SELECT count(*) FROM test_table;

BEGIN;
UPDATE test_table SET fakedata='divisible by 3' WHERE (id % 3) = 0;
UPDATE test_table SET fakedata='divisible by 5' WHERE (id % 5) = 0;
UPDATE test_table SET fakedata='divisible by 7' WHERE (id % 7) = 0;
COMMIT;

SELECT * FROM test_table ORDER BY id LIMIT 10;

BEGIN;
UPDATE test_table SET toDelete =  true WHERE id < 100;
DELETE FROM test_table WHERE toDelete = true;
ROLLBACK;