Espero ter entendido o que você precisa (testado em 8.2):
INSERT INTO articles (id, name)
SELECT x.id, 'article #' || x.id
FROM generate_series(1,10000000) AS x(id);
INSERT INTO articles (id, name)
SELECT x.id, 'article #' || x.id
FROM generate_series(1,10000000) AS x(id);