On Sat, 6 May 2006, Tom Lane wrote:
> In general the distinction between a true null composite value and a
> row-of-nulls is not made very cleanly in PG. I'd be inclined to
> deprecate the former --- you cannot enter such a thing as a row of a
> table, for example, and that is the basic property that any rowtype
> ought to have no?
True - though obviously composite types are not always used as whole rows as
in the first example/test from my original message (also in the PostgreSQL
documentation describing composite types); in that case the composite type
was a single column and could indeed accept a true null.
> In short, don't do that.
Could section 8.11 of the docs be updated to include such a warning?