The fasttrun module provides transaction unsafe function to truncate temporary tables without growing pg_class size.

This module is required for 1C Enterprise support.

Fast truncate operation is not transactional, so its results cannot be rolled back and become immediately visible in all sessions regardless of isolation level.

        select fasttruncate('TABLE_NAME');
      

create or replace function f() returns void as $$
begin
  for i in 1..1000
    loop
      PERFORM fasttruncate('tt1');
    end loop;
  end;
$$ language plpgsql;