Re: unnest with generate_subscripts and same array

Can’t speak to guarantees but arrays, unlike tuples / rows, are inherently ordered and so any operation that decomposes/iterates them will do so in the internal order.

So, yes.

(without looking at code)

But, since you do not have an “ORDER BY on table_with_array_col” so the order in which rows are returned from table_with_array_col is undefined.  Better to write:

SELECT unnest(array_col), generate_subscripts(array_col)

FROM (

    SELECT array_col FROM table_with_array_col ORDER BY somefield

) sub

David J.