1.4.42

Released: October 16, 2022

orm

• [orm] [bug] The _orm.Session.execute.bind_arguments dictionary is no longer
  mutated when passed to _orm.Session.execute() and similar; instead,
  it's copied to an internal dictionary for state changes. Among other
  things, this fixes and issue where the "clause" passed to the
  _orm.Session.get_bind() method would be incorrectly referring to the
  _sql.Select construct used for the "fetch" synchronization
  strategy, when the actual query being emitted was a _dml.Delete or
  _dml.Update. This would interfere with recipes for "routing
  sessions".

  References: #8614

• [orm] [bug] A warning is emitted in ORM configurations when an explicit
  _orm.remote() annotation is applied to columns that are local to the
  immediate mapped class, when the referenced class does not include any of
  the same table columns. Ideally this would raise an error at some point as
  it's not correct from a mapping point of view.

  References: #7094

• [orm] [bug] A warning is emitted when attempting to configure a mapped class within an
  inheritance hierarchy where the mapper is not given any polymorphic
  identity, however there is a polymorphic discriminator column assigned.
  Such classes should be abstract if they never intend to load directly.

  References: #7545

• [orm] [bug] [regression] Fixed regression for 1.4 in _orm.contains_eager() where the "wrap in
  subquery" logic of _orm.joinedload() would be inadvertently triggered
  for use of the _orm.contains_eager() function with similar statements
  (e.g. those that use distinct(), limit() or offset()), which
  would then lead to secondary issues with queries that used some
  combinations of SQL label names and aliasing. This "wrapping" is not
  appropriate for _orm.contains_eager() which has always had the
  contract that the user-defined SQL statement is unmodified with the
  exception of adding the appropriate columns to be fetched.

  References: #8569

• [orm] [bug] [regression] Fixed regression where using ORM update() with synchronize_session='fetch'
  would fail due to the use of evaluators that are now used to determine the
  in-Python value for expressions in the the SET clause when refreshing
  objects; if the evaluators make use of math operators against non-numeric
  values such as PostgreSQL JSONB, the non-evaluable condition would fail to
  be detected correctly. The evaluator now limits the use of math mutation
  operators to numeric types only, with the exception of "+" that continues
  to work for strings as well. SQLAlchemy 2.0 may alter this further by
  fetching the SET values completely rather than using evaluation.

  References: #8507

engine

• [engine] [bug] Fixed issue where mixing "*" with additional explicitly-named column
  expressions within the columns clause of a _sql.select() construct
  would cause result-column targeting to sometimes consider the label name or
  other non-repeated names to be an ambiguous target.

  References: #8536

asyncio

• [asyncio] [bug] Improved implementation of asyncio.shield() used in context managers as
  added in #8145, such that the "close" operation is enclosed within
  an asyncio.Task which is then strongly referenced as the operation
  proceeds. This is per Python documentation indicating that the task is
  otherwise not strongly referenced.

  References: #8516

postgresql

• [postgresql] [usecase] _postgresql.aggregate_order_by now supports cache generation.

  References: #8574

mysql

• [mysql] [bug] Adjusted the regular expression used to match "CREATE VIEW" when
  testing for views to work more flexibly, no longer requiring the
  special keyword "ALGORITHM" in the middle, which was intended to be
  optional but was not working correctly. The change allows view reflection
  to work more completely on MySQL-compatible variants such as StarRocks.
  Pull request courtesy John Bodley.

  References: #8588

mssql

• [mssql] [bug] [regression] Fixed yet another regression in SQL Server isolation level fetch (see
  #8231, #8475), this time with "Microsoft Dynamics CRM
  Database via Azure Active Directory", which apparently lacks the
  system_views view entirely. Error catching has been extended that under
  no circumstances will this method ever fail, provided database connectivity
  is present.

  References: #8525