aggregates, distinct, order by, and case - why won't this work

["David G. Johnston" <david.g.johnston@xxxxxxxxx>]

This...on 9.3

SELECT array_agg(

distinct case when v % 2 = 0 then 'odd' else 'even' end 

order by case when v % 2 = 0 then 1 else 2 end

)

FROM (VALUES (1), (2), (3)) val (v)

I'm not particularly irked at this though I was hoping to fix a somewhat complex query of mine by simply adding a "DISTINCT" to the array_agg that I am building from derived (using CASE) data.

I am curious to the reason for the limitation, particularly as it would relate to this specific instance.

Any givers?

Thank!

David J.