1.3.13

Released: January 22, 2020

orm

• [orm] [bug] [engine] Added test support and repaired a wide variety of unnecessary reference
  cycles created for short-lived objects, mostly in the area of ORM queries.
  Thanks much to Carson Ip for the help on this.

  References: #5050, #5056, #5071

• [orm] [bug] Fixed regression in loader options introduced in 1.3.0b3 via #4468
  where the ability to create a loader option using
  PropComparator.of_type() targeting an aliased entity that is an
  inheriting subclass of the entity which the preceding relationship refers
  to would fail to produce a matching path. See also #5082 fixed
  in this same release which involves a similar kind of issue.

  References: #5107

• [orm] [bug] Fixed regression in joined eager loading introduced in 1.3.0b3 via
  #4468 where the ability to create a joined option across a
  with_polymorphic() into a polymorphic subclass using
  RelationshipProperty.of_type() and then further along regular mapped
  relationships would fail as the polymorphic subclass would not add itself
  to the load path in a way that could be located by the loader strategy. A
  tweak has been made to resolve this scenario.

  References: #5082

• [orm] [performance] Identified a performance issue in the system by which a join is constructed
  based on a mapped relationship. The clause adaption system would be used
  for the majority of join expressions including in the common case where no
  adaptation is needed. The conditions under which this adaptation occur
  have been refined so that average non-aliased joins along a simple
  relationship without a "secondary" table use about 70% less function calls.

• [orm] [bug] Repaired a warning in the ORM flush process that was not covered by test
  coverage when deleting objects that use the "version_id" feature. This
  warning is generally unreachable unless using a dialect that sets the
  "supports_sane_rowcount" flag to False, which is not typically the case
  however is possible for some MySQL configurations as well as older Firebird
  drivers, and likely some third party dialects.

  References: #5068

• [orm] [bug] Fixed bug where usage of joined eager loading would not properly wrap the
  query inside of a subquery when Query.group_by() were used against
  the query. When any kind of result-limiting approach is used, such as
  DISTINCT, LIMIT, OFFSET, joined eager loading embeds the row-limited query
  inside of a subquery so that the collection results are not impacted. For
  some reason, the presence of GROUP BY was never included in this criterion,
  even though it has a similar effect as using DISTINCT. Additionally, the
  bug would prevent using GROUP BY at all for a joined eager load query for
  most database platforms which forbid non-aggregated, non-grouped columns
  from being in the query, as the additional columns for the joined eager
  load would not be accepted by the database.

  References: #5065

engine

• [engine] [bug] Fixed issue where the collection of value processors on a
  Compiled object would be mutated when "expanding IN" parameters
  were used with a datatype that has bind value processors; in particular,
  this would mean that when using statement caching and/or baked queries, the
  same compiled._bind_processors collection would be mutated concurrently.
  Since these processors are the same function for a given bind parameter
  namespace every time, there was no actual negative effect of this issue,
  however, the execution of a Compiled object should never be
  causing any changes in its state, especially given that they are intended
  to be thread-safe and reusable once fully constructed.

  References: #5048

sql

• [sql] [usecase] A function created using GenericFunction can now specify that the
  name of the function should be rendered with or without quotes by assigning
  the quoted_name construct to the .name element of the object.
  Prior to 1.3.4, quoting was never applied to function names, and some
  quoting was introduced in #4467 but no means to force quoting for
  a mixed case name was available. Additionally, the quoted_name
  construct when used as the name will properly register its lowercase name
  in the function registry so that the name continues to be available via the
  func. registry.

  References: #5079

postgresql

• [postgresql] [bug] Fixed issue where the PostgreSQL dialect would fail to parse a reflected
  CHECK constraint that was a boolean-valued function (as opposed to a
  boolean-valued expression).

  References: #5039

• [postgresql] [tests] Improved detection of two phase transactions requirement for the PostgreSQL
  database by testing that max_prepared_transactions is set to a value
  greater than 0. Pull request courtesy Federico Caselli.

  References: #5057

• [postgresql] [usecase] Added support for prefixes to the CTE construct, to allow
  support for Postgresql 12 "MATERIALIZED" and "NOT MATERIALIZED" phrases.
  Pull request courtesy Marat Sharafutdinov.

  References: #5040

mssql

• [mssql] [bug] Fixed issue where a timezone-aware datetime value being converted to
  string for use as a parameter value of a mssql.DATETIMEOFFSET
  column was omitting the fractional seconds.

  References: #5045

misc

• [bug] [ext] Fixed bug in sqlalchemy.ext.serializer where a unique
  BindParameter object could conflict with itself if it were
  present in the mapping itself, as well as the filter condition of the
  query, as one side would be used against the non-deserialized version and
  the other side would use the deserialized version. Logic is added to
  BindParameter similar to its "clone" method which will uniquify
  the parameter name upon deserialize so that it doesn't conflict with its
  original.

  References: #5086

• [bug] [tests] Fixed a few test failures which would occur on Windows due to SQLite file
  locking issues, as well as some timing issues in connection pool related
  tests; pull request courtesy Federico Caselli.

  References: #4946