:`_orm.load_only` loader options to work for composite attributes, a

use case that had never been supported previously.

.. change::

:tags: bug, postgresql, reflection

:tickets: 12600

Fixed regression caused by :ticket:`10665` where the newly modified

constraint reflection query would fail on older versions of PostgreSQL

such as version 9.6. Pull request courtesy Denis Laxalde.

.. change::

:tags: bug, mysql

:tickets: 12648

Fixed yet another regression caused by by the DEFAULT rendering changes in

2.0.40 :ticket:`12425`, similar to :ticket:`12488`, this time where using a

CURRENT_TIMESTAMP function with a fractional seconds portion inside a

textual default value would also fail to be recognized as a

non-parenthesized server default.

.. change::

:tags: bug, mssql

:tickets: 12654

Reworked SQL Server column reflection to be based on the ``sys.columns``

table rather than ``information_schema.columns`` view. By correctly using

the SQL Server ``object_id()`` function as a lead and joining to related

tables on object_id rather than names, this repairs a variety of issues in

SQL Server reflection, including:

* Issue where reflected column comments would not correctly line up

with the columns themselves in the case that the table had been ALTERed

* Correctly targets tables with awkward names such as names with brackets,

when reflecting not just the basic table / columns but also extended

information including IDENTITY, computed columns, comments which

did not work previously

* Correctly targets IDENTITY, computed status from temporary tables

which did not work previously

.. change::

:tags: bug, sql

:tickets: 12681

Fixed issue where :func:`.select` of a free-standing scalar expression that

has a unary operator applied, such as negation, would not apply result

processors to the selected column even though the correct type remains in

place for the unary expression.

.. change::

:tags: bug, sql

:tickets: 12692

Hardening of the compiler's actions for UPDATE statements that access

multiple tables to report more specifically when tables or aliases are

referenced in the SET clause; on cases where the backend does not support

secondary tables in the SET clause, an explicit error is raised, and on the

MySQL or similar backends that support such a SET clause, more specific

checking for not-properly-included tables is performed. Overall the change

is preventing these erroneous forms of UPDATE statements from being

compiled, whereas previously it was relied on the database to raise an

error, which was not always guaranteed to happen, or to be non-ambiguous,

due to cases where the parent table included the same column name as the

secondary table column being updated.

.. change::

:tags: bug, orm

:tickets: 12692

Fixed bug where the ORM would pull in the wrong column into an UPDATE when

a key name inside of the :meth:`.ValuesBase.values` method could be located

from an ORM entity mentioned in the statement, but where that ORM entity

was not the actual table that the statement was inserting or updating. An

extra check for this edge case is added to avoid this problem.

.. change::

:tags: bug, postgresql

:tickets: 12728

Re-raise catched ``CancelledError`` in the terminate method of the

asyncpg dialect to avoid possible hangs of the code execution.

.. change::

:tags: usecase, sql

:tickets: 12734

The :func:`_sql.values` construct gains a new method :meth:`_sql.Values.cte`,

which allows creation of a named, explicit-columns :class:`.CTE` against an

unnamed ``VALUES`` expression, producing a syntax that allows column-oriented

selection from a ``VALUES`` construct on modern versions of PostgreSQL, SQLite,

and MariaDB.

.. change::

:tags: bug, reflection, postgresql

:tickets: 12744

Fixes bug that would mistakenly interpret a domain or enum type

with name starting in ``interval`` as an ``INTERVAL`` type while

reflecting a table.

.. change::

:tags: usecase, postgresql

:tickets: 8664

Added ``postgresql_ops`` key to the ``dialect_options`` entry in reflected

dictionary. This maps names of columns used in the index to respective

operator class, if distinct from the default one for column's data type.

Pull request courtesy Denis Laxalde.

.. seealso::

:ref:`postgresql_operator_classes`

.. change::

:tags: engine

Improved validation of execution parameters passed to the

:meth:`_engine.Connection.execute` and similar methods to

provided a better error when tuples are passed in.

Previously the execution would fail with a difficult to

understand error message.