Released: November 16, 2018
[feature] [sql] Refactored
SQLCompilerto expose a
SQLCompiler.group_by_clause()method similar to the
methods, which can be overridden by dialects to customize how GROUP BY
renders. Pull request courtesy Samuel Chou.
This change is also backported to: 1.2.13
[bug] [orm] Fixed bug where use of
Lateralconstruct in conjunction with
Query.join()as well as
apply clause adaption to the right side of the join. "lateral" introduces
the use case of the right side of a join being correlatable. Previously,
adaptation of this clause wasn't considered. Note that in 1.2 only,
a selectable introduced by
Query.subquery()is still not adapted
due to #4304; the selectable needs to be produced by the
select()function to be the right side of the "lateral" join.
This change is also backported to: 1.2.12
[feature] [oracle] Added a new event currently used only by the cx_Oracle dialect,
DialectEvents.setiputsizes(). The event passes a dictionary of
BindParameterobjects to DBAPI-specific type objects that will be
passed, after conversion to parameter names, to the cx_Oracle
cursor.setinputsizes()method. This allows both visibility into the
setinputsizes process as well as the ability to alter the behavior of what
datatypes are passed to this method.
This change is also backported to: 1.2.9
[ext] [feature] Added new attribute
Query.lazy_loaded_fromwhich is populated
InstanceStatethat is using this
order to lazy load a relationship. The rationale for this is that
it serves as a hint for the horizontal sharding feature to use, such that
the identity token of the state can be used as the default identity token
to use for the query within id_chooser().
This change is also backported to: 1.2.9
[feature] [postgresql] Added new PG type
postgresql.REGCLASSwhich assists in casting
table names to OID values. Pull request courtesy Sebastian Bank.
This change is also backported to: 1.2.7
[feature] [orm] Added new feature
Query.only_return_tuples(). Causes the
Queryobject to return keyed tuple objects unconditionally even
if the query is against a single entity. Pull request courtesy Eric
This change is also backported to: 1.2.5
[bug] [ext] Reworked
AssociationProxyto store state that's specific to a
parent class in a separate object, so that a single
AssociationProxycan serve for multiple parent classes, as is
intrinsic to inheritance, without any ambiguity in the state returned by it.
A new method
AssociationProxy.for_class()is added to allow
inspection of class-specific state.
[bug] [oracle] Updated the parameters that can be sent to the cx_Oracle DBAPI to both allow
for all current parameters as well as for future parameters not added yet.
In addition, removed unused parameters that were deprecated in version 1.2,
and additionally we are now defaulting "threaded" to False.
[bug] [oracle] The Oracle dialect will no longer use the NCHAR/NCLOB datatypes
represent generic unicode strings or clob fields in conjunction with
UnicodeTextunless the flag
use_nchar_for_unicode=Trueis passed to
this includes CREATE TABLE behavior as well as
bound parameters. On the read side, automatic Unicode conversion under
Python 2 has been added to CHAR/VARCHAR/CLOB result rows, to match the
behavior of cx_Oracle under Python 3. In order to mitigate the performance
hit under Python 2, SQLAlchemy's very performant (when C extensions
are built) native Unicode handlers are used under Python 2.
[bug] [orm] Fixed issue regarding passive_deletes="all", where the foreign key
attribute of an object is maintained with its value even after the object
is removed from its parent collection. Previously, the unit of work would
set this to NULL even though passive_deletes indicated it should not be
[bug] [ext] The long-standing behavior of the association proxy collection maintaining
only a weak reference to the parent object is reverted; the proxy will now
maintain a strong reference to the parent for as long as the proxy
collection itself is also in memory, eliminating the "stale association
proxy" error. This change is being made on an experimental basis to see if
any use cases arise where it causes side effects.
[bug] [sql] Added "like" based operators as "comparison" operators, including
others, so that all of these operators can be the basis for an ORM
[feature] [sqlite] Added support for SQLite's json functionality via the new
SQLite implementation for
The name used for the type is
JSON, following an example found at
SQLite's own documentation. Pull request courtesy Ilja Everilä.
[engine] [feature] Added new "lifo" mode to
QueuePool, typically enabled by setting
create_engine.pool_use_lifoto True. "lifo" mode
means the same connection just checked in will be the first to be checked
out again, allowing excess connections to be cleaned up from the server
side during periods of the pool being only partially utilized. Pull request
courtesy Taem Park.
[bug] [orm] Improved the behavior of a relationship-bound many-to-one object expression
such that the retrieval of column values on the related object are now
resilient against the object being detached from its parent
Session, even if the attribute has been expired. New features
InstanceStateare used to memoize the last known value
of a particular column attribute before its expired, so that the expression
can still evaluate when the object is detached and expired at the same
time. Error conditions are also improved using modern attribute state
features to produce more specific messages as needed.
[feature] [mysql] Support added for the "WITH PARSER" syntax of CREATE FULLTEXT INDEX
in MySQL, using the
mysql_with_parserkeyword argument. Reflection
is also supported, which accommodates MySQL's special comment format
for reporting on this option as well. Additionally, the "FULLTEXT" and
"SPATIAL" index prefixes are now reflected back into the
[bug] [mysql] [orm] [postgresql] The ORM now doubles the "FOR UPDATE" clause within the subquery that
renders in conjunction with joined eager loading in some cases, as it has
been observed that MySQL does not lock the rows from a subquery. This
means the query renders with two FOR UPDATE clauses; note that on some
backends such as Oracle, FOR UPDATE clauses on subqueries are silently
ignored since they are unnecessary. Additionally, in the case of the "OF"
clause used primarily with PostgreSQL, the FOR UPDATE is rendered only on
the inner subquery when this is used so that the selectable can be targeted
to the table within the SELECT statement.
[feature] [mssql] Added
fast_executemany=Trueparameter to the SQL Server pyodbc dialect,
which enables use of pyodbc's new performance feature of the same name
when using Microsoft ODBC drivers.
[bug] [ext] Fixed multiple issues regarding de-association of scalar objects with the
delnow works, and additionally a new flag
AssociationProxy.cascade_scalar_deletesis added, which when
set to True indicates that setting a scalar attribute to
delwill also set the source association to
[ext] [feature] Added new feature
BakedQuery.to_query(), which allows for a
clean way of using one
BakedQueryas a subquery inside of another
BakedQuerywithout needing to refer explicitly to a
[feature] [sqlite] Implemented the SQLite
ON CONFLICTclause as understood at the DDL
level, e.g. for primary key, unique, and CHECK constraints as well as
specified on a
Columnto satisfy inline primary key and NOT NULL.
Pull request courtesy Denis Kataev.
[feature] [postgresql] Added rudimental support for reflection of PostgreSQL
partitioned tables, e.g. that relkind='p' is added to reflection
queries that return table information.
[ext] [feature] The
AssociationProxynow has standard column comparison operations
ColumnOperators.startswith()available when the target attribute is a
plain column - the EXISTS expression that joins to the target table is
rendered as usual, but the column expression is then use within the WHERE
criteria of the EXISTS. Note that this alters the behavior of the
.contains()method on the association proxy to make use of
ColumnOperators.contains()when used on a column-based attribute.
[feature] [orm] Added new flag
Session.bulk_save_objects()method, which defaults to True. When set
to False, the given mappings will be grouped into inserts and updates per
each object type, to allow for greater opportunities to batch common
operations together. Pull request courtesy Alessandro Cucci.
[bug] [orm] Refactored
Query.join()to further clarify the individual components
of structuring the join. This refactor adds the ability for
Query.join()to determine the most appropriate "left" side of the
join when there is more than one element in the FROM list or the query is
against multiple entities. If more than one FROM/entity matches, an error
is raised that asks for an ON clause to be specified to resolve the
ambiguity. In particular this targets the regression we saw in
#4363 but is also of general use. The codepaths within
Query.join()are now easier to follow and the error cases are
decided more specifically at an earlier point in the operation.
[bug] [sql] Fixed issue with
TypeEngine.column_expression()methods where these methods would not
work if the target type were part of a
Variant, or other target
type of a
TypeDecorator. Additionally, the SQL compiler now
calls upon the dialect-level implementation when it renders these methods
so that dialects can now provide for SQL-level processing for built-in
[bug] [orm] Fixed long-standing issue in
Querywhere a scalar subquery such
as produced by
Query.statementwould not correctly be adapted
when used in a new
Querythat required entity adaptation, such as
when the query were turned into a union, or a from_self(), etc. The change
removes the "no adaptation" annotation from the
produced by the
[bug] [declarative] [orm] Fixed bug where declarative would not update the state of the
Mapperas far as what attributes were present, when additional
attributes were added or removed after the mapper attribute collections had
already been called and memoized. Additionally, a
is now raised if a fully mapped attribute (e.g. column, relationship, etc.)
is deleted from a class that is currently mapped, since the mapper will not
function correctly if the attribute has been removed.
[bug] [mssql] Deprecated the use of
Sequencewith SQL Server in order to affect
the "start" and "increment" of the IDENTITY value, in favor of new
set these parameters directly.
Sequencewill be used to generate
CREATE SEQUENCEDDL with SQL Server in a future release.
[feature] [mysql] Added support for the parameters in an ON DUPLICATE KEY UPDATE statement on
MySQL to be ordered, since parameter order in a MySQL UPDATE clause is
significant, in a similar manner as that described at
updates_order_parameters. Pull request courtesy Maxim Bublis.
[feature] [sql] Added
Sequenceto the "string SQL" system that will render a
meaningful string expression (
"<next sequence value: my_sequence>")
when stringifying without a dialect a statement that includes a "sequence
nextvalue" expression, rather than raising a compilation error.
[bug] [orm] An informative exception is re-raised when a primary key value is not
sortable in Python during an ORM flush under Python 3, such as an
that has no
__lt__()method; normally Python 3 raises a
in this case. The flush process sorts persistent objects by primary key
in Python so the values must be sortable.
[bug] [orm] Removed the collection converter used by the
class. This converter was used only to assert that the incoming dictionary
keys matched that of their corresponding objects, and only during a bulk set
operation. The converter can interfere with a custom validator or
AttributeEvents.bulk_replace()listener that wants to convert
incoming values further. The
TypeErrorwhich would be raised by this
converter when an incoming key didn't match the value is removed; incoming
values during a bulk assignment will be keyed to their value-generated key,
and not the key that's explicitly present in the dictionary.
Overall, @converter is superseded by the
AttributeEvents.bulk_replace()event handler added as part of
[feature] [sql] Added new naming convention tokens
etc., which will render the names / keys / labels for all columns referenced
by a particular constraint in a sequence. In order to accommodate for the
length of such a naming convention, the SQL compiler's auto-truncation
feature now applies itself to constraint names as well, which creates a
shortened, deterministically generated name for the constraint that will
apply to a target backend without going over the character limit of that
The change also repairs two other issues. One is that the
token wasn't available even though this token was documented, the other was
referred_column_0_nametoken would inadvertently render the
.keyand not the
.nameof the column if these two values were
[ext] [feature] Added support for bulk
ShardedQueryclass within the horizontal sharding
extension. This also adds an additional expansion hook to the
bulk update/delete methods
[feature] [sql] Added new logic to the "expanding IN" bound parameter feature whereby if
the given list is empty, a special "empty set" expression that is specific
to different backends is generated, thus allowing IN expressions to be
fully dynamic including empty IN expressions.
[feature] [mysql] The "pre-ping" feature of the connection pool now uses
ping()method of the DBAPI connection in the case of
mysqlclient, PyMySQL and mysql-connector-python. Pull request
courtesy Maxim Bublis.
[feature] [orm] The "selectin" loader strategy now omits the JOIN in the case of a simple
one-to-many load, where it instead relies loads only from the related
table, relying upon the foreign key columns of the related table in order
to match up to primary keys in the parent table. This optimization can be
disabled by setting the
relationship.omit_joinflag to False.
Many thanks to Jayson Reis for the efforts on this.
[bug] [orm] Added new behavior to the lazy load that takes place when the "old" value of
a many-to-one is retrieved, such that exceptions which would be raised due
lazy="raise"or a detached session error are skipped.
[feature] [sql] The Python builtin
dir()is now supported for a SQLAlchemy "properties"
object, such as that of a Core columns collection (e.g.
mapper.attrs, etc. Allows iPython autocompletion to work as well.
Pull request courtesy Uwe Korn.
[feature] [orm] Added
.infodictionary to the
InstanceStateclass, the object
that comes from calling
inspect()on a mapped object.
[feature] [sql] Added new feature
FunctionElement.as_comparison()which allows a SQL
function to act as a binary comparison operation that can work within the
[bug] [orm] A long-standing oversight in the ORM, the
__delete__method for a many-
to-one relationship was non-functional, e.g. for an operation such as
del a.b. This is now implemented and is equivalent to setting the attribute