Re: NOT ENFORCED constraint feature

Alvaro Herrera <alvherre@alvh.no-ip.org>

From: Alvaro Herrera <alvherre@alvh.no-ip.org>

To: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com>

Cc: Amul Sul <sulamul@gmail.com>, Peter Eisentraut <peter@eisentraut.org>, jian he <jian.universality@gmail.com>, pgsql-hackers <pgsql-hackers@postgresql.org>, Joel Jacobson <joel@compiler.org>

Date: 2025-02-03T07:50:41Z

Lists: pgsql-hackers

Commits

Same data as JSON: GET /api/v1/messages/:b64id/commits the thread's linked commits as JSON, with link sources. API reference →

Add support for NOT ENFORCED in foreign key constraints
- eec0040c4bcd 18.0 landed
Expand test a bit
- 5d5f415816a6 18.0 landed
refactor: Pass relation OID instead of Relation to createForeignKeyCheckTriggers()
- ef7a5af77d44 18.0 landed
refactor: Split ATExecAlterConstraintInternal()
- 639238b978fe 18.0 landed
refactor: Move some code that updates pg_constraint to a separate function
- a3280e2a494f 18.0 landed
Move RemoveInheritedConstraint() call slightly earlier
- dabccf45139a 18.0 landed
refactor: Split tryAttachPartitionForeignKey()
- 1d26c2d2c4b8 18.0 landed
refactor: re-add ATExecAlterChildConstr()
- 64224a834ce4 18.0 landed
Add ATAlterConstraint struct for ALTER .. CONSTRAINT
- 80d7f990496b 18.0 landed
refactor: split ATExecAlterConstrRecurse()
- 7a947ed25b54 18.0 landed
Add support for NOT ENFORCED in CHECK constraints
- ca87c415e2fc 18.0 landed

On 2025-Feb-03, Ashutosh Bapat wrote:

> VALID, NOT ENFORCED changed to VALID, ENFORCED - data validation
> required, constraint is enforced

There's no such thing as a VALID NOT ENFORCED constraint.  It just
cannot exist.

> NOT VALID, NOT ENFORCED changed to NOT_VALID, ENFORCED - no data
> validation required, constraint is enforced on the new tuples/changes

This may make sense, but it needs special nonstandard syntax.  If you
start with a NOT VALID NOT ENFORCED constraint (which is the only way to
have a NOT ENFORCED constraint) and apply ALTER TABLE ALTER CONSTRAINT
ENFORCE, you will end up with a VALID ENFORCED constraint, therefore
validation must be run.

If you wanted to add a nonstandard command
ALTER TABLE ALTER CONSTRAINT ENFORCE NO VALIDATE
then maybe the transition you suggest could be made.
It should be a separate patch from regular ALTER CONSTRAINT ENFORCE
though, just in case some problems with it emerge later and we're forced
to revert it, we can still keep the standard command.

-- 
Álvaro Herrera        Breisgau, Deutschland  —  https://www.EnterpriseDB.com/
"Use it up, wear it out, make it do, or do without"