title: firebase google or query support or any alternative solution
body: <p>We have just started exploring firebase for our new app. The app basically needs chat between users and Group chat.</p>
  
  <p>For the chat application we are creating: <strong>MessageThread(id, User:userA, User:userB, UserGroup:group, Array:deletedBy, ...)</strong></p>
  
  <p>The main problem is firebase doesn't support OR queries and IN queries, which I need in my use-case. For example:</p>
  
  <p>Dummy query to access user's conversations list:
  <strong>fetch MessageThread(s) where (currentUser.id==userA.id) OR (currentUser.id==userB.id) OR (currentUser.id IN group.members)</strong></p>
  
  <p>I am missing something to understand Firebase? What is the other alternative way to design our database to solve this problem?</p>