title: Database, Using json field instead of ManyToManyField?
body: <p>Suppose reviews can have zero or more tags. </p>
  
  <p>One could implement this using three tables, <code>Review/Tag/ReviewTagRelation</code>.<br>
  ReviewTagRelation would have foreign key to Review and Tag table.</p>
  
  <p>Or using two tables <code>Review/Tag</code>. Review has a json field to hold the list of tag ids.</p>
  
  <p>Traditional approach seems to be the one using the three tables.<br>
  I wonder if it is ok to use the two tables approach when there's no need to reference reviews from tags.  </p>
  
  <p>i.e. I only need to know what tags are associated with a given review.</p>