title: using array fields in mongoDB
body: <p>I'm working on a scheme that will heavily use array fields in mongo documents,
  are there any known problems with the approach of holding rather large arrays of other documents etc?</p>
  
  <p>performance issues?</p>
  
  <p>being rather new to mongo and coming from SQL background the approach seems "out of place" for me since it's bit different than the approach of grouping all records in a table by a set of "primary keys" instead of holding the "primary keys" once and holding the rest of the data in arrays.</p>
  
  <p>the "primary keys" approach is my other option to use in mongo as well</p>
  
  <p>what is best?</p>