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

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."

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