Hi, > 2) Is there any particular reason functions like that aren't built > into Postgres? They seem like they would be useful. (Or maybe I > missed them?)
LEAST() and GREATEST() expressions do the same thing as yours smallest() and largest(). See https://www.postgresql.org/docs/current/functions-conditional.html
That might also answer the first question - just drop smallest() and largest() and you will get two functions instead of four :-)
Now to be a little more serious, if you want a single function to both support variadic number of arguments AND all of them in a single array, how could the function decide whether smallest(ARRAY[1,2,3]) shall return 1 or ARRAY[1,2,3] (which is the smallest out of all arguments)? I would suggest not to declare such overloaded function even if it was possible, as it might confuse the reader easily. Instead, I would go for
SELECT min(u) FROM unnest(ARRAY[1,2,3]) u or just define a separate least_array() / greatest_array() variant. Regards, Ondřej Bouda
