title: key/value (general) and tokyo cabinet (python tc-specific) question
body: <p>i have been in the RDBMS world for many years now but wish to explore the whole nosql movement.  so here's my first question:</p>
  
  <p>is it bad practice to have the possibility of duplicate keys?  for example, an address book keyed off of last name (most probably search item?) could have multiple entities.  is it bad practice to use the last name then?  is the key supposed to be the most "searchable" definition of the entity?  are there any resources for "best practices" in this whole new world (for me)?</p>
  
  <p>i'm intrigued by tokyo cabinet (and specifically the tc interface) but don't know how to iterate through different entities that have the same key (e.g. see above).  i can only get the first entity.  anyway, thanks in advance for the help</p>