Re: Odd error when using UNION and COLLATE

On Wed, Jul 20, 2016 at 06:03:08PM -0400, Tom Lane wrote:
> Greg Stark <stark(at)mit(dot)edu> writes:
> > But I think I agree that it's surprising that the collate clause isn't
> > working in the ORDER BY on a column produced by a UNION. Certainly
> > that's where people usually want to put it.
>
> See this ancient comment in transformSetOperationStmt:
>
> * For now, we don't support resjunk sort clauses on the output of a
> * setOperation tree --- you can only use the SQL92-spec options of
> * selecting an output column by name or number. Enforce by checking that
> * transformSortClause doesn't add any items to tlist.
>
> Perhaps sometime we ought to make an effort to relax that.

Oh, I didn't see that above the error block.

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