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.klaver@aklaver.com