On Mon, Dec 5, 2022 at 1:04 PM Tom Lane <t...@sss.pgh.pa.us> wrote: > "David G. Johnston" <david.g.johns...@gmail.com> writes: > > Can we please add "first_value" and "last_value" if we are going to add > > "some_random_value" to our library of aggregates? > > First and last according to what ordering? We have those in the > window-aggregate case, and I don't think we want to encourage people > to believe that "first" and "last" are meaningful otherwise. > > ANY_VALUE at least makes it clear that you're getting an unspecified > one of the inputs.
I have personally implemented first_value() and last_value() in the past in cases where I had guaranteed the ordering myself, or didn't care what ordering was used. I think they're perfectly sensible. But if we don't add them to core, at least they're easy to add in user-space. -- Robert Haas EDB: http://www.enterprisedb.com
