- The ``version_id_generator`` parameter of ``Mapper`` can now be specified

to rely upon server generated version identifiers, using triggers
or other database-provided versioning features, by passing the value
``False``.  The ORM will use RETURNING when available to immediately
load the new version identifier, else it will emit a second SELECT.
[ticket:2793]
- The ``eager_defaults`` flag of :class:`.Mapper` will now allow the
newly generated default values to be fetched using an inline
RETURNING clause, rather than a second SELECT statement, for backends
that support RETURNING.
- Added a new variant to :meth:`.ValuesBase.returning` called
:meth:`.ValuesBase.return_defaults`; this allows arbitrary columns
to be added to the RETURNING clause of the statement without interfering
with the compilers usual "implicit returning" feature, which is used to
efficiently fetch newly generated primary key values.  For supporting
backends, a dictionary of all fetched values is present at
:attr:`.ResultProxy.returned_defaults`.
- add a glossary entry for RETURNING
- add documentation for version id generation, [ticket:867]

1 files changed, 2 insertions, 1 deletions

diff --git a/lib/sqlalchemy/sql/expression.py b/lib/sqlalchemy/sql/expression.py
index bbbe0b235..01091bc0a 100644
--- a/lib/sqlalchemy/sql/expression.py
+++ b/lib/sqlalchemy/sql/expression.py
@@ -49,7 +49,7 @@ from .selectable import Alias, Join, Select, Selectable, TableClause, \
         subquery, HasPrefixes, Exists, ScalarSelect
 
 
-from .dml import Insert, Update, Delete
+from .dml import Insert, Update, Delete, UpdateBase, ValuesBase
 
 # factory functions - these pull class-bound constructors and classmethods
 # from SQL elements and selectables into public functions.  This allows
@@ -101,6 +101,7 @@ from .elements import _literal_as_text, _clause_element_as_expr,\
 from .selectable import _interpret_as_from
 
 
+
 # old names for compatibility
 _Executable = Executable
 _BindParamClause = BindParameter