[HACKERS] Proposal: generate_iterator functions

[Pavel Stehule]

Hello

this function can help with array's iteration.

create function generate_iterator(anyarray)
returns setof integer
as $$
select i
  from generate_series(array_lower($1,1),
                                       array_upper($1,1)) g(i)
$$ language sql;

-- multidimensional
create function generate_iterator(anyarray, integer)
returns setof integer
as $$
select generate_series(array_lower($1,$2),
                                      array_upper($1,$2)) g(i)
$$ language sql;

It can be internal function, not only shortcut for generate_series

sample:

create function array_sort(anyarray)
returns anyarray
as $$
select array(select $1[i] from generate_iterator($1) order by 1)
$$ language sql;

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