1.4.5

Released: April 2, 2021

orm

• [orm] [bug] [regression] Fixed regression where the _orm.joinedload() loader strategy would
  not successfully joinedload to a mapper that is mapper against a
  CTE construct.

  References: #6172

• [orm] [bug] [regression] Scaled back the warning message added in #5171 to not warn for
  overlapping columns in an inheritance scenario where a particular
  relationship is local to a subclass and therefore does not represent an
  overlap.

  References: #6171

sql

• [sql] [bug] [postgresql] Fixed bug in new _functions.FunctionElement.render_derived() feature
  where column names rendered out explicitly in the alias SQL would not have
  proper quoting applied for case sensitive names and other non-alphanumeric
  names.

  References: #6183

• [sql] [bug] [regression] Fixed regression where use of the Operators.in_() method with a
  _sql.Select object against a non-table-bound column would produce
  an AttributeError, or more generally using a _sql.ScalarSelect
  that has no datatype in a binary expression would produce invalid state.

  References: #6181

• [sql] [bug] Added a new flag to the _engine.Dialect class called
  _engine.Dialect.supports_statement_cache. This flag now needs to be present
  directly on a dialect class in order for SQLAlchemy's
  query cache <sql_caching> to take effect for that dialect. The
  rationale is based on discovered issues such as #6173 revealing
  that dialects which hardcode literal values from the compiled statement,
  often the numerical parameters used for LIMIT / OFFSET, will not be
  compatible with caching until these dialects are revised to use the
  parameters present in the statement only. For third party dialects where
  this flag is not applied, the SQL logging will show the message "dialect
  does not support caching", indicating the dialect should seek to apply this
  flag once they have verified that no per-statement literal values are being
  rendered within the compilation phase.

  References: #6184

schema

• [schema] [bug] Introduce a new parameter _types.Enum.omit_aliases in
  _types.Enum type allow filtering aliases when using a pep435 Enum.
  Previous versions of SQLAlchemy kept aliases in all cases, creating
  database enum type with additional states, meaning that they were treated
  as different values in the db. For backward compatibility this flag
  defaults to False in the 1.4 series, but will be switched to True
  in a future version. A deprecation warning is raise if this flag is not
  specified and the passed enum contains aliases.

  References: #6146

mypy

• [mypy] [bug] Fixed issue in mypy plugin where newly added support for
  _orm.as_declarative() needed to more fully add the
  DeclarativeMeta class to the mypy interpreter's state so that it does
  not result in a name not found error; additionally improves how global
  names are setup for the plugin including the Mapped name.

  References: #sqlalchemy/sqlalchemy2-stubs/#14

asyncio

• [asyncio] [bug] Fixed issue where the asyncio extension could not be loaded
  if running Python 3.6 with the backport library of
  contextvars installed.

  References: #6166

postgresql

• [postgresql] [bug] [regression] Fixed regression caused by #6023 where the PostgreSQL cast
  operator applied to elements within an _types.ARRAY when using
  psycopg2 would fail to use the correct type in the case that the datatype
  were also embedded within an instance of the _types.Variant
  adapter.

  Additionally, repairs support for the correct CREATE TYPE to be emitted
  when using a Variant(ARRAY(some_schema_type)).

  This change is also backported to: 1.3.25

  References: #6182

• [postgresql] [bug] Fixed typo in the fix for #6099 released in 1.4.4 that completely
  prevented this change from working correctly, i.e. the error message did not match
  what was actually emitted by pg8000.

  References: #6099

• [postgresql] [bug] Fixed issue where the PostgreSQL PGInspector, when generated
  against an _engine.Engine, would fail for .get_enums(),
  .get_view_names(), .get_foreign_table_names() and
  .get_table_oid() when used against a "future" style engine and not the
  connection directly.

  References: #6170

mysql

• [mysql] [bug] [regression] Fixed regression in the MySQL dialect where the reflection query used to
  detect if a table exists would fail on very old MySQL 5.0 and 5.1 versions.

  References: #6163

mssql

• [mssql] [bug] Fixed a regression in MSSQL 2012+ that prevented the order by clause
  to be rendered when offset=0 is used in a subquery.

  References: #6163

oracle

• [oracle] [bug] [regression] Fixed critical regression where the Oracle compiler would not maintain the
  correct parameter values in the LIMIT/OFFSET for a select due to a caching
  issue.

  References: #6173