This order of operations is more in line with SQLite's documented table
rebuild procedure and ensures that changes aren't committed if foreign key
integrity is broken.
SQLite 3.26 changed the behavior of table and column renaming operations to
repoint foreign key references even if foreign key checks are disabled.
This makes the workarounds in place to simulate this behavior unnecessary on
SQLite 3.26+. Refs #30033.
Refs #29182.
The previous implementation was following a procedure explicitly documented
as incorrect and was the origin of the breakage experienced on SQLite 3.26
release that were addressed by c8ffdbe514.
Thanks to Richard Hipp for pointing out the usage of the incorrect procedure.
Prior to this change foreign key constraint references could be left pointing
at tables dropped during operations simulating unsupported table alterations
because of an unexpected failure to disable foreign key constraint checks.
SQLite3 does not allow disabling such checks while in a transaction so they
must be disabled beforehand.
Thanks ezaquarii for the report and Carlton and Tim for the review.
SQLite 3.26 repoints foreign key constraints on table renames even when
foreign_keys pragma is off which breaks every operation that requires
a table rebuild to simulate unsupported ALTER TABLE statements.
The newly introduced legacy_alter_table pragma disables this behavior
and restores the previous schema editor assumptions.
Thanks Florian Apolloner, Christoph Trassl, Chris Lamb for the report and
troubleshooting assistance.
Removed DatabaseIntrospection.table_name_converter()/column_name_converter()
and use instead DatabaseIntrospection.identifier_converter().
Removed DatabaseFeatures.uppercases_column_names.
Thanks Tim Graham for the initial patch and review and Simon Charette
for the review.
Since CPython implements a C level attrgetter(*attrs) it even outperforms the
most common case of a single known related object since the resulting attribute
values tuple is built in C.
Added a test for constraint names in the database.
Updated SQLite introspection to use sqlparse to allow reading the
constraint name for table check and unique constraints.
Co-authored-by: Ian Foote <python@ian.feete.org>
Adjusted known related objects handling of target fields which relies on
from and to_fields and has the side effect of fixing a bug bug causing
N+1 queries when using reverse foreign objects.
Thanks Carsten Fuchs for the report.
Tim Graham
Mariusz Felisiak
Simon Charette
Nick Pope
Sergey Fedoseev
Simon Charette
Dakota Hawkins
Prabakaran Kumaresshan
Tim Fiedler
Tom Forbes
Ian Foote
Hasan Ramezani
Srinivas Reddy Thatiparthy