:released: August 11, 2025

.. change::

:tags: usecase, oracle

:tickets: 12711

Extended :class:`_oracle.VECTOR` to support sparse vectors. This update

introduces :class:`_oracle.VectorStorageType` to specify sparse or dense

storage and added :class:`_oracle.SparseVector`. Pull request courtesy

Suraj Shaw.

.. change::

:tags: bug, orm

:tickets: 12748

Fixed issue where using the ``post_update`` feature would apply incorrect

"pre-fetched" values to the ORM objects after a multi-row UPDATE process

completed. These "pre-fetched" values would come from any column that had

an :paramref:`.Column.onupdate` callable or a version id generator used by

:paramref:`.orm.Mapper.version_id_generator`; for a version id generator

that delivered random identifiers like timestamps or UUIDs, this incorrect

data would lead to a DELETE statement against those same rows to fail in

the next step.

.. change::

:tags: bug, postgresql

:tickets: 12778

Fixed regression in PostgreSQL dialect where JSONB subscription syntax

would generate incorrect SQL for JSONB-returning functions, causing syntax

errors. The dialect now properly wraps function calls and expressions in

parentheses when using the ``[]`` subscription syntax, generating

``(function_call)[index]`` instead of ``function_call[index]`` to comply

with PostgreSQL syntax requirements.

.. change::

:tags: usecase, engine

:tickets: 12784

Added new parameter :paramref:`.create_engine.skip_autocommit_rollback`

which provides for a per-dialect feature of preventing the DBAPI

``.rollback()`` from being called under any circumstances, if the

connection is detected as being in "autocommit" mode. This improves upon

a critical performance issue identified in MySQL dialects where the network

overhead of the ``.rollback()`` call remains prohibitive even if autocommit

mode is set.

.. seealso::

:ref:`dbapi_autocommit_skip_rollback`

.. change::

:tags: bug, orm

:tickets: 12787

Fixed issue where :paramref:`_orm.mapped_column.use_existing_column`

parameter in :func:`_orm.mapped_column` would not work when the

:func:`_orm.mapped_column` is used inside of an ``Annotated`` type alias in

polymorphic inheritance scenarios. The parameter is now properly recognized

and processed during declarative mapping configuration.

.. change::

:tags: bug, orm

:tickets: 12790

Improved the implementation of the :func:`_orm.selectin_polymorphic`

inheritance loader strategy to properly render the IN expressions using

chunks of 500 records each, in the same manner as that of the

:func:`_orm.selectinload` relationship loader strategy. Previously, the IN

expression would be arbitrarily large, leading to failures on databases

that have limits on the size of IN expressions including Oracle Database.