.. changelog::
:version: 2.0.21
- :include_notes_from: unreleased_20
+ :released: September 18, 2023
+
+ .. change::
+ :tags: bug, sql
+ :tickets: 9610
+
+ Adjusted the operator precedence for the string concatenation operator to
+ be equal to that of string matching operators, such as
+ :meth:`.ColumnElement.like`, :meth:`.ColumnElement.regexp_match`,
+ :meth:`.ColumnElement.match`, etc., as well as plain ``==`` which has the
+ same precedence as string comparison operators, so that parenthesis will be
+ applied to a string concatenation expression that follows a string match
+ operator. This provides for backends such as PostgreSQL where the "regexp
+ match" operator is apparently of higher precedence than the string
+ concatenation operator.
+
+ .. change::
+ :tags: bug, sql
+ :tickets: 10342
+
+ Qualified the use of ``hashlib.md5()`` within the DDL compiler, which is
+ used to generate deterministic four-character suffixes for long index and
+ constraint names in DDL statements, to include the Python 3.9+
+ ``usedforsecurity=False`` parameter so that Python interpreters built for
+ restricted environments such as FIPS do not consider this call to be
+ related to security concerns.
+
+ .. change::
+ :tags: bug, postgresql
+ :tickets: 10226
+
+ Fixed regression which appeared in 2.0 due to :ticket:`8491` where the
+ revised "ping" used for PostgreSQL dialects when the
+ :paramref:`_sa.create_engine.pool_pre_ping` parameter is in use would
+ interfere with the use of asyncpg with PGBouncer "transaction" mode, as the
+ multiple PostgreSQL commands emitted by asnycpg could be broken out among
+ multiple connections leading to errors, due to the lack of any transaction
+ around this newly revised "ping". The ping is now invoked within a
+ transaction, in the same way that is implicit with all other backends that
+ are based on the pep-249 DBAPI; this guarantees that the series of PG
+ commands sent by asyncpg for this command are invoked on the same backend
+ connection without it jumping to a different connection mid-command. The
+ transaction is not used if the asyncpg dialect is used in "AUTOCOMMIT"
+ mode, which remains incompatible with pgbouncer transaction mode.
+
+
+ .. change::
+ :tags: bug, orm
+ :tickets: 10279
+
+ Adjusted the ORM's interpretation of the "target" entity used within
+ :class:`.Update` and :class:`.Delete` to not interfere with the target
+ "from" object passed to the statement, such as when passing an ORM-mapped
+ :class:`_orm.aliased` construct that should be maintained within a phrase
+ like "UPDATE FROM". Cases like ORM session synchonize using "SELECT"
+ statements such as with MySQL/ MariaDB will still have issues with
+ UPDATE/DELETE of this form so it's best to disable synchonize_session when
+ using DML statements of this type.
+
+ .. change::
+ :tags: bug, orm
+ :tickets: 10348
+
+ Added new capability to the :func:`_orm.selectin_polymorphic` loader option
+ which allows other loader options to be bundled as siblings, referring to
+ one of its subclasses, within the sub-options of parent loader option.
+ Previously, this pattern was only supported if the
+ :func:`_orm.selectin_polymorphic` were at the top level of the options for
+ the query. See new documentation section for example.
+
+ As part of this change, improved the behavior of the
+ :meth:`_orm.Load.selectin_polymorphic` method / loader strategy so that the
+ subclass load does not load most already-loaded columns from the parent
+ table, when the option is used against a class that is already being
+ relationship-loaded. Previously, the logic to load only the subclass
+ columns worked only for a top level class load.
+
+ .. seealso::
+
+ :ref:`polymorphic_selectin_as_loader_option_target_plus_opts`
+
+ .. change::
+ :tags: bug, typing
+ :tickets: 10264, 9284
+
+ Fixed regression introduced in 2.0.20 via :ticket:`9600` fix which
+ attempted to add more formal typing to
+ :paramref:`_schema.MetaData.naming_convention`. This change prevented basic
+ naming convention dictionaries from passing typing and has been adjusted so
+ that a plain dictionary of strings for keys as well as dictionaries that
+ use constraint types as keys or a mix of both, are again accepted.
+
+ As part of this change, lesser used forms of the naming convention
+ dictionary are also typed, including that it currently allows for
+ ``Constraint`` type objects as keys as well.
+
+ .. change::
+ :tags: usecase, typing
+ :tickets: 10288
+
+ Made the contained type for :class:`.Mapped` covariant; this is to allow
+ greater flexibility for end-user typing scenarios, such as the use of
+ protocols to represent particular mapped class structures that are passed
+ to other functions. As part of this change, the contained type was also
+ made covariant for dependent and related types such as
+ :class:`_orm.base.SQLORMOperations`, :class:`_orm.WriteOnlyMapped`, and
+ :class:`_sql.SQLColumnExpression`. Pull request courtesy Roméo Després.
+
+
+ .. change::
+ :tags: bug, engine
+ :tickets: 10275
+
+ Fixed a series of reflection issues affecting the PostgreSQL,
+ MySQL/MariaDB, and SQLite dialects when reflecting foreign key constraints
+ where the target column contained parenthesis in one or both of the table
+ name or column name.
+
+
+ .. change::
+ :tags: bug, sql
+ :tickets: 10280
+
+ The :class:`.Values` construct will now automatically create a proxy (i.e.
+ a copy) of a :class:`_sql.column` if the column were already associated
+ with an existing FROM clause. This allows that an expression like
+ ``values_obj.c.colname`` will produce the correct FROM clause even in the
+ case that ``colname`` was passed as a :class:`_sql.column` that was already
+ used with a previous :class:`.Values` or other table construct.
+ Originally this was considered to be a candidate for an error condition,
+ however it's likely this pattern is already in widespread use so it's
+ now added to support.
+
+ .. change::
+ :tags: bug, setup
+ :tickets: 10321
+
+ Fixed very old issue where the full extent of SQLAlchemy modules, including
+ ``sqlalchemy.testing.fixtures``, could not be imported outside of a pytest
+ run. This suits inspection utilities such as ``pkgutil`` that attempt to
+ import all installed modules in all packages.
+
+ .. change::
+ :tags: usecase, sql
+ :tickets: 10269
+
+ Adjusted the :class:`_types.Enum` datatype to accept an argument of
+ ``None`` for the :paramref:`_types.Enum.length` parameter, resulting in a
+ VARCHAR or other textual type with no length in the resulting DDL. This
+ allows for new elements of any length to be added to the type after it
+ exists in the schema. Pull request courtesy Eugene Toder.
+
+
+ .. change::
+ :tags: bug, typing
+ :tickets: 9878
+
+ Fixed the type annotation for ``__class_getitem__()`` as applied to the
+ ``Visitable`` class at the base of expression constructs to accept ``Any``
+ for a key, rather than ``str``, which helps with some IDEs such as PyCharm
+ when attempting to write typing annotations for SQL constructs which
+ include generic selectors. Pull request courtesy Jordan Macdonald.
+
+
+ .. change::
+ :tags: bug, typing
+ :tickets: 10353
+
+ Repaired the core "SQL element" class ``SQLCoreOperations`` to support the
+ ``__hash__()`` method from a typing perspective, as objects like
+ :class:`.Column` and ORM :class:`.InstrumentedAttribute` are hashable and
+ are used as dictionary keys in the public API for the :class:`_dml.Update`
+ and :class:`_dml.Insert` constructs. Previously, type checkers were not
+ aware the root SQL element was hashable.
+
+ .. change::
+ :tags: bug, typing
+ :tickets: 10337
+
+ Fixed typing issue with :meth:`_sql.Existing.select_from` that
+ prevented its use with ORM classes.
+
+ .. change::
+ :tags: usecase, sql
+ :tickets: 9873
+
+ Added new generic SQL function :class:`_functions.aggregate_strings`, which
+ accepts a SQL expression and a decimeter, concatenating strings on multiple
+ rows into a single aggregate value. The function is compiled on a
+ per-backend basis, into functions such as ``group_concat(),``
+ ``string_agg()``, or ``LISTAGG()``.
+ Pull request courtesy Joshua Morris.
+
+ .. change::
+ :tags: typing, bug
+ :tickets: 10131
+
+ Update type annotations for ORM loading options, restricting them to accept
+ only `"*"` instead of any string for string arguments. Pull request
+ courtesy Janek Nouvertné.
.. changelog::
:version: 2.0.20
projects / thirdparty / sqlalchemy / sqlalchemy.git / commitdiff
