primary key before emitting an INSERT, and merges distinct objects with duplicate primary keys together as they are encountered, which is essentially semi-deterministic at best. This behavior matches what happens already with persistent objects. fixes #3601
fail to emit an UPDATE in the case where the attribute were set to None and not previously loaded. fixes #3599
statement. This feature is available by passing the :paramref:`~.sqlalchemy.sql.expression.update.preserve_parameter_order` flag either to the core :class:`.Update` construct or alternatively adding it to the :paramref:`.Query.update.update_args` dictionary at the ORM-level, also passing the parameters themselves as a list of 2-tuples. Thanks to Gorka Eguileor for implementation and tests. adapted from pullreq github:200
versions 0.8.0 and 0.8.1, due :ticket:`2714`. The case where joined eager loading needs to join out over a subclass-bound relationship when "with_polymorphic" were also used would fail to join from the correct entity. fixes #3593
limit/offset criteria that forces a subquery b. the relationship uses "secondary" c. the primaryjoin of the relationship refers to a column that is either not part of the primary key, or is a PK col in a joined-inheritance subclass table that is under a different attribute name than the parent table's primary key column d. the query defers the columns that are present in the primaryjoin, typically via not being included in load_only(); the necessary column(s) would not be present in the subquery and produce invalid SQL. fixes #3592
scope of a :meth:`.Session.flush` operation that's raising an exception, as has been observed in some MySQL SAVEPOINT cases, prevents the original database exception from being observed when it was emitted during flush, but only on Py2K because Py2K does not support exception chaining; on Py3K the originating exception is chained. As a workaround, a warning is emitted in this specific case showing at least the string message of the original database error before we proceed to raise the rollback-originating exception. fixes #2696
added onto the end of a query in some inappropriate situations, such as when querying from an exists() of a single-inheritance subclass. fixes #3582