Re: Wrong results from function that selects from vier after "created or replace"

create function my_constant()
  immutable
  return 42;

create function my_dependant()
  immutable
  language plpgsql
  v constant int not null := my_constant();
  return v;

select 'my_dependant(): '||my_dependant()::text;

create or replace function my_constant()
  immutable
  language plpgsql
  return 17;

select 'my_dependant(): '||my_dependant()::text;

When I run this, I see “42” at the start and “17” after recompiling the function “my_constant()”.

Should I understand that this outcome, while it might have wrongly seemed to me to support my bad mental model, actually tells me nothing? In other words, should I understand that the _definition_ of “immutable” would allow some future PG implementation justifiably still to return “42” after recompiling “my_constant()”.

And should I understand that I might to continue to see “42” quite literally forever (even after pg-stop and pg-start) —until I actually drop the function “my_constant()”.