Re: Check whether a NOT NULL check constraint has been validated

On 11/30/25 19:07, Adrian Klaver wrote:
> On 11/30/25 16:59, Stuart Campbell wrote:
>> Hello,
>>
>> I have several NOT NULL check constraints in my schema that were
>> originally added as NOT VALID. I would like to determine whether they
>> have all since been validated, or not.
>>
>> I thought maybe pg_constraint.convalidated might help, but it seems
>> like the version of Postgres I'm using (16) doesn't store not null
>> constraints in that table. And even in later versions, maybe it
>> doesn't hold the information I need.
>>
>> Is there another way to discover this?
>
> 1) Select count(*) from <table> where <col> IS NULL;
>
> 2) From here
>
> https://www.postgresql.org/docs/current/sql-altertable.html#SQL-
> ALTERTABLE-NOTES
>
> ALTER TABLE <table> VALIDATE CONSTRAINT <constraint_name>;
>
> As described:
>
> ". Once the constraint is in place, no new violations can be inserted,
> and the existing problems can be corrected at leisure until VALIDATE
> CONSTRAINT finally succeeds."

Realized I was looking at current docs and I should be looking at your
version

From the 16 version of the docs:

"This form adds a new constraint to a table using the same constraint
syntax as CREATE TABLE, plus the option NOT VALID, which is currently
only allowed for foreign key and CHECK constraints."

Now I am not sure what you did.

Are you saying you used a CHECK constraint to check for NULL values?

If so then pg_constraint.convalidated would work.

If not are you sure you are on Postgres 16?

>
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>

--
Adrian Klaver
adrian(dot)klaver(at)aklaver(dot)com