SQLAlchemy 2.1 Documentation
Changes and Migration
- What’s New in SQLAlchemy 2.1?
- 2.1 Changelog
- 2.0 Changelog¶
- 2.0.37
- 2.0.36
- 2.0.35
- 2.0.34
- 2.0.33
- 2.0.32
- 2.0.31
- 2.0.30
- 2.0.29
- 2.0.28
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- 2.0.25
- 2.0.24
- 2.0.23
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- 2.0.21
- 2.0.20
- 2.0.19
- 2.0.18
- 2.0.17
- 2.0.16
- 2.0.15
- 2.0.14
- 2.0.13
- 2.0.12
- 2.0.11
- 2.0.10
- 2.0.9
- 2.0.8
- 2.0.7
- 2.0.6
- 2.0.5.post1
- 2.0.4
- 2.0.3
- 2.0.2
- 2.0.1
- 2.0.0
- 2.0.0rc3
- 2.0.0rc2
- 2.0.0rc1
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- 2.0.0b3
- 2.0.0b2
- 2.0.0b1
- 1.4 Changelog
- 1.3 Changelog
- 1.2 Changelog
- 1.1 Changelog
- 1.0 Changelog
- 0.9 Changelog
- 0.8 Changelog
- 0.7 Changelog
- 0.6 Changelog
- 0.5 Changelog
- 0.4 Changelog
- 0.3 Changelog
- 0.2 Changelog
- 0.1 Changelog
- SQLAlchemy 2.0 - Major Migration Guide
- What’s New in SQLAlchemy 2.0?
- What’s New in SQLAlchemy 1.4?
- What’s New in SQLAlchemy 1.3?
- What’s New in SQLAlchemy 1.2?
- What’s New in SQLAlchemy 1.1?
- What’s New in SQLAlchemy 1.0?
- What’s New in SQLAlchemy 0.9?
- What’s New in SQLAlchemy 0.8?
- What’s New in SQLAlchemy 0.7?
- What’s New in SQLAlchemy 0.6?
- What’s new in SQLAlchemy 0.5?
- What’s new in SQLAlchemy 0.4?
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- 2.0 Changelog
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- 2.0.32
- 2.0.31
- 2.0.30
- 2.0.29
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- 2.0.14
- 2.0.13
- 2.0.12
- 2.0.11
- 2.0.10
- 2.0.9
- 2.0.8
- 2.0.7
- 2.0.6
- 2.0.5.post1
- 2.0.4
- 2.0.3
- 2.0.2
- 2.0.1
- 2.0.0
- 2.0.0rc3
- 2.0.0rc2
- 2.0.0rc1
- 2.0.0b4
- 2.0.0b3
- 2.0.0b2
- 2.0.0b1
2.0 Changelog¶
2.0.37¶
no release dateorm¶
Fixed regression caused by an internal code change in response to recent Mypy releases that caused the very unusual case of a list of ORM-mapped attribute expressions passed to
ColumnOperators.in_()
to no longer be accepted.References: #12019
Fixed issue regarding
Union
types that would be present in theregistry.type_annotation_map
of aregistry
or declarative base class, where aMapped[]
element that included one of the subtypes present in thatUnion
would be matched to that entry, potentially ignoring other entries that matched exactly. The correct behavior now takes place such that an entry should only match intype_annotation_map
exactly, as aUnion
type is a self-contained type. For example, an attribute withMapped[float]
would previously match to atype_annotation_map
entryUnion[float, Decimal]
; this will no longer match and will now only match to an entry that statesfloat
. Pull request courtesy Frazer McLean.References: #11370
sql¶
Fixed issue in “lambda SQL” feature where the tracking of bound parameters could be corrupted if the same lambda were evaluated across multiple compile phases, including when using the same lambda across multiple engine instances or with statement caching disabled.
References: #12084
postgresql¶
The
Range
type now supports__contains__
. Pull request courtesy of Frazer McLean.Fixes issue in get_multi_indexes in postgresql dialect, where an error would be thrown when attempting to use alembic with a vector index from the pgvecto.rs extension.
mariadb¶
Added sql types
INET4
andINET6
in the MariaDB dialect.
oracle¶
Added new table option oracle_tablespace to specify the TABLESPACE option when creating a table in Oracle. This allows users to define the tablespace in which the table should be created. Pull request courtesy of Miguel Grillo.
Use the connection attribute
max_identifier_length
available in oracledb since version 2.5 when determining the identifier length in the Oracle dialect.References: #12032
Fixed compilation of
TABLE
function when used in a from clause in Oracle Database dialect.References: #12100
Fixed issue in oracledb / cx_oracle dialects where output type handlers for
CLOB
were being routed toNVARCHAR
rather thanVARCHAR
, causing a double conversion to take place.References: #12150
2.0.36¶
Released: October 15, 2024orm¶
Added new parameter
mapped_column.hash
to ORM constructs such assqlalchemy.orm.mapped_column()
,sqlalchemy.orm.relationship()
, etc., which is interpreted for ORM Native Dataclasses in the same way as other dataclass-specific field parameters.References: #11923
Fixed bug in ORM bulk update/delete where using RETURNING with bulk update/delete in combination with
populate_existing
would fail to accommodate thepopulate_existing
option.References: #11912
Continuing from #11912, columns marked with
mapped_column.onupdate
,mapped_column.server_onupdate
, orComputed
are now refreshed in ORM instances when running an ORM enabled UPDATE with WHERE criteria, even if the statement does not use RETURNING orpopulate_existing
.References: #11917
Fixed regression caused by fixes to joined eager loading in #11449 released in 2.0.31, where a particular joinedload case could not be asserted correctly. We now have an example of that case so the assertion has been repaired to allow for it.
References: #11965
Improved the error message emitted when trying to map as dataclass a class while also manually providing the
__table__
attribute. This usage is currently not supported.References: #11973
Refined the check which the ORM lazy loader uses to detect “this would be loading by primary key and the primary key is NULL, skip loading” to take into account the current setting for the
Mapper.allow_partial_pks
parameter. If this parameter isFalse
, then a composite PK value that has partial NULL elements should also be skipped. This can apply to some composite overlapping foreign key configurations.References: #11995
Fixed bug in ORM “update with WHERE clause” feature where an explicit
.returning()
would interfere with the “fetch” synchronize strategy due to an assumption that the ORM mapped class featured the primary key columns in a specific position within the RETURNING. This has been fixed to use appropriate ORM column targeting.References: #11997
sql¶
Datatypes that are binary based such as
VARBINARY
will resolve toLargeBinary
when theTypeEngine.as_generic()
method is called.References: #11978
Fixed regression from 1.4 where some datatypes such as those derived from
TypeDecorator
could not be pickled when they were part of a larger SQL expression composition due to internal supporting structures themselves not being pickleable.References: #12002
schema¶
Fixed bug where SQL functions passed to
Column.server_default
would not be rendered with the particular form of parenthesization now required by newer versions of MySQL and MariaDB. Pull request courtesy of huuya.References: #11317
postgresql¶
Fixed bug in reflection of table comments where unrelated text would be returned if an entry in the
pg_description
table happened to share the same oid (objoid) as the table being reflected.References: #11961
The
JSON
andJSONB
datatypes will now render a “bind cast” in all cases for all PostgreSQL backends, including psycopg2, whereas previously it was only enabled for some backends. This allows greater accuracy in allowing the database server to recognize when a string value is to be interpreted as JSON.References: #11994
mysql¶
Improved a query used for the MySQL 8 backend when reflecting foreign keys to be better optimized. Previously, for a database that had millions of columns across all tables, the query could be prohibitively slow; the query has been reworked to take better advantage of existing indexes.
References: #11975
2.0.35¶
Released: September 16, 2024orm¶
Fixed issue where it was not possible to use
typing.Literal
withMapped[]
on Python 3.8 and 3.9. Pull request courtesy Frazer McLean.References: #11820
Fixed issue in ORM evaluator where two datatypes being evaluated with the SQL concatenator operator would not be checked for
UnevaluatableError
based on their datatype; this missed the case ofJSONB
values being used in a concatenate operation which is supported by PostgreSQL as well as how SQLAlchemy renders the SQL for this operation, but does not work at the Python level. By implementingUnevaluatableError
for this combination, ORM update statements will now fall back to “expire” when a concatenated JSON value used in a SET clause is to be synchronized to a Python object.References: #11849
An warning is emitted if
joinedload()
orsubqueryload()
are used as a top level option against a statement that is not a SELECT statement, such as with aninsert().returning()
. There are no JOINs in INSERT statements nor is there a “subquery” that can be repurposed for subquery eager loading, and for UPDATE/DELETE joinedload does not support these either, so it is never appropriate for this use to pass silently.References: #11853
Fixed issue where using loader options such as
selectinload()
with additional criteria in combination with ORM DML such asinsert()
with RETURNING would not correctly set up internal contexts required for caching to work correctly, leading to incorrect results.References: #11855
mysql¶
Fixed issue in mariadbconnector dialect where query string arguments that weren’t checked integer or boolean arguments would be ignored, such as string arguments like
unix_socket
, etc. As part of this change, the argument parsing for particular elements such asclient_flags
,compress
,local_infile
has been made more consistent across all MySQL / MariaDB dialect which accept each argument. Pull request courtesy Tobias Alex-Petersen.References: #11870
sqlite¶
The changes made for SQLite CHECK constraint reflection in versions 2.0.33 and 2.0.34 , #11832 and #11677, have now been fully reverted, as users continued to identify existing use cases that stopped working after this change. For the moment, because SQLite does not provide any consistent way of delivering information about CHECK constraints, SQLAlchemy is limited in what CHECK constraint syntaxes can be reflected, including that a CHECK constraint must be stated all on a single, independent line (or inline on a column definition) without newlines, tabs in the constraint definition or unusual characters in the constraint name. Overall, reflection for SQLite is tailored towards being able to reflect CREATE TABLE statements that were originally created by SQLAlchemy DDL constructs. Long term work on a DDL parser that does not rely upon regular expressions may eventually improve upon this situation. A wide range of additional cross-dialect CHECK constraint reflection tests have been added as it was also a bug that these changes did not trip any existing tests.
References: #11840
2.0.34¶
Released: September 4, 2024orm¶
Fixed regression caused by issue #11814 which broke support for certain flavors of PEP 593
Annotated
in the type_annotation_map when builtin types such aslist
,dict
were used without an element type. While this is an incomplete style of typing, these types nonetheless previously would be located in the type_annotation_map correctly.References: #11831
sqlite¶
2.0.33¶
Released: September 3, 2024general¶
The pin for
setuptools<69.3
inpyproject.toml
has been removed. This pin was to prevent a sudden change in setuptools to use PEP 625 from taking place, which would change the file name of SQLAlchemy’s source distribution on pypi to be an all lower case name, which is likely to cause problems with various build environments that expected the previous naming style. However, the presence of this pin is holding back environments that otherwise want to use a newer setuptools, so we’ve decided to move forward with this change, with the assumption that build environments will have largely accommodated the setuptools change by now.References: #11818
orm¶
Fixed regression from 1.3 where the column key used for a hybrid property might be populated with that of the underlying column that it returns, for a property that returns an ORM mapped column directly, rather than the key used by the hybrid property itself.
This change is also backported to: 1.4.54
References: #11728
Correctly cleanup the internal top-level module registry when no inner modules or classes are registered into it.
References: #11788
Improvements to the ORM annotated declarative type map lookup dealing with composed types such as
dict[str, Any]
linking to JSON (or others) with or without “future annotations” mode.References: #11814
engine¶
Fixed issue in internal reflection cache where particular reflection scenarios regarding same-named quoted_name() constructs would not be correctly cached. Pull request courtesy Felix Lüdin.
References: #11687
sql¶
Fixed regression in
Select.with_statement_hint()
and others where the generative behavior of the method stopped producing a copy of the object.References: #11703
schema¶
Fixed bug where the
metadata
element of anEnum
datatype would not be transferred to the newMetaData
object when the type had been copied via aTable.to_metadata()
operation, leading to inconsistent behaviors within create/drop sequences.References: #11802
typing¶
Fixed typing issue with
Select.with_only_columns()
.References: #11782
postgresql¶
Fixed critical issue in the asyncpg driver where a rollback or commit that fails specifically for the
MissingGreenlet
condition or any other error that is not raised by asyncpg itself would discard the asyncpg transaction in any case, even though the transaction were still idle, leaving to a server side condition with an idle transaction that then goes back into the connection pool. The flags for “transaction closed” are now not reset for errors that are raised outside of asyncpg itself. When asyncpg itself raises an error for.commit()
or.rollback()
, asyncpg does then discard of this transaction.This change is also backported to: 1.4.54
References: #11819
Revising the asyncpg
terminate()
fix first made in #10717 which improved the resiliency of this call under all circumstances, addingasyncio.CancelledError
to the list of exceptions that are intercepted as failing for a graceful.close()
which will then proceed to call.terminate()
.References: #11821
mysql¶
Fixed issue in MySQL dialect where using INSERT..FROM SELECT in combination with ON DUPLICATE KEY UPDATE would erroneously render on MySQL 8 and above the “AS new” clause, leading to syntax failures. This clause is required on MySQL 8 to follow the VALUES clause if use of the “new” alias is present, however is not permitted to follow a FROM SELECT clause.
References: #11731
sqlite¶
Improvements to the regex used by the SQLite dialect to reflect the name and contents of a CHECK constraint. Constraints with newline, tab, or space characters in either or both the constraint text and constraint name are now properly reflected. Pull request courtesy Jeff Horemans.
References: #11677
Improvements to the regex used by the SQLite dialect to reflect the name and contents of a UNIQUE constraint that is defined inline within a column definition inside of a SQLite CREATE TABLE statement, accommodating for tab characters present within the column / constraint line. Pull request courtesy John A Stevenson.
References: #11746
mssql¶
Added error “The server failed to resume the transaction” to the list of error strings for the pymssql driver in determining a disconnect scenario, as observed by one user using pymssql under otherwise unknown conditions as leaving an unusable connection in the connection pool which fails to ping cleanly.
References: #11822
tests¶
Added missing
array_type
property to the testing suiteSuiteRequirements
class.
2.0.32¶
Released: August 5, 2024general¶
Restored legacy class names removed from
sqlalalchemy.orm.collections.*
, includingMappedCollection
,mapped_collection()
,column_mapped_collection()
,attribute_mapped_collection()
. Pull request courtesy Takashi Kajinami.References: #11435
orm¶
The
aliased.name
parameter toaliased()
may now be combined with thealiased.flat
parameter, producing per-table names based on a name-prefixed naming convention. Pull request courtesy Eric Atkin.References: #11575
Fixed regression going back to 1.4 where accessing a collection using the “dynamic” strategy on a transient object and attempting to query would raise an internal error rather than the expected
NoResultFound
that occurred in 1.3.This change is also backported to: 1.4.53
References: #11562
Fixed issue where using the
Query.enable_eagerloads()
andQuery.yield_per()
methods at the same time, in order to disable eager loading that’s configured on the mapper directly, would be silently ignored, leading to errors or unexpected eager population of attributes.References: #10834
Fixed regression appearing in 2.0.21 caused by #10279 where using a
delete()
orupdate()
against an ORM class that is the base of an inheritance hierarchy, while also specifying that subclasses should be loaded polymorphically, would leak the polymorphic joins into the UPDATE or DELETE statement as well creating incorrect SQL.References: #11625
Fixed regression from version 1.4 in
Session.bulk_insert_mappings()
where using theSession.bulk_insert_mappings.return_defaults
parameter would not populate the passed in dictionaries with newly generated primary key values.References: #11661
Added a warning noting when an
ConnectionEvents.engine_connect()
event may be leaving a transaction open, which can alter the behavior of aSession
using such an engine as bind. On SQLAlchemy 2.1Session.join_transaction_mode
will instead be ignored in all cases when the session bind is anEngine
.References: #11163
examples¶
Fixed issue in history_meta example where the “version” column in the versioned table needs to default to the most recent version number in the history table on INSERT, to suit the use case of a table where rows are deleted, and can then be replaced by new rows that re-use the same primary key identity. This fix adds an additonal SELECT query per INSERT in the main table, which may be inefficient; for cases where primary keys are not re-used, the default function may be omitted. Patch courtesy Philipp H. v. Loewenfeld.
References: #10267
engine¶
Fixed issue in “insertmanyvalues” feature where a particular call to
cursor.fetchall()
were not wrapped in SQLAlchemy’s exception wrapper, which apparently can raise a database exception during fetch when using pyodbc.References: #11532
sql¶
Follow up of #11471 to fix caching issue where using the
CompoundSelectState.add_cte()
method of theCompoundSelectState
construct would not set a correct cache key which distinguished between different CTE expressions. Also added tests that would detect issues similar to the one fixed in #11544.References: #11471
Fixed bug where the
Operators.nulls_first()
andOperators.nulls_last()
modifiers would not be treated the same way asOperators.desc()
andOperators.asc()
when determining if an ORDER BY should be against a label name already in the statement. All four modifiers are now treated the same within ORDER BY.References: #11592
schema¶
typing¶
Fixed internal typing issues to establish compatibility with mypy 1.11.0. Note that this does not include issues which have arisen with the deprecated mypy plugin used by SQLAlchemy 1.4-style code; see the addiional change note for this plugin indicating revised compatibility.
mypy¶
The deprecated mypy plugin is no longer fully functional with the latest series of mypy 1.11.0, as changes in the mypy interpreter are no longer compatible with the approach used by the plugin. If code is dependent on the mypy plugin with sqlalchemy2-stubs, it’s recommended to pin mypy to be below the 1.11.0 series. Seek upgrading to the 2.0 series of SQLAlchemy and migrating to the modern type annotations.
This change is also backported to: 1.4.53
postgresql¶
It is now considered a pool-invalidating disconnect event when psycopg2 throws an “SSL SYSCALL error: Success” error message, which can occur when the SSL connection to Postgres is terminated abnormally.
References: #11522
Fixed issue where the
collate()
construct, which explicitly sets a collation for a given expression, would maintain collation settings for the underlying type object from the expression, causing SQL expressions to have both collations stated at once when used in further expressions for specific dialects that render explicit type casts, such as that of asyncpg. Thecollate()
construct now assigns its own type to explicitly include the new collation, assuming it’s a string type.References: #11576
mysql¶
Fixed issue in MySQL dialect where ENUM values that contained percent signs were not properly escaped for the driver.
References: #11479
sqlite¶
Fixed reflection of computed column in SQLite to properly account for complex expressions.
This change is also backported to: 1.4.53
References: #11582
mssql¶
Fixed issue where SQL Server drivers don’t support bound parameters when rendering the “frame specification” for a window function, e.g. “ROWS BETWEEN”, etc.
This change is also backported to: 1.4.53
References: #11514
oracle¶
Added API support for server-side cursors for the oracledb async dialect, allowing use of the
AsyncConnection.stream()
and similar stream methods.References: #10820
Implemented two-phase transactions for the oracledb dialect. Historically, this feature never worked with the cx_Oracle dialect, however recent improvements to the oracledb successor now allow this to be possible. The two phase transaction API is available at the Core level via the
Connection.begin_twophase()
method.References: #11480
Fixed table reflection on Oracle 10.2 and older where compression options are not supported.
References: #11557
Implemented bitwise operators for Oracle which was previously non-functional due to a non-standard syntax used by this database. Oracle’s support for bitwise “or” and “xor” starts with server version 21. Additionally repaired the implementation of “xor” for SQLite.
As part of this change, the dialect compliance test suite has been enhanced to include support for server-side bitwise tests; third party dialect authors should refer to new “supports_bitwise” methods in the requirements.py file to enable these tests.
References: #11663
2.0.31¶
Released: June 18, 2024general¶
Set up full Python 3.13 support to the extent currently possible, repairing issues within internal language helpers as well as the serializer extension module.
For version 1.4, this also modernizes the “extras” names in setup.cfg to use dashes and not underscores for two-word names. Underscore names are still present to accommodate potential compatibility issues.
This change is also backported to: 1.4.53
References: #11417
Set up full Python 3.13 support to the extent currently possible, repairing issues within internal language helpers as well as the serializer extension module.
References: #11417
orm¶
Added missing parameter
with_polymorphic.name
that allows specifying the name of returnedAliasedClass
.References: #11361
Fixed issue where a
MetaData
collection would not be serializable, if anEnum
orBoolean
datatype were present which had been adapted. This specific scenario in turn could occur when using theEnum
orBoolean
within ORM Annotated Declarative form where type objects frequently get copied.References: #11365
Fixed issue where the
selectinload()
andsubqueryload()
loader options would fail to take effect when made against an inherited subclass that itself included a subclass-specificMapper.with_polymorphic
setting.References: #11446
Fixed very old issue involving the
joinedload.innerjoin
parameter where making use of this parameter mixed into a query that also included joined eager loads along a self-referential or other cyclical relationship, along with complicating factors like inner joins added for secondary tables and such, would have the chance of splicing a particular inner join to the wrong part of the query. Additional state has been added to the internal method that does this splice to make a better decision as to where splicing should proceed.References: #11449
Fixed bug in ORM Declarative where the
__table__
directive could not be declared as a class function withdeclared_attr()
on a superclass, including an__abstract__
class as well as coming from the declarative base itself. This was a regression since 1.4 where this was working, and there were apparently no tests for this particular use case.References: #11509
engine¶
Modified the internal representation used for adapting asyncio calls to greenlets to allow for duck-typed compatibility with third party libraries that implement SQLAlchemy’s “greenlet-to-asyncio” pattern directly. Running code within a greenlet that features the attribute
__sqlalchemy_greenlet_provider__ = True
will allow calls tosqlalchemy.util.await_only()
directly.This change is also backported to: 1.4.53
sql¶
Fixed caching issue where using the
TextualSelect.add_cte()
method of theTextualSelect
construct would not set a correct cache key which distinguished between different CTE expressions.This change is also backported to: 1.4.53
References: #11471
Fixed issue when serializing an
over()
clause with unbounded range or rows.References: #11422
Added missing methods
FunctionFilter.within_group()
andWithinGroup.filter()
References: #11423
Fixed bug in
FunctionFilter.filter()
that would mutate the existing function in-place. It now behaves like the rest of the SQLAlchemy API, returning a new instance instead of mutating the original one.References: #11426
schema¶
Added
Column.insert_default
as an alias ofColumn.default
for compatibility withmapped_column()
.References: #11374
mysql¶
Added missing foreign key reflection option
SET DEFAULT
in the MySQL and MariaDB dialects. Pull request courtesy of Quentin Roche.References: #11285
2.0.30¶
Released: May 5, 2024orm¶
Added new attribute
ORMExecuteState.is_from_statement
to detect statements created usingSelect.from_statement()
, and enhancedFromStatement
to setORMExecuteState.is_select
,ORMExecuteState.is_insert
,ORMExecuteState.is_update
, andORMExecuteState.is_delete
according to the element that is sent to theSelect.from_statement()
method itself.References: #11220
Fixed issue in
selectin_polymorphic()
loader option where attributes defined withcomposite()
on a superclass would cause an internal exception on load.References: #11291
Fixed regression from 1.4 where using
defaultload()
in conjunction with a non-propagating loader likecontains_eager()
would nonetheless propagate thecontains_eager()
to a lazy load operation, causing incorrect queries as this option is only intended to come from an original load.References: #11292
Fixed issue in ORM Annotated Declarative where typing issue where literals defined using PEP 695 type aliases would not work with inference of
Enum
datatypes. Pull request courtesy of Alc-Alc.References: #11305
Fixed issue in
selectin_polymorphic()
loader option where the SELECT emitted would only accommodate for the child-most class among the result rows that were returned, leading intermediary-class attributes to be unloaded if there were no concrete instances of that intermediary-class present in the result. This issue only presented itself for multi-level inheritance hierarchies.References: #11327
Fixed issue in
Session.bulk_save_objects()
where the form of the identity key produced when usingreturn_defaults=True
would be incorrect. This could lead to an errors during pickling as well as identity map mismatches.References: #11332
Fixed issue where attribute key names in
Bundle
would not be correct when using ORM enabledselect
vs.Query
, when the statement contained duplicate column names.References: #11347
engine¶
Fixed issue in the
Connection.execution_options.logging_token
option, where changing the value oflogging_token
on a connection that has already logged messages would not be updated to reflect the new logging token. This in particular prevented the use ofSession.connection()
to change the option on the connection, since the BEGIN logging message would already have been emitted.References: #11210
Fixed issue in cursor handling which affected handling of duplicate
Column
or similar objcts in the columns clause ofselect()
, both in combination with arbitarytext()
clauses in the SELECT list, as well as when attempting to retrieveResult.mappings()
for the object, which would lead to an internal error.References: #11306
typing¶
Fixed typing regression caused by #11055 in version 2.0.29 that added
ParamSpec
to the asynciorun_sync()
methods, where usingAsyncConnection.run_sync()
withMetaData.reflect()
would fail on mypy due to a mypy issue. Pull request courtesy of Francisco R. Del Roio.References: #11200
Fixed issue in typing for
Bundle
where creating a nestedBundle
structure were not allowed.
misc¶
2.0.29¶
Released: March 23, 2024orm¶
Added support for the PEP 695
TypeAliasType
construct as well as the python 3.12 nativetype
keyword to work with ORM Annotated Declarative form when using these constructs to link to a PEP 593Annotated
container, allowing the resolution of theAnnotated
to proceed when these constructs are used in aMapped
typing container.References: #11130
Fixed Declarative issue where typing a relationship using
Relationship
rather thanMapped
would inadvertently pull in the “dynamic” relationship loader strategy for that attribute.References: #10611
Fixed issue in ORM annotated declarative where using
mapped_column()
with anmapped_column.index
ormapped_column.unique
setting of False would be overridden by an incomingAnnotated
element that featured that parameter set toTrue
, even though the immediatemapped_column()
element is more specific and should take precedence. The logic to reconcile the booleans has been enhanced to accommodate a local value ofFalse
as still taking precedence over an incomingTrue
value from the annotated element.References: #11091
Fixed regression from version 2.0.28 caused by the fix for #11085 where the newer method of adjusting post-cache bound parameter values would interefere with the implementation for the
subqueryload()
loader option, which has some more legacy patterns in use internally, when the additional loader criteria feature were used with this loader option.References: #11173
engine¶
Fixed issue in “Insert Many Values” Behavior for INSERT statements feature where using a primary key column with an “inline execute” default generator such as an explicit
Sequence
with an explcit schema name, while at the same time using theConnection.execution_options.schema_translate_map
feature would fail to render the sequence or the parameters properly, leading to errors.References: #11157
Made a change to the adjustment made in version 2.0.10 for #9618, which added the behavior of reconciling RETURNING rows from a bulk INSERT to the parameters that were passed to it. This behavior included a comparison of already-DB-converted bound parameter values against returned row values that was not always “symmetrical” for SQL column types such as UUIDs, depending on specifics of how different DBAPIs receive such values versus how they return them, necessitating the need for additional “sentinel value resolver” methods on these column types. Unfortunately this broke third party column types such as UUID/GUID types in libraries like SQLModel which did not implement this special method, raising an error “Can’t match sentinel values in result set to parameter sets”. Rather than attempt to further explain and document this implementation detail of the “insertmanyvalues” feature including a public version of the new method, the approach is intead revised to no longer need this extra conversion step, and the logic that does the comparison now works on the pre-converted bound parameter value compared to the post-result-processed value, which should always be of a matching datatype. In the unusual case that a custom SQL column type that also happens to be used in a “sentinel” column for bulk INSERT is not receiving and returning the same value type, the “Can’t match” error will be raised, however the mitigation is straightforward in that the same Python datatype should be passed as that returned.
References: #11160
sql¶
Fixed regression from the 1.4 series where the refactor of the
TypeEngine.with_variant()
method introduced at “with_variant()” clones the original TypeEngine rather than changing the type failed to accommodate for the.copy()
method, which will lose the variant mappings that are set up. This becomes an issue for the very specific case of a “schema” type, which includes types such asEnum
andARRAY
, when they are then used in the context of an ORM Declarative mapping with mixins where copying of types comes into play. The variant mapping is now copied as well.References: #11176
typing¶
postgresql¶
The PostgreSQL dialect now returns
DOMAIN
instances when reflecting a column that has a domain as type. Previously, the domain data type was returned instead. As part of this change, the domain reflection was improved to also return the collation of the text types. Pull request courtesy of Thomas Stephenson.References: #10693
tests¶
Backported to SQLAlchemy 2.0 an improvement to the test suite with regards to how asyncio related tests are run, now using the newer Python 3.11
asyncio.Runner
or a backported equivalent, rather than relying on the previous implementation based onasyncio.get_running_loop()
. This should hopefully prevent issues with large suite runs on CPU loaded hardware where the event loop seems to become corrupted, leading to cascading failures.References: #11187
2.0.28¶
Released: March 4, 2024orm¶
Adjusted the fix made in #10570, released in 2.0.23, where new logic was added to reconcile possibly changing bound parameter values across cache key generations used within the
with_expression()
construct. The new logic changes the approach by which the new bound parameter values are associated with the statement, avoiding the need to deep-copy the statement which can result in a significant performance penalty for very deep / complex SQL constructs. The new approach no longer requires this deep-copy step.References: #11085
Fixed regression caused by #9779 where using the “secondary” table in a relationship
and_()
expression would fail to be aliased to match how the “secondary” table normally renders within aSelect.join()
expression, leading to an invalid query.References: #11010
engine¶
Added new core execution option
Connection.execution_options.preserve_rowcount
. When set, thecursor.rowcount
attribute from the DBAPI cursor will be unconditionally memoized at statement execution time, so that whatever value the DBAPI offers for any kind of statement will be available using theCursorResult.rowcount
attribute from theCursorResult
. This allows the rowcount to be accessed for statements such as INSERT and SELECT, to the degree supported by the DBAPI in use. The “Insert Many Values” Behavior for INSERT statements also supports this option and will ensureCursorResult.rowcount
is correctly set for a bulk INSERT of rows when set.References: #10974
asyncio¶
An error is raised if a
QueuePool
or other non-asyncio pool class is passed tocreate_async_engine()
. This engine only accepts asyncio-compatible pool classes includingAsyncAdaptedQueuePool
. Other pool classes such asNullPool
are compatible with both synchronous and asynchronous engines as they do not perform any locking.References: #8771
tests¶
pytest support in the tox.ini file has been updated to support pytest 8.1.
2.0.27¶
Released: February 13, 2024postgresql¶
2.0.26¶
Released: February 11, 2024orm¶
Replaced the “loader depth is excessively deep” warning with a shorter message added to the caching badge within SQL logging, for those statements where the ORM disabled the cache due to a too-deep chain of loader options. The condition which this warning highlights is difficult to resolve and is generally just a limitation in the ORM’s application of SQL caching. A future feature may include the ability to tune the threshold where caching is disabled, but for now the warning will no longer be a nuisance.
References: #10896
Fixed issue where it was not possible to use a type (such as an enum) within a
Mapped
container type if that type were declared locally within the class body. The scope of locals used for the eval now includes that of the class body itself. In addition, the expression withinMapped
may also refer to the class name itself, if used as a string or with future annotations mode.References: #10899
Fixed issue where using
Session.delete()
along with theMapper.version_id_col
feature would fail to use the correct version identifier in the case that an additional UPDATE were emitted against the target object as a result of the use ofrelationship.post_update
on the object. The issue is similar to #10800 just fixed in version 2.0.25 for the case of updates alone.References: #10967
Fixed issue where an assertion within the implementation for
with_expression()
would raise if a SQL expression that was not cacheable were used; this was a 2.0 regression since 1.4.References: #10990
examples¶
Fixed regression in history_meta example where the use of
MetaData.to_metadata()
to make a copy of the history table would also copy indexes (which is a good thing), but causing naming conflicts indexes regardless of naming scheme used for those indexes. A “_history” suffix is now added to these indexes in the same way as is achieved for the table name.References: #10920
Fixed the performance example scripts in examples/performance to mostly work with the Oracle database, by adding the
Identity
construct to all the tables and allowing primary generation to occur on this backend. A few of the “raw DBAPI” cases still are not compatible with Oracle.
sql¶
Fixed issues in
case()
where the logic for determining the type of the expression could result inNullType
if the last element in the “whens” had no type, or in other cases where the type could resolve toNone
. The logic has been updated to scan all given expressions so that the first non-null type is used, as well as to always ensure a type is present. Pull request courtesy David Evans.References: #10843
typing¶
Fixed the type signature for the
PoolEvents.checkin()
event to indicate that the givenDBAPIConnection
argument may beNone
in the case where the connection has been invalidated.
postgresql¶
Added support for reflection of PostgreSQL CHECK constraints marked with “NO INHERIT”, setting the key
no_inherit=True
in the reflected data. Pull request courtesy Ellis Valentiner.References: #10777
Support the
USING <method>
option for PostgreSQLCREATE TABLE
to specify the access method to use to store the contents for the new table. Pull request courtesy Edgar Ramírez-Mondragón.See also
References: #10904
Correctly type PostgreSQL RANGE and MULTIRANGE types as
Range[T]
andSequence[Range[T]]
. Introduced utility sequenceMultiRange
to allow better interoperability of MULTIRANGE types.References: #9736
Differentiate between INT4 and INT8 ranges and multi-ranges types when inferring the database type from a
Range
orMultiRange
instance, preferring INT4 if the values fit into it.Fixed regression in the asyncpg dialect caused by #10717 in release 2.0.24 where the change that now attempts to gracefully close the asyncpg connection before terminating would not fall back to
terminate()
for other potential connection-related exceptions other than a timeout error, not taking into account cases where the graceful.close()
attempt fails for other reasons such as connection errors.References: #10863
Fixed an issue regarding the use of the
Uuid
datatype with theUuid.as_uuid
parameter set to False, when using PostgreSQL dialects. ORM-optimized INSERT statements (e.g. the “insertmanyvalues” feature) would not correctly align primary key UUID values for bulk INSERT statements, resulting in errors. Similar issues were fixed for the pymssql driver as well.
mysql¶
Fixed issue where NULL/NOT NULL would not be properly reflected from a MySQL column that also specified the VIRTUAL or STORED directives. Pull request courtesy Georg Wicke-Arndt.
References: #10850
Fixed issue in asyncio dialects asyncmy and aiomysql, where their
.close()
method is apparently not a graceful close. replace with non-standard.ensure_closed()
method that’s awaitable and move.close()
to the so-called “terminate” case.References: #10893
mssql¶
Fixed an issue regarding the use of the
Uuid
datatype with theUuid.as_uuid
parameter set to False, when using the pymssql dialect. ORM-optimized INSERT statements (e.g. the “insertmanyvalues” feature) would not correctly align primary key UUID values for bulk INSERT statements, resulting in errors. Similar issues were fixed for the PostgreSQL drivers as well.
oracle¶
Changed the default arraysize of the Oracle dialects so that the value set by the driver is used, that is 100 at the time of writing for both cx_oracle and oracledb. Previously the value was set to 50 by default. The setting of 50 could cause significant performance regressions compared to when using cx_oracle/oracledb alone to fetch many hundreds of rows over slower networks.
References: #10877
2.0.25¶
Released: January 2, 2024orm¶
Added preliminary support for Python 3.12 pep-695 type alias structures, when resolving custom type maps for ORM Annotated Declarative mappings.
References: #10807
Fixed issue where when making use of the
relationship.post_update
feature at the same time as using a mapper version_id_col could lead to a situation where the second UPDATE statement emitted by the post-update feature would fail to make use of the correct version identifier, assuming an UPDATE was already emitted in that flush which had already bumped the version counter.References: #10800
Fixed issue where ORM Annotated Declarative would mis-interpret the left hand side of a relationship without any collection specified as uselist=True if the left type were given as a class and not a string, without using future-style annotations.
References: #10815
sql¶
typing¶
Fixed regressions caused by typing added to the
sqlalchemy.sql.functions
module in version 2.0.24, as part of #6810:Further enhancements to pep-484 typing to allow SQL functions from
sqlalchemy.sql.expression.func
derived elements to work more effectively with ORM-mapped attributes (#10801)Fixed the argument types passed to functions so that literal expressions like strings and ints are again interpreted correctly (#10818)
asyncio¶
Fixed critical issue in asyncio version of the connection pool where calling
AsyncEngine.dispose()
would produce a new connection pool that did not fully re-establish the use of asyncio-compatible mutexes, leading to the use of a plainthreading.Lock()
which would then cause deadlocks in an asyncio context when using concurrency features likeasyncio.gather()
.This change is also backported to: 1.4.51
References: #10813
oracle¶
Added support for python-oracledb in asyncio mode, using the newly released version of the
oracledb
DBAPI that includes asyncio support. For the 2.0 series, this is a preview release, where the current implementation does not yet have include support forAsyncConnection.stream()
. Improved support is planned for the 2.1 release of SQLAlchemy.References: #10679
2.0.24¶
Released: December 28, 2023orm¶
Improved a fix first implemented for #3208 released in version 0.9.8, where the registry of classes used internally by declarative could be subject to a race condition in the case where individual mapped classes are being garbage collected at the same time while new mapped classes are being constructed, as can happen in some test suite configurations or dynamic class creation environments. In addition to the weakref check already added, the list of items being iterated is also copied first to avoid “list changed while iterating” errors. Pull request courtesy Yilei Yang.
This change is also backported to: 1.4.51
References: #10782
Fixed issue where use of
foreign()
annotation on a non-initializedmapped_column()
construct would produce an expression without a type, which was then not updated at initialization time of the actual column, leading to issues such as relationships not determininguse_get
appropriately.References: #10597
Improved the error message produced when the unit of work process sets the value of a primary key column to NULL due to a related object with a dependency rule on that column being deleted, to include not just the destination object and column name but also the source column from which the NULL value is originating. Pull request courtesy Jan Vollmer.
References: #10668
Modified the
__init_subclass__()
method used byMappedAsDataclass
,DeclarativeBase
andDeclarativeBaseNoMeta
to accept arbitrary**kw
and to propagate them to thesuper()
call, allowing greater flexibility in arranging custom superclasses and mixins which make use of__init_subclass__()
keyword arguments. Pull request courtesy Michael Oliver.References: #10732
Ensured the use case of
Bundle
objects used in thereturning()
portion of ORM-enabled INSERT, UPDATE and DELETE statements is tested and works fully. This was never explicitly implemented or tested previously and did not work correctly in the 1.4 series; in the 2.0 series, ORM UPDATE/DELETE with WHERE criteria was missing an implementation method preventingBundle
objects from working.References: #10776
Fixed 2.0 regression in
MutableList
where a routine that detects sequences would not correctly filter out string or bytes instances, making it impossible to assign a string value to a specific index (while non-sequence values would work fine).References: #10784
engine¶
Fixed URL-encoding of the username and password components of
URL
objects when converting them to string using theURL.render_as_string()
method, by using Python standard libraryurllib.parse.quote
while allowing for plus signs and spaces to remain unchanged as supported by SQLAlchemy’s non-standard URL parsing, rather than the legacy home-grown routine from many years ago. Pull request courtesy of Xavier NUNN.References: #10662
sql¶
Fixed issue in stringify for SQL elements, where a specific dialect is not passed, where a dialect-specific element such as the PostgreSQL “on conflict do update” construct is encountered and then fails to provide for a stringify dialect with the appropriate state to render the construct, leading to internal errors.
References: #10753
Fixed issue where stringifying or compiling a
CTE
that was against a DML construct such as aninsert()
construct would fail to stringify, due to a mis-detection that the statement overall is an INSERT, leading to internal errors.
schema¶
typing¶
asyncio¶
The
async_fallback
dialect argument is now deprecated, and will be removed in SQLAlchemy 2.1. This flag has not been used for SQLAlchemy’s test suite for some time. asyncio dialects can still run in a synchronous style by running code within a greenlet usinggreenlet_spawn()
.
postgresql¶
Adjusted the asyncpg dialect such that when the
terminate()
method is used to discard an invalidated connection, the dialect will first attempt to gracefully close the connection using.close()
with a timeout, if the operation is proceeding within an async event loop context only. This allows the asyncpg driver to attend to finalizing aTimeoutError
including being able to close a long-running query server side, which otherwise can keep running after the program has exited.References: #10717
mysql¶
tests¶
Improvements to the test suite to further harden its ability to run when Python
greenlet
is not installed. There is now a tox target that includes the token “nogreenlet” that will run the suite with greenlet not installed (note that it still temporarily installs greenlet as part of the tox config, however).References: #10747
2.0.23¶
Released: November 2, 2023orm¶
Implemented the
Session.bulk_insert_mappings.render_nulls
parameter for new style bulk ORM inserts, allowingrender_nulls=True
as an execution option. This allows for bulk ORM inserts with a mixture ofNone
values in the parameter dictionaries to use a single batch of rows for a given set of dicationary keys, rather than breaking up into batches that omit the NULL columns from each INSERT.References: #10575
Fixed issue where the
__allow_unmapped__
directive failed to allow for legacyColumn
/deferred()
mappings that nonetheless had annotations such asAny
or a specific type withoutMapped[]
as their type, without errors related to locating the attribute name.References: #10516
Fixed caching bug where using the
with_expression()
construct in conjunction with loader optionsselectinload()
,lazyload()
would fail to substitute bound parameter values correctly on subsequent caching runs.References: #10570
Fixed bug in ORM annotated declarative where using a
ClassVar
that nonetheless referred in some way to an ORM mapped class name would fail to be interpreted as aClassVar
that’s not mapped.References: #10472
sql¶
Implemented “literal value processing” for the
Interval
datatype for both the PostgreSQL and Oracle dialects, allowing literal rendering of interval values. Pull request courtesy Indivar Mishra.References: #9737
Fixed issue where using the same bound parameter more than once with
literal_execute=True
in some combinations with other literal rendering parameters would cause the wrong values to render due to an iteration issue.This change is also backported to: 1.4.50
References: #10142
Added compiler-level None/NULL handling for the “literal processors” of all datatypes that include literal processing, that is, where a value is rendered inline within a SQL statement rather than as a bound parameter, for all those types that do not feature explicit “null value” handling. Previously this behavior was undefined and inconsistent.
References: #10535
Removed unused placeholder method
TypeEngine.compare_against_backend()
This method was used by very old versions of Alembic. See https://github.com/sqlalchemy/alembic/issues/1293 for details.
asyncio¶
Fixed bug with method
AsyncSession.close_all()
that was not working correctly. Also added functionclose_all_sessions()
that’s the equivalent ofclose_all_sessions()
. Pull request courtesy of Bryan不可思议.References: #10421
postgresql¶
Fixed 2.0 regression caused by #7744 where chains of expressions involving PostgreSQL JSON operators combined with other operators such as string concatenation would lose correct parenthesization, due to an implementation detail specific to the PostgreSQL dialect.
References: #10479
Fixed SQL handling for “insertmanyvalues” when using the
BIT
datatype with the asyncpg backend. TheBIT
on asyncpg apparently requires the use of an asyncpg-specificBitString
type which is currently exposed when using this DBAPI, making it incompatible with other PostgreSQL DBAPIs that all work with plain bitstrings here. A future fix in version 2.1 will normalize this datatype across all PG backends. Pull request courtesy Sören Oldag.References: #10532
mysql¶
Repaired a new incompatibility in the MySQL “pre-ping” routine where the
False
argument passed toconnection.ping()
, which is intended to disable an unwanted “automatic reconnect” feature, is being deprecated in MySQL drivers and backends, and is producing warnings for some versions of MySQL’s native client drivers. It’s removed for mysqlclient, whereas for PyMySQL and drivers based on PyMySQL, the parameter will be deprecated and removed at some point, so API introspection is used to future proof against these various stages of removal.This change is also backported to: 1.4.50
References: #10492
mariadb¶
Adjusted the MySQL / MariaDB dialects to default a generated column to NULL when using MariaDB, if
Column.nullable
was not specified with an explicitTrue
orFalse
value, as MariaDB does not support the “NOT NULL” phrase with a generated column. Pull request courtesy Indivar.References: #10056
Established a workaround for what seems to be an intrinsic issue across MySQL/MariaDB drivers where a RETURNING result for DELETE DML which returns no rows using SQLAlchemy’s “empty IN” criteria fails to provide a cursor.description, which then yields result that returns no rows, leading to regressions for the ORM that in the 2.0 series uses RETURNING for bulk DELETE statements for the “synchronize session” feature. To resolve, when the specific case of “no description when RETURNING was given” is detected, an “empty result” with a correct cursor description is generated and used in place of the non-working cursor.
References: #10505
mssql¶
Added support for the
aioodbc
driver implemented for SQL Server, which builds on top of the pyodbc and general aio* dialect architecture.See also
aioodbc - in the SQL Server dialect documentation.
References: #6521
Fixed issue where identity column reflection would fail for a bigint column with a large identity start value (more than 18 digits).
This change is also backported to: 1.4.50
References: #10504
oracle¶
Fixed issue in
Interval
datatype where the Oracle implementation was not being used for DDL generation, leading to theday_precision
andsecond_precision
parameters to be ignored, despite being supported by this dialect. Pull request courtesy Indivar.References: #10509
Fixed issue where the cx_Oracle dialect claimed to support a lower cx_Oracle version (7.x) than was actually supported in practice within the 2.0 series of SQLAlchemy. The dialect imports symbols that are only in cx_Oracle 8 or higher, so runtime dialect checks as well as setup.cfg requirements have been updated to reflect this compatibility.
References: #10470
2.0.22¶
Released: October 12, 2023orm¶
Added method
Session.get_one()
that behaves likeSession.get()
but raises an exception instead of returningNone
if no instance was found with the provided primary key. Pull request courtesy of Carlos Sousa.References: #10202
Added an option to permanently close sessions. Set to
False
the new parameterSession.close_resets_only
will prevent aSession
from performing any other operation afterSession.close()
has been called.Added new method
Session.reset()
that will reset aSession
to its initial state. This is an alias ofSession.close()
, unlessSession.close_resets_only
is set toFalse
.References: #7787
Fixed a wide range of
mapped_column()
parameters that were not being transferred when using themapped_column()
object inside of a pep-593Annotated
object, includingmapped_column.sort_order
,mapped_column.deferred
,mapped_column.autoincrement
,mapped_column.system
,mapped_column.info
etc.Additionally, it remains not supported to have dataclass arguments, such as
mapped_column.kw_only
,mapped_column.default_factory
etc. indicated within themapped_column()
received byAnnotated
, as this is not supported with pep-681 Dataclass Transforms. A warning is now emitted when these parameters are used withinAnnotated
in this way (and they continue to be ignored).Fixed issue where calling
Result.unique()
with a new-styleselect()
query in the ORM, where one or more columns yields values that are of “unknown hashability”, typically when using JSON functions likefunc.json_build_object()
without providing a type, would fail internally when the returned values were not actually hashable. The behavior is repaired to test the objects as they are received for hashability in this case, raising an informative error message if not. Note that for values of “known unhashability”, such as when theJSON
orARRAY
types are used directly, an informative error message was already raised.The “hashabiltiy testing” fix here is applied to legacy
Query
as well, however in the legacy case,Result.unique()
is used for nearly all queries, so no new warning is emitted here; the legacy behavior of falling back to usingid()
in this case is maintained, with the improvement that an unknown type that turns out to be hashable will now be uniqufied, whereas previously it would not.References: #10459
Fixed regression in recently revised “insertmanyvalues” feature (likely issue #9618) where the ORM would inadvertently attempt to interpret a non-RETURNING result as one with RETURNING, in the case where the
implicit_returning=False
parameter were applied to the mappedTable
, indicating that “insertmanyvalues” cannot be used if the primary key values are not provided.References: #10453
Fixed bug where ORM
with_loader_criteria()
would not apply itself to aSelect.join()
where the ON clause were given as a plain SQL comparison, rather than as a relationship target or similar.update - this was found to also fix an issue where single-inheritance criteria would not be correctly applied to a subclass entity that only appeared in the
select_from()
list, see #11412Fixed issue where
Mapped
symbols likeWriteOnlyMapped
andDynamicMapped
could not be correctly resolved when referenced as an element of a sub-module in the given annotation, assuming string-based or “future annotations” style annotations.References: #10412
Fixed issue with
__allow_unmapped__
declarative option where types that were declared using collection types such aslist[SomeClass]
vs. the typing constructList[SomeClass]
would fail to be recognized correctly. Pull request courtesy Pascal Corpet.References: #10385
engine¶
Fixed issue within some dialects where the dialect could incorrectly return an empty result set for an INSERT statement that does not actually return rows at all, due to artfacts from pre- or post-fetching the primary key of the row or rows still being present. Affected dialects included asyncpg, all mssql dialects.
Fixed issue where under some garbage collection / exception scenarios the connection pool’s cleanup routine would raise an error due to an unexpected set of state, which can be reproduced under specific conditions.
References: #10414
sql¶
Fixed issue where referring to a FROM entry in the SET clause of an UPDATE statement would not include it in the FROM clause of the UPDATE statement, if that entry were nowhere else in the statement; this occurs currently for CTEs that were added using
Update.add_cte()
to provide the desired CTE at the top of the statement.References: #10408
Fixed 2.0 regression where the
DDL
construct would no longer__repr__()
due to the removedon
attribute not being accommodated. Pull request courtesy Iuri de Silvio.References: #10443
typing¶
asyncio¶
Fixed the
AsyncSession.get.execution_options
parameter which was not being propagated to the underlyingSession
and was instead being ignored.
mariadb¶
Modified the mariadb-connector driver to pre-load the
cursor.rowcount
value for all queries, to suit tools such as Pandas that hardcode to callingResult.rowcount
in this way. SQLAlchemy normally pre-loadscursor.rowcount
only for UPDATE/DELETE statements and otherwise passes through to the DBAPI where it can return -1 if no value is available. However, mariadb-connector does not support invokingcursor.rowcount
after the cursor itself is closed, raising an error instead. Generic test support has been added to ensure all backends support the allowingResult.rowcount
to succceed (that is, returning an integer value with -1 for “not available”) after the result is closed.References: #10396
Additional fixes for the mariadb-connector dialect to support UUID data values in the result in INSERT..RETURNING statements.
mssql¶
Fixed bug where the rule that prevents ORDER BY from emitting within subqueries on SQL Server was not being disabled in the case where the
select.fetch()
method were used to limit rows in conjunction with WITH TIES or PERCENT, preventing valid subqueries with TOP / ORDER BY from being used.References: #10458
2.0.21¶
Released: September 18, 2023orm¶
Adjusted the ORM’s interpretation of the “target” entity used within
Update
andDelete
to not interfere with the target “from” object passed to the statement, such as when passing an ORM-mappedaliased
construct that should be maintained within a phrase like “UPDATE FROM”. Cases like ORM session synchonize using “SELECT” statements such as with MySQL/ MariaDB will still have issues with UPDATE/DELETE of this form so it’s best to disable synchonize_session when using DML statements of this type.References: #10279
Added new capability to the
selectin_polymorphic()
loader option which allows other loader options to be bundled as siblings, referring to one of its subclasses, within the sub-options of parent loader option. Previously, this pattern was only supported if theselectin_polymorphic()
were at the top level of the options for the query. See new documentation section for example.As part of this change, improved the behavior of the
Load.selectin_polymorphic()
method / loader strategy so that the subclass load does not load most already-loaded columns from the parent table, when the option is used against a class that is already being relationship-loaded. Previously, the logic to load only the subclass columns worked only for a top level class load.References: #10348
engine¶
Fixed a series of reflection issues affecting the PostgreSQL, MySQL/MariaDB, and SQLite dialects when reflecting foreign key constraints where the target column contained parenthesis in one or both of the table name or column name.
References: #10275
sql¶
Adjusted the
Enum
datatype to accept an argument ofNone
for theEnum.length
parameter, resulting in a VARCHAR or other textual type with no length in the resulting DDL. This allows for new elements of any length to be added to the type after it exists in the schema. Pull request courtesy Eugene Toder.References: #10269
Added new generic SQL function
aggregate_strings
, which accepts a SQL expression and a decimeter, concatenating strings on multiple rows into a single aggregate value. The function is compiled on a per-backend basis, into functions such asgroup_concat(),
string_agg()
, orLISTAGG()
. Pull request courtesy Joshua Morris.References: #9873
Adjusted the operator precedence for the string concatenation operator to be equal to that of string matching operators, such as
ColumnElement.like()
,ColumnElement.regexp_match()
,ColumnElement.match()
, etc., as well as plain==
which has the same precedence as string comparison operators, so that parenthesis will be applied to a string concatenation expression that follows a string match operator. This provides for backends such as PostgreSQL where the “regexp match” operator is apparently of higher precedence than the string concatenation operator.References: #9610
Qualified the use of
hashlib.md5()
within the DDL compiler, which is used to generate deterministic four-character suffixes for long index and constraint names in DDL statements, to include the Python 3.9+usedforsecurity=False
parameter so that Python interpreters built for restricted environments such as FIPS do not consider this call to be related to security concerns.References: #10342
The
Values
construct will now automatically create a proxy (i.e. a copy) of acolumn
if the column were already associated with an existing FROM clause. This allows that an expression likevalues_obj.c.colname
will produce the correct FROM clause even in the case thatcolname
was passed as acolumn
that was already used with a previousValues
or other table construct. Originally this was considered to be a candidate for an error condition, however it’s likely this pattern is already in widespread use so it’s now added to support.References: #10280
schema¶
Modified the rendering of the Oracle only
Identity.order
parameter that’s part of bothSequence
andIdentity
to only take place for the Oracle backend, and not other backends such as that of PostgreSQL. A future release will rename theIdentity.order
,Sequence.order
andIdentity.on_null
parameters to Oracle-specific names, deprecating the old names, these parameters only apply to Oracle.This change is also backported to: 1.4.50
References: #10207
typing¶
Made the contained type for
Mapped
covariant; this is to allow greater flexibility for end-user typing scenarios, such as the use of protocols to represent particular mapped class structures that are passed to other functions. As part of this change, the contained type was also made covariant for dependent and related types such asSQLORMOperations
,WriteOnlyMapped
, andSQLColumnExpression
. Pull request courtesy Roméo Després.References: #10288
Fixed regression introduced in 2.0.20 via #9600 fix which attempted to add more formal typing to
MetaData.naming_convention
. This change prevented basic naming convention dictionaries from passing typing and has been adjusted so that a plain dictionary of strings for keys as well as dictionaries that use constraint types as keys or a mix of both, are again accepted.As part of this change, lesser used forms of the naming convention dictionary are also typed, including that it currently allows for
Constraint
type objects as keys as well.Fixed the type annotation for
__class_getitem__()
as applied to theVisitable
class at the base of expression constructs to acceptAny
for a key, rather thanstr
, which helps with some IDEs such as PyCharm when attempting to write typing annotations for SQL constructs which include generic selectors. Pull request courtesy Jordan Macdonald.References: #9878
Repaired the core “SQL element” class
SQLCoreOperations
to support the__hash__()
method from a typing perspective, as objects likeColumn
and ORMInstrumentedAttribute
are hashable and are used as dictionary keys in the public API for theUpdate
andInsert
constructs. Previously, type checkers were not aware the root SQL element was hashable.References: #10353
Fixed typing issue with
Existing.select_from()
that prevented its use with ORM classes.References: #10337
Update type annotations for ORM loading options, restricting them to accept only “*” instead of any string for string arguments. Pull request courtesy Janek Nouvertné.
References: #10131
postgresql¶
Fixed regression which appeared in 2.0 due to #8491 where the revised “ping” used for PostgreSQL dialects when the
create_engine.pool_pre_ping
parameter is in use would interfere with the use of asyncpg with PGBouncer “transaction” mode, as the multiple PostgreSQL commands emitted by asnycpg could be broken out among multiple connections leading to errors, due to the lack of any transaction around this newly revised “ping”. The ping is now invoked within a transaction, in the same way that is implicit with all other backends that are based on the pep-249 DBAPI; this guarantees that the series of PG commands sent by asyncpg for this command are invoked on the same backend connection without it jumping to a different connection mid-command. The transaction is not used if the asyncpg dialect is used in “AUTOCOMMIT” mode, which remains incompatible with pgbouncer transaction mode.References: #10226
misc¶
Fixed very old issue where the full extent of SQLAlchemy modules, including
sqlalchemy.testing.fixtures
, could not be imported outside of a pytest run. This suits inspection utilities such aspkgutil
that attempt to import all installed modules in all packages.References: #10321
2.0.20¶
Released: August 15, 2023orm¶
Implemented the “RETURNING ‘*’” use case for ORM enabled DML statements. This will render in as many cases as possible and return the unfiltered result set, however is not supported for multi-parameter “ORM bulk INSERT” statements that have specific column rendering requirements.
References: #10192
Fixed fundamental issue which prevented some forms of ORM “annotations” from taking place for subqueries which made use of
Select.join()
against a relationship target. These annotations are used whenever a subquery is used in special situations such as withinPropComparator.and_()
and other ORM-specific scenarios.This change is also backported to: 1.4.50
References: #10223
Fixed issue where the ORM’s generation of a SELECT from a joined inheritance model with same-named columns in superclass and subclass would somehow not send the correct list of column names to the
CTE
construct, when the RECURSIVE column list were generated.References: #10169
Fixed fairly major issue where execution options passed to
Session.execute()
, as well as execution options local to the ORM executed statement itself, would not be propagated along to eager loaders such as that ofselectinload()
,immediateload()
, andsqlalchemy.orm.subqueryload()
, making it impossible to do things such as disabling the cache for a single statement or usingschema_translate_map
for a single statement, as well as the use of user-custom execution options. A change has been made where all user-facing execution options present forSession.execute()
will be propagated along to additional loaders.As part of this change, the warning for “excessively deep” eager loaders leading to caching being disabled can be silenced on a per-statement basis by sending
execution_options={"compiled_cache": None}
toSession.execute()
, which will disable caching for the full series of statements within that scope.References: #10231
Fixed issue where internal cloning used by the ORM for expressions like
Comparator.any()
to produce correlated EXISTS constructs would interfere with the “cartesian product warning” feature of the SQL compiler, leading the SQL compiler to warn when all elements of the statement were correctly joined.References: #10124
Fixed issue where the
lazy="immediateload"
loader strategy would place an internal loading token into the ORM mapped attribute under circumstances where the load should not occur, such as in a recursive self-referential load. As part of this change, thelazy="immediateload"
strategy now honors therelationship.join_depth
parameter for self-referential eager loads in the same way as that of other eager loaders, where leaving it unset or set at zero will lead to a self-referential immediateload not occurring, setting it to a value of one or greater will immediateload up until that given depth.References: #10139
Fixed issue where dictionary-based collections such as
attribute_keyed_dict()
did not fully pickle/unpickle correctly, leading to issues when attempting to mutate such a collection after unpickling.References: #10175
Fixed issue where chaining
load_only()
or other wildcard use ofdefer()
from another eager loader using aaliased()
against a joined inheritance subclass would fail to take effect for columns local to the superclass.References: #10125
Fixed issue where an ORM-enabled
select()
construct would not render any CTEs added only via theSelect.add_cte()
method that were not otherwise referenced in the statement.References: #10167
examples¶
The dogpile_caching examples have been updated for 2.0 style queries. Within the “caching query” logic itself there is one conditional added to differentiate between
Query
andselect()
when performing an invalidation operation.
engine¶
Fixed critical issue where setting
create_engine.isolation_level
toAUTOCOMMIT
(as opposed to using theEngine.execution_options()
method) would fail to restore “autocommit” to a pooled connection if an alternate isolation level were temporarily selected usingConnection.execution_options.isolation_level
.References: #10147
sql¶
Fixed issue where unpickling of a
Column
or otherColumnElement
would fail to restore the correct “comparator” object, which is used to generate SQL expressions specific to the type object.This change is also backported to: 1.4.50
References: #10213
typing¶
Added new typing only utility functions
Nullable()
andNotNullable()
to type a column or ORM class as, respectively, nullable or not nullable. These function are no-op at runtime, returning the input unchanged.References: #10173
Typing improvements:
CursorResult
is returned for some forms ofSession.execute()
where DML without RETURNING is usedfixed type for
Query.with_for_update.of
parameter withinQuery.with_for_update()
improvements to
_DMLColumnArgument
type used by some DML methods to pass column expressionsAdd overload to
literal()
so that it is inferred that the return type isBindParameter[NullType]
whereliteral.type_
param is NoneAdd overloads to
ColumnElement.op()
so that the inferred type whenColumnElement.op.return_type
is not provided isCallable[[Any], BinaryExpression[Any]]
Add missing overload to
ColumnElement.__add__()
Pull request courtesy Mehdi Gmira.
References: #9185
Fixed issue in
Session
andAsyncSession
methods such asSession.connection()
where theSession.connection.execution_options
parameter were hardcoded to an internal type that is not user-facing.References: #10182
asyncio¶
Added new methods
AsyncConnection.aclose()
as a synonym forAsyncConnection.close()
andAsyncSession.aclose()
as a synonym forAsyncSession.close()
to theAsyncConnection
andAsyncSession
objects, to provide compatibility with Python standard library@contextlib.aclosing
construct. Pull request courtesy Grigoriev Semyon.References: #9698
mysql¶
Updated aiomysql dialect since the dialect appears to be maintained again. Re-added to the ci testing using version 0.2.0.
This change is also backported to: 1.4.50
2.0.19¶
Released: July 15, 2023orm¶
Fixed issue where setting a relationship collection directly, where an object in the new collection were already present, would not trigger a cascade event for that object, leading to it not being added to the
Session
if it were not already present. This is similar in nature to #6471 and is a more apparent issue due to the removal ofcascade_backrefs
in the 2.0 series. TheAttributeEvents.append_wo_mutation()
event added as part of #6471 is now also emitted for existing members of a collection that are present in a bulk set of that same collection.References: #10089
Fixed issue where objects that were associated with an unloaded collection via backref, but were not merged into the
Session
due to the removal ofcascade_backrefs
in the 2.0 series, would not emit a warning that these objects were not being included in a flush, even though they were pending members of the collection; in other such cases, a warning is emitted when a collection being flushed contains non-attached objects which will be essentially discarded. The addition of the warning for backref-pending collection members establishes greater consistency with collections that may be present or non-present and possibly flushed or not flushed at different times based on different relationship loading strategies.References: #10090
Fixed additional regression caused by #9805 where more aggressive propagation of the “ORM” flag on statements could lead to an internal attribute error when embedding an ORM
Query
construct that nonetheless contained no ORM entities within a Core SQL statement, in this case ORM-enabled UPDATE and DELETE statements.References: #10098
engine¶
Renamed
Row.t
andRow.tuple()
toRow._t
andRow._tuple()
; this is to suit the policy that all methods and pre-defined attributes onRow
should be in the style of Python standard librarynamedtuple
where all fixed names have a leading underscore, to avoid name conflicts with existing column names. The previous method/attribute is now deprecated and will emit a deprecation warning.References: #10093
Added detection for non-string, non-
URL
objects to themake_url()
function, allowingArgumentError
to be thrown immediately, rather than causing failures later on. Special logic ensures that mock forms ofURL
are allowed through. Pull request courtesy Grigoriev Semyon.References: #10079
postgresql¶
Fixed regression caused by improvements to PostgreSQL URL parsing in #10004 where “host” query string arguments that had colons in them, to support various third party proxy servers and/or dialects, would not parse correctly as these were evaluted as
host:port
combinations. Parsing has been updated to consider a colon as indicating ahost:port
value only if the hostname contains only alphanumeric characters with dots or dashes only (e.g. no slashes), followed by exactly one colon followed by an all-integer token of zero or more integers. In all other cases, the full string is taken as a host.References: #10069
Fixed issue where comparisons to the
CITEXT
datatype would cast the right side toVARCHAR
, leading to the right side not being interpreted as aCITEXT
datatype, for the asyncpg, psycopg3 and pg80000 dialects. This led to theCITEXT
type being essentially unusable for practical use; this is now fixed and the test suite has been corrected to properly assert that expressions are rendered correctly.References: #10096
2.0.18¶
Released: July 5, 2023engine¶
Adjusted the
create_engine.schema_translate_map
feature such that all schema names in the statement are now tokenized, regardless of whether or not a specific name is in the immediate schema translate map given, and to fallback to substituting the original name when the key is not in the actual schema translate map at execution time. These two changes allow for repeated use of a compiled object with schema schema_translate_maps that include or dont include various keys on each run, allowing cached SQL constructs to continue to function at runtime when schema translate maps with different sets of keys are used each time. In addition, added detection of schema_translate_map dictionaries which gain or lose aNone
key across calls for the same statement, which affects compilation of the statement and is not compatible with caching; an exception is raised for these scenarios.References: #10025
sql¶
Fixed issue where the
ColumnOperators.regexp_match()
when using “flags” would not produce a “stable” cache key, that is, the cache key would keep changing each time causing cache pollution. The same issue existed forColumnOperators.regexp_replace()
with both the flags and the actual replacement expression. The flags are now represented as fixed modifier strings rendered as safestrings rather than bound parameters, and the replacement expression is established within the primary portion of the “binary” element so that it generates an appropriate cache key.Note that as part of this change, the
ColumnOperators.regexp_match.flags
andColumnOperators.regexp_replace.flags
have been modified to render as literal strings only, whereas previously they were rendered as full SQL expressions, typically bound parameters. These parameters should always be passed as plain Python strings and not as SQL expression constructs; it’s not expected that SQL expression constructs were used in practice for this parameter, so this is a backwards-incompatible change.The change also modifies the internal structure of the expression generated, for
ColumnOperators.regexp_replace()
with or without flags, and forColumnOperators.regexp_match()
with flags. Third party dialects which may have implemented regexp implementations of their own (no such dialects could be located in a search, so impact is expected to be low) would need to adjust the traversal of the structure to accommodate.This change is also backported to: 1.4.49
References: #10042
Fixed issue in mostly-internal
CacheKey
construct where the__ne__()
operator were not properly implemented, leading to nonsensical results when comparingCacheKey
instances to each other.This change is also backported to: 1.4.49
extensions¶
Added new option to
association_proxy()
association_proxy.create_on_none_assignment
; when an association proxy which refers to a scalar relationship is assigned the valueNone
, and the referenced object is not present, a new object is created via the creator. This was apparently an undefined behavior in the 1.2 series that was silently removed.References: #10013
typing¶
Improved typing when using standalone operator functions from
sqlalchemy.sql.operators
such assqlalchemy.sql.operators.eq
.References: #10054
Fixed some of the typing within the
aliased()
construct to correctly accept aTable
object that’s been aliased withTable.alias()
, as well as general support forFromClause
objects to be passed as the “selectable” argument, since this is all supported.References: #10061
postgresql¶
Added multi-host support for the asyncpg dialect. General improvements and error checking added to the PostgreSQL URL routines for the “multihost” use case added as well. Pull request courtesy Ilia Dmitriev.
See also
References: #10004
Added new parameter
native_inet_types=False
to all PostgreSQL dialects, which indicates converters used by the DBAPI to convert rows from PostgreSQLINET
andCIDR
columns into Pythonipaddress
datatypes should be disabled, returning strings instead. This allows code written to work with strings for these datatypes to be migrated to asyncpg, psycopg, or pg8000 without code changes other than adding this parameter to thecreate_engine()
orcreate_async_engine()
function call.See also
References: #9945
mariadb¶
mssql¶
Added support for creation and reflection of COLUMNSTORE indexes in MSSQL dialect. Can be specified on indexes specifying
mssql_columnstore=True
.References: #7340
Fixed issue where performing
Cast
to a string type with an explicit collation would render the COLLATE clause inside the CAST function, which resulted in a syntax error.References: #9932
2.0.17¶
Released: June 23, 2023orm¶
Fixed regression in the 2.0 series where a query that used
undefer_group()
withselectinload()
orsubqueryload()
would raise anAttributeError
. Pull request courtesy of Matthew Martin.References: #9870
Fixed issue in ORM Annotated Declarative which prevented a
declared_attr
from being used on a mixin which did not return aMapped
datatype, and instead returned a supplemental ORM datatype such asAssociationProxy
. The Declarative runtime would erroneously try to interpret this annotation as needing to beMapped
and raise an error.References: #9957
Fixed typing issue where using the
AssociationProxy
return type from adeclared_attr
function was disallowed.References: #9957
Fixed regression introduced in 2.0.16 by #9879 where passing a callable to the
mapped_column.default
parameter ofmapped_column
while also settinginit=False
would interpret this value as a Dataclass default value which would be assigned directly to new instances of the object directly, bypassing the default generator taking place as theColumn.default
value generator on the underlyingColumn
. This condition is now detected so that the previous behavior is maintained, however a deprecation warning for this ambiguous use is emitted; to populate the default generator for aColumn
, themapped_column.insert_default
parameter should be used, which disambiguates from themapped_column.default
parameter whose name is fixed as per pep-681.References: #9936
Additional hardening and documentation for the ORM
Session
“state change” system, which detects concurrent use ofSession
andAsyncSession
objects; an additional check is added within the process to acquire connections from the underlying engine, which is a critical section with regards to internal connection management.References: #9973
Fixed issue in ORM loader strategy logic which further allows for long chains of
contains_eager()
loader options across complex inheriting polymorphic / aliased / of_type() relationship chains to take proper effect in queries.References: #10006
Fixed issue in support for the
Enum
datatype in theregistry.type_annotation_map
first added as part of #8859 where using a customEnum
with fixed configuration in the map would fail to transfer theEnum.name
parameter, which among other issues would prevent PostgreSQL enums from working if the enum values were passed as individual values. Logic has been updated so that “name” is transferred over, but also that the defaultEnum
which is against the plain Python enum.Enum class or other “empty” enum won’t set a hardcoded name of"enum"
either.References: #9963
orm declarative¶
A warning is emitted when an ORM
relationship()
and otherMapperProperty
objects are assigned to two different class attributes at once; only one of the attributes will be mapped. A warning for this condition was already in place forColumn
andmapped_column
objects.References: #3532
extensions¶
Fixed issue in mypy plugin for use with mypy 1.4.
This change is also backported to: 1.4.49
typing¶
Fixed typing issue which prevented
WriteOnlyMapped
andDynamicMapped
attributes from being used fully within ORM queries.References: #9985
postgresql¶
The pg8000 dialect now supports RANGE and MULTIRANGE datatypes, using the existing RANGE API described at Range and Multirange Types. Range and multirange types are supported in the pg8000 driver from version 1.29.8. Pull request courtesy Tony Locke.
References: #9965
2.0.16¶
Released: June 10, 2023platform¶
Compatibility improvements allowing the complete test suite to pass on Python 3.12.0b1.
orm¶
Improved
DeferredReflection.prepare()
to accept arbitrary**kw
arguments that are passed toMetaData.reflect()
, allowing use cases such as reflection of views as well as dialect-specific arguments to be passed. Additionally, modernized theDeferredReflection.prepare.bind
argument so that either anEngine
orConnection
are accepted as the “bind” argument.References: #9828
Fixed issue where
DeclarativeBaseNoMeta
declarative base class would not function with non-mapped mixins or abstract classes, raising anAttributeError
instead.References: #9862
Fixed regression in the 2.0 series where the default value of
validates.include_backrefs
got changed toFalse
for thevalidates()
function. This default is now restored toTrue
.References: #9820
Fixed bug in new feature which allows a WHERE clause to be used in conjunction with ORM Bulk UPDATE by Primary Key, added in version 2.0.11 as part of #9583, where sending dictionaries that did not include the primary key values for each row would run through the bulk process and include “pk=NULL” for the rows, silently failing. An exception is now raised if primary key values for bulk UPDATE are not supplied.
References: #9917
Fixed an issue where generating dataclasses fields that specified a
default
value and setinit=False
would not work. The dataclasses behavior in this case is to set the default value on the class, that’s not compatible with the descriptors used by SQLAlchemy. To support this case the default is transformed to adefault_factory
when generating the dataclass.References: #9879
A deprecation warning is emitted whenever a property is added to a
Mapper
where an ORM mapped property were already configured, or an attribute is already present on the class. Previously, there was a non-deprecation warning for this case that did not emit consistently. The logic for this warning has been improved so that it detects end-user replacement of attribute while not having false positives for internal Declarative and other cases where replacement of descriptors with new ones is expected.References: #9841
Improved the argument chacking on the
map_imperatively.local_table
parameter of theregistry.map_imperatively()
method, ensuring only aTable
or otherFromClause
is passed, and not an existing mapped class, which would lead to undefined behavior as the object were further interpreted for a new mapping.References: #9869
The
InstanceState.unloaded_expirable
attribute is a synonym forInstanceState.unloaded
, and is now deprecated; this attribute was always implementation-specific and should not have been public.References: #9913
asyncio¶
Added new
create_async_engine.async_creator
parameter tocreate_async_engine()
, which accomplishes the same purpose as thecreate_engine.creator
parameter ofcreate_engine()
. This is a no-argument callable that provides a new asyncio connection, using the asyncio database driver directly. Thecreate_async_engine()
function will wrap the driver-level connection in the appropriate structures. Pull request courtesy of Jack Wotherspoon.References: #8215
postgresql¶
Cast
NAME
columns toTEXT
when usingARRAY_AGG
in PostgreSQL reflection. This seems to improve compatibility with some PostgreSQL derivatives that may not support aggregations on theNAME
type.References: #9838
Unified the custom PostgreSQL operator definitions, since they are shared among multiple different data types.
References: #9041
Added support for PostgreSQL 10
NULLS NOT DISTINCT
feature of unique indexes and unique constraint using the dialect optionpostgresql_nulls_not_distinct
. Updated the reflection logic to also correctly take this option into account. Pull request courtesy of Pavel Siarchenia.References: #8240
Use proper precedence on PostgreSQL specific operators, such as
@>
. Previously the precedence was wrong, leading to wrong parenthesis when rendering against andANY
orALL
construct.References: #9836
Fixed issue where the
ColumnOperators.like.escape
and similar parameters did not allow an empty string as an argument that would be passed through as the “escape” character; this is a supported syntax by PostgreSQL. Pull requset courtesy Martin Caslavsky.References: #9907
2.0.15¶
Released: May 19, 2023orm¶
As more projects are using new-style “2.0” ORM querying, it’s becoming apparent that the conditional nature of “autoflush”, being based on whether or not the given statement refers to ORM entities, is becoming more of a key behavior. Up until now, the “ORM” flag for a statement has been loosely based around whether or not the statement returns rows that correspond to ORM entities or columns; the original purpose of the “ORM” flag was to enable ORM-entity fetching rules which apply post-processing to Core result sets as well as ORM loader strategies to the statement. For statements that don’t build on rows that contain ORM entities, the “ORM” flag was considered to be mostly unnecessary.
It still may be the case that “autoflush” would be better taking effect for all usage of
Session.execute()
and related methods, even for purely Core SQL constructs. However, this still could impact legacy cases where this is not expected and may be more of a 2.1 thing. For now however, the rules for the “ORM-flag” have been opened up so that a statement that includes ORM entities or attributes anywhere within, including in the WHERE / ORDER BY / GROUP BY clause alone, within scalar subqueries, etc. will enable this flag. This will cause “autoflush” to occur for such statements and also be visible via theORMExecuteState.is_orm_statement
event-level attribute.References: #9805
postgresql¶
Repaired the base
Uuid
datatype for the PostgreSQL dialect to make full use of the PG-specificUUID
dialect-specific datatype when “native_uuid” is selected, so that PG driver behaviors are included. This issue became apparent due to the insertmanyvalues improvement made as part of #9618, where in a similar manner as that of #9739, the asyncpg driver is very sensitive to datatype casts being present or not, and the PostgreSQL driver-specific nativeUUID
datatype must be invoked when this generic type is used so that these casts take place.References: #9808
2.0.14¶
Released: May 18, 2023orm¶
Modified the
JoinedLoader
implementation to use a simpler approach in one particular area where it previously used a cached structure that would be shared among threads. The rationale is to avoid a potential race condition which is suspected of being the cause of a particular crash that’s been reported multiple times. The cached structure in question is still ultimately “cached” via the compiled SQL cache, so a performance degradation is not anticipated.References: #9777
Fixed regression where use of
update()
ordelete()
within aCTE
construct, then used in aselect()
, would raise aCompileError
as a result of ORM related rules for performing ORM-level update/delete statements.References: #9767
Fixed issue in new ORM Annotated Declarative where using a
ForeignKey
(or other column-level constraint) inside ofmapped_column()
which is then copied out to models via pep-593Annotated
would apply duplicates of each constraint to theColumn
as produced in the targetTable
, leading to incorrect CREATE TABLE DDL as well as migration directives under Alembic.References: #9766
Fixed issue where using additional relationship criteria with the
joinedload()
loader option, where the additional criteria itself contained correlated subqueries that referred to the joined entities and therefore also required “adaption” to aliased entities, would be excluded from this adaption, producing the wrong ON clause for the joinedload.References: #9779
sql¶
Generalized the MSSQL
try_cast()
function into thesqlalchemy.
import namespace so that it may be implemented by third party dialects as well. Within SQLAlchemy, thetry_cast()
function remains a SQL Server-only construct that will raiseCompileError
if used with backends that don’t support it.try_cast()
implements a CAST where un-castable conversions are returned as NULL, instead of raising an error. Theoretically, the construct could be implemented by third party dialects for Google BigQuery, DuckDB, and Snowflake, and possibly others.Pull request courtesy Nick Crews.
References: #9752
Fixed issue in
values()
construct where an internal compilation error would occur if the construct were used inside of a scalar subquery.References: #9772
postgresql¶
Fixed apparently very old issue where the
ENUM.create_type
parameter, when set to its non-default ofFalse
, would not be propagated when theColumn
which it’s a part of were copied, as is common when using ORM Declarative mixins.References: #9773
tests¶
Fixed test that relied on the
sys.getsizeof()
function to not run on pypy, where this function appears to have different behavior than it does on cpython.References: #9789
2.0.13¶
Released: May 10, 2023orm¶
Fixed issue where ORM Annotated Declarative would not resolve forward references correctly in all cases; in particular, when using
from __future__ import annotations
in combination with Pydantic dataclasses.References: #9717
Fixed issue in new Using RETURNING with upsert statements feature where the
populate_existing
execution option was not being propagated to the loading option, preventing existing attributes from being refreshed in-place.References: #9746
Fixed loader strategy pathing issues where eager loaders such as
joinedload()
/selectinload()
would fail to traverse fully for many-levels deep following a load that had awith_polymorphic()
or similar construct as an interim member.References: #9715
Fixed issue in
mapped_column()
construct where the correct warning for “column X named directly multiple times” would not be emitted when ORM mapped attributes referred to the sameColumn
, if themapped_column()
construct were involved, raising an internal assertion instead.References: #9630
sql¶
Implemented the “cartesian product warning” for UPDATE and DELETE statements, those which include multiple tables that are not correlated together in some way.
References: #9721
Fixed the base class for dialect-specific float/double types; Oracle
BINARY_DOUBLE
now subclassesDouble
, and internal types forFloat
for asyncpg and pg8000 now correctly subclassFloat
.Fixed issue where
update()
construct that included multiple tables and no VALUES clause would raise with an internal error. Current behavior forUpdate
with no values is to generate a SQL UPDATE statement with an empty “set” clause, so this has been made consistent for this specific sub-case.
schema¶
Improved how table columns are added, avoiding unnecessary allocations, significantly speeding up the creation of many table, like when reflecting entire schemas.
References: #9597
typing¶
Fixed typing for the
Session.get.with_for_update
parameter ofSession.get()
andSession.refresh()
(as well as corresponding methods onAsyncSession
) to accept booleanTrue
and all other argument forms accepted by the parameter at runtime.References: #9762
Added type
ColumnExpressionArgument
as a public-facing type that indicates column-oriented arguments which are passed to SQLAlchemy constructs, such asSelect.where()
,and_()
and others. This may be used to add typing to end-user functions which call these methods.References: #9656
asyncio¶
Added a new helper mixin
AsyncAttrs
that seeks to improve the use of lazy-loader and other expired or deferred ORM attributes with asyncio, providing a simple attribute accessor that provides anawait
interface to any ORM attribute, whether or not it needs to emit SQL.See also
References: #9731
Fixed issue in semi-private
await_only()
andawait_fallback()
concurrency functions where the given awaitable would remain un-awaited if the function threw aGreenletError
, which could cause “was not awaited” warnings later on if the program continued. In this case, the given awaitable is now cancelled before the exception is thrown.
postgresql¶
Fixed another regression due to the “insertmanyvalues” change in 2.0.10 as part of #9618, in a similar way as regression #9701, where
LargeBinary
datatypes also need additional casts on when using the asyncpg driver specifically in order to work with the new bulk INSERT format.References: #9739
oracle¶
Added reflection support in the Oracle dialect to expression based indexes and the ordering direction of index expressions.
References: #9597
misc¶
2.0.12¶
Released: April 30, 2023orm¶
Fixed critical caching issue where the combination of
aliased()
andhybrid_property()
expression compositions would cause a cache key mismatch, leading to cache keys that held onto the actualaliased()
object while also not matching that of equivalent constructs, filling up the cache.This change is also backported to: 1.4.48
References: #9728
mysql¶
Fixed issues regarding reflection of comments for
Table
andColumn
objects, where the comments contained control characters such as newlines. Additional testing support for these characters as well as extended Unicode characters in table and column comments (the latter of which aren’t supported by MySQL/MariaDB) added to testing overall.References: #9722
2.0.11¶
Released: April 26, 2023orm¶
The ORM bulk INSERT and UPDATE features now add these capabilities:
The requirement that extra parameters aren’t passed when using ORM INSERT using the “orm” dml_strategy setting is lifted.
The requirement that additional WHERE criteria is not passed when using ORM UPDATE using the “bulk” dml_strategy setting is lifted. Note that in this case, the check for expected row count is turned off.
Fixed 2.0 regression where use of
bindparam()
inside ofInsert.values()
would fail to be interpreted correctly when executing theInsert
statement using the ORMSession
, due to the new ORM-enabled insert feature not implementing this use case.
engine¶
A series of performance enhancements to
Row
:__getattr__
performance of the row’s “named tuple” interface has been improved; within this change, theRow
implementation has been streamlined, removing constructs and logic that were specific to the 1.4 and prior series of SQLAlchemy. As part of this change, the serialization format ofRow
has been modified slightly, however rows which were pickled with previous SQLAlchemy 2.0 releases will be recognized within the new format. Pull request courtesy J. Nick Koston.Improved row processing performance for “binary” datatypes by making the “bytes” handler conditional on a per driver basis. As a result, the “bytes” result handler has been removed for nearly all drivers other than psycopg2, all of which in modern forms support returning Python “bytes” directly. Pull request courtesy J. Nick Koston.
Additional refactorings inside of
Row
to improve performance by Federico Caselli.
Fixed regression which prevented the
URL.normalized_query
attribute ofURL
from functioning.References: #9682
sql¶
Added support for slice access with
ColumnCollection
, e.g.table.c[0:5]
,subquery.c[:-1]
etc. Slice access returns a subColumnCollection
in the same way as passing a tuple of keys. This is a natural continuation of the key-tuple access added for #8285, where it appears to be an oversight that the slice access use case was omitted.References: #8285
typing¶
Improved typing of
RowMapping
to indicate that it support alsoColumn
as index objects, not only string names. Pull request courtesy Andy Freeland.References: #9644
postgresql¶
Fixed critical regression caused by #9618, which modified the architecture of the insertmanyvalues feature for 2.0.10, which caused floating point values to lose all decimal places when being inserted using the insertmanyvalues feature with either the psycopg2 or psycopg drivers.
References: #9701
mssql¶
Implemented the
Double
type for SQL Server, where it will renderDOUBLE PRECISION
at DDL time. This is implemented using a new MSSQL datatypeDOUBLE_PRECISION
which also may be used directly.
oracle¶
Fixed issue in Oracle dialects where
Decimal
returning types such asNumeric
would return floating point values, rather thanDecimal
objects, when these columns were used in theInsert.returning()
clause to return INSERTed values.
2.0.10¶
Released: April 21, 2023orm¶
Fixed bug where various ORM-specific getters such as
ORMExecuteState.is_column_load
,ORMExecuteState.is_relationship_load
,ORMExecuteState.loader_strategy_path
etc. would throw anAttributeError
if the SQL statement itself were a “compound select” such as a UNION.This change is also backported to: 1.4.48
References: #9634
Fixed issue where the
declared_attr.directive()
modifier was not correctly honored for subclasses when applied to the__mapper_args__
special method name, as opposed to direct use ofdeclared_attr
. The two constructs should have identical runtime behaviors.References: #9625
Made an improvement to the
with_loader_criteria()
loader option to allow it to be indicated in theExecutable.options()
method of a top-level statement that is not itself an ORM statement. Examples includeselect()
that’s embedded in compound statements such asunion()
, within anInsert.from_select()
construct, as well as within CTE expressions that are not ORM related at the top level.References: #9635
Fixed bug in ORM bulk insert feature where additional unnecessary columns would be rendered in the INSERT statement if RETURNING of individual columns were requested.
References: #9685
Fixed bug in ORM Declarative Dataclasses where the
query_expression()
andcolumn_property()
constructs, which are documented as read-only constructs in the context of a Declarative mapping, could not be used with aMappedAsDataclass
class without addinginit=False
, which in the case ofquery_expression()
was not possible as noinit
parameter was included. These constructs have been modified from a dataclass perspective to be assumed to be “read only”, settinginit=False
by default and no longer including them in the pep-681 constructor. The dataclass parameters forcolumn_property()
init
,default
,default_factory
,kw_only
are now deprecated; these fields don’t apply tocolumn_property()
as used in a Declarative dataclasses configuration where the construct would be read-only. Also added read-specific parameterquery_expression.compare
toquery_expression()
;query_expression.repr
was already present.References: #9628
Added missing
mapped_column.active_history
parameter tomapped_column()
construct.
engine¶
Added
create_pool_from_url()
andcreate_async_pool_from_url()
to create aPool
instance from an input url passed as string orURL
.References: #9613
Repaired a major shortcoming which was identified in the “Insert Many Values” Behavior for INSERT statements performance optimization feature first introduced in the 2.0 series. This was a continuation of the change in 2.0.9 which disabled the SQL Server version of the feature due to a reliance in the ORM on apparent row ordering that is not guaranteed to take place. The fix applies new logic to all “insertmanyvalues” operations, which takes effect when a new parameter
Insert.returning.sort_by_parameter_order
on theInsert.returning()
orUpdateBase.return_defaults()
methods, that through a combination of alternate SQL forms, direct correspondence of client side parameters, and in some cases downgrading to running row-at-a-time, will apply sorting to each batch of returned rows using correspondence to primary key or other unique values in each row which can be correlated to the input data.Performance impact is expected to be minimal as nearly all common primary key scenarios are suitable for parameter-ordered batching to be achieved for all backends other than SQLite, while “row-at-a-time” mode operates with a bare minimum of Python overhead compared to the very heavyweight approaches used in the 1.x series. For SQLite, there is no difference in performance when “row-at-a-time” mode is used.
It’s anticipated that with an efficient “row-at-a-time” INSERT with RETURNING batching capability, the “insertmanyvalues” feature can be later be more easily generalized to third party backends that include RETURNING support but not necessarily easy ways to guarantee a correspondence with parameter order.
typing¶
Added typing information for recently added operators
ColumnOperators.icontains()
,ColumnOperators.istartswith()
,ColumnOperators.iendswith()
, and bitwise operatorsColumnOperators.bitwise_and()
,ColumnOperators.bitwise_or()
,ColumnOperators.bitwise_xor()
,ColumnOperators.bitwise_not()
,ColumnOperators.bitwise_lshift()
ColumnOperators.bitwise_rshift()
. Pull request courtesy Martijn Pieters.References: #9650
Updates to the codebase to pass typing with Mypy 1.2.0.
Fixed typing issue where
PropComparator.and_()
expressions would not be correctly typed inside of loader options such asselectinload()
.References: #9669
postgresql¶
Added
prepared_statement_name_func
connection argument option in the asyncpg dialect. This option allows passing a callable used to customize the name of the prepared statement that will be created by the driver when executing queries. Pull request courtesy Pavel Sirotkin.References: #9608
Add missing
Range.intersection()
method. Pull request courtesy Yurii Karabas.References: #9509
Restored the
ENUM.name
parameter as optional in the signature forENUM
, as this is chosen automatically from a given pep-435Enum
type.References: #9611
Fixed issue where the comparison for
ENUM
against a plain string would cast that right-hand side type as VARCHAR, which due to more explicit casting added to dialects such as asyncpg would produce a PostgreSQL type mismatch error.References: #9621
Fixed issue that prevented reflection of expression based indexes with long expressions in PostgreSQL. The expression where erroneously truncated to the identifier length (that’s 63 bytes by default).
References: #9615
mssql¶
Restored the insertmanyvalues feature for Microsoft SQL Server. This feature was disabled in version 2.0.9 due to an apparent reliance on the ordering of RETURNING that is not guaranteed. The architecture of the “insertmanyvalues” feature has been reworked to accommodate for specific organizations of INSERT statements and result row handling that can guarantee the correspondence of returned rows to input records.
oracle¶
Fixed issue where the
Uuid
datatype could not be used in an INSERT..RETURNING clause with the Oracle dialect.
2.0.9¶
Released: April 5, 2023orm¶
Fixed endless loop which could occur when using “relationship to aliased class” feature and also indicating a recursive eager loader such as
lazy="selectinload"
in the loader, in combination with another eager loader on the opposite side. The check for cycles has been fixed to include aliased class relationships.This change is also backported to: 1.4.48
References: #9590
mariadb¶
Added
row_number
as reserved word in MariaDb.References: #9588
mssql¶
The SQLAlchemy “insertmanyvalues” feature which allows fast INSERT of many rows while also supporting RETURNING is temporarily disabled for SQL Server. As the unit of work currently relies upon this feature such that it matches existing ORM objects to returned primary key identities, this particular use pattern does not work with SQL Server in all cases as the order of rows returned by “OUTPUT inserted” may not always match the order in which the tuples were sent, leading to the ORM making the wrong decisions about these objects in subsequent operations.
The feature will be re-enabled in an upcoming release and will again take effect for multi-row INSERT statements, however the unit-of-work’s use of the feature will be disabled, possibly for all dialects, unless ORM-mapped tables also include a “sentinel” column so that the returned rows can be referenced back to the original data passed in.
References: #9603
Changed the bulk INSERT strategy used for SQL Server “executemany” with pyodbc when
fast_executemany
is set toTrue
by usingfast_executemany
/cursor.executemany()
for bulk INSERT that does not include RETURNING, restoring the same behavior as was used in SQLAlchemy 1.4 when this parameter is set.New performance details from end users have shown that
fast_executemany
is still much faster for very large datasets as it uses ODBC commands that can receive all rows in a single round trip, allowing for much larger datasizes than the batches that can be sent by “insertmanyvalues” as was implemented for SQL Server.While this change was made such that “insertmanyvalues” continued to be used for INSERT that includes RETURNING, as well as if
fast_executemany
were not set, due to #9603, the “insertmanyvalues” strategy has been disabled for SQL Server across the board in any case.References: #9586
2.0.8¶
Released: March 31, 2023orm¶
Exceptions such as
TypeError
andValueError
raised by Python dataclasses when making use of theMappedAsDataclass
mixin class orregistry.mapped_as_dataclass()
decorator are now wrapped within anInvalidRequestError
wrapper along with informative context about the error message, referring to the Python dataclasses documentation as the authoritative source of background information on the cause of the exception.References: #9563
Fixed issue in ORM Annotated Declarative where using a recursive type (e.g. using a nested Dict type) would result in a recursion overflow in the ORM’s annotation resolution logic, even if this datatype were not necessary to map the column.
References: #9553
Fixed issue where the
mapped_column()
construct would raise an internal error if used on a Declarative mixin and included themapped_column.deferred
parameter.References: #9550
Expanded the warning emitted when a plain
column()
object is present in a Declarative mapping to include any arbitrary SQL expression that is not declared within an appropriate property type such ascolumn_property()
,deferred()
, etc. These attributes are otherwise not mapped at all and remain unchanged within the class dictionary. As it seems likely that such an expression is usually not what’s intended, this case now warns for all such otherwise ignored expressions, rather than just thecolumn()
case.References: #9537
Fixed regression where accessing the expression value of a hybrid property on a class that was either unmapped or not-yet-mapped (such as calling upon it within a
declared_attr()
method) would raise an internal error, as an internal fetch for the parent class’ mapper would fail and an instruction for this failure to be ignored were inadvertently removed in 2.0.References: #9519
Fields that are declared on Declarative Mixins and then combined with classes that make use of
MappedAsDataclass
, where those mixin fields are not themselves part of a dataclass, now emit a deprecation warning as these fields will be ignored in a future release, as Python dataclasses behavior is to ignore these fields. Type checkers will not see these fields under pep-681.See also
When transforming <cls> to a dataclass, attribute(s) originate from superclass <cls> which is not a dataclass. - background on rationale
References: #9350
Fixed issue where the
BindParameter.render_literal_execute()
method would fail when called on a parameter that also had ORM annotations associated with it. In practice, this would be observed as a failure of SQL compilation when using some combinations of a dialect that uses “FETCH FIRST” such as Oracle along with aSelect
construct that usesSelect.limit()
, within some ORM contexts, including if the statement were embedded within a relationship primaryjoin expression.References: #9526
Towards maintaining consistency with unit-of-work changes made for #5984 and #8862, both of which disable “lazy=’raise’” handling within
Session
processes that aren’t triggered by attribute access, theSession.delete()
method will now also disable “lazy=’raise’” handling when it traverses relationship paths in order to process the “delete” and “delete-orphan” cascade rules. Previously, there was no easy way to generically callSession.delete()
on an object that had “lazy=’raise’” set up such that only the necessary relationships would be loaded. As “lazy=’raise’” is primarily intended to catch SQL loading that emits on attribute access,Session.delete()
is now made to behave like otherSession
methods includingSession.merge()
as well asSession.flush()
along with autoflush.References: #9549
Fixed issue where an annotation-only
Mapped
directive could not be used in a Declarative mixin class, without that attribute attempting to take effect for single- or joined-inheritance subclasses of mapped classes that had already mapped that attribute on a superclass, producing conflicting column errors and/or warnings.References: #9564
Properly type
Insert.from_select.names
to accept a list of string or columns or mapped attributes.References: #9514
examples¶
Fixed issue in “versioned history” example where using a declarative base that is derived from
DeclarativeBase
would fail to be mapped. Additionally, repaired the given test suite so that the documented instructions for running the example using Python unittest now work again.
typing¶
Fixed typing for
deferred()
andquery_expression()
to work correctly with 2.0 style mappings.References: #9536
postgresql¶
Fixed critical regression in PostgreSQL dialects such as asyncpg which rely upon explicit casts in SQL in order for datatypes to be passed to the driver correctly, where a
String
datatype would be cast along with the exact column length being compared, leading to implicit truncation when comparing aVARCHAR
of a smaller length to a string of greater length regardless of operator in use (e.g. LIKE, MATCH, etc.). The PostgreSQL dialect now omits the length fromVARCHAR
when rendering these casts.References: #9511
mysql¶
misc¶
Implemented missing methods
copy
andpop
in OrderedSet class.References: #9487
2.0.7¶
Released: March 18, 2023typing¶
Fixed typing issue where
composite()
would not allow an arbitrary callable as the source of the composite class.References: #9502
postgresql¶
2.0.6¶
Released: March 13, 2023orm¶
Fixed bug where the “active history” feature was not fully implemented for composite attributes, making it impossible to receive events that included the “old” value. This seems to have been the case with older SQLAlchemy versions as well, where “active_history” would be propagated to the underlying column-based attributes, but an event handler listening to the composite attribute itself would not be given the “old” value being replaced, even if the composite() were set up with active_history=True.
Additionally, fixed a regression that’s local to 2.0 which disallowed active_history on composite from being assigned to the impl with
attr.impl.active_history=True
.References: #9460
Fixed regression involving pickling of Python rows between the cython and pure Python implementations of
Row
, which occurred as part of refactoring code for version 2.0 with typing. A particular constant were turned into a string basedEnum
for the pure Python version ofRow
whereas the cython version continued to use an integer constant, leading to deserialization failures.References: #9418
sql¶
Fixed regression where the fix for #8098, which was released in the 1.4 series and provided a layer of concurrency-safe checks for the lambda SQL API, included additional fixes in the patch that failed to be applied to the main branch. These additional fixes have been applied.
References: #9461
Fixed regression where the
select()
construct would not be able to render if it were given no columns and then used in the context of an EXISTS, raising an internal exception instead. While an empty “SELECT” is not typically valid SQL, in the context of EXISTS databases such as PostgreSQL allow it, and in any case the condition now no longer raises an internal exception.References: #9440
typing¶
Fixed typing issue where
ColumnElement.cast()
did not allow aTypeEngine
argument independent of the type of theColumnElement
itself, which is the purpose ofColumnElement.cast()
.References: #9451
Fixed issues to allow typing tests to pass under Mypy 1.1.1.
oracle¶
Fixed reflection bug where Oracle “name normalize” would not work correctly for reflection of symbols that are in the “PUBLIC” schema, such as synonyms, meaning the PUBLIC name could not be indicated as lower case on the Python side for the
Table.schema
argument. Using uppercase “PUBLIC” would work, but would then lead to awkward SQL queries including a quoted"PUBLIC"
name as well as indexing the table under uppercase “PUBLIC”, which was inconsistent.References: #9459
2.0.5.post1¶
Released: March 5, 2023orm¶
Added constructor arguments to the built-in mapping collection types including
KeyFuncDict
,attribute_keyed_dict()
,column_keyed_dict()
so that these dictionary types may be constructed in place given the data up front; this provides further compatibility with tools such as Python dataclasses.asdict()
which relies upon invoking these classes directly as ordinary dictionary classes.References: #9418
Fixed multiple regressions due to #8372, involving
attribute_mapped_collection()
(now calledattribute_keyed_dict()
).First, the collection was no longer usable with “key” attributes that were not themselves ordinary mapped attributes; attributes linked to descriptors and/or association proxy attributes have been fixed.
Second, if an event or other operation needed access to the “key” in order to populate the dictionary from an mapped attribute that was not loaded, this also would raise an error inappropriately, rather than trying to load the attribute as was the behavior in 1.4. This is also fixed.
For both cases, the behavior of #8372 has been expanded. #8372 introduced an error that raises when the derived key that would be used as a mapped dictionary key is effectively unassigned. In this change, a warning only is emitted if the effective value of the “.key” attribute is
None
, where it cannot be unambiguously determined if thisNone
was intentional or not.None
will be not supported as mapped collection dictionary keys going forward (as it typically refers to NULL which means “unknown”). Settingattribute_keyed_dict.ignore_unpopulated_attribute
will now cause suchNone
keys to be ignored as well.References: #9424
Identified that the
sqlite
andmssql+pyodbc
dialects are now compatible with the SQLAlchemy ORM’s “versioned rows” feature, since SQLAlchemy now computes rowcount for a RETURNING statement in this specific case by counting the rows returned, rather than relying uponcursor.rowcount
. In particular, the ORM versioned rows use case (documented at Configuring a Version Counter) should now be fully supported with the SQL Server pyodbc dialect.Added support for the
Mapper.polymorphic_load
parameter to be applied to each mapper in an inheritance hierarchy more than one level deep, allowing columns to load for all classes in the hierarchy that indicate"selectin"
using a single statement, rather than ignoring elements on those intermediary classes that nonetheless indicate they also would participate in"selectin"
loading and were not part of the base-most SELECT statement.References: #9373
Continued the fix for #8853, allowing the
Mapped
name to be fully qualified regardless of whether or notfrom __annotations__ import future
were present. This issue first fixed in 2.0.0b3 confirmed that this case worked via the test suite, however the test suite apparently was not testing the behavior for the nameMapped
not being locally present at all; string resolution has been updated to ensure theMapped
symbol is locatable as applies to how the ORM uses these functions.
orm declarative¶
Fixed issue where new
mapped_column.use_existing_column
feature would not work if the two same-named columns were mapped under attribute names that were differently-named from an explicit name given to the column itself. The attribute names can now be differently named when using this parameter.References: #9332
engine¶
A small optimization to the Cython implementation of
Result
using a cdef for a particular int value to avoid Python overhead. Pull request courtesy Matus Valo.References: #9343
Fixed bug where
Row
objects could not be reliably unpickled across processes due to an accidental reliance on an unstable hash value.References: #9423
sql¶
Restore the
nullslast()
andnullsfirst()
legacy functions into thesqlalchemy
import namespace. Previously, the newernulls_last()
andnulls_first()
functions were available, but the legacy ones were inadvertently removed.References: #9390
schema¶
Validate that when provided the
MetaData.schema
argument ofMetaData
is a string.
typing¶
Exported the type returned by
scoped_session.query_property()
using a new public typeQueryPropertyDescriptor
.References: #9338
Fixed bug where the
Connection.scalars()
method was not typed as allowing a multiple-parameters list, which is now supported using insertmanyvalues operations.Improved typing for the mapping passed to
Insert.values()
andUpdate.values()
to be more open-ended about collection type, by indicating read-onlyMapping
instead of writeableDict
which would error out on too limited of a key type.References: #9376
Added missing init overload to the
Numeric
type object so that pep-484 type checkers may properly resolve the complete type, deriving from theNumeric.asdecimal
parameter whetherDecimal
orfloat
objects will be represented.References: #9391
Fixed typing bug where
Select.from_statement()
would not accepttext()
orTextualSelect
objects as a valid type. Additionally repaired thecolumns
method to have a return type, which was missing.References: #9398
Fixed typing issue where
with_polymorphic()
would not record the class type correctly.References: #9340
postgresql¶
Fixed issue in PostgreSQL
ExcludeConstraint
where literal values were being compiled as bound parameters and not direct inline values as is required for DDL.References: #9349
Fixed issue where the PostgreSQL
ExcludeConstraint
construct would not be copyable within operations such asTable.to_metadata()
as well as within some Alembic scenarios, if the constraint contained textual expression elements.References: #9401
mysql¶
The support for pool ping listeners to receive exception events via the
DialectEvents.handle_error()
event added in 2.0.0b1 for #5648 failed to take into account dialect-specific ping routines such as that of MySQL and PostgreSQL. The dialect feature has been reworked so that all dialects participate within event handling. Additionally, a new boolean elementExceptionContext.is_pre_ping
is added which identifies if this operation is occurring within the pre-ping operation.For this release, third party dialects which implement a custom
Dialect.do_ping()
method can opt in to the newly improved behavior by having their method no longer catch exceptions or check exceptions for “is_disconnect”, instead just propagating all exceptions outwards. Checking the exception for “is_disconnect” is now done by an enclosing method on the default dialect, which ensures that the event hook is invoked for all exception scenarios before testing the exception as a “disconnect” exception. If an existingdo_ping()
method continues to catch exceptions and check “is_disconnect”, it will continue to work as it did previously, buthandle_error
hooks will not have access to the exception if it isn’t propagated outwards.References: #5648
sqlite¶
Fixed regression for SQLite connections where use of the
deterministic
parameter when establishing database functions would fail for older SQLite versions, those prior to version 3.8.3. The version checking logic has been improved to accommodate for this case.References: #9379
mssql¶
Fixed issue in the new
Uuid
datatype which prevented it from working with the pymssql driver. As pymssql seems to be maintained again, restored testing support for pymssql.References: #9414
Tweaked the pymssql dialect to take better advantage of RETURNING for INSERT statements in order to retrieve last inserted primary key values, in the same way as occurs for the mssql+pyodbc dialect right now.
misc¶
Fixed issue in automap where calling
AutomapBase.prepare()
from a specific mapped class, rather than from theAutomapBase
directly, would not use the correct base class when automap detected new tables, instead using the given class, leading to mappers trying to configure inheritance. While one should normally callAutomapBase.prepare()
from the base in any case, it shouldn’t misbehave that badly when called from a subclass.References: #9367
Fixed regression caused by typing added to
sqlalchemy.ext.mutable
for #8667, where the semantics of the.pop()
method changed such that the method was non-working. Pull request courtesy Nils Philippsen.References: #9380
2.0.4¶
Released: February 17, 2023orm¶
To accommodate a change in column ordering used by ORM Declarative in SQLAlchemy 2.0, a new parameter
mapped_column.sort_order
has been added that can be used to control the order of the columns defined in the table by the ORM, for common use cases such as mixins with primary key columns that should appear first in tables. The change notes at ORM Declarative Applies Column Orders Differently; Control behavior using sort_order illustrate the default change in ordering behavior (which is part of all SQLAlchemy 2.0 releases) as well as use of themapped_column.sort_order
to control column ordering when using mixins and multiple classes (new in 2.0.4).References: #9297
The
Session.refresh()
method will now immediately load a relationship-bound attribute that is explicitly named within theSession.refresh.attribute_names
collection even if it is currently linked to the “select” loader, which normally is a “lazy” loader that does not fire off during a refresh. The “lazy loader” strategy will now detect that the operation is specifically a user-initiatedSession.refresh()
operation which named this attribute explicitly, and will then call upon the “immediateload” strategy to actually emit SQL to load the attribute. This should be helpful in particular for some asyncio situations where the loading of an unloaded lazy-loaded attribute must be forced, without using the actual lazy-loading attribute pattern not supported in asyncio.References: #9298
Fixed regression introduced in version 2.0.2 due to #9217 where using DML RETURNING statements, as well as
Select.from_statement()
constructs as was “fixed” in #9217, in conjunction with ORM mapped classes that used expressions such as withcolumn_property()
, would lead to an internal error within Core where it would attempt to match the expression by name. The fix repairs the Core issue, and also adjusts the fix in #9217 to not take effect for the DML RETURNING use case, where it adds unnecessary overhead.References: #9273
Marked the internal
EvaluatorCompiler
module as private to the ORM, and renamed it to_EvaluatorCompiler
. For users that may have been relying upon this, the nameEvaluatorCompiler
is still present, however this use is not supported and will be removed in a future release.
orm declarative¶
Added new parameter
dataclasses_callable
to both theMappedAsDataclass
class as well as theregistry.mapped_as_dataclass()
method which allows an alternative callable to Pythondataclasses.dataclass
to be used in order to produce dataclasses. The use case here is to drop in Pydantic’s dataclass function instead. Adjustments have been made to the mixin support added for #9179 in version 2.0.1 so that the__annotations__
collection of the mixin is rewritten to not include theMapped
container, in the same way as occurs with mapped classes, so that the Pydantic dataclasses constructor is not exposed to unknown types.References: #9266
sql¶
Fixed issue where element types of a tuple value would be hardcoded to take on the types from a compared-to tuple, when the comparison were using the
ColumnOperators.in_()
operator. This was inconsistent with the usual way that types are determined for a binary expression, which is that the actual element type on the right side is considered first before applying the left-hand-side type.References: #9313
Added public property
Table.autoincrement_column
that returns the column identified as autoincrementing in the column.References: #9277
typing¶
Improved the typing support for the Hybrid Attributes extension, updated all documentation to use ORM Annotated Declarative mappings, and added a new modifier called
hybrid_property.inplace
. This modifier provides a way to alter the state of ahybrid_property
in place, which is essentially what very early versions of hybrids did, before SQLAlchemy version 1.2.0 #3912 changed this to remove in-place mutation. This in-place mutation is now restored on an opt-in basis to allow a single hybrid to have multiple methods set up, without the need to name all the methods the same and without the need to carefully “chain” differently-named methods in order to maintain the composition. Typing tools such as Mypy and Pyright do not allow same-named methods on a class, so with this change a succinct method of setting up hybrids with typing support is restored.References: #9321
oracle¶
Adjusted the behavior of the
thick_mode
parameter for the python-oracledb dialect to correctly acceptFalse
as a value. Previously, onlyNone
would indicate that thick mode should be disabled.References: #9295
2.0.3¶
Released: February 9, 2023sql¶
Fixed critical regression in SQL expression formulation in the 2.0 series due to #7744 which improved support for SQL expressions that contained many elements against the same operator repeatedly; parenthesis grouping would be lost with expression elements beyond the first two elements.
References: #9271
typing¶
2.0.2¶
Released: February 6, 2023orm¶
Added new event hook
MapperEvents.after_mapper_constructed()
, which supplies an event hook to take place right as theMapper
object has been fully constructed, but before theregistry.configure()
call has been called. This allows code that can create additional mappings and table structures based on the initial configuration of aMapper
, which also integrates within Declarative configuration. Previously, when using Declarative, where theMapper
object is created within the class creation process, there was no documented means of running code at this point. The change is to immediately benefit custom mapping schemes such as that of the Versioning with a History Table example, which generate additional mappers and tables in response to the creation of mapped classes.References: #9220
The infrequently used
Mapper.iterate_properties
attribute andMapper.get_property()
method, which are primarily used internally, no longer implicitly invoke theregistry.configure()
process. Public access to these methods is extremely rare and the only benefit to havingregistry.configure()
would have been allowing “backref” properties be present in these collections. In order to support the newMapperEvents.after_mapper_constructed()
event, iteration and access to the internalMapperProperty
objects is now possible without triggering an implicit configure of the mapper itself.The more-public facing route to iteration of all mapper attributes, the
Mapper.attrs
collection and similar, will still implicitly invoke theregistry.configure()
step thus making backref attributes available.In all cases, the
registry.configure()
is always available to be called directly.References: #9220
Fixed obscure ORM inheritance issue caused by #8705 where some scenarios of inheriting mappers that indicated groups of columns from the local table and the inheriting table together under a
column_property()
would nonetheless warn that properties of the same name were being combined implicitly.References: #9232
Fixed regression where using the
Mapper.version_id_col
feature with a regular Python-side incrementing column would fail to work for SQLite and other databases that don’t support “rowcount” with “RETURNING”, as “RETURNING” would be assumed for such columns even though that’s not what actually takes place.References: #9228
Fixed regression when using
Select.from_statement()
in an ORM context, where matching of columns to SQL labels based on name alone was disabled for ORM-statements that weren’t fully textual. This would prevent arbitrary SQL expressions with column-name labels from matching up to the entity to be loaded, which previously would work within the 1.4 and previous series, so the previous behavior has been restored.References: #9217
orm declarative¶
Fixed regression caused by the fix for #9171, which itself was fixing a regression, involving the mechanics of
__init__()
on classes that extend fromDeclarativeBase
. The change made it such that__init__()
was applied to the user-defined base if there were no__init__()
method directly on the class. This has been adjusted so that__init__()
is applied only if no other class in the hierarchy of the user-defined base has an__init__()
method. This again allows user-defined base classes based onDeclarativeBase
to include mixins that themselves include a custom__init__()
method.References: #9249
Fixed issue in ORM Declarative Dataclass mappings related to newly added support for mixins added in 2.0.1 via #9179, where a combination of using mixins plus ORM inheritance would mis-classify fields in some cases leading to field-level dataclass arguments such as
init=False
being lost.References: #9226
Repaired ORM Declarative mappings to allow for the
Mapper.primary_key
parameter to be specified within__mapper_args__
when usingmapped_column()
. Despite this usage being directly in the 2.0 documentation, theMapper
was not accepting themapped_column()
construct in this context. Ths feature was already working for theMapper.version_id_col
andMapper.polymorphic_on
parameters.As part of this change, the
__mapper_args__
attribute may be specified without usingdeclared_attr()
on a non-mapped mixin class, including a"primary_key"
entry that refers toColumn
ormapped_column()
objects locally present on the mixin; Declarative will also translate these columns into the correct ones for a particular mapped class. This again was working already for theMapper.version_id_col
andMapper.polymorphic_on
parameters. Additionally, elements within"primary_key"
may be indicated as string names of existing mapped properties.References: #9240
An explicit error is raised if a mapping attempts to mix the use of
MappedAsDataclass
withregistry.mapped_as_dataclass()
within the same class hierarchy, as this produces issues with the dataclass function being applied at the wrong time to the mapped class, leading to errors during the mapping process.References: #9211
examples¶
Reworked the Versioning with a History Table to work with version 2.0, while at the same time improving the overall working of this example to use newer APIs, including a newly added hook
MapperEvents.after_mapper_constructed()
.References: #9220
sql¶
Added a full suite of new SQL bitwise operators, for performing database-side bitwise expressions on appropriate data values such as integers, bit-strings, and similar. Pull request courtesy Yegor Statkevich.
See also
References: #8780
asyncio¶
Repaired a regression caused by the fix for #8419 which caused asyncpg connections to be reset (i.e. transaction
rollback()
called) and returned to the pool normally in the case that the connection were not explicitly returned to the connection pool and was instead being intercepted by Python garbage collection, which would fail if the garbage collection operation were being called outside of the asyncio event loop, leading to a large amount of stack trace activity dumped into logging and standard output.The correct behavior is restored, which is that all asyncio connections that are garbage collected due to not being explicitly returned to the connection pool are detached from the pool and discarded, along with a warning, rather than being returned the pool, as they cannot be reliably reset. In the case of asyncpg connections, the asyncpg-specific
terminate()
method will be used to end the connection more gracefully within this process as opposed to just dropping it.This change includes a small behavioral change that is hoped to be useful for debugging asyncio applications, where the warning that’s emitted in the case of asyncio connections being unexpectedly garbage collected has been made slightly more aggressive by moving it outside of a
try/except
block and into afinally:
block, where it will emit unconditionally regardless of whether the detach/termination operation succeeded or not. It will also have the effect that applications or test suites which promote Python warnings to exceptions will see this as a full exception raise, whereas previously it was not possible for this warning to actually propagate as an exception. Applications and test suites which need to tolerate this warning in the interim should adjust the Python warnings filter to allow these warnings to not raise.The behavior for traditional sync connections remains unchanged, that garbage collected connections continue to be returned to the pool normally without emitting a warning. This will likely be changed in a future major release to at least emit a similar warning as is emitted for asyncio drivers, as it is a usage error for pooled connections to be intercepted by garbage collection without being properly returned to the pool.
References: #9237
mysql¶
Fixed regression caused by issue #9058 which adjusted the MySQL dialect’s
has_table()
to again use “DESCRIBE”, where the specific error code raised by MySQL version 8 when using a non-existent schema name was unexpected and failed to be interpreted as a boolean result.References: #9251
Added support for MySQL 8’s new
AS <name> ON DUPLICATE KEY
syntax when usingInsert.on_duplicate_key_update()
, which is required for newer versions of MySQL 8 as the previous syntax usingVALUES()
now emits a deprecation warning with those versions. Server version detection is employed to determine if traditional MariaDB / MySQL < 8VALUES()
syntax should be used, vs. the newer MySQL 8 required syntax. Pull request courtesy Caspar Wylie.References: #8626
sqlite¶
Fixed the SQLite dialect’s
has_table()
function to correctly report False for queries that include a non-None schema name for a schema that doesn’t exist; previously, a database error was raised.References: #9251
2.0.1¶
Released: February 1, 2023orm¶
Fixed regression where ORM models that used joined table inheritance with a composite foreign key would encounter an internal error in the mapper internals.
References: #9164
Improved the error reporting when linking strategy options from a base class to another attribute that’s off a subclass, where
of_type()
should be used. Previously, whenLoad.options()
is used, the message would lack informative detail thatof_type()
should be used, which was not the case when linking the options directly. The informative detail now emits even ifLoad.options()
is used.References: #9182
orm declarative¶
Added support for PEP 484
NewType
to be used in theregistry.type_annotation_map
as well as withinMapped
constructs. These types will behave in the same way as custom subclasses of types right now; they must appear explicitly within theregistry.type_annotation_map
to be mapped.References: #9175
When using the
MappedAsDataclass
superclass, all classes within the hierarchy that are subclasses of this class will now be run through the@dataclasses.dataclass
function whether or not they are actually mapped, so that non-ORM fields declared on non-mapped classes within the hierarchy will be used when mapped subclasses are turned into dataclasses. This behavior applies both to intermediary classes mapped with__abstract__ = True
as well as to the user-defined declarative base itself, assumingMappedAsDataclass
is present as a superclass for these classes.This allows non-mapped attributes such as
InitVar
declarations on superclasses to be used, without the need to run the@dataclasses.dataclass
decorator explicitly on each non-mapped class. The new behavior is considered as correct as this is what the PEP 681 implementation expects when using a superclass to indicate dataclass behavior.References: #9179
Added support for PEP 586
Literal[]
to be used in theregistry.type_annotation_map
as well as withinMapped
constructs. To use custom types such as these, they must appear explicitly within theregistry.type_annotation_map
to be mapped. Pull request courtesy Frederik Aalund.As part of this change, the support for
Enum
in theregistry.type_annotation_map
has been expanded to include support forLiteral[]
types consisting of string values to be used, in addition toenum.Enum
datatypes. If aLiteral[]
datatype is used withinMapped[]
that is not linked inregistry.type_annotation_map
to a specific datatype, aEnum
will be used by default.References: #9187
Fixed issue involving the use of
Enum
within theregistry.type_annotation_map
where theEnum.native_enum
parameter would not be correctly copied to the mapped column datatype, if it were overridden as stated in the documentation to set this parameter to False.References: #9200
Fixed regression in
DeclarativeBase
class where the registry’s default constructor would not be applied to the base itself, which is different from how the previousdeclarative_base()
construct works. This would prevent a mapped class with its own__init__()
method from callingsuper().__init__()
in order to access the registry’s default constructor and automatically populate attributes, instead hittingobject.__init__()
which would raise aTypeError
on any arguments.References: #9171
Improved the ruleset used to interpret PEP 593
Annotated
types when used with Annotated Declarative mapping, the inner type will be checked for “Optional” in all cases which will be added to the criteria by which the column is set as “nullable” or not; if the type within theAnnotated
container is optional (or unioned withNone
), the column will be considered nullable if there are no explicitmapped_column.nullable
parameters overriding it.References: #9177
sql¶
Corrected the fix for #7664, released in version 2.0.0, to also include
DropSchema
which was inadvertently missed in this fix, allowing stringification without a dialect. The fixes for both constructs is backported to the 1.4 series as of 1.4.47.References: #7664
Fixed regression related to the implementation for the new “insertmanyvalues” feature where an internal
TypeError
would occur in arrangements where ainsert()
would be referenced inside of anotherinsert()
via a CTE; made additional repairs for this use case for positional dialects such as asyncpg when using “insertmanyvalues”.References: #9173
typing¶
Opened up typing on
Select.with_for_update.of
to also accept table and mapped class arguments, as seems to be available for the MySQL dialect.References: #9174
Fixed typing for limit/offset methods including
Select.limit()
,Select.offset()
,Query.limit()
,Query.offset()
to allowNone
, which is the documented API to “cancel” the current limit/offset.References: #9183
Fixed typing issue where
mapped_column()
objects typed asMapped
wouldn’t be accepted in schema constraints such asForeignKey
,UniqueConstraint
orIndex
.References: #9170
Fixed typing for
ColumnElement.cast()
to accept bothType[TypeEngine[T]]
andTypeEngine[T]
; previously onlyTypeEngine[T]
was accepted. Pull request courtesy Yurii Karabas.References: #9156
2.0.0¶
Released: January 26, 2023orm¶
Improved the notification of warnings that are emitted within the configure mappers or flush process, which are often invoked as part of a different operation, to add additional context to the message that indicates one of these operations as the source of the warning within operations that may not be obviously related.
References: #7305
orm extensions¶
Added new option to horizontal sharding API
set_shard_id
which sets the effective shard identifier to query against, for both the primary query as well as for all secondary loaders including relationship eager loaders as well as relationship and column lazy loaders.References: #7226
Added new feature to
AutomapBase
for autoload of classes across multiple schemas which may have overlapping names, by providing aAutomapBase.prepare.modulename_for_table
parameter which allows customization of the__module__
attribute of newly generated classes, as well as a new collectionAutomapBase.by_module
, which stores a dot-separated namespace of module names linked to classes based on the__module__
attribute.Additionally, the
AutomapBase.prepare()
method may now be invoked any number of times, with or without reflection enabled; only newly added tables that were not previously mapped will be processed on each call. Previously, theMetaData.reflect()
method would need to be called explicitly each time.See also
Generating Mappings from Multiple Schemas - illustrates use of both techniques at once.
References: #5145
sql¶
Fixed stringify for a the
CreateSchema
DDL construct, which would fail with anAttributeError
when stringified without a dialect. Update: Note this fix failed to accommodate forDropSchema
; a followup fix in version 2.0.1 repairs this case. The fix for both elements is backported to 1.4.47.References: #7664
typing¶
Added typing for the built-in generic functions that are available from the
func
namespace, which accept a particular set of arguments and return a particular type, such as forcount
,current_timestamp
, etc.References: #9129
Corrected the type passed for “lambda statements” so that a plain lambda is accepted by mypy, pyright, others without any errors about argument types. Additionally implemented typing for more of the public API for lambda statements and ensured
StatementLambdaElement
is part of theExecutable
hierarchy so it’s typed as accepted byConnection.execute()
.References: #9120
The
ColumnOperators.in_()
andColumnOperators.not_in()
methods are typed to includeIterable[Any]
rather thanSequence[Any]
for more flexibility in argument type.References: #9122
The
or_()
andand_()
from a typing perspective require the first argument to be present, however these functions still accept zero arguments which will emit a deprecation warning at runtime. Typing is also added to support sending the fixed literalFalse
foror_()
andTrue
forand_()
as the first argument only, however the documentation now indicates sending thefalse()
andtrue()
constructs in these cases as a more explicit approach.References: #9123
Fixed typing issue where iterating over a
Query
object was not correctly typed.References: #9125
Fixed typing issue where the object type when using
Result
as a context manager were not preserved, indicatingResult
in all cases rather than the specificResult
sub-type. Pull request courtesy Martin Baláž.References: #9136
Fixed issue where using the
relationship.remote_side
and similar parameters, passing an annotated declarative object typed asMapped
, would not be accepted by the type checker.References: #9150
Added typing to legacy operators such as
isnot()
,notin_()
, etc. which previously were referencing the newer operators but were not themselves typed.References: #9148
postgresql¶
Added support to the asyncpg dialect to return the
cursor.rowcount
value for SELECT statements when available. While this is not a typical use forcursor.rowcount
, the other PostgreSQL dialects generally provide this value. Pull request courtesy Michael Gorven.This change is also backported to: 1.4.47
References: #9048
mysql¶
Added support to MySQL index reflection to correctly reflect the
mysql_length
dictionary, which previously was being ignored.This change is also backported to: 1.4.47
References: #9047
mssql¶
The newly added comment reflection and rendering capability of the MSSQL dialect, added in #7844, will now be disabled by default if it cannot be determined that an unsupported backend such as Azure Synapse may be in use; this backend does not support table and column comments and does not support the SQL Server routines in use to generate them as well as to reflect them. A new parameter
supports_comments
is added to the dialect which defaults toNone
, indicating that comment support should be auto-detected. When set toTrue
orFalse
, the comment support is either enabled or disabled unconditionally.See also
References: #9142
2.0.0rc3¶
Released: January 18, 2023orm¶
Added a new parameter to
Mapper
calledMapper.polymorphic_abstract
. The purpose of this directive is so that the ORM will not consider the class to be instantiated or loaded directly, only subclasses. The actual effect is that theMapper
will prevent direct instantiation of instances of the class and will expect that the class does not have a distinct polymorphic identity configured.In practice, the class that is mapped with
Mapper.polymorphic_abstract
can be used as the target of arelationship()
as well as be used in queries; subclasses must of course include polymorphic identities in their mappings.The new parameter is automatically applied to classes that subclass the
AbstractConcreteBase
class, as this class is not intended to be instantiated.References: #9060
Fixed issue where using a pep-593
Annotated
type in theregistry.type_annotation_map
which itself contained a generic plain container orcollections.abc
type (e.g.list
,dict
,collections.abc.Sequence
, etc. ) as the target type would produce an internal error when the ORM were trying to interpret theAnnotated
instance.References: #9099
Added an error message when a
relationship()
is mapped against an abstract container type, such asMapped[Sequence[B]]
, without providing therelationship.container_class
parameter which is necessary when the type is abstract. Previously the abstract container would attempt to be instantiated at a later step and fail.References: #9100
sql¶
Fixed bug / regression where using
bindparam()
with the same name as a column in theUpdate.values()
method ofUpdate
, as well as theInsert.values()
method ofInsert
in 2.0 only, would in some cases silently fail to honor the SQL expression in which the parameter were presented, replacing the expression with a new parameter of the same name and discarding any other elements of the SQL expression, such as SQL functions, etc. The specific case would be statements that were constructed against ORM entities rather than plainTable
instances, but would occur if the statement were invoked with aSession
or aConnection
.Update
part of the issue was present in both 2.0 and 1.4 and is backported to 1.4.This change is also backported to: 1.4.47
References: #9075
typing¶
Fixes to the annotations within the
sqlalchemy.ext.hybrid
extension for more effective typing of user-defined methods. The typing now uses PEP 612 features, now supported by recent versions of Mypy, to maintain argument signatures forhybrid_method
. Return values for hybrid methods are accepted as SQL expressions in contexts such asSelect.where()
while still supporting SQL methods.References: #9096
mypy¶
Adjustments made to the mypy plugin to accommodate for some potential changes being made for issue #236 sqlalchemy2-stubs when using SQLAlchemy 1.4. These changes are being kept in sync within SQLAlchemy 2.0. The changes are also backwards compatible with older versions of sqlalchemy2-stubs.
This change is also backported to: 1.4.47
Fixed crash in mypy plugin which could occur on both 1.4 and 2.0 versions if a decorator for the
mapped()
decorator were used that was referenced in an expression with more than two components (e.g.@Backend.mapper_registry.mapped
). This scenario is now ignored; when using the plugin, the decorator expression needs to be two components (i.e.@reg.mapped
).This change is also backported to: 1.4.47
References: #9102
postgresql¶
Fixed regression where psycopg3 changed an API call as of version 3.1.8 to expect a specific object type that was previously not enforced, breaking connectivity for the psycopg3 dialect.
References: #9106
oracle¶
2.0.0rc2¶
Released: January 9, 2023orm¶
Fixed issue where an overly restrictive ORM mapping rule were added in 2.0 which prevented mappings against
TableClause
objects, such as those used in the view recipe on the wiki.References: #9071
typing¶
The Data Class Transforms argument
field_descriptors
was renamed tofield_specifiers
in the accepted version of PEP 681.References: #9067
postgresql¶
Implemented missing
JSONB
operations:@@
usingComparator.path_match()
@?
usingComparator.path_exists()
#-
usingComparator.delete_path()
Pull request courtesy of Guilherme Martins Crocetti.
References: #7147
mysql¶
Restored the behavior of
Inspector.has_table()
to report on temporary tables for MySQL / MariaDB. This is currently the behavior for all other included dialects, but was removed for MySQL in 1.4 due to no longer using the DESCRIBE command; there was no documented support for temp tables being reported by theInspector.has_table()
method in this version or on any previous version, so the previous behavior was undefined.As SQLAlchemy 2.0 has added formal support for temp table status via
Inspector.has_table()
, the MySQL /MariaDB dialect has been reverted to use the “DESCRIBE” statement as it did in the SQLAlchemy 1.3 series and previously, and test support is added to include MySQL / MariaDB for this behavior. The previous issues with ROLLBACK being emitted which 1.4 sought to improve upon don’t apply in SQLAlchemy 2.0 due to simplifications in howConnection
handles transactions.DESCRIBE is necessary as MariaDB in particular has no consistently available public information schema of any kind in order to report on temp tables other than DESCRIBE/SHOW COLUMNS, which rely on throwing an error in order to report no results.
References: #9058
oracle¶
Supported use case for foreign key constraints where the local column is marked as “invisible”. The errors normally generated when a
ForeignKeyConstraint
is created that check for the target column are disabled when reflecting, and the constraint is skipped with a warning in the same way which already occurs for anIndex
with a similar issue.References: #9059
2.0.0rc1¶
Released: December 28, 2022general¶
Fixed regression where the base compat module was calling upon
platform.architecture()
in order to detect some system properties, which results in an over-broad system call against the system-levelfile
call that is unavailable under some circumstances, including within some secure environment configurations.This change is also backported to: 1.4.46
References: #8995
orm¶
Added a new default value for the
Mapper.eager_defaults
parameter “auto”, which will automatically fetch table default values during a unit of work flush, if the dialect supports RETURNING for the INSERT being run, as well as insertmanyvalues available. Eager fetches for server-side UPDATE defaults, which are very uncommon, continue to only take place ifMapper.eager_defaults
is set toTrue
, as there is no batch-RETURNING form for UPDATE statements.References: #8889
Adjustments to the
Session
in terms of extensibility, as well as updates to theShardedSession
extension:Session.get()
now acceptsSession.get.bind_arguments
, which in particular may be useful when using the horizontal sharding extension.Session.get_bind()
accepts arbitrary kw arguments, which assists in developing code that uses aSession
class which overrides this method with additional arguments.Added a new ORM execution option
identity_token
which may be used to directly affect the “identity token” that will be associated with newly loaded ORM objects. This token is how sharding approaches (namely theShardedSession
, but can be used in other cases as well) separate object identities across different “shards”.See also
The
SessionEvents.do_orm_execute()
event hook may now be used to affect all ORM-related options, includingautoflush
,populate_existing
, andyield_per
; these options are re-consumed subsequent to event hooks being invoked before they are acted upon. Previously, options likeautoflush
would have been already evaluated at this point. The newidentity_token
option is also supported in this mode and is now used by the horizontal sharding extension.The
ShardedSession
class replaces theShardedSession.id_chooser
hook with a new hookShardedSession.identity_chooser
, which no longer relies upon the legacyQuery
object.ShardedSession.id_chooser
is still accepted in place ofShardedSession.identity_chooser
with a deprecation warning.
References: #7837
The behavior of “joining an external transaction into a Session” has been revised and improved, allowing explicit control over how the
Session
will accommodate an incomingConnection
that already has a transaction and possibly a savepoint already established. The new parameterSession.join_transaction_mode
includes a series of option values which can accommodate the existing transaction in several ways, most importantly allowing aSession
to operate in a fully transactional style using savepoints exclusively, while leaving the externally initiated transaction non-committed and active under all circumstances, allowing test suites to rollback all changes that take place within tests.Additionally, revised the
Session.close()
method to fully close out savepoints that may still be present, which also allows the “external transaction” recipe to proceed without warnings if theSession
did not explicitly end its own SAVEPOINT transactions.References: #9015
Removed the requirement that the
__allow_unmapped__
attribute be used on Declarative Dataclass Mapped class when non-Mapped[]
annotations are detected; previously, an error message that was intended to support legacy ORM typed mappings would be raised, which additionally did not mention correct patterns to use with Dataclasses specifically. This error message is now no longer raised ifregistry.mapped_as_dataclass()
orMappedAsDataclass
is used.See also
References: #8973
Fixed issue in the internal SQL traversal for DML statements like
Update
andDelete
which would cause among other potential issues, a specific issue using lambda statements with the ORM update/delete feature.This change is also backported to: 1.4.46
References: #9033
Fixed bug where
Session.merge()
would fail to preserve the current loaded contents of relationship attributes that were indicated with therelationship.viewonly
parameter, thus defeating strategies that useSession.merge()
to pull fully loaded objects from caches and other similar techniques. In a related change, fixed issue where an object that contains a loaded relationship that was nonetheless configured aslazy='raise'
on the mapping would fail when passed toSession.merge()
; checks for “raise” are now suspended within the merge process assuming theSession.merge.load
parameter remains at its default ofTrue
.Overall, this is a behavioral adjustment to a change introduced in the 1.4 series as of #4994, which took “merge” out of the set of cascades applied by default to “viewonly” relationships. As “viewonly” relationships aren’t persisted under any circumstances, allowing their contents to transfer during “merge” does not impact the persistence behavior of the target object. This allows
Session.merge()
to correctly suit one of its use cases, that of adding objects to aSession
that were loaded elsewhere, often for the purposes of restoring from a cache.This change is also backported to: 1.4.45
References: #8862
Fixed issues in
with_expression()
where expressions that were composed of columns that were referenced from the enclosing SELECT would not render correct SQL in some contexts, in the case where the expression had a label name that matched the attribute which usedquery_expression()
, even whenquery_expression()
had no default expression. For the moment, if thequery_expression()
does have a default expression, that label name is still used for that default, and an additional label with the same name will continue to be ignored. Overall, this case is pretty thorny so further adjustments might be warranted.This change is also backported to: 1.4.45
References: #8881
A warning is emitted if a backref name used in
relationship()
names an attribute on the target class which already has a method or attribute assigned to that name, as the backref declaration will replace that attribute.References: #4629
A series of changes and improvements regarding
Session.refresh()
. The overall change is that primary key attributes for an object are now included in a refresh operation unconditionally when relationship-bound attributes are to be refreshed, even if not expired and even if not specified in the refresh.Improved
Session.refresh()
so that if autoflush is enabled (as is the default forSession
), the autoflush takes place at an earlier part of the refresh process so that pending primary key changes are applied without errors being raised. Previously, this autoflush took place too late in the process and the SELECT statement would not use the correct key to locate the row and anInvalidRequestError
would be raised.When the above condition is present, that is, unflushed primary key changes are present on the object, but autoflush is not enabled, the refresh() method now explicitly disallows the operation to proceed, and an informative
InvalidRequestError
is raised asking that the pending primary key changes be flushed first. Previously, this use case was simply broken andInvalidRequestError
would be raised anyway. This restriction is so that it’s safe for the primary key attributes to be refreshed, as is necessary for the case of being able to refresh the object with relationship-bound secondary eagerloaders also being emitted. This rule applies in all cases to keep API behavior consistent regardless of whether or not the PK cols are actually needed in the refresh, as it is unusual to be refreshing some attributes on an object while keeping other attributes “pending” in any case.The
Session.refresh()
method has been enhanced such that attributes which arerelationship()
-bound and linked to an eager loader, either at mapping time or via last-used loader options, will be refreshed in all cases even when a list of attributes is passed that does not include any columns on the parent row. This builds upon the feature first implemented for non-column attributes as part of #1763 fixed in 1.4 allowing eagerly-loaded relationship-bound attributes to participate in theSession.refresh()
operation. If the refresh operation does not indicate any columns on the parent row to be refreshed, the primary key columns will nonetheless be included in the refresh operation, which allows the load to proceed into the secondary relationship loaders indicated as it does normally. Previously anInvalidRequestError
error would be raised for this condition (#8703)Fixed issue where an unnecessary additional SELECT would be emitted in the case where
Session.refresh()
were called with a combination of expired attributes, as well as an eager loader such asselectinload()
that emits a “secondary” query, if the primary key attributes were also in an expired state. As the primary key attributes are now included in the refresh automatically, there is no additional load for these attributes when a relationship loader goes to select for them (#8997)Fixed regression caused by #8126 released in 2.0.0b1 where the
Session.refresh()
method would fail with anAttributeError
, if passed both an expired column name as well as the name of a relationship-bound attribute that was linked to a “secondary” eagerloader such as theselectinload()
eager loader (#8996)
Improved a fix first made in version 1.4 for #8456 which scaled back the usage of internal “polymorphic adapters”, that are used to render ORM queries when the
Mapper.with_polymorphic
parameter is used. These adapters, which are very complex and error prone, are now used only in those cases where an explicit user-supplied subquery is used forMapper.with_polymorphic
, which includes only the use case of concrete inheritance mappings that use thepolymorphic_union()
helper, as well as the legacy use case of using an aliased subquery for joined inheritance mappings, which is not needed in modern use.For the most common case of joined inheritance mappings that use the built-in polymorphic loading scheme, which includes those which make use of the
Mapper.polymorphic_load
parameter set toinline
, polymorphic adapters are now no longer used. This has both a positive performance impact on the construction of queries as well as a substantial simplification of the internal query rendering process.The specific issue targeted was to allow a
column_property()
to refer to joined-inheritance classes within a scalar subquery, which now works as intuitively as is feasible.References: #8168
engine¶
Fixed a long-standing race condition in the connection pool which could occur under eventlet/gevent monkeypatching schemes in conjunction with the use of eventlet/gevent
Timeout
conditions, where a connection pool checkout that’s interrupted due to the timeout would fail to clean up the failed state, causing the underlying connection record and sometimes the database connection itself to “leak”, leaving the pool in an invalid state with unreachable entries. This issue was first identified and fixed in SQLAlchemy 1.2 for #4225, however the failure modes detected in that fix failed to accommodate forBaseException
, rather thanException
, which prevented eventlet/geventTimeout
from being caught. In addition, a block within initial pool connect has also been identified and hardened with aBaseException
-> “clean failed connect” block to accommodate for the same condition in this location. Big thanks to Github user @niklaus for their tenacious efforts in identifying and describing this intricate issue.This change is also backported to: 1.4.46
References: #8974
Fixed issue where
Result.freeze()
method would not work for textual SQL using eithertext()
orConnection.exec_driver_sql()
.This change is also backported to: 1.4.45
References: #8963
sql¶
An informative re-raise is now thrown in the case where any “literal bindparam” render operation fails, indicating the value itself and the datatype in use, to assist in debugging when literal params are being rendered in a statement.
This change is also backported to: 1.4.45
References: #8800
Fixed issue in lambda SQL feature where the calculated type of a literal value would not take into account the type coercion rules of the “compared to type”, leading to a lack of typing information for SQL expressions, such as comparisons to
JSON
elements and similar.This change is also backported to: 1.4.46
References: #9029
Fixed a series of issues regarding the position and sometimes the identity of rendered bound parameters, such as those used for SQLite, asyncpg, MySQL, Oracle and others. Some compiled forms would not maintain the order of parameters correctly, such as the PostgreSQL
regexp_replace()
function, the “nesting” feature of theCTE
construct first introduced in #4123, and selectable tables formed by using theFunctionElement.column_valued()
method with Oracle.This change is also backported to: 1.4.45
References: #8827
Added test support to ensure that all compiler
visit_xyz()
methods across allCompiler
implementations in SQLAlchemy accept a**kw
parameter, so that all compilers accept additional keyword arguments under all circumstances.References: #8988
The
SQLCompiler.construct_params()
method, as well as theSQLCompiler.params
accessor, will now return the exact parameters that correspond to a compiled statement that used therender_postcompile
parameter to compile. Previously, the method returned a parameter structure that by itself didn’t correspond to either the original parameters or the expanded ones.Passing a new dictionary of parameters to
SQLCompiler.construct_params()
for aSQLCompiler
that was constructed withrender_postcompile
is now disallowed; instead, to make a new SQL string and parameter set for an alternate set of parameters, a new methodSQLCompiler.construct_expanded_state()
is added which will produce a new expanded form for the given parameter set, using theExpandedState
container which includes a new SQL statement and new parameter dictionary, as well as a positional parameter tuple.References: #6114
To accommodate for third party dialects with different character escaping needs regarding bound parameters, the system by which SQLAlchemy “escapes” (i.e., replaces with another character in its place) special characters in bound parameter names has been made extensible for third party dialects, using the
SQLCompiler.bindname_escape_chars
dictionary which can be overridden at the class declaration level on anySQLCompiler
subclass. As part of this change, also added the dot"."
as a default “escaped” character.References: #8994
typing¶
asyncio¶
Removed non-functional
merge()
method fromAsyncResult
. This method has never worked and was included withAsyncResult
in error.This change is also backported to: 1.4.45
References: #8952
postgresql¶
Fixed bug where the PostgreSQL
Insert.on_conflict_do_update.constraint
parameter would accept anIndex
object, however would not expand this index out into its individual index expressions, instead rendering its name in an ON CONFLICT ON CONSTRAINT clause, which is not accepted by PostgreSQL; the “constraint name” form only accepts unique or exclude constraint names. The parameter continues to accept the index but now expands it out into its component expressions for the render.This change is also backported to: 1.4.46
References: #9023
Made an adjustment to how the PostgreSQL dialect considers column types when it reflects columns from a table, to accommodate for alternative backends which may return NULL from the PG
format_type()
function.This change is also backported to: 1.4.45
References: #8748
Added support for explicit use of PG full text functions with asyncpg and psycopg (SQLAlchemy 2.0 only), with regards to the
REGCONFIG
type cast for the first argument, which previously would be incorrectly cast to a VARCHAR, causing failures on these dialects that rely upon explicit type casts. This includes support forto_tsvector
,to_tsquery
,plainto_tsquery
,phraseto_tsquery
,websearch_to_tsquery
,ts_headline
, each of which will determine based on number of arguments passed if the first string argument should be interpreted as a PostgreSQL “REGCONFIG” value; if so, the argument is typed using a newly added type objectREGCONFIG
which is then explicitly cast in the SQL expression.References: #8977
Fixed regression where newly revised PostgreSQL range types such as
INT4RANGE
could not be set up as the impl of aTypeDecorator
custom type, instead raising aTypeError
.References: #9020
The
Range.__eq___()
will now returnNotImplemented
when comparing with an instance of a different class, instead of raising anAttributeError
exception.References: #8984
sqlite¶
Added support for the SQLite backend to reflect the “DEFERRABLE” and “INITIALLY” keywords which may be present on a foreign key construct. Pull request courtesy Michael Gorven.
This change is also backported to: 1.4.45
References: #8903
Added support for reflection of expression-oriented WHERE criteria included in indexes on the SQLite dialect, in a manner similar to that of the PostgreSQL dialect. Pull request courtesy Tobias Pfeiffer.
This change is also backported to: 1.4.45
References: #8804
oracle¶
Fixed issue in Oracle compiler where the syntax for
FunctionElement.column_valued()
was incorrect, rendering the nameCOLUMN_VALUE
without qualifying the source table correctly.This change is also backported to: 1.4.45
References: #8945
tests¶
Fixed issue in tox.ini file where changes in the tox 4.0 series to the format of “passenv” caused tox to not function correctly, in particular raising an error as of tox 4.0.6.
This change is also backported to: 1.4.46
Added new exclusion rule for third party dialects called
unusual_column_name_characters
, which can be “closed” for third party dialects that don’t support column names with unusual characters such as dots, slashes, or percent signs in them, even if the name is properly quoted.This change is also backported to: 1.4.46
References: #9002
2.0.0b4¶
Released: December 5, 2022orm¶
Added a new parameter
mapped_column.use_existing_column
to accommodate the use case of a single-table inheritance mapping that uses the pattern of more than one subclass indicating the same column to take place on the superclass. This pattern was previously possible by usingdeclared_attr()
in conjunction with locating the existing column in the.__table__
of the superclass, however is now updated to work withmapped_column()
as well as with pep-484 typing, in a simple and succinct way.References: #8822
Added support custom user-defined types which extend the Python
enum.Enum
base class to be resolved automatically to SQLAlchemyEnum
SQL types, when using the Annotated Declarative Table feature. The feature is made possible through new lookup features added to the ORM type map feature, and includes support for changing the arguments of theEnum
that’s generated by default as well as setting up specificenum.Enum
types within the map with specific arguments.References: #8859
Added
mapped_column.compare
parameter to relevant ORM attribute constructs includingmapped_column()
,relationship()
etc. to provide for the Python dataclassescompare
parameter onfield()
, when using the Declarative Dataclass Mapping feature. Pull request courtesy Simon Schiele.References: #8905
Additional performance enhancements within ORM-enabled SQL statements, specifically targeting callcounts within the construction of ORM statements, using combinations of
aliased()
withunion()
and similar “compound” constructs, in addition to direct performance improvements to thecorresponding_column()
internal method that is used heavily by the ORM by constructs likealiased()
and similar.References: #8796
Fixed issue where use of an unknown datatype within a
Mapped
annotation for a column-based attribute would silently fail to map the attribute, rather than reporting an exception; an informative exception message is now raised.References: #8888
Fixed a suite of issues involving
Mapped
use with dictionary types, such asMapped[Dict[str, str] | None]
, would not be correctly interpreted in Declarative ORM mappings. Support to correctly “de-optionalize” this type including for lookup intype_annotation_map
has been fixed.References: #8777
Fixed bug in Declarative Dataclass Mapping feature where using plain dataclass fields with the
__allow_unmapped__
directive in a mapping would not create a dataclass with the correct class-level state for those fields, copying the rawField
object to the class inappropriately after dataclasses itself had replaced theField
object with the class-level default value.References: #8880
Fixed regression where flushing a mapped class that’s mapped against a subquery, such as a direct mapping or some forms of concrete table inheritance, would fail if the
Mapper.eager_defaults
parameter were used.References: #8812
Fixed regression in 2.0.0b3 caused by #8759 where indicating the
Mapped
name using a qualified name such assqlalchemy.orm.Mapped
would fail to be recognized by Declarative as indicating theMapped
construct.References: #8853
orm extensions¶
Added support for the
association_proxy()
extension function to take part within Pythondataclasses
configuration, when using the native dataclasses feature described at Declarative Dataclass Mapping. Included are attribute-level arguments includingassociation_proxy.init
andassociation_proxy.default_factory
.Documentation for association proxy has also been updated to use “Annotated Declarative Table” forms within examples, including type annotations used for
AssocationProxy
itself.References: #8878
sql¶
Added
ScalarValues
that can be used as a column element allowing usingValues
insideIN
clauses or in conjunction withANY
orALL
collection aggregates. This new class is generated using the methodValues.scalar_values()
. TheValues
instance is now coerced to aScalarValues
when used in aIN
orNOT IN
operation.References: #6289
Fixed critical memory issue identified in cache key generation, where for very large and complex ORM statements that make use of lots of ORM aliases with subqueries, cache key generation could produce excessively large keys that were orders of magnitude bigger than the statement itself. Much thanks to Rollo Konig Brock for their very patient, long term help in finally identifying this issue.
This change is also backported to: 1.4.44
References: #8790
The approach to the
numeric
pep-249 paramstyle has been rewritten, and is now fully supported, including by features such as “expanding IN” and “insertmanyvalues”. Parameter names may also be repeated in the source SQL construct which will be correctly represented within the numeric format using a single parameter. Introduced an additional numeric paramstyle callednumeric_dollar
, which is specifically what’s used by the asyncpg dialect; the paramstyle is equivalent tonumeric
except numeric indicators are indicated by a dollar-sign rather than a colon. The asyncpg dialect now usesnumeric_dollar
paramstyle directly, rather than compiling toformat
style first.The
numeric
andnumeric_dollar
paramstyles assume that the target backend is capable of receiving the numeric parameters in any order, and will match the given parameter values to the statement based on matching their position (1-based) to the numeric indicator. This is the normal behavior of “numeric” paramstyles, although it was observed that the SQLite DBAPI implements a not-used “numeric” style that does not honor parameter ordering.References: #8849
Adjusted the rendering of
RETURNING
, in particular when usingInsert
, such that it now renders columns using the same logic as that of theSelect
construct to generate labels, which will include disambiguating labels, as well as that a SQL function surrounding a named column will be labeled using the column name itself. This establishes better cross-compatibility when selecting rows from eitherSelect
constructs or from DML statements that useUpdateBase.returning()
. A narrower scale change was also made for the 1.4 series that adjusted the function label issue only.References: #8770
schema¶
Stricter rules are in place for appending of
Column
objects toTable
objects, both moving some previous deprecation warnings to exceptions, and preventing some previous scenarios that would cause duplicate columns to appear in tables, whenTable.extend_existing
were set toTrue
, for both programmaticTable
construction as well as during reflection operations.See Stricter rules for replacement of Columns in Table objects with same-names, keys for a rundown of these changes.
References: #8925
typing¶
Added a new type
SQLColumnExpression
which may be indicated in user code to represent any SQL column oriented expression, including both those based onColumnElement
as well as on ORMQueryableAttribute
. This type is a real class, not an alias, so can also be used as the foundation for other objects. An additional ORM-specific subclassSQLORMExpression
is also included.References: #8847
Adjusted internal use of the Python
enum.IntFlag
class which changed its behavioral contract in Python 3.11. This was not causing runtime failures however caused typing runs to fail under Python 3.11.References: #8783
The
sqlalchemy.ext.mutable
extension andsqlalchemy.ext.automap
extensions are now fully pep-484 typed. Huge thanks to Gleb Kisenkov for their efforts on this.Corrected typing support for the
relationship.secondary
argument which may also accept a callable (lambda) that returns aFromClause
.Improved the typing for
sessionmaker
andasync_sessionmaker
, so that the default type of their return value will beSession
orAsyncSession
, without the need to type this explicitly. Previously, Mypy would not automaticaly infer these return types from its generic base.As part of this change, arguments for
Session
,AsyncSession
,sessionmaker
andasync_sessionmaker
beyond the initial “bind” argument have been made keyword-only, which includes parameters that have always been documented as keyword arguments, such asSession.autoflush
,Session.class_
, etc.Pull request courtesy Sam Bull.
References: #8842
Fixed issue where passing a callbale function returning an iterable of column elements to
relationship.order_by
was flagged as an error in type checkers.References: #8776
postgresql¶
Complementing #8690, new comparison methods such as
Range.adjacent_to()
,Range.difference()
,Range.union()
, etc., were added to the PG-specific range objects, bringing them in par with the standard operators implemented by the underlyingAbstractRange.comparator_factory
.In addition, the
__bool__()
method of the class has been corrected to be consistent with the common Python containers behavior as well as how other popular PostgreSQL drivers do: it now tells whether the range instance is not empty, rather than the other way around.Pull request courtesy Lele Gaifax.
References: #8765
Changed the paramstyle used by asyncpg from
format
tonumeric_dollar
. This has two main benefits since it does not require additional processing of the statement and allows for duplicate parameters to be present in the statements.References: #8926
For the PostgreSQL and SQL Server dialects only, adjusted the compiler so that when rendering column expressions in the RETURNING clause, the “non anon” label that’s used in SELECT statements is suggested for SQL expression elements that generate a label; the primary example is a SQL function that may be emitting as part of the column’s type, where the label name should match the column’s name by default. This restores a not-well defined behavior that had changed in version 1.4.21 due to #6718, #6710. The Oracle dialect has a different RETURNING implementation and was not affected by this issue. Version 2.0 features an across the board change for its widely expanded support of RETURNING on other backends.
This change is also backported to: 1.4.44
References: #8770
Added additional type-detection for the new PostgreSQL
Range
type, where previous cases that allowed the psycopg2-native range objects to be received directly by the DBAPI without SQLAlchemy intercepting them stopped working, as we now have our own value object. TheRange
object has been enhanced such that SQLAlchemy Core detects it in otherwise ambiguous situations (such as comparison to dates) and applies appropriate bind handlers. Pull request courtesy Lele Gaifax.References: #8884
mssql¶
Fixed regression caused by the combination of #8177, re-enable setinputsizes for SQL server unless fast_executemany + DBAPI executemany is used for a statement, along with #6047, implement “insertmanyvalues”, which bypasses DBAPI executemany in place of a custom DBAPI execute for INSERT statements. setinputsizes would incorrectly not be used for a multiple parameter-set INSERT statement that used “insertmanyvalues” if fast_executemany were turned on, as the check would incorrectly assume this is a DBAPI executemany call. The “regression” would then be that the “insertmanyvalues” statement format is apparently slightly more sensitive to multiple rows that don’t use the same types for each row, so in such a case setinputsizes is especially needed.
The fix repairs the fast_executemany check so that it only disables setinputsizes if true DBAPI executemany is to be used.
References: #8917
oracle¶
tests¶
Fixed issue where the
--disable-asyncio
parameter to the test suite would fail to not actually run greenlet tests and would also not prevent the suite from using a “wrapping” greenlet for the whole suite. This parameter now ensures that no greenlet or asyncio use will occur within the entire run when set.This change is also backported to: 1.4.44
References: #8793
2.0.0b3¶
Released: November 4, 2022orm¶
Fixed issue in joined eager loading where an assertion fail would occur with a particular combination of outer/inner joined eager loads, when eager loading across three mappers where the middle mapper was an inherited subclass mapper.
This change is also backported to: 1.4.43
References: #8738
Fixed bug involving
Select
constructs, where combinations ofSelect.select_from()
withSelect.join()
, as well as when usingSelect.join_from()
, would cause thewith_loader_criteria()
feature as well as the IN criteria needed for single-table inheritance queries to not render, in cases where the columns clause of the query did not explicitly include the left-hand side entity of the JOIN. The correct entity is now transferred to theJoin
object that’s generated internally, so that the criteria against the left side entity is correctly added.This change is also backported to: 1.4.43
References: #8721
An informative exception is now raised when the
with_loader_criteria()
option is used as a loader option added to a specific “loader path”, such as when using it withinLoad.options()
. This use is not supported aswith_loader_criteria()
is only intended to be used as a top level loader option. Previously, an internal error would be generated.This change is also backported to: 1.4.43
References: #8711
Improved “dictionary mode” for
Session.get()
so that synonym names which refer to primary key attribute names may be indicated in the named dictionary.This change is also backported to: 1.4.43
References: #8753
Fixed issue where “selectin_polymorphic” loading for inheritance mappers would not function correctly if the
Mapper.polymorphic_on
parameter referred to a SQL expression that was not directly mapped on the class.This change is also backported to: 1.4.43
References: #8704
Fixed issue where the underlying DBAPI cursor would not be closed when using the
Query
object as an iterator, if a user-defined exception case were raised within the iteration process, thereby causing the iterator to be closed by the Python interpreter. When usingQuery.yield_per()
to create server-side cursors, this would lead to the usual MySQL-related issues with server side cursors out of sync, and without direct access to theResult
object, end-user code could not access the cursor in order to close it.To resolve, a catch for
GeneratorExit
is applied within the iterator method, which will close the result object in those cases when the iterator were interrupted, and by definition will be closed by the Python interpreter.As part of this change as implemented for the 1.4 series, ensured that
.close()
methods are available on allResult
implementations includingScalarResult
,MappingResult
. The 2.0 version of this change also includes new context manager patterns for use withResult
classes.This change is also backported to: 1.4.43
References: #8710
orm declarative¶
Added support in ORM declarative annotations for class names specified for
relationship()
, as well as the name of theMapped
symbol itself, to be different names than their direct class name, to support scenarios such as whereMapped
is imported asfrom sqlalchemy.orm import Mapped as M
, or where related class names are imported with an alternate name in a similar fashion. Additionally, a target class name given as the lead argument forrelationship()
will always supersede the name given in the left hand annotation, so that otherwise un-importable names that also don’t match the class name can still be used in annotations.References: #8759
Improved support for legacy 1.4 mappings that use annotations which don’t include
Mapped[]
, by ensuring the__allow_unmapped__
attribute can be used to allow such legacy annotations to pass through Annotated Declarative without raising an error and without being interpreted in an ORM runtime context. Additionally improved the error message generated when this condition is detected, and added more documentation for how this situation should be handled. Unfortunately the 1.4 WARN_SQLALCHEMY_20 migration warning cannot detect this particular configurational issue at runtime with its current architecture.References: #8692
Changed a fundamental configuration behavior of
Mapper
, whereColumn
objects that are explicitly present in theMapper.properties
dictionary, either directly or enclosed within a mapper property object, will now be mapped within the order of how they appear within the mappedTable
(or other selectable) itself (assuming they are in fact part of that table’s list of columns), thereby maintaining the same order of columns in the mapped selectable as is instrumented on the mapped class, as well as what renders in an ORM SELECT statement for that mapper. Previously (where “previously” means since version 0.0.1),Column
objects in theMapper.properties
dictionary would always be mapped first, ahead of when the other columns in the mappedTable
would be mapped, causing a discrepancy in the order in which the mapper would assign attributes to the mapped class as well as the order in which they would render in statements.The change most prominently takes place in the way that Declarative assigns declared columns to the
Mapper
, specifically howColumn
(ormapped_column()
) objects are handled when they have a DDL name that is explicitly different from the mapped attribute name, as well as when constructs such asdeferred()
etc. are used. The new behavior will see the column ordering within the mappedTable
being the same order in which the attributes are mapped onto the class, assigned within theMapper
itself, and rendered in ORM statements such as SELECT statements, independent of how theColumn
was configured against theMapper
.References: #8705
Fixed issue in new dataclass mapping feature where a column declared on the decalrative base / abstract base / mixin would leak into the constructor for an inheriting subclass under some circumstances.
References: #8718
Fixed issues within the declarative typing resolver (i.e. which resolves
ForwardRef
objects) where types that were declared for columns in one particular source file would raiseNameError
when the ultimate mapped class were in another source file. The types are now resolved in terms of the module for each class in which the types are used.References: #8742
engine¶
To better support the use case of iterating
Result
andAsyncResult
objects where user-defined exceptions may interrupt the iteration, both objects as well as variants such asScalarResult
,MappingResult
,AsyncScalarResult
,AsyncMappingResult
now support context manager usage, where the result will be closed at the end of the context manager block.In addition, ensured that all the above mentioned
Result
objects include aResult.close()
method as well asResult.closed
accessors, includingScalarResult
andMappingResult
which previously did not have a.close()
method.References: #8710
Added new parameter
PoolEvents.reset.reset_state
parameter to thePoolEvents.reset()
event, with deprecation logic in place that will continue to accept event hooks using the previous set of arguments. This indicates various state information about how the reset is taking place and is used to allow custom reset schemes to take place with full context given.Within this change a fix that’s also backported to 1.4 is included which re-enables the
PoolEvents.reset()
event to continue to take place under all circumstances, including whenConnection
has already “reset” the connection.The two changes together allow custom reset schemes to be implemented using the
PoolEvents.reset()
event, instead of thePoolEvents.checkin()
event (which continues to function as it always has).References: #8717
Fixed issue where the
PoolEvents.reset()
event hook would not be be called in all cases when aConnection
were closed and was in the process of returning its DBAPI connection to the connection pool.The scenario was when the
Connection
had already emitted.rollback()
on its DBAPI connection within the process of returning the connection to the pool, where it would then instruct the connection pool to forego doing its own “reset” to save on the additional method call. However, this prevented custom pool reset schemes from being used within this hook, as such hooks by definition are doing more than just calling.rollback()
, and need to be invoked under all circumstances. This was a regression that appeared in version 1.4.For version 1.4, the
PoolEvents.checkin()
remains viable as an alternate event hook to use for custom “reset” implementations. Version 2.0 will feature an improved version ofPoolEvents.reset()
which is called for additional scenarios such as termination of asyncio connections, and is also passed contextual information about the reset, to allow for “custom connection reset” schemes which can respond to different reset scenarios in different ways.This change is also backported to: 1.4.43
References: #8717
sql¶
Fixed issue which prevented the
literal_column()
construct from working properly within the context of aSelect
construct as well as other potential places where “anonymized labels” might be generated, if the literal expression contained characters which could interfere with format strings, such as open parenthesis, due to an implementation detail of the “anonymous label” structure.This change is also backported to: 1.4.43
References: #8724
typing¶
Corrected various typing issues within the engine and async engine packages.
postgresql¶
Added new methods
Range.contains()
andRange.contained_by()
to the newRange
data object, which mirror the behavior of the PostgreSQL@>
and<@
operators, as well as thecomparator_factory.contains()
andcomparator_factory.contained_by()
SQL operator methods. Pull request courtesy Lele Gaifax.References: #8706
Refined the new approach to range objects described at New RANGE / MULTIRANGE support and changes for PostgreSQL backends to accommodate driver-specific range and multirange objects, to better accommodate both legacy code as well as when passing results from raw SQL result sets back into new range or multirange expressions.
References: #8690
mssql¶
Fixed issue with
Inspector.has_table()
, which when used against a temporary table with the SQL Server dialect would fail on some Azure variants, due to an unnecessary information schema query that is not supported on those server versions. Pull request courtesy Mike Barry.This change is also backported to: 1.4.43
References: #8714
Fixed issue with
Inspector.has_table()
, which when used against a view with the SQL Server dialect would erroneously returnFalse
, due to a regression in the 1.4 series which removed support for this on SQL Server. The issue is not present in the 2.0 series which uses a different reflection architecture. Test support is added to ensurehas_table()
remains working per spec re: views.This change is also backported to: 1.4.43
References: #8700
oracle¶
Fixed issue where bound parameter names, including those automatically derived from similarly-named database columns, which contained characters that normally require quoting with Oracle would not be escaped when using “expanding parameters” with the Oracle dialect, causing execution errors. The usual “quoting” for bound parameters used by the Oracle dialect is not used with the “expanding parameters” architecture, so escaping for a large range of characters is used instead, now using a list of characters/escapes that are specific to Oracle.
This change is also backported to: 1.4.43
References: #8708
Fixed issue where the
nls_session_parameters
view queried on first connect in order to get the default decimal point character may not be available depending on Oracle connection modes, and would therefore raise an error. The approach to detecting decimal char has been simplified to test a decimal value directly, instead of reading system views, which works on any backend / driver.This change is also backported to: 1.4.43
References: #8744
2.0.0b2¶
Released: October 20, 2022orm¶
Removed the warning that emits when using ORM-enabled update/delete regarding evaluation of columns by name, first added in #4073; this warning actually covers up a scenario that otherwise could populate the wrong Python value for an ORM mapped attribute depending on what the actual column is, so this deprecated case is removed. In 2.0, ORM enabled update/delete uses “auto” for “synchronize_session”, which should do the right thing automatically for any given UPDATE expression.
References: #8656
orm declarative¶
Added support for mapped classes that are also
Generic
subclasses, to be specified as aGenericAlias
object (e.g.MyClass[str]
) within statements and calls toinspect()
.References: #8665
Improved the
DeclarativeBase
class so that when combined with other mixins likeMappedAsDataclass
, the order of the classes may be in either order.References: #8665
Fixed bug in new ORM typed declarative mappings where the ability to use
Optional[MyClass]
or similar forms such asMyClass | None
in the type annotation for a many-to-one relationship was not implemented, leading to errors. Documentation has also been added for this use case to the relationship configuration documentation.References: #8668
Fixed issue with new dataclass mapping feature where arguments passed to the dataclasses API could sometimes be mis-ordered when dealing with mixins that override
mapped_column()
declarations, leading to initializer problems.References: #8688
sql¶
Fixed bug in new “insertmanyvalues” feature where INSERT that included a subquery with
bindparam()
inside of it would fail to render correctly in “insertmanyvalues” format. This affected psycopg2 most directly as “insertmanyvalues” is used unconditionally with this driver.References: #8639
typing¶
Fixed typing issue where pylance strict mode would report “instance variable overrides class variable” when using a method to define
__tablename__
,__mapper_args__
or__table_args__
.References: #8645
Fixed typing issue where pylance strict mode would report “partially unknown” datatype for the
mapped_column()
construct.References: #8644
mssql¶
Fixed regression caused by SQL Server pyodbc change #8177 where we now use
setinputsizes()
by default; for VARCHAR, this fails if the character size is greater than 4000 (or 2000, depending on data) characters as the incoming datatype is NVARCHAR, which has a limit of 4000 characters, despite the fact that VARCHAR can handle unlimited characters. Additional pyodbc-specific typing information is now passed tosetinputsizes()
when the datatype’s size is > 2000 characters. The change is also applied to theJSON
type which was also impacted by this issue for large JSON serializations.References: #8661
The
Sequence
construct restores itself to the DDL behavior it had prior to the 1.4 series, where creating aSequence
with no additional arguments will emit a simpleCREATE SEQUENCE
instruction without any additional parameters for “start value”. For most backends, this is how things worked previously in any case; however, for MS SQL Server, the default value on this database is-2**63
; to prevent this generally impractical default from taking effect on SQL Server, theSequence.start
parameter should be provided. As usage ofSequence
is unusual for SQL Server which for many years has standardized onIDENTITY
, it is hoped that this change has minimal impact.References: #7211
2.0.0b1¶
Released: October 13, 2022general¶
Migrated the codebase to remove all pre-2.0 behaviors and architectures that were previously noted as deprecated for removal in 2.0, including, but not limited to:
removal of all Python 2 code, minimum version is now Python 3.7
Engine
andConnection
now use the new 2.0 style of working, which includes “autobegin”, library level autocommit removed, subtransactions and “branched” connections removedResult objects use 2.0-style behaviors;
Row
is fully a named tuple without “mapping” behavior, useRowMapping
for “mapping” behaviorAll Unicode encoding/decoding architecture has been removed from SQLAlchemy. All modern DBAPI implementations support Unicode transparently thanks to Python 3, so the
convert_unicode
feature as well as related mechanisms to look for bytestrings in DBAPIcursor.description
etc. have been removed.The
.bind
attribute and parameter fromMetaData
,Table
, and from all DDL/DML/DQL elements that previously could refer to a “bound engine”The standalone
sqlalchemy.orm.mapper()
function is removed; all classical mapping should be done through theregistry.map_imperatively()
method ofregistry
.The
Query.join()
method no longer accepts strings for relationship names; the long-documented approach of usingClass.attrname
for join targets is now standard.Query.join()
no longer accepts the “aliased” and “from_joinpoint” argumentsQuery.join()
no longer accepts chains of multiple join targets in one method call.Query.from_self()
,Query.select_entity_from()
andQuery.with_polymorphic()
are removed.The
relationship.cascade_backrefs
parameter must now remain at its new default ofFalse
; thesave-update
cascade no longer cascades along a backref.the
Session.future
parameter must always be set toTrue
. 2.0-style transactional patterns forSession
are now always in effect.Loader options no longer accept strings for attribute names. The long-documented approach of using
Class.attrname
for loader option targets is now standard.Legacy forms of
select()
removed, includingselect([cols])
, the “whereclause” and keyword parameters ofsome_table.select()
.Legacy “in-place mutator” methods on
Select
such asappend_whereclause()
,append_order_by()
etc are removed.Removed the very old “dbapi_proxy” module, which in very early SQLAlchemy releases was used to provide a transparent connection pool over a raw DBAPI connection.
References: #7257
The
Query.instances()
method is deprecated. The behavioral contract of this method, which is that it can iterate objects through arbitrary result sets, is long obsolete and no longer tested. Arbitrary statements can return objects by using constructs such as :meth`.Select.from_statement` oraliased()
.
platform¶
The SQLAlchemy C extensions have been replaced with all new implementations written in Cython. Like the C extensions before, pre-built wheel files for a wide range of platforms are available on pypi so that building is not an issue for common platforms. For custom builds,
python setup.py build_ext
works as before, needing only the additional Cython install.pyproject.toml
is also part of the source now which will establish the proper build dependencies when using pip.See also
References: #7256
SQLAlchemy’s source build and installation now includes a
pyproject.toml
file for full PEP 517 support.References: #7311
orm¶
Added new feature to all included dialects that support RETURNING called “insertmanyvalues”. This is a generalization of the “fast executemany” feature first introduced for the psycopg2 driver in 1.4 at ORM Batch inserts with psycopg2 now batch statements with RETURNING in most cases, which allows the ORM to batch INSERT statements into a much more efficient SQL structure while still being able to fetch newly generated primary key and SQL default values using RETURNING.
The feature now applies to the many dialects that support RETURNING along with multiple VALUES constructs for INSERT, including all PostgreSQL drivers, SQLite, MariaDB, MS SQL Server. Separately, the Oracle dialect also gains the same capability using native cx_Oracle or OracleDB features.
References: #6047
Added new parameter
AttributeEvents.include_key
, which will include the dictionary or list key for operations such as__setitem__()
(e.g.obj[key] = value
) and__delitem__()
(e.g.del obj[key]
), using a new keyword parameter “key” or “keys”, depending on event, e.g.AttributeEvents.append.key
,AttributeEvents.bulk_replace.keys
. This allows event handlers to take into account the key that was passed to the operation and is of particular importance for dictionary operations working withMappedCollection
.References: #8375
Added new parameter
Operators.op.python_impl
, available fromOperators.op()
and also when using thecustom_op
constructor directly, which allows an in-Python evaluation function to be provided along with the custom SQL operator. This evaluation function becomes the implementation used when the operator object is used given plain Python objects as operands on both sides, and in particular is compatible with thesynchronize_session='evaluate'
option used with ORM-Enabled INSERT, UPDATE, and DELETE statements.References: #3162
The
Session
(and by extensionAsyncSession
) now has new state-tracking functionality that will proactively trap any unexpected state changes which occur as a particular transactional method proceeds. This is to allow situations where theSession
is being used in a thread-unsafe manner, where event hooks or similar may be calling unexpected methods within operations, as well as potentially under other concurrency situations such as asyncio or gevent to raise an informative message when the illegal access first occurs, rather than passing silently leading to secondary failures due to theSession
being in an invalid state.References: #7433
The
composite()
mapping construct now supports automatic resolution of values when used with a Pythondataclass
; the__composite_values__()
method no longer needs to be implemented as this method is derived from inspection of the dataclass.Additionally, classes mapped by
composite
now support ordering comparison operations, e.g.<
,>=
, etc.See the new documentation at Composite Column Types for examples.
Added very experimental feature to the
selectinload()
andimmediateload()
loader options calledselectinload.recursion_depth
/immediateload.recursion_depth
, which allows a single loader option to automatically recurse into self-referential relationships. Is set to an integer indicating depth, and may also be set to -1 to indicate to continue loading until no more levels deep are found. Major internal changes toselectinload()
andimmediateload()
allow this feature to work while continuing to make correct use of the compilation cache, as well as not using arbitrary recursion, so any level of depth is supported (though would emit that many queries). This may be useful for self-referential structures that must be loaded fully eagerly, such as when using asyncio.A warning is also emitted when loader options are connected together with arbitrary lengths (that is, without using the new
recursion_depth
option) when excessive recursion depth is detected in related object loading. This operation continues to use huge amounts of memory and performs extremely poorly; the cache is disabled when this condition is detected to protect the cache from being flooded with arbitrary statements.References: #8126
Added new parameter
Session.autobegin
, which when set toFalse
will prevent theSession
from beginning a transaction implicitly. TheSession.begin()
method must be called explicitly first in order to proceed with operations, otherwise an error is raised whenever any operation would otherwise have begun automatically. This option can be used to create a “safe”Session
that won’t implicitly start new transactions.As part of this change, also added a new status variable
origin
which may be useful for event handling code to be aware of the origin of a particularSessionTransaction
.References: #6928
Declarative mixins which use
Column
objects that containForeignKey
references no longer need to usedeclared_attr()
to achieve this mapping; theForeignKey
object is copied along with theColumn
itself when the column is applied to the declared mapping.Added
load_only.raiseload
parameter to theload_only()
loader option, so that the unloaded attributes may have “raise” behavior rather than lazy loading. Previously there wasn’t really a way to do this with theload_only()
option directly.To better accommodate explicit typing, the names of some ORM constructs that are typically constructed internally, but nonetheless are sometimes visible in messaging as well as typing, have been changed to more succinct names which also match the name of their constructing function (with different casing), in all cases maintaining aliases to the old names for the forseeable future:
RelationshipProperty
becomes an alias for the primary nameRelationship
, which is constructed as always from therelationship()
functionSynonymProperty
becomes an alias for the primary nameSynonym
, constructed as always from thesynonym()
functionCompositeProperty
becomes an alias for the primary nameComposite
, constructed as always from thecomposite()
function
For consistency with the prominent ORM concept
Mapped
, the names of the dictionary-oriented collections,attribute_mapped_collection()
,column_mapped_collection()
, andMappedCollection
, are changed toattribute_keyed_dict()
,column_keyed_dict()
andKeyFuncDict
, using the phrase “dict” to minimize any confusion against the term “mapped”. The old names will remain indefinitely with no schedule for removal.References: #8608
All
Result
objects will now consistently raiseResourceClosedError
if they are used after a hard close, which includes the “hard close” that occurs after calling “single row or value” methods likeResult.first()
andResult.scalar()
. This was already the behavior of the most common class of result objects returned for Core statement executions, i.e. those based onCursorResult
, so this behavior is not new. However, the change has been extended to properly accommodate for the ORM “filtering” result objects returned when using 2.0 style ORM queries, which would previously behave in “soft closed” style of returning empty results, or wouldn’t actually “soft close” at all and would continue yielding from the underlying cursor.As part of this change, also added
Result.close()
to the baseResult
class and implemented it for the filtered result implementations that are used by the ORM, so that it is possible to call theCursorResult.close()
method on the underlyingCursorResult
when theyield_per
execution option is in use to close a server side cursor before remaining ORM results have been fetched. This was again already available for Core result sets but the change makes it available for 2.0 style ORM results as well.This change is also backported to: 1.4.27
References: #7274
Fixed issue where the
registry.map_declaratively()
method would return an internal “mapper config” object and not theMapper
object as stated in the API documentation.Fixed performance regression which appeared at least in version 1.3 if not earlier (sometime after 1.0) where the loading of deferred columns, those explicitly mapped with
defer()
as opposed to non-deferred columns that were expired, from a joined inheritance subclass would not use the “optimized” query which only queried the immediate table that contains the unloaded columns, instead running a full ORM query which would emit a JOIN for all base tables, which is not necessary when only loading columns from the subclass.References: #7463
The internals for the
Load
object and related loader strategy patterns have been mostly rewritten, to take advantage of the fact that only attribute-bound paths, not strings, are now supported. The rewrite hopes to make it more straightforward to address new use cases and subtle issues within the loader strategy system going forward.References: #6986
Made an improvement to the “deferred” / “load_only” set of strategy options where if a certain object is loaded from two different logical paths within one query, attributes that have been configured by at least one of the options to be populated will be populated in all cases, even if other load paths for that same object did not set this option. previously, it was based on randomness as to which “path” addressed the object first.
References: #8166
Fixed issue in ORM enabled UPDATE when the statement is created against a joined-inheritance subclass, updating only local table columns, where the “fetch” synchronization strategy would not render the correct RETURNING clause for databases that use RETURNING for fetch synchronization. Also adjusts the strategy used for RETURNING in UPDATE FROM and DELETE FROM statements.
References: #8344
Removed the unused
**kw
arguments frombegin
andbegin_nested
. These kw aren’t used and appear to have been added to the API in error.References: #7703
Changed the attribute access method used by
attribute_mapped_collection()
andcolumn_mapped_collection()
(now calledattribute_keyed_dict()
andcolumn_keyed_dict()
) , used when populating the dictionary, to assert that the data value on the object to be used as the dictionary key is actually present, and is not instead using “None” due to the attribute never being actually assigned. This is used to prevent a mis-population of None for a key when assigning via a backref where the “key” attribute on the object is not yet assigned.As the failure mode here is a transitory condition that is not typically persisted to the database, and is easy to produce via the constructor of the class based on the order in which parameters are assigned, it is very possible that many applications include this behavior already which is silently passed over. To accommodate for applications where this error is now raised, a new parameter
attribute_keyed_dict.ignore_unpopulated_attribute
is also added to bothattribute_keyed_dict()
andcolumn_keyed_dict()
that instead causes the erroneous backref assignment to be skipped.References: #8372
Added new parameter
AbstractConcreteBase.strict_attrs
to theAbstractConcreteBase
declarative mixin class. The effect of this parameter is that the scope of attributes on subclasses is correctly limited to the subclass in which each attribute is declared, rather than the previous behavior where all attributes of the entire hierarchy are applied to the base “abstract” class. This produces a cleaner, more correct mapping where subclasses no longer have non-useful attributes on them which are only relevant to sibling classes. The default for this parameter is False, which leaves the previous behavior unchanged; this is to support existing code that makes explicit use of these attributes in queries. To migrate to the newer approach, apply explicit attributes to the abstract base class as needed.References: #8403
The behavior of
defer()
regarding primary key and “polymorphic discriminator” columns is revised such that these columns are no longer deferrable, either explicitly or when using a wildcard such asdefer('*')
. Previously, a wildcard deferral would not load PK/polymorphic columns which led to errors in all cases, as the ORM relies upon these columns to produce object identities. The behavior of explicit deferral of primary key columns is unchanged as these deferrals already were implicitly ignored.References: #7495
Fixed bug in the behavior of the
Mapper.eager_defaults
parameter such that client-side SQL default or onupdate expressions in the table definition alone will trigger a fetch operation using RETURNING or SELECT when the ORM emits an INSERT or UPDATE for the row. Previously, only server side defaults established as part of table DDL and/or server-side onupdate expressions would trigger this fetch, even though client-side SQL expressions would be included when the fetch was rendered.References: #7438
engine¶
The
DialectEvents.handle_error()
event is now moved to theDialectEvents
suite from theEngineEvents
suite, and now participates in the connection pool “pre ping” event for those dialects that make use of disconnect codes in order to detect if the database is live. This allows end-user code to alter the state of “pre ping”. Note that this does not include dialects which contain a native “ping” method such as that of psycopg2 or most MySQL dialects.References: #5648
The
ConnectionEvents.set_connection_execution_options()
andConnectionEvents.set_engine_execution_options()
event hooks now allow the given options dictionary to be modified in-place, where the new contents will be received as the ultimate execution options to be acted upon. Previously, in-place modifications to the dictionary were not supported.Generalized the
create_engine.isolation_level
parameter to the base dialect so that it is no longer dependent on individual dialects to be present. This parameter sets up the “isolation level” setting to occur for all new database connections as soon as they are created by the connection pool, where the value then stays set without being reset on every checkin.The
create_engine.isolation_level
parameter is essentially equivalent in functionality to using theEngine.execution_options.isolation_level
parameter viaEngine.execution_options()
for an engine-wide setting. The difference is in that the former setting assigns the isolation level just once when a connection is created, the latter sets and resets the given level on each connection checkout.References: #6342
Some small API changes regarding engines and dialects:
The
Dialect.set_isolation_level()
,Dialect.get_isolation_level()
, :meth: dialect methods will always be passed the raw DBAPI connectionThe
Connection
andEngine
classes no longer share a baseConnectable
superclass, which has been removed.Added a new interface class
PoolProxiedConnection
- this is the public facing interface for the familiar_ConnectionFairy
class which is nonetheless a private class.
References: #7122
Fixed regression where the
CursorResult.fetchmany()
method would fail to autoclose a server-side cursor (i.e. whenstream_results
oryield_per
is in use, either Core or ORM oriented results) when the results were fully exhausted.This change is also backported to: 1.4.27
References: #7274
Fixed issue in future
Engine
where calling uponEngine.begin()
and entering the context manager would not close the connection if the actual BEGIN operation failed for some reason, such as an event handler raising an exception; this use case failed to be tested for the future version of the engine. Note that the “future” context managers which handlebegin()
blocks in Core and ORM don’t actually run the “BEGIN” operation until the context managers are actually entered. This is different from the legacy version which runs the “BEGIN” operation up front.This change is also backported to: 1.4.27
References: #7272
The
QueuePool
now ignoresmax_overflow
whenpool_size=0
, properly making the pool unlimited in all cases.References: #8523
For improved security, the
URL
object will now use password obfuscation by default whenstr(url)
is called. To stringify a URL with cleartext password, theURL.render_as_string()
may be used, passing theURL.render_as_string.hide_password
parameter asFalse
. Thanks to our contributors for this pull request.References: #8567
The
Inspector.has_table()
method will now consistently check for views of the given name as well as tables. Previously this behavior was dialect dependent, with PostgreSQL, MySQL/MariaDB and SQLite supporting it, and Oracle and SQL Server not supporting it. Third party dialects should also seek to ensure theirInspector.has_table()
method searches for views as well as tables for the given name.References: #7161
Fixed issue in
Result.columns()
method where calling uponResult.columns()
with a single index could in some cases, particularly ORM result object cases, cause theResult
to yield scalar objects rather thanRow
objects, as though theResult.scalars()
method had been called. In SQLAlchemy 1.4, this scenario emits a warning that the behavior will change in SQLAlchemy 2.0.References: #7953
Passing a
DefaultGenerator
object such as aSequence
to theConnection.execute()
method is deprecated, as this method is typed as returning aCursorResult
object, and not a plain scalar value. TheConnection.scalar()
method should be used instead, which has been reworked with new internal codepaths to suit invoking a SELECT for default generation objects without going through theConnection.execute()
method.Removed the previously deprecated
case_sensitive
parameter fromcreate_engine()
, which would impact only the lookup of string column names in Core-only result set rows; it had no effect on the behavior of the ORM. The effective behavior of whatcase_sensitive
refers towards remains at its default value ofTrue
, meaning that string names looked up inrow._mapping
will match case-sensitively, just like any other Python mapping.Note that the
case_sensitive
parameter was not in any way related to the general subject of case sensitivity control, quoting, and “name normalization” (i.e. converting for databases that consider all uppercase words to be case insensitive) for DDL identifier names, which remains a normal core feature of SQLAlchemy.Removed legacy and deprecated package
sqlalchemy.databases
. Please usesqlalchemy.dialects
instead.References: #7258
The
create_engine.implicit_returning
parameter is deprecated on thecreate_engine()
function only; the parameter remains available on theTable
object. This parameter was originally intended to enable the “implicit returning” feature of SQLAlchemy when it was first developed and was not enabled by default. Under modern use, there’s no reason this parameter should be disabled, and it has been observed to cause confusion as it degrades performance and makes it more difficult for the ORM to retrieve recently inserted server defaults. The parameter remains available onTable
to specifically suit database-level edge cases which make RETURNING infeasible, the sole example currently being SQL Server’s limitation that INSERT RETURNING may not be used on a table that has INSERT triggers on it.References: #6962
sql¶
Added long-requested case-insensitive string operators
ColumnOperators.icontains()
,ColumnOperators.istartswith()
,ColumnOperators.iendswith()
, which produce case-insensitive LIKE compositions (using ILIKE on PostgreSQL, and the LOWER() function on all other backends) to complement the existing LIKE composition operatorsColumnOperators.contains()
,ColumnOperators.startswith()
, etc. Huge thanks to Matias Martinez Rebori for their meticulous and complete efforts in implementing these new methods.References: #3482
Added new syntax to the
FromClause.c
collection on allFromClause
objects allowing tuples of keys to be passed to__getitem__()
, along with support for theselect()
construct to handle the resulting tuple-like collection directly, allowing the syntaxselect(table.c['a', 'b', 'c'])
to be possible. The sub-collection returned is itself aColumnCollection
which is also directly consumable byselect()
and similar now.See also
References: #8285
Added new backend-agnostic
Uuid
datatype generalized from the PostgreSQL dialects to now be a core type, as well as migratedUUID
from the PostgreSQL dialect. The SQL ServerUNIQUEIDENTIFIER
datatype also becomes a UUID-handling datatype. Thanks to Trevor Gross for the help on this.References: #7212
Added
Double
,DOUBLE
,DOUBLE_PRECISION
datatypes to the basesqlalchemy.
module namespace, for explicit use of double/double precision as well as generic “double” datatypes. UseDouble
for generic support that will resolve to DOUBLE/DOUBLE PRECISION/FLOAT as needed for different backends.References: #5465
Altered the compilation mechanics of the
Insert
construct such that the “autoincrement primary key” column value will be fetched viacursor.lastrowid
or RETURNING even if present in the parameter set or within theInsert.values()
method as a plain bound value, for single-row INSERT statements on specific backends that are known to generate autoincrementing values even when explicit NULL is passed. This restores a behavior that was in the 1.3 series for both the use case of separate parameter set as well asInsert.values()
. In 1.4, the parameter set behavior unintentionally changed to no longer do this, but theInsert.values()
method would still fetch autoincrement values up until 1.4.21 where #6770 changed the behavior yet again again unintentionally as this use case was never covered.The behavior is now defined as “working” to suit the case where databases such as SQLite, MySQL and MariaDB will ignore an explicit NULL primary key value and nonetheless invoke an autoincrement generator.
References: #7998
Added modified ISO-8601 rendering (i.e. ISO-8601 with the T converted to a space) when using
literal_binds
with the SQL compilers provided by the PostgreSQL, MySQL, MariaDB, MSSQL, Oracle dialects. For Oracle, the ISO format is wrapped inside of an appropriate TO_DATE() function call. Previously this rendering was not implemented for dialect-specific compilation.References: #5052
Added new parameter
HasCTE.add_cte.nest_here
toHasCTE.add_cte()
which will “nest” a givenCTE
at the level of the parent statement. This parameter is equivalent to using theHasCTE.cte.nesting
parameter, but may be more intuitive in some scenarios as it allows the nesting attribute to be set simultaneously along with the explicit level of the CTE.The
HasCTE.add_cte()
method also accepts multiple CTE objects.References: #7759
The FROM clauses that are established on a
select()
construct when using theSelect.select_from()
method will now render first in the FROM clause of the rendered SELECT, which serves to maintain the ordering of clauses as was passed to theSelect.select_from()
method itself without being affected by the presence of those clauses also being mentioned in other parts of the query. If other elements of theSelect
also generate FROM clauses, such as the columns clause or WHERE clause, these will render after the clauses delivered bySelect.select_from()
assuming they were not explictly passed toSelect.select_from()
also. This improvement is useful in those cases where a particular database generates a desirable query plan based on a particular ordering of FROM clauses and allows full control over the ordering of FROM clauses.References: #7888
The
Enum.length
parameter, which sets the length of theVARCHAR
column for non-native enumeration types, is now used unconditionally when emitting DDL for theVARCHAR
datatype, including when theEnum.native_enum
parameter is set toTrue
for target backends that continue to useVARCHAR
. Previously the parameter would be erroneously ignored in this case. The warning previously emitted for this case is now removed.References: #7791
The in-place type detection for Python integers, as occurs with an expression such as
literal(25)
, will now apply value-based adaption as well to accommodate Python large integers, where the datatype determined will beBigInteger
rather thanInteger
. This accommodates for dialects such as that of asyncpg which both sends implicit typing information to the driver as well as is sensitive to numeric scale.References: #7909
Added
if_exists
andif_not_exists
parameters for all “Create” / “Drop” constructs includingCreateSequence
,DropSequence
,CreateIndex
,DropIndex
, etc. allowing generic “IF EXISTS” / “IF NOT EXISTS” phrases to be rendered within DDL. Pull request courtesy Jesse Bakker.References: #7354
Improved the construction of SQL binary expressions to allow for very long expressions against the same associative operator without special steps needed in order to avoid high memory use and excess recursion depth. A particular binary operation
A op B
can now be joined against another elementop C
and the resulting structure will be “flattened” so that the representation as well as SQL compilation does not require recursion.One effect of this change is that string concatenation expressions which use SQL functions come out as “flat”, e.g. MySQL will now render
concat('x', 'y', 'z', ...)`
rather than nesting together two-element functions likeconcat(concat('x', 'y'), 'z')
. Third-party dialects which override the string concatenation operator will need to implement a new methoddef visit_concat_op_expression_clauselist()
to accompany the existingdef visit_concat_op_binary()
method.References: #7744
Implemented full support for “truediv” and “floordiv” using the “/” and “//” operators. A “truediv” operation between two expressions using
Integer
now considers the result to beNumeric
, and the dialect-level compilation will cast the right operand to a numeric type on a dialect-specific basis to ensure truediv is achieved. For floordiv, conversion is also added for those databases that don’t already do floordiv by default (MySQL, Oracle) and theFLOOR()
function is rendered in this case, as well as for cases where the right operand is not an integer (needed for PostgreSQL, others).The change resolves issues both with inconsistent behavior of the division operator on different backends and also fixes an issue where integer division on Oracle would fail to be able to fetch a result due to inappropriate outputtypehandlers.
References: #4926
Added an additional lookup step to the compiler which will track all FROM clauses which are tables, that may have the same name shared in multiple schemas where one of the schemas is the implicit “default” schema; in this case, the table name when referring to that name without a schema qualification will be rendered with an anonymous alias name at the compiler level in order to disambiguate the two (or more) names. The approach of schema-qualifying the normally unqualified name with the server-detected “default schema name” value was also considered, however this approach doesn’t apply to Oracle nor is it accepted by SQL Server, nor would it work with multiple entries in the PostgreSQL search path. The name collision issue resolved here has been identified as affecting at least Oracle, PostgreSQL, SQL Server, MySQL and MariaDB.
References: #7471
Python string values for which a SQL type is determined from the type of the value, mainly when using
literal()
, will now apply theString
type, rather than theUnicode
datatype, for Python string values that test as “ascii only” using Pythonstr.isascii()
. If the string is notisascii()
, theUnicode
datatype will be bound instead, which was used in all string detection previously. This behavior only applies to in-place detection of datatypes when using ``literal()`` or other contexts that have no existing datatype, which is not usually the case under normalColumn
comparison operations, where the type of theColumn
being compared always takes precedence.Use of the
Unicode
datatype can determine literal string formatting on backends such as SQL Server, where a literal value (i.e. usingliteral_binds
) will be rendered asN'<value>'
instead of'value'
. For normal bound value handling, theUnicode
datatype also may have implications for passing values to the DBAPI, again in the case of SQL Server, the pyodbc driver supports the use of setinputsizes mode which will handleString
versusUnicode
differently.References: #7551
The
array_agg
will now set the array dimensions to 1. ImprovedARRAY
processing to acceptNone
values as value of a multi-array.References: #7083
schema¶
Expanded on the “conditional DDL” system implemented by the
ExecutableDDLElement
class (renamed fromDDLElement
) to be directly available onSchemaItem
constructs such asIndex
,ForeignKeyConstraint
, etc. such that the conditional logic for generating these elements is included within the default DDL emitting process. This system can also be accommodated by a future release of Alembic to support conditional DDL elements within all schema-management systems.References: #7631
Added parameter
DropConstraint.if_exists
to theDropConstraint
construct which result in “IF EXISTS” DDL being added to the DROP statement. This phrase is not accepted by all databases and the operation will fail on a database that does not support it as there is no similarly compatible fallback within the scope of a single DDL statement. Pull request courtesy Mike Fiedler.References: #8141
Implemented the DDL event hooks
DDLEvents.before_create()
,DDLEvents.after_create()
,DDLEvents.before_drop()
,DDLEvents.after_drop()
for allSchemaItem
objects that include a distinct CREATE or DROP step, when that step is invoked as a distinct SQL statement, including forForeignKeyConstraint
,Sequence
,Index
, and PostgreSQL’sENUM
.References: #8394
Rearchitected the schema reflection API to allow participating dialects to make use of high performing batch queries to reflect the schemas of many tables at once using fewer queries by an order of magnitude. The new performance features are targeted first at the PostgreSQL and Oracle backends, and may be applied to any dialect that makes use of SELECT queries against system catalog tables to reflect tables. The change also includes new API features and behavioral improvements to the
Inspector
object, including consistent, cached behavior of methods likeInspector.has_table()
,Inspector.get_table_names()
and new methodsInspector.has_schema()
andInspector.has_index()
.See also
Major Architectural, Performance and API Enhancements for Database Reflection - full background
References: #4379
The warnings that are emitted regarding reflection of indexes or unique constraints, when the
Table.include_columns
parameter is used to exclude columns that are then found to be part of those constraints, have been removed. When theTable.include_columns
parameter is used it should be expected that the resultingTable
construct will not include constraints that rely upon omitted columns. This change was made in response to #8100 which repairedTable.include_columns
in conjunction with foreign key constraints that rely upon omitted columns, where the use case became clear that omitting such constraints should be expected.References: #8102
Added support for comments on
Constraint
objects, including DDL and reflection; the field is added to the baseConstraint
class and corresponding constructors, however PostgreSQL is the only included backend to support the feature right now. See parameters such asForeignKeyConstraint.comment
,UniqueConstraint.comment
orCheckConstraint.comment
.References: #5677
Add support for Partitioning and Sample pages on MySQL and MariaDB reflected options. The options are stored in the table dialect options dictionary, so the following keyword need to be prefixed with
mysql_
ormariadb_
depending on the backend. Supported options are:stats_sample_pages
partition_by
partitions
subpartition_by
These options are also reflected when loading a table from database, and will populate the table
Table.dialect_options
. Pull request courtesy of Ramon Will.References: #4038
typing¶
The
TypeEngine.with_variant()
method now returns a copy of the originalTypeEngine
object, rather than wrapping it inside theVariant
class, which is effectively removed (the import symbol remains for backwards compatibility with code that may be testing for this symbol). While the previous approach maintained in-Python behaviors, maintaining the original type allows for clearer type checking and debugging.TypeEngine.with_variant()
also accepts multiple dialect names per call as well, in particular this is helpful for related backend names such as"mysql", "mariadb"
.References: #6980
postgresql¶
Added a new PostgreSQL
DOMAIN
datatype, which follows the same CREATE TYPE / DROP TYPE behaviors as that of PostgreSQLENUM
. Much thanks to David Baumgold for the efforts on this.See also
References: #7316
Added overridable methods
PGDialect_asyncpg.setup_asyncpg_json_codec
andPGDialect_asyncpg.setup_asyncpg_jsonb_codec
codec, which handle the required task of registering JSON/JSONB codecs for these datatypes when using asyncpg. The change is that methods are broken out as individual, overridable methods to support third party dialects that need to alter or disable how these particular codecs are set up.This change is also backported to: 1.4.27
References: #7284
Added literal type rendering for the
ARRAY
andARRAY
datatypes. The generic stringify will render using brackets, e.g.[1, 2, 3]
and the PostgreSQL specific will use the ARRAY literal e.g.ARRAY[1, 2, 3]
. Multiple dimensions and quoting are also taken into account.References: #8138
Adds support for PostgreSQL multirange types, introduced in PostgreSQL 14. Support for PostgreSQL ranges and multiranges has now been generalized to the psycopg3, psycopg2 and asyncpg backends, with room for further dialect support, using a backend-agnostic
Range
data object that’s constructor-compatible with the previously used psycopg2 object. See the new documentation for usage patterns.In addition, range type handling has been enhanced so that it automatically renders type casts, so that in-place round trips for statements that don’t provide the database with any context don’t require the
cast()
construct to be explicit for the database to know the desired type (discussed at #8540).Thanks very much to @zeeeeeb for the pull request implementing and testing the new datatypes and psycopg support.
The “ping” query emitted when configuring
create_engine.pool_pre_ping
for psycopg, asyncpg and pg8000, but not for psycopg2, has been changed to be an empty query (;
) instead ofSELECT 1
; additionally, for the asyncpg driver, the unnecessary use of a prepared statement for this query has been fixed. Rationale is to eliminate the need for PostgreSQL to produce a query plan when the ping is emitted. The operation is not currently supported by thepsycopg2
driver which continues to useSELECT 1
.References: #8491
SQLAlchemy now requires PostgreSQL version 9 or greater. Older versions may still work in some limited use cases.
The parameter
UUID.as_uuid
ofUUID
, previously specific to the PostgreSQL dialect but now generalized for Core (along with a new backend-agnosticUuid
datatype) now defaults toTrue
, indicating that PythonUUID
objects are accepted by this datatype by default. Additionally, the SQL ServerUNIQUEIDENTIFIER
datatype has been converted to be a UUID-receiving type; for legacy code that makes use ofUNIQUEIDENTIFIER
using string values, set theUNIQUEIDENTIFIER.as_uuid
parameter toFalse
.References: #7225
The
ENUM.name
parameter for the PostgreSQL-specificENUM
datatype is now a required keyword argument. The “name” is necessary in any case in order for theENUM
to be usable as an error would be raised at SQL/DDL render time if “name” were not present.In support of new PostgreSQL features including the psycopg3 dialect as well as extended “fast insertmany” support, the system by which typing information for bound parameters is passed to the PostgreSQL database has been redesigned to use inline casts emitted by the SQL compiler, and is now applied to all PostgreSQL dialects. This is in contrast to the previous approach which would rely upon the DBAPI in use to render these casts itself, which in cases such as that of pg8000 and the adapted asyncpg driver, would use the pep-249
setinputsizes()
method, or with the psycopg2 driver would rely on the driver itself in most cases, with some special exceptions made for ARRAY.The new approach now has all PostgreSQL dialects rendering these casts as needed using PostgreSQL double-colon style within the compiler, and the use of
setinputsizes()
is removed for PostgreSQL dialects, as this was not generally part of these DBAPIs in any case (pg8000 being the only exception, which added the method at the request of SQLAlchemy developers).Advantages to this approach include per-statement performance, as no second pass over the compiled statement is required at execution time, better support for all DBAPIs, as there is now one consistent system of applying typing information, and improved transparency, as the SQL logging output, as well as the string output of a compiled statement, will show these casts present in the statement directly, whereas previously these casts were not visible in logging output as they would occur after the statement were logged.
The
Operators.match()
operator now usesplainto_tsquery()
for PostgreSQL full text search, rather thanto_tsquery()
. The rationale for this change is to provide better cross-compatibility with match on other database backends. Full support for all PostgreSQL full text functions remains available through the use offunc
in conjunction withOperators.bool_op()
(an improved version ofOperators.op()
for boolean operators).References: #7086
Removed support for multiple deprecated drivers:
pypostgresql for PostgreSQL. This is available as an external driver at https://github.com/PyGreSQL
pygresql for PostgreSQL.
Please switch to one of the supported drivers or to the external version of the same driver.
References: #7258
Added support for
psycopg
dialect supporting both sync and async execution. This dialect is available under thepostgresql+psycopg
name for both thecreate_engine()
andcreate_async_engine()
engine-creation functions.References: #6842
Update psycopg2 dialect to use the DBAPI interface to execute two phase transactions. Previously SQL commands were execute to handle this kind of transactions.
References: #7238
Introduced the type
JSONPATH
that can be used in cast expressions. This is required by some PostgreSQL dialects when using functions such asjsonb_path_exists
orjsonb_path_match
that accept ajsonpath
as input.See also
JSON Types - PostgreSQL JSON types.
References: #8216
The PostgreSQL dialect now supports reflection of expression based indexes. The reflection is supported both when using
Inspector.get_indexes()
and when reflecting aTable
usingTable.autoload_with
. Thanks to immerrr and Aidan Kane for the help on this ticket.References: #7442
mysql¶
The
ROLLUP
function will now correctly renderWITH ROLLUP
on MySql and MariaDB, allowing the use of group by rollup with these backend.References: #8503
Fixed issue in MySQL
Insert.on_duplicate_key_update()
which would render the wrong column name when an expression were used in a VALUES expression. Pull request courtesy Cristian Sabaila.This change is also backported to: 1.4.27
References: #7281
Removed support for the OurSQL driver for MySQL and MariaDB, as this driver does not seem to be maintained.
References: #7258
mariadb¶
Added a new execution option
is_delete_using=True
, which is consumed by the ORM when using an ORM-enabled DELETE statement in conjunction with the “fetch” synchronization strategy; this option indicates that the DELETE statement is expected to use multiple tables, which on MariaDB is the DELETE..USING syntax. The option then indicates that RETURNING (newly implemented in SQLAlchemy 2.0 for MariaDB for #7011) should not be used for databases that are known to not support “DELETE..USING..RETURNING” syntax, even though they support “DELETE..USING”, which is MariaDB’s current capability.The rationale for this option is that the current workings of ORM-enabled DELETE doesn’t know up front if a DELETE statement is against multiple tables or not until compilation occurs, which is cached in any case, yet it needs to be known so that a SELECT for the to-be-deleted row can be emitted up front. Instead of applying an across-the-board performance penalty for all DELETE statements by proactively checking them all for this relatively unusual SQL pattern, the
is_delete_using=True
execution option is requested via a new exception message that is raised within the compilation step. This exception message is specifically (and only) raised when: the statement is an ORM-enabled DELETE where the “fetch” synchronization strategy has been requested; the backend is MariaDB or other backend with this specific limitation; the statement has been detected within the initial compilation that it would otherwise emit “DELETE..USING..RETURNING”. By applying the execution option, the ORM knows to run a SELECT upfront instead. A similar option is implemented for ORM-enabled UPDATE but there is not currently a backend where it is needed.References: #8344
Added INSERT..RETURNING and DELETE..RETURNING support for the MariaDB dialect. UPDATE..RETURNING is not yet supported by MariaDB. MariaDB supports INSERT..RETURNING as of 10.5.0 and DELETE..RETURNING as of 10.0.5.
References: #7011
sqlite¶
Added new parameter to SQLite for reflection methods called
sqlite_include_internal=True
; when omitted, local tables that start with the prefixsqlite_
, which per SQLite documentation are noted as “internal schema” tables such as thesqlite_sequence
table generated to support “AUTOINCREMENT” columns, will not be included in reflection methods that return lists of local objects. This prevents issues for example when using Alembic autogenerate, which previously would consider these SQLite-generated tables as being remove from the model.See also
References: #8234
Added RETURNING support for the SQLite dialect. SQLite supports RETURNING since version 3.35.
References: #6195
The SQLite dialect now supports UPDATE..FROM syntax, for UPDATE statements that may refer to additional tables within the WHERE criteria of the statement without the need to use subqueries. This syntax is invoked automatically when using the
Update
construct when more than one table or other entity or selectable is used.References: #7185
The SQLite dialect now defaults to
QueuePool
when a file based database is used. This is set along with setting thecheck_same_thread
parameter toFalse
. It has been observed that the previous approach of defaulting toNullPool
, which does not hold onto database connections after they are released, did in fact have a measurable negative performance impact. As always, the pool class is customizable via thecreate_engine.poolclass
parameter.References: #7490
SQLite datetime, date, and time datatypes now use Python standard lib
fromisoformat()
methods in order to parse incoming datetime, date, and time string values. This improves performance vs. the previous regular expression-based approach, and also automatically accommodates for datetime and time formats that contain either a six-digit “microseconds” format or a three-digit “milliseconds” format.References: #7029
Removed the warning that emits from the
Numeric
type about DBAPIs not supporting Decimal values natively. This warning was oriented towards SQLite, which does not have any real way without additional extensions or workarounds of handling precision numeric values more than 15 significant digits as it only uses floating point math to represent numbers. As this is a known and documented limitation in SQLite itself, and not a quirk of the pysqlite driver, there’s no need for SQLAlchemy to warn for this. The change does not otherwise modify how precision numerics are handled. Values can continue to be handled asDecimal()
orfloat()
as configured with theNumeric
,Float
, and related datatypes, just without the ability to maintain precision beyond 15 significant digits when using SQLite, unless alternate representations such as strings are used.References: #7299
mssql¶
Implemented reflection of the “clustered index” flag
mssql_clustered
for the SQL Server dialect. Pull request courtesy John Lennox.References: #8288
Added support table and column comments on MSSQL when creating a table. Added support for reflecting table comments. Thanks to Daniel Hall for the help in this pull request.
References: #7844
The
use_setinputsizes
parameter for themssql+pyodbc
dialect now defaults toTrue
; this is so that non-unicode string comparisons are bound by pyodbc to pyodbc.SQL_VARCHAR rather than pyodbc.SQL_WVARCHAR, allowing indexes against VARCHAR columns to take effect. In order for thefast_executemany=True
parameter to continue functioning, theuse_setinputsizes
mode now skips thecursor.setinputsizes()
call specifically whenfast_executemany
is True and the specific method in use iscursor.executemany()
, which doesn’t support setinputsizes. The change also adds appropriate pyodbc DBAPI typing to values that are typed asUnicode
orUnicodeText
, as well as altered the baseJSON
datatype to consider JSON string values asUnicode
rather thanString
.References: #8177
Removed support for the mxodbc driver due to lack of testing support. ODBC users may use the pyodbc dialect which is fully supported.
References: #7258
oracle¶
Add support for the new oracle driver
oracledb
.References: #8054
Implemented DDL and reflection support for
FLOAT
datatypes which include an explicit “binary_precision” value. Using the Oracle-specificFLOAT
datatype, the new parameterFLOAT.binary_precision
may be specified which will render Oracle’s precision for floating point types directly. This value is interpreted during reflection. Upon reflecting back aFLOAT
datatype, the datatype returned is one ofDOUBLE_PRECISION
for aFLOAT
for a precision of 126 (this is also Oracle’s default precision forFLOAT
),REAL
for a precision of 63, andFLOAT
for a custom precision, as per Oracle documentation.As part of this change, the generic
Float.precision
value is explicitly rejected when generating DDL for Oracle, as this precision cannot be accurately converted to “binary precision”; instead, an error message encourages the use ofTypeEngine.with_variant()
so that Oracle’s specific form of precision may be chosen exactly. This is a backwards-incompatible change in behavior, as the previous “precision” value was silently ignored for Oracle.References: #5465
Full “RETURNING” support is implemented for the cx_Oracle dialect, covering two individual types of functionality:
multi-row RETURNING is implemented, meaning multiple RETURNING rows are now received for DML statements that produce more than one row for RETURNING.
”executemany RETURNING” is also implemented - this allows RETURNING to yield row-per statement when
cursor.executemany()
is used. The implementation of this part of the feature delivers dramatic performance improvements to ORM inserts, in the same way as was added for psycopg2 in the SQLAlchemy 1.4 change ORM Batch inserts with psycopg2 now batch statements with RETURNING in most cases.
References: #6245
Oracle will now use FETCH FIRST N ROWS / OFFSET syntax for limit/offset support by default for Oracle 12c and above. This syntax was already available when
Select.fetch()
were used directly, it’s now implied forSelect.limit()
andSelect.offset()
as well.References: #8221
Materialized views on oracle are now reflected as views. On previous versions of SQLAlchemy the views were returned among the table names, not among the view names. As a side effect of this change they are not reflected by default by
MetaData.reflect()
, unlessviews=True
is set. To get a list of materialized views, use the new inspection methodInspector.get_materialized_view_names()
.Adjustments made to the BLOB / CLOB / NCLOB datatypes in the cx_Oracle and oracledb dialects, to improve performance based on recommendations from Oracle developers.
References: #7494
Related to the deprecation for
create_engine.implicit_returning
, the “implicit_returning” feature is now enabled for the Oracle dialect in all cases; previously, the feature would be turned off when an Oracle 8/8i version were detected, however online documentation indicates both versions support the same RETURNING syntax as modern versions.References: #6962
cx_Oracle 7 is now the minimum version for cx_Oracle.
misc¶
Removed the “sybase” internal dialect that was deprecated in previous SQLAlchemy versions. Third party dialect support is available.
See also
References: #7258
Removed the “firebird” internal dialect that was deprecated in previous SQLAlchemy versions. Third party dialect support is available.
See also
References: #7258
flambé! the dragon and The Alchemist image designs created and generously donated by Rotem Yaari.
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