psql -h localhost test -c "drop table stuff"
psql -h localhost test -c "create table stuff as select (random())::numeric as randnum from generate_series(1,1000000)"
psql -h localhost test -c "analyze stuff"

time psql -h localhost test -c "select percentile_disc(0) within group (order by randnum) from stuff;"
time psql -h localhost test -c "select percentile_disc(0) within group (order by randnum) from stuff;"
time psql -h localhost test -c "select percentile_disc(0) within group (order by randnum) from stuff;"
time psql -h localhost test -c "select percentile_disc(0) within group (order by randnum) from stuff;"
time psql -h localhost test -c "select percentile_disc(0) within group (order by randnum) from stuff;"