Re: Aggregate ORDER BY patch

>>>>> "Tom" == Tom Lane <tgl@sss.pgh.pa.us> writes:

 >> What about error handling? If the user specifies agg(distinct x)
 >> where x is not sortable, do we leave it to the planner to detect
 >> that (which means not reporting the error position?)

 Tom> Well, at the moment there's only going to be a sort-based
 Tom> implementation, so I don't object to throwing an error for that
 Tom> as soon as possible.  OTOH I wouldn't recommend expending a lot
 Tom> of code to do it there.  I would hope that most of the parser's
 Tom> work for this can be shared with the existing support for
 Tom> query-level ORDER BY/DISTINCT.

The code already uses transformSortClause for most of the work, but
reusing the existing code for DISTINCT would have required more
refactoring than I was happy with, because transformDistinct etc.
all have error message text which is specific to SELECT DISTINCT etc.
Let's see how it falls out in the next patch.

-- 
Andrew.