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From: Peter Eisentraut <[email protected]>
To: Alvaro Herrera <[email protected]>
Cc: pgsql-hackers <[email protected]>
Subject: Re: Catalog domain not-null constraints
Date: Mon, 27 Nov 2023 08:08:08 +0100
Message-ID: <[email protected]> (raw)
In-Reply-To: <[email protected]>
References: <[email protected]>

On 23.11.23 17:38, Alvaro Herrera wrote:
> If you create a table with column of domain that has a NOT NULL
> constraint, what happens?  I mean, is the table column marked
> attnotnull, and how does it behave?

No, the domain does not affect the catalog entry for the column.  This 
is the same way it behaves now.

> Is there a separate pg_constraint
> row for the constraint in the table?  What happens if you do
> ALTER TABLE ... DROP NOT NULL for that column?

Those are separate.  After dropping the NOT NULL for a column, null 
values for the column could still be rejected by a domain.  (This is the 
same way CHECK constraints work.)

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