Re: [HACKERS] Serial and NULL values

Bruce Momjian <maillist@candle.pha.pa.us> writes:
>> Offhand I don't see any fundamental reason why serial columns should
>> be restricted to be nonnull, but evidently someone did at some point.

> The actual null is not the issue.  The issue is that if we have a
> SERIAL column, and we try to put a NULL in there, shouldn't it put the
> default sequence number in there?

No, I wouldn't expect that at all.  A default is inserted when you
don't supply anything at all for the column.  Inserting an explicit
NULL means you want a NULL, and barring a NOT NULL constraint on
the column, that's what the system ought to insert.  I can see no
possible justification for creating a type-specific exception to
that behavior.

If the original asker really wants to substitute something else for
an explicit null insertion, he could do it with a rule or a trigger.
But I don't think SERIAL ought to act that way all by itself.
        regards, tom lane