Repaired a major shortcoming which was identified in the :ref:`engine_insertmanyvalues` 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 :paramref:`_dml.Insert.returning.sort_by_parameter_order` on the :meth:`_dml.Insert.returning` or :meth:`_dml.UpdateBase.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. Fixes: #9618 References: #9603 Change-Id: I1d79353f5f19638f752936ba1c35e4dc235a8b7c
Removed versionadded and versionchanged for version prior to 1.2 since they are no longer useful. Change-Id: I5c53d1188bc5fec3ab4be39ef761650ed8fa6d3e
Fixes: #9588 References: #9585 Change-Id: Ic6668311ea488339023d7aab1a186f8465131fd8
Fixed issue where string datatypes such as :class:`.CHAR`, :class:`.VARCHAR`, :class:`.TEXT`, as well as binary :class:`.BLOB`, could not be produced with an explicit length of zero, which has special meaning for MySQL. Pull request courtesy J. Nick Koston. Fixes: #9544 Closes: #9543 Pull-request: https://github.com/sqlalchemy/sqlalchemy/pull/9543 Pull-request-sha: dc17fc3e93f0ba90881c4efb06016ddf83c7af8b Change-Id: I96925d45f16887f5dfd68a5d4f9284b3abc46d25
The support for pool ping listeners to receive exception events via the :meth:`.ConnectionEvents.handle_error` event added in 2.0.0b1 for :ticket:`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 element :attr:`.ExceptionContext.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 :meth:`_engine.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 existing ``do_ping()`` method continues to catch exceptions and check "is_disconnect", it will continue to work as it did previously, but ``handle_error`` hooks will not have access to the exception if it isn't propagated outwards. Fixes: #5648 Change-Id: I6535d5cb389e1a761aad8c37cfeb332c548b876d
Remove ``typing.Self`` workaround, now using :pep:`673` for most methods that return ``Self``. Pull request courtesy Yurii Karabas. Fixes: #9254 Closes: #9255 Pull-request: https://github.com/sqlalchemy/sqlalchemy/pull/9255 Pull-request-sha: 2947df8ada79f5c3afe9c838e65993302199c2f7 Change-Id: Ic32015ad52e95a61f3913d43ea436aa9402804df
Fixed regression caused by issue :ticket:`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. 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. Fixes: #9251 Change-Id: I5ef9cf0887865c3c521d88bca0ba18954a108241
Added support for MySQL 8's new ``AS <name> ON DUPLICATE KEY`` syntax when using :meth:`_mysql.Insert.on_duplicate_key_update`, which is required for newer versions of MySQL 8 as the previous syntax using ``VALUES()`` now emits a deprecation warning with those versions. Server version detection is employed to determine if traditional MariaDB / MySQL < 8 ``VALUES()`` syntax should be used, vs. the newer MySQL 8 required syntax. Pull request courtesy Caspar Wylie. Fixes: #8626 Closes: #9210 Pull-request: https://github.com/sqlalchemy/sqlalchemy/pull/9210 Pull-request-sha: 1c8dfbf0b4c439d9ca2c194524c47eb7239ee3c5 Change-Id: I42c463837af06bc15b60c534159804193df07f02