Scheduled biweekly dependency update for week 11

[pyup-bot]

Update SQLAlchemy from 1.1.11 to 1.2.5.

Changelog

1.2.5

:released: March 6, 2018

 .. change::
     :tags: bug, sql
     :tickets: 4210
     :versions: 1.3.0b1

     Fixed bug in :class:.`CTE` construct along the same lines as that of
     :ticket:`4204` where a :class:`.CTE` that was aliased would not copy itself
     correctly during a "clone" operation as is frequent within the ORM as well
     as when using the :meth:`.ClauseElement.params` method.

 .. change::
     :tags: bug, orm
     :tickets: 4199

     Fixed bug in new "polymorphic selectin" loading when a selection of
     polymorphic objects were to be partially loaded from a relationship
     lazy loader, leading to an "empty IN" condition within the load that
     raises an error for the "inline" form of "IN".

 .. change::
     :tags: bug, sql
     :tickets: 4204

     Fixed bug in CTE rendering where a :class:`.CTE` that was also turned into
     an :class:`.Alias` would not render its "ctename AS aliasname" clause
     appropriately if there were more than one reference to the CTE in a FROM
     clause.

 .. change::
     :tags: bug, orm
     :tickets: 4209
     :versions: 1.3.0b1

     Fixed 1.2 regression where a mapper option that contains an
     :class:`.AliasedClass` object, as is typical when using the
     :meth:`.QueryableAttribute.of_type` method, could not be pickled.   1.1's
     behavior was to omit the aliased class objects from the path, so this
     behavior is restored.

 .. change::
     :tags: feature, orm
     :versions: 1.3.0b1

     Added new feature :meth:`.Query.only_return_tuples`.  Causes the
     :class:`.Query` object to return keyed tuple objects unconditionally even
     if the query is against a single entity.   Pull request courtesy Eric
     Atkin.


 .. change::
     :tags: bug, sql
     :tickets: 4198

     Fixed bug in new "expanding IN parameter" feature where the bind parameter
     processors for values wasn't working at all, tests failed to cover this
     pretty basic case which includes that ENUM values weren't working.

.. changelog::

1.2.4

:released: February 22, 2018

 .. change::
     :tags: bug, orm
     :tickets: 4193

     Fixed 1.2 regression in ORM versioning feature where a mapping against a
     :func:`.select` or :func:`.alias` that also used a versioning column
     against the underlying table would fail due to the check added as part of
     :ticket:`3673`.

 .. change::
     :tags: bug, engine
     :tickets: 4190

     Fixed regression caused in 1.2.3 due to fix from :ticket:`4181` where
     the changes to the event system involving :class:`.Engine` and
     :class:`.OptionEngine` did not accommodate for event removals, which
     would raise an ``AttributeError`` when invoked at the class
     level.

 .. change::
     :tags: bug, sql
     :tickets: 4197

     Fixed bug where CTE expressions would not have their name or alias name
     quoted when the given name is case sensitive or otherwise requires quoting.
     Pull request courtesy Eric Atkin.

.. changelog::

1.2.3

:released: February 16, 2018

 .. change::
     :tags: bug, oracle
     :tickets: 4182

     Fixed bug in cx_Oracle disconnect detection, used by pre_ping and other
     features, where an error could be raised as DatabaseError which includes a
     numeric error code; previously we weren't checking in this case for a
     disconnect code.

 .. change::
     :tags: bug, sqlite

     Fixed the import error raised when a platform
     has neither pysqlite2 nor sqlite3 installed, such
     that the sqlite3-related import error is raised,
     not the pysqlite2 one which is not the actual
     failure mode.  Pull request courtesy Robin.

 .. change::
     :tags: bug, orm
     :tickets: 4175

     Fixed bug where the :class:`.Bundle` object did not
     correctly report upon the primary :class:`.Mapper` object
     represened by the bundle, if any.   An immediate
     side effect of this issue was that the new selectinload
     loader strategy wouldn't work with the horizontal sharding
     extension.

 .. change::
     :tags: bug, sql
     :tickets: 4180

     Fixed bug where the :class:`.Enum` type wouldn't handle
     enum "aliases" correctly, when more than one key refers to the
     same value.  Pull request courtesy Daniel Knell.


 .. change::
     :tags: bug, engine
     :tickets: 4181

     Fixed bug where events associated with an :class:`Engine`
     at the class level would be doubled when the
     :meth:`.Engine.execution_options` method were used.  To
     achieve this, the semi-private class :class:`.OptionEngine`
     no longer accepts events directly at the class level
     and will raise an error; the class only propagates class-level
     events from its parent :class:`.Engine`.   Instance-level
     events continue to work as before.

 .. change::
     :tags: bug, tests
     :tickets: 3265

     A test added in 1.2 thought to confirm a Python 2.7 behavior turns out to
     be confirming the behavior only as of Python 2.7.8. Python bug 8743 still
     impacts set comparison in Python 2.7.7 and earlier, so the test in question
     involving AssociationSet no longer runs for these older Python 2.7
     versions.

 .. change::
     :tags: feature, oracle

     The ON DELETE options for foreign keys are now part of
     Oracle reflection.  Oracle does not support ON UPDATE
     cascades.  Pull request courtesy Miroslav Shubernetskiy.



 .. change::
     :tags: bug, orm
     :tickets: 4188

     Fixed bug in concrete inheritance mapping where user-defined
     attributes such as hybrid properties that mirror the names
     of mapped attributes from sibling classes would be overwritten by
     the mapper as non-accessible at the instance level.   Additionally
     ensured that user-bound descriptors are not implicitly invoked at the class
     level during the mapper configuration stage.

 .. change::
     :tags: bug, orm
     :tickets: 4178

     Fixed bug where the :func:`.orm.reconstructor` event
     helper would not be recognized if it were applied to the
     ``__init__()`` method of the mapped class.

 .. change::
     :tags: bug, engine
     :tickets: 4170

     The :class:`.URL` object now allows query keys to be specified multiple
     times where their values will be joined into a list.  This is to support
     the plugins feature documented at :class:`.CreateEnginePlugin` which
     documents that "plugin" can be passed multiple times. Additionally, the
     plugin names can be passed to :func:`.create_engine` outside of the URL
     using the new :paramref:`.create_engine.plugins` parameter.

 .. change::
     :tags: feature, sql
     :tickets: 3906

     Added support for :class:`.Enum` to persist the values of the enumeration,
     rather than the keys, when using a Python pep-435 style enumerated object.
     The user supplies a callable function that will return the string values to
     be persisted.  This allows enumerations against non-string values to be
     value-persistable as well.  Pull request courtesy Jon Snyder.

 .. change::
     :tags: feature, orm

     Added new argument :paramref:`.attributes.set_attribute.inititator`
     to the :func:`.attributes.set_attribute` function, allowing an
     event token received from a listener function to be propagated
     to subsequent set events.

.. changelog::

1.2.2

:released: January 24, 2018

 .. change::
     :tags: bug, mssql
     :tickets: 4164

     Added ODBC error code 10054 to the list of error
     codes that count as a disconnect for ODBC / MSSQL server.


 .. change::
     :tags: bug, orm
     :tickets: 4171

     Fixed 1.2 regression regarding new bulk_replace event
     where a backref would fail to remove an object from the
     previous owner when a bulk-assignment assigned the
     object to a new owner.

 .. change::
     :tags: bug, oracle
     :tickets: 4163

     The cx_Oracle dialect now calls setinputsizes() with cx_Oracle.NCHAR
     unconditionally when the NVARCHAR2 datatype, in SQLAlchemy corresponding
     to sqltypes.Unicode(), is in use.  Per cx_Oracle's author this allows
     the correct conversions to occur within the Oracle client regardless
     of the setting for NLS_NCHAR_CHARACTERSET.

 .. change::
     :tags: bug, mysql

     Added more MySQL 8.0 reserved words to the MySQL dialect
     for quoting purposes.  Pull request courtesy
     Riccardo Magliocchetti.

.. changelog::

1.2.1

:released: January 15, 2018

 .. change::
     :tags: bug, orm
     :tickets: 4159

     Fixed regression where pickle format of a Load / _UnboundLoad object (e.g.
     loader options) changed and ``__setstate__()`` was raising an
     UnboundLocalError for an object received from the legacy format, even
     though an attempt was made to do so.  tests are now added to ensure this
     works.

 .. change::
     :tags: bug, ext
     :tickets: 4150

     Fixed regression in association proxy due to :ticket:`3769`
     (allow for chained any() / has()) where contains() against
     an association proxy chained in the form
     (o2m relationship, associationproxy(m2o relationship, m2o relationship))
     would raise an error regarding the re-application of contains()
     on the final link of the chain.

 .. change::
     :tags: bug, orm
     :tickets: 4153

     Fixed regression caused by new lazyload caching scheme in :ticket:`3954`
     where a query that makes use of loader options with of_type would cause
     lazy loads of unrelated paths to fail with a TypeError.

 .. change::
     :tags: bug, oracle
     :tickets: 4157

     Fixed regression where the removal of most setinputsizes
     rules from cx_Oracle dialect impacted the TIMESTAMP
     datatype's ability to retrieve fractional seconds.



 .. change::
     :tags: bug, tests

     Removed an oracle-specific requirements rule from the public
     test suite that was interfering with third party dialect
     suites.

 .. change::
     :tags: bug, mssql
     :tickets: 4154

     Fixed regression in 1.2 where newly repaired quoting
     of collation names in :ticket:`3785` breaks SQL Server,
     which explicitly does not understand a quoted collation
     name.   Whether or not mixed-case collation names are
     quoted or not is now deferred down to a dialect-level
     decision so that each dialect can prepare these identifiers
     directly.

 .. change::
     :tags: bug, orm
     :tickets: 4156

     Fixed bug in new "selectin" relationship loader where the loader could try
     to load a non-existent relationship when loading a collection of
     polymorphic objects, where only some of the mappers include that
     relationship, typically when :meth:`.PropComparator.of_type` is being used.

 .. change::
     :tags: bug, tests

     Added a new exclusion rule group_by_complex_expression
     which disables tests that use "GROUP BY <expr>", which seems
     to be not viable for at least two third party dialects.

 .. change::
     :tags: bug, oracle

     Fixed regression in Oracle imports where a missing comma caused
     an undefined symbol to be present.  Pull request courtesy
     Miroslav Shubernetskiy.

.. changelog::

1.2.0

:released: December 27, 2017

 .. change::
     :tags: orm, feature
     :tickets: 4137

     Added a new data member to the identity key tuple
     used by the ORM's identity map, known as the
     "identity_token".  This token defaults to None but
     may be used by database sharding schemes to differentiate
     objects in memory with the same primary key that come
     from different databases.   The horizontal sharding
     extension integrates this token applying the shard
     identifier to it, thus allowing primary keys to be
     duplicated across horizontally sharded backends.

     .. seealso::

         :ref:`change_4137`

 .. change::
     :tags: bug, mysql
     :tickets: 4115

     Fixed regression from issue 1.2.0b3 where "MariaDB" version comparison can
     fail for some particular MariaDB version strings under Python 3.

 .. change::
     :tags: enhancement, sql
     :tickets: 959

     Implemented "DELETE..FROM" syntax for Postgresql, MySQL, MS SQL Server
     (as well as within the unsupported Sybase dialect) in a manner similar
     to how "UPDATE..FROM" works.  A DELETE statement that refers to more than
     one table will switch into "multi-table" mode and render the appropriate
     "USING" or multi-table "FROM" clause as understood by the database.
     Pull request courtesy Pieter Mulder.

     .. seealso::

         :ref:`change_959`

 .. change::
    :tags: bug, sql
    :tickets: 2694

    Reworked the new "autoescape" feature introduced in
    :ref:`change_2694` in 1.2.0b2 to be fully automatic; the escape
    character now defaults to a forwards slash ``"/"`` and
    is applied to percent, underscore, as well as the escape
    character itself, for fully automatic escaping.  The
    character can also be changed using the "escape" parameter.

    .. seealso::

         :ref:`change_2694`


 .. change::
     :tags: bug, sql
     :tickets: 4147

     Fixed bug where the :meth:`.Table.tometadata` method would not properly
     accommodate :class:`.Index` objects that didn't consist of simple
     column expressions, such as indexes against a :func:`.text` construct,
     indexes that used SQL expressions or :attr:`.func`, etc.   The routine
     now copies expressions fully to a new :class:`.Index` object while
     substituting all table-bound :class:`.Column` objects for those
     of the target table.

 .. change::
     :tags: bug, sql
     :tickets: 4142

     Changed the "visit name" of :class:`.ColumnElement` from "column" to
     "column_element", so that when this element is used as the basis for a
     user-defined SQL element, it is not assumed to behave like a table-bound
     :class:`.ColumnClause` when processed by various SQL traversal utilities,
     as are commonly used by the ORM.

 .. change::
     :tags: bug, sql, ext
     :tickets: 4141

     Fixed issue in :class:`.ARRAY` datatype which is essentially the same
     issue as that of :ticket:`3832`, except not a regression, where
     column attachment events on top of :class:`.ARRAY` would not fire
     correctly, thus interfering with systems which rely upon this.   A key
     use case that was broken by this is the use of mixins to declare
     columns that make use of :meth:`.MutableList.as_mutable`.

 .. change::
     :tags: feature, engine
     :tickets: 4089

     The "password" attribute of the :class:`.url.URL` object can now be
     any user-defined or user-subclassed string object that responds to the
     Python ``str()`` builtin.   The object passed will be maintained as the
     datamember :attr:`.url.URL.password_original` and will be consulted
     when the :attr:`.url.URL.password` attribute is read to produce the
     string value.

 .. change::
     :tags: bug, orm
     :tickets: 4130

     Fixed bug in :func:`.contains_eager` query option where making use of a
     path that used :meth:`.PropComparator.of_type` to refer to a subclass
     across more than one level of joins would also require that the "alias"
     argument were provided with the same subtype in order to avoid adding
     unwanted FROM clauses to the query; additionally,  using
     :func:`.contains_eager` across subclasses that use :func:`.aliased` objects
     of subclasses as the :meth:`.PropComparator.of_type` argument will also
     render correctly.




 .. change::
     :tags: feature, postgresql

     Added new :class:`.postgresql.MONEY` datatype.  Pull request courtesy
     Cleber J Santos.

 .. change::
     :tags: bug, sql
     :tickets: 4140

     Fixed bug in new "expanding bind parameter" feature whereby if multiple
     params were used in one statement, the regular expression would not
     match the parameter name correctly.

 .. change::
     :tags: enhancement, ext
     :tickets: 4135

     Added new method :meth:`.baked.Result.with_post_criteria` to baked
     query system, allowing non-SQL-modifying transformations to take place
     after the query has been pulled from the cache.  Among other things,
     this method can be used with :class:`.horizontal_shard.ShardedQuery`
     to set the shard identifier.   :class:`.horizontal_shard.ShardedQuery`
     has also been modified such that its :meth:`.ShardedQuery.get` method
     interacts correctly with that of :class:`.baked.Result`.

 .. change::
     :tags: bug, oracle
     :tickets: 4064

     Added some additional rules to fully handle ``Decimal('Infinity')``,
     ``Decimal('-Infinity')`` values with cx_Oracle numerics when using
     ``asdecimal=True``.

 .. change::
     :tags: bug, mssql
     :tickets: 4121

     Fixed bug where sqltypes.BINARY and sqltypes.VARBINARY datatypes
     would not include correct bound-value handlers for pyodbc,
     which allows the pyodbc.NullParam value to be passed that
     helps with FreeTDS.




 .. change::
     :tags: feature, misc

     Added a new errors section to the documentation with background
     about common error messages.   Selected exceptions within SQLAlchemy
     will include a link in their string output to the relevant section
     within this page.

 .. change::
     :tags: bug, orm
     :tickets: 4032

     The :meth:`.Query.exists` method will now disable eager loaders for when
     the query is rendered.  Previously, joined-eager load joins would be rendered
     unnecessarily as well as subquery eager load queries would be needlessly
     generated.   The new behavior matches that of the :meth:`.Query.subquery`
     method.

.. changelog::

1.2.0b3

:released: December 27, 2017
 :released: October 13, 2017

 .. change::
     :tags: feature, postgresql
     :tickets: 4109

     Added a new flag ``use_batch_mode`` to the psycopg2 dialect.  This flag
     enables the use of psycopg2's ``psycopg2.extras.execute_batch``
     extension when the :class:`.Engine` calls upon
     ``cursor.executemany()``. This extension provides a critical
     performance increase by over an order of magnitude when running INSERT
     statements in batch.  The flag is False by default as it is considered
     to be experimental for now.

     .. seealso::

         :ref:`change_4109`

 .. change::
     :tags: bug, mssql
     :tickets: 4061

     SQL Server supports what SQLAlchemy calls "native boolean"
     with its BIT type, as this type only accepts 0 or 1 and the
     DBAPIs return its value as True/False.   So the SQL Server
     dialects now enable "native boolean" support, in that a
     CHECK constraint is not generated for a :class:`.Boolean`
     datatype.  The only difference vs. other native boolean
     is that there are no "true" / "false" constants so "1" and
     "0" are still rendered here.


 .. change::
     :tags: bug, oracle
     :tickets: 4064

     Partial support for persisting and retrieving the Oracle value
     "infinity" is implemented with cx_Oracle, using Python float values
     only, e.g. ``float("inf")``.  Decimal support is not yet fulfilled by
     the cx_Oracle DBAPI driver.

 .. change::
     :tags: bug, oracle

     The cx_Oracle dialect has been reworked and modernized to take advantage of
     new patterns that weren't present in the old 4.x series of cx_Oracle. This
     includes that the minimum cx_Oracle version is the 5.x series and that
     cx_Oracle 6.x is now fully tested. The most significant change involves
     type conversions, primarily regarding the numeric / floating point and LOB
     datatypes, making more effective use of cx_Oracle type handling hooks to
     simplify how bind parameter and result data is processed.

     .. seealso::

         :ref:`change_cxoracle_12`

 .. change::
     :tags: bug, oracle
     :tickets: 3997

     two phase support for cx_Oracle has been completely removed for all
     versions of cx_Oracle, whereas in 1.2.0b1 this change only took effect for
     the 6.x series of cx_Oracle.  This feature never worked correctly
     in any version of cx_Oracle and in cx_Oracle 6.x, the API which SQLAlchemy
     relied upon was removed.

     .. seealso::

         :ref:`change_cxoracle_12`

 .. change::
     :tags: bug, oracle

     The column keys present in a result set when using :meth:`.Insert.returning`
     with the cx_Oracle backend now use the correct column / label names
     like that of all other dialects.  Previously, these came out as
     ``ret_nnn``.

     .. seealso::

         :ref:`change_cxoracle_12`

 .. change::
     :tags: bug, oracle

     Several parameters to the cx_Oracle dialect are now deprecated and will
     have no effect: ``auto_setinputsizes``, ``exclude_setinputsizes``,
     ``allow_twophase``.

     .. seealso::

         :ref:`change_cxoracle_12`


 .. change::
     :tags: bug, sql
     :tickets: 4075

     Added a new method :meth:`.DefaultExecutionContext.get_current_parameters`
     which is used within a function-based default value generator in
     order to retrieve the current parameters being passed to the statement.
     The new function differs from the
     :attr:`.DefaultExecutionContext.current_parameters` attribute in
     that it also provides for optional grouping of parameters that
     correspond to a multi-valued "insert" construct.  Previously it was not
     possible to identify the subset of parameters that were relevant to
     the function call.

     .. seealso::

         :ref:`change_4075`

         :ref:`context_default_functions`

 .. change::
     :tags: bug, orm
     :tickets: 4050

     Fixed regression introduced in 1.2.0b1 due to :ticket:`3934` where the
     :class:`.Session` would fail to "deactivate" the transaction, if a
     rollback failed (the target issue is when MySQL loses track of a SAVEPOINT).
     This would cause a subsequent call to :meth:`.Session.rollback` to raise
     an error a second time, rather than completing and bringing the
     :class:`.Session` back to ACTIVE.

 .. change::
     :tags: bug, postgresql
     :tickets: 4041

     Fixed bug where the pg8000 driver would fail if using
     :meth:`.MetaData.reflect` with a schema name, since the schema name would
     be sent as a "quoted_name" object that's a string subclass, which pg8000
     doesn't recognize.   The quoted_name type is added to pg8000's
     py_types collection on connect.

 .. change::
     :tags: bug, postgresql
     :tickets: 4016

     Enabled UUID support for the pg8000 driver, which supports native Python
     uuid round trips for this datatype.  Arrays of UUID are still not supported,
     however.

 .. change::
     :tags: mssql, bug
     :tickets: 4057

     Fixed the pymssql dialect so that percent signs in SQL text, such
     as used in modulus expressions or literal textual values, are
     **not** doubled up, as seems to be what pymssql expects.  This is
     despite the fact that the pymssql DBAPI uses the "pyformat" parameter
     style which itself considers the percent sign to be significant.

 .. change::
     :tags: bug, orm, declarative
     :tickets: 4091

     A warning is emitted if a subclass attempts to override an attribute
     that was declared on a superclass using ``declared_attr.cascading``
     that the overridden attribute will be ignored. This use
     case cannot be fully supported down to further subclasses without more
     complex development efforts, so for consistency the "cascading" is
     honored all the way down regardless of overriding attributes.

 .. change::
     :tags: bug, orm, declarative
     :tickets: 4092

     A warning is emitted if the ``declared_attr.cascading`` attribute is
     used with a special declarative name such as ``__tablename__``, as this
     has no effect.

 .. change::
     :tags: feature, engine
     :tickets: 4077

     Added ``__next__()`` and ``next()`` methods to :class:`.ResultProxy`,
     so that the ``next()`` builtin function works on the object directly.
     :class:`.ResultProxy` has long had an ``__iter__()`` method which already
     allows it to respond to the ``iter()`` builtin.   The implementation
     for ``__iter__()`` is unchanged, as performance testing has indicated
     that iteration using a ``__next__()`` method with ``StopIteration``
     is about 20% slower in both Python 2.7 and 3.6.

 .. change::
     :tags: feature, mssql
     :tickets: 4086

     Added a new :class:`.mssql.TIMESTAMP` datatype, that
     correctly acts like a binary datatype for SQL Server
     rather than a datetime type, as SQL Server breaks the
     SQL standard here.  Also added :class:`.mssql.ROWVERSION`,
     as the "TIMESTAMP" type in SQL Server is deprecated in
     favor of ROWVERSION.

 .. change::
     :tags: bug, orm
     :tickets: 4084

     Fixed issue where the :func:`.make_transient_to_detached` function
     would expire all attributes on the target object, including "deferred"
     attributes, which has the effect of the attribute being undeferred
     for the next refesh, causing an unexpected load of the attribute.

 .. change::
     :tags: bug, orm
     :tickets: 4026

     Fixed bug in :ref:`change_3948` which prevented "selectin" and
     "inline" settings in a multi-level class hierarchy from interacting
     together as expected.    A new example is added to the documentation.

     .. seealso::

         :ref:`polymorphic_selectin_and_withpoly`

 .. change::
     :tags: bug, oracle
     :tickets: 4042

     Fixed bug where an index reflected under Oracle with an expression like
     "column DESC" would not be returned, if the table also had no primary
     key, as a result of logic that attempts to filter out the
     index implicitly added by Oracle onto the primary key columns.

 .. change::
 	:tags: bug, orm
 	:tickets: 4071

 	Removed the warnings that are emitted when the LRU caches employed
 	by the mapper as well as loader strategies reach their threshold; the
 	purpose of this warning was at first a guard against excess cache keys
 	being generated but became basically a check on the "creating many
 	engines" antipattern.   While this is still an antipattern, the presense
 	of test suites which both create an engine per test as well as raise
 	on all warnings will be an inconvenience; it should not be critical
 	that such test suites change their architecture just for this warning
 	(though engine-per-test suite is always better).

 .. change::
     :tags: bug, orm
     :tickets: 4049

     Fixed regression where the use of a :func:`.undefer_group` option
     in conjunction with a lazy loaded relationship option would cause
     an attribute error, due to a bug in the SQL cache key generation
     added in 1.2 as part of :ticket:`3954`.

 .. change::
     :tags: bug, oracle
     :tickets: 4045

     Fixed more regressions caused by cx_Oracle 6.0; at the moment, the only
     behavioral change for users is disconnect detection now detects for
     cx_Oracle.DatabaseError in addition to cx_Oracle.InterfaceError, as
     this behavior seems to have changed.   Other issues regarding numeric
     precision and uncloseable connections are pending with the upstream
     cx_Oracle issue tracker.

 .. change::
     :tags: bug, mssql
     :tickets: 4060

     Fixed bug where the SQL Server dialect could pull columns from multiple
     schemas when reflecting a self-referential foreign key constraint, if
     multiple schemas contained a constraint of the same name against a
     table of the same name.


 .. change::
     :tags: feature, mssql
     :tickets: 4058

     Added support for "AUTOCOMMIT" isolation level, as established
     via :meth:`.Connection.execution_options`, to the
     PyODBC and pymssql dialects.   This isolation level sets the
     appropriate DBAPI-specific flags on the underlying
     connection object.

 .. change::
     :tags: bug, orm
     :tickets: 4073

     Modified the change made to the ORM update/delete evaluator in
     :ticket:`3366` such that if an unmapped column expression is present
     in the update or delete, if the evaluator can match its name to the
     mapped columns of the target class, a warning is emitted, rather than
     raising UnevaluatableError.  This is essentially the pre-1.2 behavior,
     and is to allow migration for applications that are currently relying
     upon this pattern.  However, if the given attribute name cannot be
     matched to the columns of the mapper, the UnevaluatableError is
     still raised, which is what was fixed in :ticket:`3366`.

 .. change::
     :tags: bug, sql
     :tickets: 4087

     Fixed bug in new SQL comments feature where table and column comment
     would not be copied when using :meth:`.Table.tometadata`.

 .. change::
     :tags: bug, sql
     :tickets: 4102

     In release 1.1, the :class:`.Boolean` type was broken in that
     boolean coercion via ``bool()`` would occur for backends that did not
     feature "native boolean", but would not occur for native boolean backends,
     meaning the string ``"0"`` now behaved inconsistently. After a poll, a
     consensus was reached that non-boolean values should be raising an error,
     especially in the ambiguous case of string ``"0"``; so the :class:`.Boolean`
     datatype will now raise ``ValueError`` if an incoming value is not
     within the range ``None, True, False, 1, 0``.

     .. seealso::

         :ref:`change_4102`

 .. change::
     :tags: bug, sql
     :tickets: 4063

     Refined the behavior of :meth:`.Operators.op` such that in all cases,
     if the :paramref:`.Operators.op.is_comparison` flag is set to True,
     the return type of the resulting expression will be
     :class:`.Boolean`, and if the flag is False, the return type of the
     resulting expression will be the same type as that of the left-hand
     expression, which is the typical default behavior of other operators.
     Also added a new parameter :paramref:`.Operators.op.return_type` as well
     as a helper method :meth:`.Operators.bool_op`.

     .. seealso::

         :ref:`change_4063`

 .. change::
     :tags: bug, mysql
     :tickets: 4072

     Changed the name of the ``.values`` attribute of the new MySQL
     INSERT..ON DUPLICATE KEY UPDATE construct to ``.inserted``, as
     :class:`.Insert` already has a method called :meth:`.Insert.values`.
     The ``.inserted`` attribute ultimately renders the MySQL ``VALUES()``
     function.

 .. change::
     :tags: bug, mssql, orm
     :tickets: 4062

     Added a new class of "rowcount support" for dialects that is specific to
     when "RETURNING", which on SQL Server looks like "OUTPUT inserted", is in
     use, as the PyODBC backend isn't able to give us rowcount on an UPDATE or
     DELETE statement when OUTPUT is in effect.  This primarily affects the ORM
     when a flush is updating a row that contains server-calcluated values,
     raising an error if the backend does not return the expected row count.
     PyODBC now states that it supports rowcount except if OUTPUT.inserted is
     present, which is taken into account by the ORM during a flush as to
     whether it will look for a rowcount.

 .. change::
     :tags: bug, sql
     :tickets: 4088

     Internal refinements to the :class:`.Enum`, :class:`.Interval`, and
     :class:`.Boolean` types, which now extend a common mixin
     :class:`.Emulated` that indicates a type that provides Python-side
     emulation of a DB native type, switching out to the DB native type when a
     supporting backend is in use.   The Postgresql :class:`.INTERVAL` type
     when used directly will now include the correct type coercion rules for
     SQL expressions that also take effect for :class:`.sqltypes.Interval`
     (such as adding a date to an interval yields a datetime).


 .. change::
     :tags: bug, mssql, orm

     Enabled the "sane_rowcount" flag for the pymssql dialect, indicating
     that the DBAPI now reports the correct number of rows affected from
     an UPDATE or DELETE statement.  This impacts mostly the ORM versioning
     feature in that it now can verify the number of rows affected on a
     target version.

 .. change:: 4028
     :tags: bug, engine
     :tickets: 4028

     Made some adjustments to :class:`.Pool` and :class:`.Connection` such
     that recovery logic is not run underneath exception catches for
     ``pool.Empty``, ``AttributeError``, since when the recovery operation
     itself fails, Python 3 creates a misleading stack trace referring to the
     ``Empty`` / ``AttributeError`` as the cause, when in fact these exception
     catches are part of control flow.


 .. change::
     :tags: bug, oracle
     :tickets: 4076

     Fixed bug where Oracle 8 "non ansi" join mode would not add the
     ``(+)`` operator to expressions that used an operator other than the
     ``=`` operator.  The ``(+)`` needs to be on all columns that are part
     of the right-hand side.

 .. change::
     :tags: bug, mssql
     :tickets: 4059

     Added a rule to SQL Server index reflection to ignore the so-called
     "heap" index that is implicitly present on a table that does not
     specify a clustered index.


.. changelog::

1.2.0b2

:released: December 27, 2017
 :released: July 24, 2017

 .. change:: 4033
     :tags: bug, orm
     :tickets: 4033

     Fixed regression from 1.1.11 where adding additional non-entity
     columns to a query that includes an entity with subqueryload
     relationships would fail, due to an inspection added in 1.1.11 as a
     result of :ticket:`4011`.


.. changelog::

1.2.0b1

:released: December 27, 2017
 :released: July 10, 2017

 .. change:: scoped_autocommit
     :tags: feature, orm

     Added ``.autocommit`` attribute to :class:`.scoped_session`, proxying
     the ``.autocommit`` attribute of the underling :class:`.Session`
     currently assigned to the thread.  Pull request courtesy
     Ben Fagin.

 .. change:: 4009
     :tags: feature, mysql
     :tickets: 4009

     Added support for MySQL's ON DUPLICATE KEY UPDATE
     MySQL-specific :class:`.mysql.dml.Insert` object.
     Pull request courtesy Michael Doronin.

     .. seealso::

         :ref:`change_4009`

 .. change:: 4018
     :tags: bug, sql
     :tickets: 4018

     The rules for type coercion between :class:`.Numeric`, :class:`.Integer`,
     and date-related types now include additional logic that will attempt
     to preserve the settings of the incoming type on the "resolved" type.
     Currently the target for this is the ``asdecimal`` flag, so that
     a math operation between :class:`.Numeric` or :class:`.Float` and
     :class:`.Integer` will preserve the "asdecimal" flag as well as
     if the type should be the :class:`.Float` subclass.

     .. seealso::

         :ref:`change_floats_12`

 .. change:: 4020
     :tags: bug, sql, mysql
     :tickets: 4020

     The result processor for the :class:`.Float` type now unconditionally
     runs values through the ``float()`` processor if the dialect
     specifies that it also supports "native decimal" mode.  While most
     backends will deliver Python ``float`` objects for a floating point
     datatype, the MySQL backends in some cases lack the typing information
     in order to provide this and return ``Decimal`` unless the float
     conversion is done.

     .. seealso::

         :ref:`change_floats_12`

 .. change:: 4017
     :tags: bug, sql
     :tickets: 4017

     Added some extra strictness to the handling of Python "float" values
     passed to SQL statements.  A "float" value will be associated with the
     :class:`.Float` datatype and not the Decimal-coercing :class:`.Numeric`
     datatype as was the case before, eliminating a confusing warning
     emitted on SQLite as well as unecessary coercion to Decimal.

     .. seealso::

         :ref:`change_floats_12`

 .. change:: 3058
     :tags: feature, orm
     :tickets: 3058

     Added a new feature :func:`.orm.with_expression` that allows an ad-hoc
     SQL expression to be added to a specific entity in a query at result
     time.  This is an alternative to the SQL expression being delivered as
     a separate element in the result tuple.

     .. seealso::

         :ref:`change_3058`

 .. change:: 3496
     :tags: bug, orm
     :tickets: 3496

     An UPDATE emitted as a result of the
     :paramref:`.relationship.post_update` feature will now integrate with
     the versioning feature to both bump the version id of the row as well
     as assert that the existing version number was matched.

     .. seealso::

         :ref:`change_3496`

 .. change:: 3769
     :tags: bug, ext
     :tickets: 3769

     The :meth:`.AssociationProxy.any`, :meth:`.AssociationProxy.has`
     and :meth:`.AssociationProxy.contains` comparison methods now support
     linkage to an attribute that is itself also an
     :class:`.AssociationProxy`, recursively.

     .. seealso::

         :ref:`change_3769`

 .. change:: 3853
     :tags: bug, ext
     :tickets: 3853

     Implemented in-place mutation operators ``__ior__``, ``__iand__``,
     ``__ixor__`` and ``__isub__`` for :class:`.mutable.MutableSet`
     and ``__iadd__`` for :class:`.mutable.MutableList` so that change
     events are fired off when these mutator methods are used to alter the
     collection.

     .. seealso::

         :ref:`change_3853`

 .. change:: 3847
     :tags: bug, declarative
     :tickets: 3847

     A warning is emitted if the :attr:`.declared_attr.cascading` modifier
     is used with a declarative attribute that is itself declared on
     a class that is to be mapped, as opposed to a declarative mixin
     class or ``__abstract__`` class.  The :attr:`.declared_attr.cascading`
     modifier currently only applies to mixin/abstract classes.

 .. change:: 4003
     :tags: feature, oracle
     :tickets: 4003

     The Oracle dialect now inspects unique and check constraints when using
     :meth:`.Inspector.get_unique_constraints`,
     :meth:`.Inspector.get_check_constraints`.
     As Oracle does not have unique constraints that are separate from a unique
     :class:`.Index`, a :class:`.Table` that's reflected will still continue
     to not have :class:`.UniqueConstraint` objects associated with it.
     Pull requests courtesy Eloy Felix.

     .. seealso::

         :ref:`change_4003`

 .. change:: 3948
     :tags: feature, orm
     :tickets: 3948

     Added a new style of mapper-level inheritance loading
     "polymorphic selectin".  This style of loading
     emits queries for each subclass in an inheritance
     hierarchy subsequent to the load of the base
     object type, using IN to specify the desired
     primary key values.

     .. seealso::

         :ref:`change_3948`

 .. change:: 3472
     :tags: bug, orm
     :tickets: 3471, 3472

     Repaired several use cases involving the
     :paramref:`.relationship.post_update` feature when used in conjunction
     with a column that has an "onupdate" value.   When the UPDATE emits,
     the corresponding object attribute is now expired or refreshed so that
     the newly generated "onupdate" value can populate on the object;
     previously the stale value would remain.  Additionally, if the target
     attribute is set in Python for the INSERT of the object, the value is
     now re-sent during the UPDATE so that the "onupdate" does not overwrite
     it (note this works just as well for server-generated onupdates).
     Finally, the :meth:`.SessionEvents.refresh_flush` event is now emitted
     for these attributes when refreshed within the flush.

     .. seealso::

         :ref:`change_3471`

 .. change:: 3996
     :tags: bug, orm
     :tickets: 3996

     Fixed bug where programmatic version_id counter in conjunction with
     joined table inheritance would fail if the version_id counter
     were not actually incremented and no other values on the base table
     were modified, as the UPDATE would have an empty SET clause.  Since
     programmatic version_id where version counter is not incremented
     is a documented use case, this specific condition is now detected
     and the UPDATE now sets the version_id value to itself, so that
     concurrency checks still take place.

 .. change:: 3848
     :tags: bug, orm, declarative
     :tickets: 3848

     Fixed bug where using :class:`.declared_attr` on an
     :class:`.AbstractConcreteBase` where a particular return value were some
     non-mapped symbol, including ``None``, would cause the attribute
     to hard-evaluate just once and store the value to the object
     dictionary, not allowing it to invoke for subclasses.   This behavior
     is normal when :class:`.declared_attr` is on a mapped class, and
     does not occur on a mixin or abstract class.  Since
     :class:`.AbstractConcreteBase` is both "abstract" and actually
     "mapped", a special exception case is made here so that the
     "abstract" behavior takes precedence for :class:`.declared_attr`.

 .. change:: 3673
     :tags: bug, orm
     :tickets: 3673

     The versioning feature does not support NULL for the version counter.
     An exception is now raised if the version id is programmatic and
     was set to NULL for an UPDATE.  Pull request courtesy Diana Clarke.

 .. change:: 3999
     :tags: bug, sql
     :tickets: 3999

     The operator precedence for all comparison operators such as LIKE, IS,
     IN, MATCH, equals, greater than, less than, etc. has all been merged
     into one level, so that expressions which make use of these against
     each other will produce parentheses between them.   This suits the
     stated operator precedence of databases like Oracle, MySQL and others
     which place all of these operators as equal precedence, as well as
     Postgresql as of 9.5 which has also flattened its operator precendence.

     .. seealso::

         :ref:`change_3999`


 .. change:: 3796
     :tags: bug, orm
     :tickets: 3796

     Removed a very old keyword argument from :class:`.scoped_session`
     called ``scope``.  This keyword was never documented and was an
     early attempt at allowing for variable scopes.

     .. seealso::

         :ref:`change_3796`

 .. change:: 3871
     :tags: bug, mysql
     :tickets: 3871

     Added support for views that are unreflectable due to stale
     table definitions, when calling :meth:`.MetaData.reflect`; a warning
     is emitted for the table that cannot respond to ``DESCRIBE``,
     but the operation succeeds.

 .. change:: baked_opts
     :tags: feature, ext

     Added new flag :paramref:`.Session.enable_baked_queries` to the
     :class:`.Session` to allow baked queries to be disabled
     session-wide, reducing memory use.   Also added new :class:`.Bakery`
     wrapper so that the bakery returned by :paramref:`.BakedQuery.bakery`
     can be inspected.

 .. change:: 3988
     :tags: bug, orm
     :tickets: 3988

     Fixed bug where combining a "with_polymorphic" load in conjunction
     with subclass-linked relationships that specify joinedload with
     innerjoin=True, would fail to demote those "innerjoins" to
     "outerjoins" to suit the other polymorphic classes that don't
     support that relationship.   This applies to both a single and a
     joined inheritance polymorphic load.

 .. change:: 3991
     :tags: bug, orm
     :tickets: 3991

     Added new argument :paramref:`.with_for_update` to the
     :meth:`.Session.refresh` method.  When the :meth:`.Query.with_lockmode`
     method were deprecated in favor of :meth:`.Query.with_for_update`,
     the :meth:`.Session.refresh` method was never updated to reflect
     the new option.

     .. seealso::

         :ref:`change_3991`

 .. change:: 3984
     :tags: bug, orm
     :tickets: 3984

     Fixed bug where a :func:`.column_property` that is also marked as
     "deferred" would be marked as "expired" during a flush, causing it
     to be loaded along with the unexpiry of regular attributes even
     though this attribute was never accessed.

 .. change:: 3873
     :tags: bug, sql
     :tickets: 3873

     Repaired issue where the type of an expression that used
     :meth:`.ColumnOperators.is_` or similar would not be a "boolean" type,
     instead the type would be "nulltype", as well as when using custom
     comparison operators against an untyped expression.   This typing can
     impact how the expression behaves in larger contexts as well as
     in result-row-handling.

 .. change:: 3941
     :tags: bug, ext
     :tickets: 3941

     Improved the association proxy list collection so that premature
     autoflush against a newly created association object can be prevented
     in the case where ``list.append()`` is being used, and a lazy load
     would be invoked when the association proxy accesses the endpoint
     collection.  The endpoint collection is now accessed first before
     the creator is invoked to produce the association object.

 .. change:: 3969
     :tags: bug, sql
     :tickets: 3969

     Fixed the negation of a :class:`.Label` construct so that the
     inner element is negated correctly, when the :func:`.not_` modifier
     is applied to the labeled expression.

 .. change:: 3944
     :tags: feature, orm
     :tickets: 3944

     Added a new kind of eager loading called "selectin" loading.  This
     style of loading is very similar to "subquery" eager loading,
     except that it uses an IN expression given a list of primary key
     values from the loaded parent objects, rather than re-stating the
     original query.   This produces a more efficient query that is
     "baked" (e.g. the SQL string is cached) and also works in the
     context of :meth:`.Query.yield_per`.

     .. seealso::

         :ref:`change_3944`

 .. change::
     :tags: bug, orm
     :tickets: 3967

     Fixed bug in subquery eager loading where the "join_depth" parameter
     for self-referential relationships would not be correctly honored,
     loading all available levels deep rather than correctly counting
     the specified number of levels for eager loading.

 .. change::
     :tags: bug, orm

     Added warnings to the LRU "compiled cache" used by the :class:`.Mapper`
     (and ultimately will be for other ORM-based LRU caches) such that
     when the cache starts hitting its size limits, the application will
     emit a warning that this is a performance-degrading situation that
     may require attention.   The LRU caches can reach their size limits
     primarily if an application is making use of an unbounded number
     of :class:`.Engine` objects, which is an antipattern.  Otherwise,
     this may suggest an issue that should be brought to the SQLAlchemy
     developer's attention.

 .. change:: 3964
     :tags: bug, postgresql
     :tickets: 3964

     Fixed bug where the base :class:`.sqltypes.ARRAY` datatype would not
     invoke the bind/result processors of :class:`.postgresql.ARRAY`.

 .. change:: 3963
     :tags: bug, orm
     :tickets: 3963

     Fixed bug to improve upon the specificity of loader options that
     take effect subsequent to the lazy load of a related entity, so
     that the loader options will match to an aliased or non-aliased
     entity more specifically if those options include entity information.

 .. change:: 3954
     :tags: feature, orm
     :tickets: 3954

     The ``lazy="select"`` loader strategy now makes used of the
     :class:`.BakedQuery` query caching system in all cases.  This
     removes most overhead of generating a :class:`.Query` object and
     running it into a :func:`.select` and then string SQL statement from
     the process of lazy-loading related collections and objects.  The
     "baked" lazy loader has also been improved such that it can now
     cache in most cases where query load options are used.

     .. seealso::

         :ref:`change_3954`

 .. change:: 3740
     :tags: bug, sql
     :tickets: 3740

     The system by which percent signs in SQL statements are "doubled"
     for escaping purposes has been refined.   The "doubling" of percent
     signs mostly associated with the :obj:`.literal_column` construct
     as well as operators like :meth:`.ColumnOperators.contains` now
     occurs based on the stated paramstyle of the DBAPI in use; for
     percent-sensitive paramstyles as are common with the Postgresql
     and MySQL drivers the doubling will occur, for others like that
     of SQLite it will not.   This allows more database-agnostic use
     of the :obj:`.literal_column` construct to be possible.

     .. seealso::

         :ref:`change_3740`

 .. change:: 3959
     :tags: bug, postgresql
     :tickets: 3959

     Added support for all possible "fields" identifiers when reflecting the
     Postgresql ``INTERVAL`` datatype, e.g. "YEAR", "MONTH", "DAY TO
     MINUTE", etc..   In addition, the :class:`.postgresql.INTERVAL`
     datatype itself now includes a new parameter
     :paramref:`.postgresql.INTERVAL.fields` where these qualifiers can be
     specified; the qualifier is also reflected back into the resulting
     datatype upon reflection / inspection.

     .. seealso::

         :ref:`change_3959`

 .. change:: 3957
     :tags: bug, sql
     :tickets: 3957

     Fixed bug where a column-level :class:`.CheckConstraint` would fail
     to compile the SQL expression using the underlying dialect compiler
     as well as apply proper flags to generate literal values as
     inline, in the case that the sqltext is a Core expression and
     not just a plain string.   This was long-ago fixed for table-level
     check constraints in 0.9 as part of :ticket:`2742`, which more commonly
     feature Core SQL expressions as opposed to plain string expressions.

 .. change:: 2626
     :tags: bug, mssql
     :tickets: 2626

     The SQL Server dialect now allows for a database and/or owner name
     with a dot inside of it, using brackets explicitly in the string around
     the owner and optionally the database name as well.  In addition,
     sending the :class:`.quoted_name` construct for the schema name will
     not split on the dot and will deliver the full string as the "owner".
     :class:`.quoted_name` is also now available from the ``sqlalchemy.sql``
     import space.

     .. seealso::

         :ref:`change_2626`

 .. change:: 3953
     :tags: feature, sql
     :tickets: 3953

     Added a new kind of :func:`.bindparam` called "expanding".  This is
     for use in ``IN`` expressions where the list of elements is rendered
     into individual bound parameters at statement execution time, rather
     than at statement compilation time.  This allows both a single bound
     parameter name to be linked to an IN expression of multiple elements,
     as well as allows query caching to be used with IN expressions.  The
     new feature allows the related features of "select in" loading and
     "polymorphic in" loading to make use of the baked query extension
     to reduce call overhead.   This feature should be considered to be
     **experimental** for 1.2.

     .. seealso::

         :ref:`change_3953`

 .. change:: 3923
     :tags: bug, sql
     :tickets: 3923

     Fixed bug where a SQL-oriented Python-side column default could fail to
     be executed properly upon INSERT in the "pre-execute" codepath, if the
     SQL itself were an untyped expression, such as plain text.  The "pre-
     execute" codepath is fairly uncommon however can apply to non-integer
     primary key columns with SQL defaults when RETURNING is not used.

 .. change:: 3785
     :tags: bug, sql
     :tickets: 3785

     The expression used for COLLATE as rendered by the column-level
     :func:`.expression.collate` and :meth:`.ColumnOperators.collate` is now
     quoted as an identifier when the name is case sensitive, e.g. has
     uppercase characters.  Note that this does not impact type-level
     collation, which is already quoted.

     .. seealso::

         :ref:`change_3785`

 .. change:: 3229
     :tags: feature, orm, ext
     :tickets: 3229

     The :meth:`.Query.update` method can now accommodate both
     hybrid attributes as well as composite attributes as a source
     of the key to be placed in the SET clause.   For hybrids, an
     additional decorator :meth:`.hybrid_property.update_expression`
     is supplied for which the user supplies a tuple-returning function.

     .. seealso::

         :ref:`change_3229`

 .. change:: 3753
     :tags: bug, orm
     :tickets: 3753

     The :func:`.attributes.flag_modified` function now raises
     :class:`.InvalidRequestError` if the named attribute key is not
     present within the object, as this is assumed to be present
     in the flush process.  To mark an object "dirty" for a flush
     without referring to any specific attribute, the
     :func:`.attributes.flag_dirty` function may be used.

     .. seealso::

         :ref:`change_3753`

 .. change:: 3911_3912
     :tags: bug, ext
     :tickets: 3911, 3912

     The :class:`sqlalchemy.ext.hybrid.hybrid_property` class now supports
     calling mutators like ``setter``, ``expression`` etc. multiple times
     across subclasses, and now provides a ``getter`` mutator, so that
     a particular hybrid can be repurposed across subclasses or other
     classes.  This now matches the behavior of ``property`` in standard
     Python.

     .. seealso::

         :ref:`change_3911_3912`



 .. change:: 1546
     :tags: feature, sql, postgresql, mysql, oracle
     :tickets: 1546

     Added support for SQL comments on :class:`.Table` and :class:`.Column`
     objects, via the new :paramref:`.Table.comment` and
     :paramref:`.Column.comment` arguments.   The comments are included
     as part of DDL on table creation, either inline or via an appropriate
     ALTER statement, and are also reflected back within table reflection,
     as well as via the :class:`.Inspector`.   Supported backends currently
     include MySQL, Postgresql, and Oracle.  Many thanks to Frazer McLean
     for a large amount of effort on this.

     .. seealso::

         :ref:`change_1546`

 .. change:: 3919
     :tags: feature, engine
     :tickets: 3919

     Added native "pessimistic disconnection" handling to the :class:`.Pool`
     object.  The new parameter :paramref:`.Pool.pre_ping`, available from
     the engine as :paramref:`.create_engine.pool_pre_ping`, applies an
     efficient form of the "pre-ping" recipe featured in the pooling
     documentation, which upon each connection check out, emits a simple
     statement, typically "SELECT 1", to test the connection for liveness.
     If the existing connection is no longer able to respond to commands,
     the connection is transparently recycled, and all other connections
     made prior to the current timestamp are invalidated.

     .. seealso::

         :ref:`pool_disconnects_pessimistic`

         :ref:`change_3919`

 .. change:: 3939
     :tags: bug, sql
     :tickets: 3939

     Fixed bug where the use of an :class:`.Alias` object in a column
     context would raise an argument error when it tried to group itself
     into a parenthesized expression.   Using :class:`.Alias` in this way
     is not yet a fully supported API, however it applies to some end-user
     recipes and may have a more prominent role in support of some
     future Postgresql features.

 .. change:: 3366
     :tags: bug, orm
     :tickets: 3366

     The "evaluate" strategy used by :meth:`.Query.update` and
     :meth:`.Query.delete` can now accommodate a simple
     object comparison from a many-to-one relationship to an instance,
     when the attribute names of the primary key / foreign key columns
     don't match the actual names of the columns.  Previously this would
     do a simple name-based match and fail with an AttributeError.

 .. change:: 3896_a
     :tags: feature, orm
     :tickets: 3896

     Added new attribute event :meth:`.AttributeEvents.bulk_replace`.
     This event is triggered when a collection is assigned to a
     relationship, before the incoming collection is compared with the
     existing one.  This early event allows for conversion of incoming
     non-ORM objects as well.  The event is integrated with the
     ``validates`` decorator.

     .. seealso::

         :ref:`change_3896_event`

 .. change:: 3896_b
     :tags: bug, orm
     :tickets: 3896

     The ``validates`` decorator now allows the decorated method to receive
     objects from a "bulk collection set" operation that have not yet
     been compared to the existing collection.  This allows incoming values
     to be converted to compatible ORM objects as is already allowed
     from an "append" event.   Note that this means that the
     ``validates`` method is called for **all** values during a collection
     assignment, rather than just the ones that are new.

     .. seealso::

         :ref:`change_3896_validates`

 .. change:: 3938
     :tags: bug, engine
     :tickets: 3938

     Fixed bug where in the unusual case of passing a
     :class:`.Compiled` object directly to :meth:`.Connection.execute`,
     the dialect with which the :class:`.Compiled` object were generated
     was not consulted for the paramstyle of the string statement, instead
     assuming it would match the dialect-level paramstyle, causing
     mismatches to occur.

 .. change:: 3303
     :tags: feature, orm
     :tickets: 3303

     Added new event handler :meth:`.AttributeEvents.modified` which is
     triggered when the func:`.attributes.flag_modified` function is
     invoked, which is common when using the :mod:`sqlalchemy.ext.mutable`
     extension module.

     .. seealso::

         :ref:`change_3303`

 .. change:: 3918
     :tags: bug, ext
     :tickets: 3918

     Fixed a bug in the ``sqlalchemy.ext.serializer`` extension whereby
     an "annotated" SQL element (as produced by the ORM for many types
     of SQL expressions) could not be reliably serialized.  Also bumped
     the default pickle level for the serializer to "HIGHEST_PROTOCOL".

 .. change:: 3891
     :tags: bug, orm
     :tickets: 3891

     Fixed bug in single-table inheritance where the select_from()
     argument would not be taken into account when limiting rows
     to a subclass.  Previously, only expressions in the
     columns requested would be taken into account.

     .. seealso::

         :ref:`change_3891`

 .. change:: 3913
     :tags: bug, orm
     :tickets: 3913

     When assigning a collection to an attribute mapped by a relationship,
     the previous collection is no longer mutated.  Previously, the old
     collection would be emptied out in conjunction with the "item remove"
     events that fire off; the events now fire off without affecting
     the old collection.

     .. seealso::

         :ref:`change_3913`

 .. change:: 3932
     :tags: bug, oracle
     :tickets: 3932

     The cx_Oracle dialect now supports "sane multi rowcount", that is,
     when a series of parameter sets are executed via DBAPI
     ``cursor.executemany()``, we can make use of ``cursor.rowcount`` to
     verify the number of rows matched.  This has an impact within the
     ORM when detecting concurrent modification scenarios, in that
     some simple conditions can now be detected even when the ORM
     is batching statements, as well as when the more strict versioning
     feature is used, the ORM can still use statement batching.  The
     flag is enabled for cx_Oracle assuming at least version 5.0, which
     is now commonplace.

 .. change:: 3907
     :tags: feature, sql
     :tickets: 3907

     The longstanding behavior of the :meth:`.ColumnOperators.in_` and
     :meth:`.ColumnOperators.notin_` operators emitting a warning when
     the right-hand condition is an empty sequence has been revised;
     a simple "static" expression of "1 != 1" or "1 = 1" is now rendered
     by default, rather than pulling in the original left-hand
     expression.  This causes the result for a NULL column comparison
     against an empty set to change from NULL to true/false.  The
     behavior is configurable, and the old behavior can be enabled
     using th

[codecov-io]

Codecov Report

Merging #117 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #117   +/-   ##
=======================================
  Coverage   95.05%   95.05%           
=======================================
  Files           5        5           
  Lines         465      465           
=======================================
  Hits          442      442           
  Misses         23       23

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