#PSQL #SQL last_value_ignore_nulls

last_value_ignore_nulls.sql

do $transaction$
begin

    create function coalesce_r_sfunc(state anyelement, value anyelement)
        returns anyelement
        immutable parallel safe
    as
    $$
    select coalesce(value, state);
    $$ language sql;

    create aggregate last_value_ignore_nulls(anyelement) (
        sfunc = coalesce_r_sfunc,
        stype = anyelement
    );

    exception
        when duplicate_function then null;

end
$transaction$;