1.3.16

Released: April 7, 2020

orm

• [orm] [bug] Fixed bug in orm.selectinload() loading option where two or more
  loaders that represent different relationships with the same string key
  name as referenced from a single orm.with_polymorphic() construct
  with multiple subclass mappers would fail to invoke each subqueryload
  separately, instead making use of a single string-based slot that would
  prevent the other loaders from being invoked.

  References: #5228

• [orm] [performance] Modified the queries used by subqueryload and selectinload to no longer
  ORDER BY the primary key of the parent entity; this ordering was there to
  allow the rows as they come in to be copied into lists directly with a
  minimal level of Python-side collation. However, these ORDER BY clauses
  can negatively impact the performance of the query as in many scenarios
  these columns are derived from a subquery or are otherwise not actual
  primary key columns such that SQL planners cannot make use of indexes. The
  Python-side collation uses the native itertools.group_by() to collate the
  incoming rows, and has been modified to allow multiple
  row-groups-per-parent to be assembled together using list.extend(), which
  should still allow for relatively fast Python-side performance. There will
  still be an ORDER BY present for a relationship that includes an explicit
  order_by parameter, however this is the only ORDER BY that will be added to
  the query for both kinds of loading.

  References: #5162

• [orm] [bug] Fixed issue where a lazyload that uses session-local "get" against a target
  many-to-one relationship where an object with the correct primary key is
  present, however it's an instance of a sibling class, does not correctly
  return None as is the case when the lazy loader actually emits a load for
  that row.

  References: #5210

orm declarative

• [bug] [declarative] [orm] The string argument accepted as the first positional argument by the
  relationship() function when using the Declarative API is no longer
  interpreted using the Python eval() function; instead, the name is dot
  separated and the names are looked up directly in the name resolution
  dictionary without treating the value as a Python expression. However,
  passing a string argument to the other relationship() parameters
  that necessarily must accept Python expressions will still use eval();
  the documentation has been clarified to ensure that there is no ambiguity
  that this is in use.

  References: #5238

sql

• [sql] [types] Add ability to literal compile a DateTime, Date
  or :class:"Time" when using the string dialect for debugging purposes.
  This change does not impact real dialect implementation that retain
  their current behavior.

  References: #5052

schema

• [schema] [reflection] Added support for reflection of "computed" columns, which are now returned
  as part of the structure returned by Inspector.get_columns().
  When reflecting full Table objects, computed columns will
  be represented using the Computed construct.

  References: #5063

postgresql

• [postgresql] [bug] Fixed issue where a "covering" index, e.g. those which have an INCLUDE
  clause, would be reflected including all the columns in INCLUDE clause as
  regular columns. A warning is now emitted if these additional columns are
  detected indicating that they are currently ignored. Note that full
  support for "covering" indexes is part of #4458. Pull request
  courtesy Marat Sharafutdinov.

  References: #5205

mysql

• [mysql] [bug] Fixed issue in MySQL dialect when connecting to a psuedo-MySQL database
  such as that provided by ProxySQL, the up front check for isolation level
  when it returns no row will not prevent the dialect from continuing to
  connect. A warning is emitted that the isolation level could not be
  detected.

  References: #5239

sqlite

• [sqlite] [usecase] Implemented AUTOCOMMIT isolation level for SQLite when using pysqlite.

  References: #5164

mssql

• [mssql] [mysql] [oracle] [usecase] Added support for ColumnOperators.is_distinct_from() and
  ColumnOperators.isnot_distinct_from() to SQL Server,
  MySQL, and Oracle.

  References: #5137

oracle

• [oracle] [usecase] Implemented AUTOCOMMIT isolation level for Oracle when using cx_Oracle.
  Also added a fixed default isolation level of READ COMMITTED for Oracle.

  References: #5200

• [oracle] [bug] [reflection] Fixed regression / incorrect fix caused by fix for #5146 where the
  Oracle dialect reads from the "all_tab_comments" view to get table comments
  but fails to accommodate for the current owner of the table being
  requested, causing it to read the wrong comment if multiple tables of the
  same name exist in multiple schemas.

  References: #5146

misc

• [bug] [tests] Fixed an issue that prevented the test suite from running with the
  recently released py.test 5.4.0.

  References: #5201

• [enum] [types] The Enum type now supports the parameter Enum.length
  to specify the length of the VARCHAR column to create when using
  non native enums by setting Enum.native_enum to False

  References: #5183

• [installer] Ensured that the "pyproject.toml" file is not included in builds, as the
  presence of this file indicates to pip that a pep-517 installation process
  should be used. As this mode of operation appears to be not well supported
  by current tools / distros, these problems are avoided within the scope
  of SQLAlchemy installation by omitting the file.

  References: #5207