Because they walk a small part of an index to figure out how many hits there _probably_ are. Geez; you think they actually count a giant left join on the inter

Because they walk a small part of an index to figure out how many hits there _probably_ are. Geez; you think they actually count a giant left join on the internet? Also: http://www.tbray.org/ongoing/When/200x/2004/11/26/SearchSort http://www.tbray.org/ongoing/When/200x/2004/11/26/SearchSort