1.3.9

Released: October 4, 2019

• [engine] [usecase] Added new create_engine() parameter
  create_engine.max_identifier_length. This overrides the
  dialect-coded "max identifier length" in order to accommodate for databases
  that have recently changed this length and the SQLAlchemy dialect has
  not yet been adjusted to detect for that version. This parameter interacts
  with the existing create_engine.label_length parameter in that
  it establishes the maximum (and default) value for anonymously generated
  labels. Additionally, post-connection detection of max identifier lengths
  has been added to the dialect system. This feature is first being used
  by the Oracle dialect.

  References: #4857

• [oracle] [usecase] The Oracle dialect now emits a warning if Oracle version 12.2 or greater is
  used, and the create_engine.max_identifier_length parameter is
  not set. The version in this specific case defaults to that of the
  "compatibility" version set in the Oracle server configuration, not the
  actual server version. In version 1.4, the default max_identifier_length
  for 12.2 or greater will move to 128 characters. In order to maintain
  forwards compatibility, applications should set
  create_engine.max_identifier_length to 30 in order to maintain
  the same length behavior, or to 128 in order to test the upcoming behavior.
  This length determines among other things how generated constraint names
  are truncated for statements like CREATE CONSTRAINT and DROP CONSTRAINT, which means a the new length may produce a name-mismatch
  against a name that was generated with the old length, impacting database
  migrations.

  References: #4857

• [sqlite] [usecase] Added support for sqlite "URI" connections, which allow for sqlite-specific
  flags to be passed in the query string such as "read only" for Python
  sqlite3 drivers that support this.

  References: #4863

• [bug] [tests] Fixed unit test regression released in 1.3.8 that would cause failure for
  Oracle, SQL Server and other non-native ENUM platforms due to new
  enumeration tests added as part of #4285 enum sortability in the
  unit of work; the enumerations created constraints that were duplicated on
  name.

  References: #4285

• [bug] [oracle] Restored adding cx_Oracle.DATETIME to the setinputsizes() call when a
  SQLAlchemy Date, DateTime or Time datatype is
  used, as some complex queries require this to be present. This was removed
  in the 1.2 series for arbitrary reasons.

  References: #4886

• [bug] [mssql] Added identifier quoting to the schema name applied to the "use" statement
  which is invoked when a SQL Server multipart schema name is used within a
  Table that is being reflected, as well as for Inspector
  methods such as Inspector.get_table_names(); this accommodates for
  special characters or spaces in the database name. Additionally, the "use"
  statement is not emitted if the current database matches the target owner
  database name being passed.

  References: #4883

• [bug] [orm] Fixed regression in selectinload loader strategy caused by #4775
  (released in version 1.3.6) where a many-to-one attribute of None would no
  longer be populated by the loader. While this was usually not noticeable
  due to the lazyloader populating None upon get, it would lead to a detached
  instance error if the object were detached.

  References: #4872

• [bug] [orm] Passing a plain string expression to Session.query() is deprecated,
  as all string coercions were removed in #4481 and this one should
  have been included. The literal_column() function may be used to
  produce a textual column expression.

  References: #4873

• [sql] [usecase] Added an explicit error message for the case when objects passed to
  Table are not SchemaItem objects, rather than resolving
  to an attribute error.

  References: #4847

• [bug] [orm] A warning is emitted for a condition in which the Session may
  implicitly swap an object out of the identity map for another one with the
  same primary key, detaching the old one, which can be an observed result of
  load operations which occur within the SessionEvents.after_flush()
  hook. The warning is intended to notify the user that some special
  condition has caused this to happen and that the previous object may not be
  in the expected state.

  References: #4890

• [bug] [sql] Characters that interfere with "pyformat" or "named" formats in bound
  parameters, namely %, (, ) and the space character, as well as a few
  other typically undesirable characters, are stripped early for a
  bindparam() that is using an anonymized name, which is typically
  generated automatically from a named column which itself includes these
  characters in its name and does not use a .key, so that they do not
  interfere either with the SQLAlchemy compiler's use of string formatting or
  with the driver-level parsing of the parameter, both of which could be
  demonstrated before the fix. The change only applies to anonymized
  parameter names that are generated and consumed internally, not end-user
  defined names, so the change should have no impact on any existing code.
  Applies in particular to the psycopg2 driver which does not otherwise quote
  special parameter names, but also strips leading underscores to suit Oracle
  (but not yet leading numbers, as some anon parameters are currently
  entirely numeric/underscore based); Oracle in any case continues to quote
  parameter names that include special characters.

  References: #4837