Re: Largest & Smallest Functions

>>>>> "Ken" == Ken Tanzer <ken(dot)tanzer(at)gmail(dot)com> writes:

Ken> Hi. Building on the [type]_larger and _smaller functions (and
Ken> lifting from the documentation), I put together a couple of
Ken> functions that will take any number of arguments:

Ken> CREATE FUNCTION largest(VARIADIC anyarray) RETURNS anyelement AS
Ken> $$ SELECT max($1[i]) FROM generate_subscripts($1, 1) g(i); $$
Ken> LANGUAGE SQL IMMUTABLE;

Ken> So far so good. I can do smallest(2,4,7), etc. But to take this a
Ken> convenient step further, sometimes I want the smallest or largest
Ken> from values already in an array. So I can create these functions:

But you don't need to create more functions, because you can do this:

select largest(variadic array[1,2,3]);
largest
---------
3

Ken> So here's my questions:

Ken> 1) Is there any way to collapse those four functions into two? (Or
Ken> is there a better way to go about this?)

See above

Ken> 2) Is there any particular reason functions like that aren't built
Ken> into Postgres? They seem like they would be useful. (Or maybe I
Ken> missed them?)

As already pointed out, greatest() and least() exist (though they were
added before VARIADIC was, so they don't use it)

Ken> 3) Bonus question--how come all the existing _larger and _smaller
Ken> functions are specific to each data type, as opposed to more
Ken> general smaller/larger functions?

Because it saves looking up the type comparison function and doing an
indirect call.

--
Andrew (irc:RhodiumToad)