id	summary	reporter	owner	description	type	status	component	version	severity	resolution	keywords	cc	stage	has_patch	needs_docs	needs_tests	needs_better_patch	easy	ui_ux
29824	Exclude using constraint	Mads Jensen	Mads Jensen	"A lot of work was done to add the check constraint to Django 2.2. On top of such a constraint, PostgreSQL has an exclusion constraint that works well on ranges, regardless if they're represented using two fields, or a single field using a range-type. Essentially, this constraint enforces a unique constraint for ranges, with a possibility for an additional check.

https://github.com/tbicr/django-pg-zero-downtime-migrations/ uses `ALTER TABLE %(table)s VALIDATE CONSTRAINT` to restrict how long the table is locked for writing. I was contemplating to touch this subject in the patch.  "	New feature	assigned	contrib.postgres	2.1	Normal		constraints postgres		Unreviewed	1	0	0	0	0	0