title: One database structure with many databases, or one global database?
body: <p>Question is this:</p>
  
  <p>Should we have 1 database per vertical or 1 database for everything?  Site will contain several for sale ads.</p>
  
  <p>A) 1 db per vertical example
  Meaning, when you view these pages:
  <a href="http://www.site.com/cars" rel="nofollow">http://www.site.com/cars</a>
  http://www.site.com/boats</p>
  
  <p>/cars literally connects to a database lets say "db_cars" and that database ONLY has car data, nothing else in it.
  /boats literally connects to a database lets say "db_boats" and that database ONLY has boat data, nothing else in it.</p>
  
  <p>Both databases have the same structure, table names "item" "seller" etc</p>
  
  <p>OR</p>
  
  <p>B) 1 db for everything example
  /cars connects to "db_everything" and filters cars based on a table linked to the items table, so WHERE item_type="cars"
  /boats connects to "db_everything" and filters cars based on a table linked to the items table, so WHERE item_type="boats"</p>
  
  <p>So would you pick A or B?  Any pros/cons to either?  Does it matter if it's MySQL, Oracle or Postgres?</p>