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Commit Graph

9 Commits

Author SHA1 Message Date
Simon Charette
0701bb8e1f Fixed #33928 -- Avoided unnecessary queries when cascade updating.
Models that use SET, SET_NULL, and SET_DEFAULT as on_delete handler
don't have to fetch objects for the sole purpose of passing them back to
a follow up UPDATE query filtered by the retrieved objects primary key.

This was achieved by flagging SET handlers as _lazy_ and having the
collector logic defer object collections until the last minute. This
should ensure that the rare cases where custom on_delete handlers are
defined remain uncalled when when dealing with an empty collection of
instances.

This reduces the number queries required to apply SET handlers from
2 to 1 where the remaining UPDATE use the same predicate as the non
removed SELECT query.

In a lot of ways this is similar to the fast-delete optimization that
was added in #18676 but for updates this time. The conditions only
happen to be simpler in this case because SET handlers are always
terminal. They never cascade to more deletes that can be combined.

Thanks Renan GEHAN for the report.
2022-08-27 14:25:55 +02:00
django-bot
9c19aff7c7 Refs #33476 -- Reformatted code with Black. 2022-02-07 20:37:05 +01:00
Mariusz Felisiak
4074f38e1d Refs #32682 -- Fixed QuerySet.delete() crash on querysets with self-referential subqueries on MySQL. 2021-04-27 10:34:47 +02:00
Étienne Loks
9a621edf62 Fixed #29016 -- Fixed incorrect foreign key nullification on related instance deletion. 2018-01-13 10:31:00 -05:00
Flavio Curella
c2e70f0265 Fixed #21127 -- Started deprecation toward requiring on_delete for ForeignKey/OneToOneField 2015-07-27 18:28:13 -04:00
Tim Graham
0ed7d15563 Sorted imports with isort; refs #23860. 2015-02-06 08:16:28 -05:00
Simon Charette
10e3faf191 Fixed #19774 -- Deprecated the contenttypes.generic module.
It contained models, forms and admin objects causing undesirable
import side effects. Refs #16368.

Thanks to Ramiro, Carl and Loïc for the review.
2014-01-26 14:42:30 -05:00
Jason Myers
7a61c68c50 PEP8 cleanup
Signed-off-by: Jason Myers <jason@jasonamyers.com>
2013-11-02 23:50:49 -05:00
Florian Apolloner
89f40e3624 Merged regressiontests and modeltests into the test root. 2013-02-26 14:36:57 +01:00