Costs: Index vs Non-Index

Hrmmm...if I'm reading this right, its more costly to create an index then
to leave it as a sequential scan, but it returns more rows? Yet, it
returns, if I do the query with a count() around the return value, 288
rows, not 334 or 1154...

udmsearch=> explain select next_index_time from url where next_index_time <= 947317073;
NOTICE: QUERY PLAN:

Seq Scan on url (cost=43.00 rows=334 width=4)

EXPLAIN
udmsearch=> create index url_next_index_time on url using btree ( next_index_time);
CREATE
udmsearch=> explain select next_index_time from url where next_index_time <= 947317073;
NOTICE: QUERY PLAN:

Index Scan using url_next_index_time on url (cost=271.68 rows=1154 width=4)

EXPLAIN

Marc G. Fournier ICQ#7615664 IRC Nick: Scrappy
Systems Administrator @ hub.org
primary: scrappy(at)hub(dot)org secondary: scrappy(at){freebsd|postgresql}.org