The mayor, nervous and evasive, admitted Wal-Mart didn’t even have one. Lorenzo Trujillo owned produce stands in the public market. Emmanuel D’Herrera, a trainer and poet, had celebrated his son’s delivery by tucking the boy’s umbilical wire in a crack atop the Moon pyramid.

Each fact table has only 4 or five dimension tables; a diagram of the set of tables and relationships resembles a snowflake–but remains to be an information mart. Data marts are often denormalized, capturing only summaries of knowledge by sorting it and aggregating a outcome table, usually throwing away detail data. Some knowledge marts are completely …