On mån, 2011-03-07 at 19:15 -0500, Tom Lane wrote:
> Or, to put it another way: the properties that define a sort order are
> the sort comparison operator, the collation, the ASC/DESC bit, and the
> NULLS FIRST/LAST bit. Given the way that the SQL committee has
> constructed the language, the operator and the two flag bits are
> attached to the ORDER BY clause, but the collation is a property of
> the expression-to-be-sorted. If we fail to preserve that distinction
> in the internal representation, we're just creating problems for
> ourselves.
You are probably right; it could be simplified.