Re: CHECK Constraint Deferrable

On Wed, Jul 5, 2023 at 3:08 PM Himanshu Upadhyaya
<upadhyaya.himanshu@gmail.com> wrote:
>
> Hi,
>
> Currently, there is no support for CHECK constraint DEFERRABLE in a create table statement.
> SQL standard specifies that CHECK constraint can be defined as DEFERRABLE.

I think this is a valid argument that this is part of SQL standard so
it would be good addition to PostgreSQL.  So +1 for the feature.

But I am wondering whether there are some real-world use cases for
deferred CHECK/NOT NULL constraints?  I mean like for foreign key
constraints if there is a cyclic dependency between two tables then
deferring the constraint is the simplest way to insert without error.

The real-world use case, at least for me, is when using an ORM. For large object-graphs ORMs have a tendency to INSERT first with NULLs then UPDATE the “NOT NULLs” later.

“Rewrite the ORM” is not an option for most of us…

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Andreas Joseph Krogh