:released: March 4, 2019
:released: November 16, 2018
.. change::
:tags: bug, ext
:tickets: 3423
Reworked :class:`.AssociationProxy` to store state that's specific to a
parent class in a separate object, so that a single
:class:`.AssociationProxy` can serve for multiple parent classes, as is
intrinsic to inheritance, without any ambiguity in the state returned by it.
A new method :meth:`.AssociationProxy.for_class` is added to allow
inspection of class-specific state.
.. seealso::
:ref:`change_3423`
.. change::
:tags: bug, oracle
:tickets: 4369
Updated the parameters that can be sent to the cx_Oracle DBAPI to both allow
for all current parameters as well as for future parameters not added yet.
In addition, removed unused parameters that were deprecated in version 1.2,
and additionally we are now defaulting "threaded" to False.
.. seealso::
:ref:`change_4369`
.. change::
:tags: bug, oracle
:tickets: 4242
The Oracle dialect will no longer use the NCHAR/NCLOB datatypes
represent generic unicode strings or clob fields in conjunction with
:class:`.Unicode` and :class:`.UnicodeText` unless the flag
``use_nchar_for_unicode=True`` is passed to :func:`_sa.create_engine` -
this includes CREATE TABLE behavior as well as ``setinputsizes()`` for
bound parameters. On the read side, automatic Unicode conversion under
Python 2 has been added to CHAR/VARCHAR/CLOB result rows, to match the
behavior of cx_Oracle under Python 3. In order to mitigate the performance
hit under Python 2, SQLAlchemy's very performant (when C extensions
are built) native Unicode handlers are used under Python 2.
.. seealso::
:ref:`change_4242`
.. change::
:tags: bug, orm
:tickets: 3844
Fixed issue regarding passive_deletes="all", where the foreign key
attribute of an object is maintained with its value even after the object
is removed from its parent collection. Previously, the unit of work would
set this to NULL even though passive_deletes indicated it should not be
modified.
.. seealso::
:ref:`change_3844`
.. change::
:tags: bug, ext
:tickets: 4268
The long-standing behavior of the association proxy collection maintaining
only a weak reference to the parent object is reverted; the proxy will now
maintain a strong reference to the parent for as long as the proxy
collection itself is also in memory, eliminating the "stale association
proxy" error. This change is being made on an experimental basis to see if
any use cases arise where it causes side effects.
.. seealso::
:ref:`change_4268`
.. change::
:tags: bug, sql
:tickets: 4302
Added "like" based operators as "comparison" operators, including
:meth:`.ColumnOperators.startswith` :meth:`.ColumnOperators.endswith`
:meth:`.ColumnOperators.ilike` :meth:`.ColumnOperators.notilike` among many
others, so that all of these operators can be the basis for an ORM
"primaryjoin" condition.
.. change::
:tags: feature, sqlite
:tickets: 3850
Added support for SQLite's json functionality via the new
SQLite implementation for :class:`_types.JSON`, :class:`_sqlite.JSON`.
The name used for the type is ``JSON``, following an example found at
SQLite's own documentation. Pull request courtesy Ilja Everilä.
.. seealso::
:ref:`change_3850`
.. change::
:tags: feature, engine
Added new "lifo" mode to :class:`.QueuePool`, typically enabled by setting
the flag :paramref:`_sa.create_engine.pool_use_lifo` to True. "lifo" mode
means the same connection just checked in will be the first to be checked
out again, allowing excess connections to be cleaned up from the server
side during periods of the pool being only partially utilized. Pull request
courtesy Taem Park.
.. seealso::
:ref:`change_pr467`
.. change::
:tags: bug, orm
:tickets: 4359
Improved the behavior of a relationship-bound many-to-one object expression
such that the retrieval of column values on the related object are now
resilient against the object being detached from its parent
:class:`.Session`, even if the attribute has been expired. New features
within the :class:`.InstanceState` are used to memoize the last known value
of a particular column attribute before its expired, so that the expression
can still evaluate when the object is detached and expired at the same
time. Error conditions are also improved using modern attribute state
features to produce more specific messages as needed.
.. seealso::
:ref:`change_4359`
.. change::
:tags: feature, mysql
:tickets: 4219
Support added for the "WITH PARSER" syntax of CREATE FULLTEXT INDEX
in MySQL, using the ``mysql_with_parser`` keyword argument. Reflection
is also supported, which accommodates MySQL's special comment format
for reporting on this option as well. Additionally, the "FULLTEXT" and
"SPATIAL" index prefixes are now reflected back into the ``mysql_prefix``
index option.
.. change::
:tags: bug, orm, mysql, postgresql
:tickets: 4246
The ORM now doubles the "FOR UPDATE" clause within the subquery that
renders in conjunction with joined eager loading in some cases, as it has
been observed that MySQL does not lock the rows from a subquery. This
means the query renders with two FOR UPDATE clauses; note that on some
backends such as Oracle, FOR UPDATE clauses on subqueries are silently
ignored since they are unnecessary. Additionally, in the case of the "OF"
clause used primarily with PostgreSQL, the FOR UPDATE is rendered only on
the inner subquery when this is used so that the selectable can be targeted
to the table within the SELECT statement.
.. seealso::
:ref:`change_4246`
.. change::
:tags: feature, mssql
:tickets: 4158
Added ``fast_executemany=True`` parameter to the SQL Server pyodbc dialect,
which enables use of pyodbc's new performance feature of the same name
when using Microsoft ODBC drivers.
.. seealso::
:ref:`change_4158`
.. change::
:tags: bug, ext
:tickets: 4308
Fixed multiple issues regarding de-association of scalar objects with the
association proxy. ``del`` now works, and additionally a new flag
:paramref:`.AssociationProxy.cascade_scalar_deletes` is added, which when
set to True indicates that setting a scalar attribute to ``None`` or
deleting via ``del`` will also set the source association to ``None``.
.. seealso::
:ref:`change_4308`
.. change::
:tags: feature, ext
:tickets: 4318
Added new feature :meth:`.BakedQuery.to_query`, which allows for a
clean way of using one :class:`.BakedQuery` as a subquery inside of another
:class:`.BakedQuery` without needing to refer explicitly to a
:class:`.Session`.
.. change::
:tags: feature, sqlite
:tickets: 4360
Implemented the SQLite ``ON CONFLICT`` clause as understood at the DDL
level, e.g. for primary key, unique, and CHECK constraints as well as
specified on a :class:`_schema.Column` to satisfy inline primary key and NOT NULL.
Pull request courtesy Denis Kataev.
.. seealso::
:ref:`change_4360`
.. change::
:tags: feature, postgresql
:tickets: 4237
Added rudimental support for reflection of PostgreSQL
partitioned tables, e.g. that relkind='p' is added to reflection
queries that return table information.
.. seealso::
:ref:`change_4237`
.. change::
:tags: feature, ext
:tickets: 4351
The :class:`.AssociationProxy` now has standard column comparison operations
such as :meth:`.ColumnOperators.like` and
:meth:`.ColumnOperators.startswith` available when the target attribute is a
plain column - the EXISTS expression that joins to the target table is
rendered as usual, but the column expression is then use within the WHERE
criteria of the EXISTS. Note that this alters the behavior of the
``.contains()`` method on the association proxy to make use of
:meth:`.ColumnOperators.contains` when used on a column-based attribute.
.. seealso::
:ref:`change_4351`
.. change::
:tags: feature, orm
Added new flag :paramref:`.Session.bulk_save_objects.preserve_order` to the
:meth:`.Session.bulk_save_objects` method, which defaults to True. When set
to False, the given mappings will be grouped into inserts and updates per
each object type, to allow for greater opportunities to batch common
operations together. Pull request courtesy Alessandro Cucci.
.. change::
:tags: bug, orm
:tickets: 4365
Refactored :meth:`_query.Query.join` to further clarify the individual components
of structuring the join. This refactor adds the ability for
:meth:`_query.Query.join` to determine the most appropriate "left" side of the
join when there is more than one element in the FROM list or the query is
against multiple entities. If more than one FROM/entity matches, an error
is raised that asks for an ON clause to be specified to resolve the
ambiguity. In particular this targets the regression we saw in
:ticket:`4363` but is also of general use. The codepaths within
:meth:`_query.Query.join` are now easier to follow and the error cases are
decided more specifically at an earlier point in the operation.
.. seealso::
:ref:`change_4365`
.. change::
:tags: bug, sql
:tickets: 3981
Fixed issue with :meth:`.TypeEngine.bind_expression` and
:meth:`.TypeEngine.column_expression` methods where these methods would not
work if the target type were part of a :class:`.Variant`, or other target
type of a :class:`.TypeDecorator`. Additionally, the SQL compiler now
calls upon the dialect-level implementation when it renders these methods
so that dialects can now provide for SQL-level processing for built-in
types.
.. seealso::
:ref:`change_3981`
.. change::
:tags: bug, orm
:tickets: 4304
Fixed long-standing issue in :class:`_query.Query` where a scalar subquery such
as produced by :meth:`_query.Query.exists`, :meth:`_query.Query.as_scalar` and other
derivations from :attr:`_query.Query.statement` would not correctly be adapted
when used in a new :class:`_query.Query` that required entity adaptation, such as
when the query were turned into a union, or a from_self(), etc. The change
removes the "no adaptation" annotation from the :func:`_expression.select` object
produced by the :attr:`_query.Query.statement` accessor.
.. change::
:tags: bug, orm, declarative
:tickets: 4133
Fixed bug where declarative would not update the state of the
:class:`_orm.Mapper` as far as what attributes were present, when additional
attributes were added or removed after the mapper attribute collections had
already been called and memoized. Additionally, a ``NotImplementedError``
is now raised if a fully mapped attribute (e.g. column, relationship, etc.)
is deleted from a class that is currently mapped, since the mapper will not
function correctly if the attribute has been removed.
.. change::
:tags: bug, mssql
:tickets: 4362
Deprecated the use of :class:`.Sequence` with SQL Server in order to affect
the "start" and "increment" of the IDENTITY value, in favor of new
parameters ``mssql_identity_start`` and ``mssql_identity_increment`` which
set these parameters directly. :class:`.Sequence` will be used to generate
real ``CREATE SEQUENCE`` DDL with SQL Server in a future release.
.. seealso::
:ref:`change_4362`
.. change::
:tags: feature, mysql
Added support for the parameters in an ON DUPLICATE KEY UPDATE statement on
MySQL to be ordered, since parameter order in a MySQL UPDATE clause is
significant, in a similar manner as that described at
:ref:`tutorial_parameter_ordered_updates`. Pull request courtesy Maxim Bublis.
.. seealso::
:ref:`change_mysql_ondupordering`
.. change::
:tags: feature, sql
:tickets: 4144
Added :class:`.Sequence` to the "string SQL" system that will render a
meaningful string expression (``"<next sequence value: my_sequence>"``)
when stringifying without a dialect a statement that includes a "sequence
nextvalue" expression, rather than raising a compilation error.
.. change::
:tags: bug, orm
:tickets: 4232
An informative exception is re-raised when a primary key value is not
sortable in Python during an ORM flush under Python 3, such as an ``Enum``
that has no ``__lt__()`` method; normally Python 3 raises a ``TypeError``
in this case. The flush process sorts persistent objects by primary key
in Python so the values must be sortable.
.. change::
:tags: orm, bug
:tickets: 3604
Removed the collection converter used by the :class:`.MappedCollection`
class. This converter was used only to assert that the incoming dictionary
keys matched that of their corresponding objects, and only during a bulk set
operation. The converter can interfere with a custom validator or
:meth:`.AttributeEvents.bulk_replace` listener that wants to convert
incoming values further. The ``TypeError`` which would be raised by this
converter when an incoming key didn't match the value is removed; incoming
values during a bulk assignment will be keyed to their value-generated key,
and not the key that's explicitly present in the dictionary.
Overall, converter is superseded by the
:meth:`.AttributeEvents.bulk_replace` event handler added as part of
:ticket:`3896`.
.. change::
:tags: feature, sql
:tickets: 3989
Added new naming convention tokens ``column_0N_name``, ``column_0_N_name``,
etc., which will render the names / keys / labels for all columns referenced
by a particular constraint in a sequence. In order to accommodate for the
length of such a naming convention, the SQL compiler's auto-truncation
feature now applies itself to constraint names as well, which creates a
shortened, deterministically generated name for the constraint that will
apply to a target backend without going over the character limit of that
backend.
The change also repairs two other issues. One is that the ``column_0_key``
token wasn't available even though this token was documented, the other was
that the ``referred_column_0_name`` token would inadvertently render the
``.key`` and not the ``.name`` of the column if these two values were
different.
.. seealso::
:ref:`change_3989`
.. change::
:tags: feature, ext
:tickets: 4196
Added support for bulk :meth:`_query.Query.update` and :meth:`_query.Query.delete`
to the :class:`.ShardedQuery` class within the horizontal sharding
extension. This also adds an additional expansion hook to the
bulk update/delete methods :meth:`_query.Query._execute_crud`.
.. seealso::
:ref:`change_4196`
.. change::
:tags: feature, sql
:tickets: 4271
Added new logic to the "expanding IN" bound parameter feature whereby if
the given list is empty, a special "empty set" expression that is specific
to different backends is generated, thus allowing IN expressions to be
fully dynamic including empty IN expressions.
.. seealso::
:ref:`change_4271`
.. change::
:tags: feature, mysql
The "pre-ping" feature of the connection pool now uses
the ``ping()`` method of the DBAPI connection in the case of
mysqlclient, PyMySQL and mysql-connector-python. Pull request
courtesy Maxim Bublis.
.. seealso::
:ref:`change_mysql_ping`
.. change::
:tags: feature, orm
:tickets: 4340
The "selectin" loader strategy now omits the JOIN in the case of a simple
one-to-many load, where it instead relies loads only from the related
table, relying upon the foreign key columns of the related table in order
to match up to primary keys in the parent table. This optimization can be
disabled by setting the :paramref:`_orm.relationship.omit_join` flag to False.
Many thanks to Jayson Reis for the efforts on this.
.. seealso::
:ref:`change_4340`
.. change::
:tags: bug, orm
:tickets: 4353
Added new behavior to the lazy load that takes place when the "old" value of
a many-to-one is retrieved, such that exceptions which would be raised due
to either ``lazy="raise"`` or a detached session error are skipped.
.. seealso::
:ref:`change_4353`
.. change::
:tags: feature, sql
The Python builtin ``dir()`` is now supported for a SQLAlchemy "properties"
object, such as that of a Core columns collection (e.g. ``.c``),
``mapper.attrs``, etc. Allows iPython autocompletion to work as well.
Pull request courtesy Uwe Korn.
.. change::
:tags: feature, orm
:tickets: 4257
Added ``.info`` dictionary to the :class:`.InstanceState` class, the object
that comes from calling :func:`_sa.inspect` on a mapped object.
.. seealso::
:ref:`change_4257`
.. change::
:tags: feature, sql
:tickets: 3831
Added new feature :meth:`.FunctionElement.as_comparison` which allows a SQL
function to act as a binary comparison operation that can work within the
ORM.
.. seealso::
:ref:`change_3831`
.. change::
:tags: bug, orm
:tickets: 4354
A long-standing oversight in the ORM, the ``__delete__`` method for a many-
to-one relationship was non-functional, e.g. for an operation such as ``del
a.b``. This is now implemented and is equivalent to setting the attribute
to ``None``.
.. seealso::
:ref:`change_4354`
=============
1.4 Changelog
=============
This document details individual issue-level changes made throughout
1.4 releases. For a narrative overview of what's new in 1.4, see
:ref:`migration_14_toplevel`.
.. changelog_imports::
.. include:: changelog_13.rst
:start-line: 5
.. changelog::
:version: 1.4.53
:include_notes_from: unreleased_14
.. changelog::