Question

I got a huge PostgreSQL database with lots of tables. I want learn all empty tables without counting each tables for performance reasons (Some of the tables have several millions rows).

Answer 1

This query will give you an approximate result, but does not include counting table rows.

SELECT relname FROM pg_class JOIN pg_namespace ON (pg_class.relnamespace = pg_namespace.oid) WHERE relpages = 0 AND pg_namespace.nspname = 'public';

This will work best after a VACUUM ANALYZE.