Re: How many fields in a table are too many - Mailing list pgsql-general

Alvaro Herrera wrote:
> On Sat, Jun 28, 2003 at 01:43:32PM -0400, Tom Lane wrote:
> > Bruce Momjian <pgman@candle.pha.pa.us> writes:
> > > Is this a TODO?
> > >     When columns can be reordered, move varlena columns to the end?
> >
> > I believe that really what you want is fixed-width NOT NULL columns
> > first, then fixed-width nullable, then var-width.  This ordering will
> > improve the odds of actually being able to use the fixed offset for
> > a particular column.
>
> This means that when you do ALTER TABLE ... SET/DROP NOT NULL the table
> may have to be completely rewritten?  Altering the physical order is
> sure to provoke a rewrite, but I think people will expect a change in
> constraints to be a fast operation.

I don't think we would change any physical ordering with ALTER TABLE ---
just do it when the table is created, if possible.

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