Re: [HACKERS] Serial and NULL values

On Fri, Oct 29, 1999 at 08:20:30PM -0400, Bruce Momjian wrote:
> > 
> > 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?
> 

It seems logical that if a value was supplied for a serial column that 
it would override the default.  After all, SERIAL is just an int column 
with a default based on a sequence, right?.  If the default is always 
used (even when a value is supplied) then that would be a REAL BIG problem. 

Without making SERIAL a distinctly different datatype, I can't see how 
a default sequence could behave differently for two tables created with 
different syntax.

My 2 cents is that the current behavior is the correct behavior.

As far as the NULL goes, since the SERIAL column is assumed to be a 
key and a unique index is created, having it NOT NULL seems like a
good idea.  I don't know anyone who would have a key value be NULL,
and even if it could be NULL, you would olny be allowd one NULL.

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