Why did PostgreSQL choose an elephant as it's logo?
In the email thread postgreSQL and history of relational databases, Oleg Bartunov states that the logo idea probably originated from a PostgreSQL logo thread on the pgsql-hackers mailing list. Quote:


  [...]
  but if you want an animal-based logo, how about some sort of elephant?
  After all, as the Agatha Christie title read, elephants can remember ...
  
  David Yang