Sqlalchemy

:released: August 3, 2017

.. change::
:tags: bug, oracle, performance, py2k
:tickets: 4035
:versions: 1.0.19, 1.1.13, 1.2.0b3

Fixed performance regression caused by the fix for :ticket:`3937` where
cx_Oracle as of version 5.3 dropped the ``.UNICODE`` symbol from its
namespace, which was interpreted as cx_Oracle's "WITH_UNICODE" mode being
turned on unconditionally, which invokes functions on the SQLAlchemy
side which convert all strings to unicode unconditionally and causing
a performance impact. In fact, per cx_Oracle's author the
"WITH_UNICODE" mode has been removed entirely as of 5.1, so the expensive unicode
conversion functions are no longer necessary and are disabled if
cx_Oracle 5.1 or greater is detected under Python 2. The warning against
"WITH_UNICODE" mode that was removed under :ticket:`3937` is also restored.

.. changelog::

:released: July 24, 2017

.. change::
:tags: bug, tests, py3k
:tickets: 4034
:versions: 1.0.18, 1.1.12, 1.2.0b2

Fixed issue in testing fixtures which was incompatible with a change
made as of Python 3.6.2 involving context managers.

.. change:: 3937
:tags: bug, oracle
:tickets: 3937
:versions: 1.1.7

A fix to cx_Oracle's WITH_UNICODE mode which was uncovered by the
fact that cx_Oracle 5.3 now seems to hardcode this flag on in
the build; an internal method that uses this mode wasn't using
the correct signature.


.. changelog::

:released: January 17, 2017

.. change::
:tags: bug, py3k
:tickets: 3886
:versions: 1.1.5

Fixed Python 3.6 DeprecationWarnings related to escaped strings without
the 'r' modifier, and added test coverage for Python 3.6.

.. change::
:tags: bug, orm
:tickets: 3884
:versions: 1.1.5

Fixed bug involving joined eager loading against multiple entities
when polymorphic inheritance is also in use which would throw
"'NoneType' object has no attribute 'isa'". The issue was introduced
by the fix for :ticket:`3611`.

.. changelog::

:released: November 15, 2016

.. change::
:tags: bug, orm
:tickets: 3849
:versions: 1.1.4

Fixed bug in :meth:`.Session.bulk_update_mappings` where an alternate-named
primary key attribute would not track properly into the UPDATE statement.

.. change::
:tags: bug, mssql
:tickets: 3810
:versions: 1.1.0

Changed the query used to get "default schema name", from one that
queries the database principals table to using the
"schema_name()" function, as issues have been reported that the
former system was unavailable on the Azure Data Warehouse edition.
It is hoped that this will finally work across all SQL Server
versions and authentication styles.

.. change::
:tags: bug, mssql
:tickets: 3814
:versions: 1.1.0

Updated the server version info scheme for pyodbc to use SQL Server
SERVERPROPERTY(), rather than relying upon pyodbc.SQL_DBMS_VER, which
continues to be unreliable particularly with FreeTDS.

.. change::
:tags: bug, orm
:tickets: 3800
:versions: 1.1.0

Fixed bug where joined eager loading would fail for a polymorphically-
loaded mapper, where the polymorphic_on was set to an un-mapped
expression such as a CASE expression.

.. change::
:tags: bug, orm
:tickets: 3798
:versions: 1.1.0

Fixed bug where the ArgumentError raised for an invalid bind
sent to a Session via :meth:`.Session.bind_mapper`,
:meth:`.Session.bind_table`,
or the constructor would fail to be correctly raised.

.. change::
:tags: bug, mssql
:tickets: 3791
:versions: 1.1.0

Added error code 20017 "unexpected EOF from the server" to the list of
disconnect exceptions that result in a connection pool reset. Pull
request courtesy Ken Robbins.

.. change::
:tags: bug, orm.declarative
:tickets: 3797
:versions: 1.1.0

Fixed bug where setting up a single-table inh subclass of a joined-table
subclass which included an extra column would corrupt the foreign keys
collection of the mapped table, thereby interfering with the
initialization of relationships.

.. change::
:tags: bug, orm
:tickets: 3781
:versions: 1.1.4

Fixed bug in :meth:`.Session.bulk_save` where an UPDATE would
not function correctly in conjunction with a mapping that
implements a version id counter.

.. 3778

.. change::
:tags: bug, orm
:tickets: 3778
:versions: 1.1.4

Fixed bug where the :attr:`_orm.Mapper.attrs`,
:attr:`_orm.Mapper.all_orm_descriptors` and other derived attributes would
fail to refresh when mapper properties or other ORM constructs were
added to the mapper/class after these accessors were first called.

.. change:: 3762
:tags: bug, mssql
:tickets: 3762
:versions: 1.1.4

Fixed bug in pyodbc dialect (as well as in the mostly non-working
adodbapi dialect) whereby a semicolon present in the password
or username fields could be interpreted as a separator for another
token; the values are now quoted when semicolons are present.

.. changelog::

:released: September 1, 2016

.. change::
:tags: bug, mysql
:tickets: 3787
:versions: 1.1.0

Added support for parsing MySQL/Connector boolean and integer
arguments within the URL query string: connection_timeout,
connect_timeout, pool_size, get_warnings,
raise_on_warnings, raw, consume_results, ssl_verify_cert, force_ipv6,
pool_reset_session, compress, allow_local_infile, use_pure.

.. change::
:tags: bug, orm
:tickets: 3773, 3774
:versions: 1.1.0

Fixed bug in subquery eager loading where a subqueryload
of an "of_type()" object linked to a second subqueryload of a plain
mapped class, or a longer chain of several "of_type()" attributes,
would fail to link the joins correctly.

.. change::
:tags: bug, sql
:tickets: 3755
:versions: 1.1.0

Fixed bug in :class:`_schema.Table` where the internal method
``_reset_exported()`` would corrupt the state of the object. This
method is intended for selectable objects and is called by the ORM
in some cases; an erroneous mapper configuration would could lead the
ORM to call this on a :class:`_schema.Table` object.

.. change::
:tags: bug, ext
:tickets: 3743
:versions: 1.1.0b3

Fixed bug in ``sqlalchemy.ext.baked`` where the unbaking of a
subquery eager loader query would fail due to a variable scoping
issue, when multiple subquery loaders were involved. Pull request
courtesy Mark Hahnenberg.

.. changelog::

:released: July 6, 2016

.. change::
:tags: bug, postgresql
:tickets: 3739
:versions: 1.1.0b3

Fixed bug whereby :class:`.TypeDecorator` and :class:`.Variant`
types were not deeply inspected enough by the PostgreSQL dialect
to determine if SMALLSERIAL or BIGSERIAL needed to be rendered
rather than SERIAL.

.. change::
:tags: bug, oracle
:tickets: 3741
:versions: 1.1.0b3

Fixed bug in :paramref:`.Select.with_for_update.of`, where the Oracle
"rownum" approach to LIMIT/OFFSET would fail to accommodate for the
expressions inside the "OF" clause, which must be stated at the topmost
level referring to expression within the subquery. The expressions are
now added to the subquery if needed.

.. change::
:tags: bug, sql
:tickets: 3735
:versions: 1.1.0b2

Fixed issue in SQL math negation operator where the type of the
expression would no longer be the numeric type of the original.
This would cause issues where the type determined result set
behaviors.

.. change::
:tags: bug, sql
:tickets: 3728
:versions: 1.1.0b2

Fixed bug whereby the ``__getstate__`` / ``__setstate__``
methods for sqlalchemy.util.Properties were
non-working due to the transition in the 1.0 series to ``__slots__``.
The issue potentially impacted some third-party applications.
Pull request courtesy Pieter Mulder.

.. change::
:tags: bug, sql
:tickets: 3724

:meth:`_expression.FromClause.count` is pending deprecation for 1.1. This function
makes use of an arbitrary column in the table and is not reliable;
for Core use, ``func.count()`` should be preferred.

.. change::
:tags: bug, sql
:tickets: 3722

Fixed bug in :class:`_expression.CTE` structure which would cause it to not
clone properly when a union was used, as is common in a recursive
CTE. The improper cloning would cause errors when the CTE is used
in various ORM contexts such as that of a :func:`.column_property`.

.. change::
:tags: bug, sql
:tickets: 3721

Fixed bug whereby :meth:`_schema.Table.tometadata` would make a duplicate
:class:`.UniqueConstraint` for each :class:`_schema.Column` object that
featured the ``unique=True`` parameter.

.. change::
:tags: bug, engine, postgresql
:tickets: 3716

Fixed bug in cross-schema foreign key reflection in conjunction
with the :paramref:`_schema.MetaData.schema` argument, where a referenced
table that is present in the "default" schema would fail since there
would be no way to indicate a :class:`_schema.Table` that has "blank" for
a schema. The special symbol :attr:`_schema.BLANK_SCHEMA` has been
added as an available value for :paramref:`_schema.Table.schema` and
:paramref:`.Sequence.schema`, indicating that the schema name
should be forced to be ``None`` even if :paramref:`_schema.MetaData.schema`
is specified.

.. change::
:tags: bug, examples
:tickets: 3704

Fixed a regression that occurred in the
examples/vertical/dictlike-polymorphic.py example which prevented it
from running.

.. changelog::