Query for monitoring wal log population.

pg_xlog_per_sec.sql

DO $$
DECLARE
	cur pg_lsn;
	cur2 pg_lsn;
BEGIN

cur := pg_current_xlog_location();

loop
	execute pg_sleep(5);

	cur2 := pg_current_xlog_location();

	RAISE NOTICE '% : %/s', to_char(clock_timestamp(), 'YYYY/MM/DD HH24:MI:SS'), pg_size_pretty(pg_xlog_location_diff(cur2, cur)/5);

	cur := cur2;

end loop;

END
$$ ;