čt 8. 11. 2018 v 7:11 odesílatel Andrew Gierth <and...@tao11.riddles.org.uk> napsal:
> >>>>> "Ken" == Ken Tanzer <ken.tan...@gmail.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 > It is work with custom functions, not with buildin least, greatest Regards Pavel > 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) > >
