#31653: PostgreSQL add constraints via NOT VALID / VALIDATE CONSTRAINT
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Reporter: Adam (Chainz) | Owner: nobody
Johnson |
Type: | Status: new
Cleanup/optimization |
Component: Migrations | Version: master
Severity: Normal | Resolution:
Keywords: | Triage Stage:
| Unreviewed
Has patch: 0 | Needs documentation: 0
Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 0
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Comment (by Adam (Chainz) Johnson):
> My interpretation is that in order for other transactions to see that
the constraint was added in a READ COMMITTED scenario the ADD CONSTRAINT
NOT VALID must be committed first; performing a ADD CONSTRAINT NOT VALID
and VALIDATE CONSTRAINT in the same transaction should result in the same
operations as ADD CONSTRAINT otherwise PostgreSQL would always do it by
default?
Yes... the one time I've used `NOT VALID` was actually in an `atomic =
False` migration so I didn't test it with atomic. I was probably too
zealous reading the PostgreSQL docs which don't mention transactions.
I think custom `django.contrib.postgres` operations would be the way. They
can document to use non-atomic migrations. Rather than `AddConstraint(...,
validate=False)` I'd suggest `AddConstraintNotValid(...)` as a subclass of
`AddConstraint`, and `ValidateConstraint`.
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Ticket URL: <https://code.djangoproject.com/ticket/31653#comment:5>
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