You will need to use dynamic SQL to acheive this, perhaps like this:
testbed:
create role stack;
create schema authorization stack;
set role stack;
create table my_table as
select generate_series(0,9) as id, null::integer as val;
create table my_table2 as
select g as id, case when g<=5 then null::integer else 1 end as val
from generate_series(0,9) g;
function:
create function get_with_nulls_rowcount(p_schema in text, p_table in text)
returns integer language plpgsql as $$
declare
n integer;
s text;
begin
--
select array_to_string(array_agg(column_name::text||' is null'), ' or ')
into s
from information_schema.columns
where table_schema=p_schema and table_name=p_table;
--
execute 'select count(*) from '||p_table||' where '||s into n;
return n;
end;$$;
query:
select table_schema, table_name,
get_with_nulls_rowcount(table_schema, table_name)
from information_schema.tables
where table_schema='stack';
result:
table_schema | table_name | get_with_nulls_rowcount
--------------+------------+-------------------------
stack | my_table | 10
stack | my_table2 | 6
(2 rows)
