avoiding persistence on Collection in Meteor

I've just started to look into using Meteor for an upcoming project, and have a question about data persistence. It sounds like you have two options: First, you can declare a "name" when instantiating a new Collection which will create a database collection which will be saved upon alteration.

Chatrooms = new Meteor.Collection("chatrooms");

The other option is to create an anonymous collection, which won't be saved.

Chatrooms = new Meteor.Collection();

But what do I do if I want to populate a Collection from the database, but not save it upon alteration on the client-side? For instance, I might want to create a collection of user Movies that will be displayed in a grid -- each having their own absolute positioning based upon the sorting and filtering applied to the collection. Upon changes to the collection, the associated views (or templates) will be re-rendered to reflect those changes. But I don't necessarily want these absolute positions to be stored in a database...

Any ideas?

I'm not very clear about your question. But perhaps, you can bind the absolute position into the collection data? They are just normal javascript objects. And the collection data will only be changed through insert/update/remove function call.

I ended up doing something like this:

movies: function() {
  var movies =  Movies.find().fetch();
  _.each(movies, function(movie, index){
    movie.left = index * 2;
    movie.top = index * 2; 
  });
  return movies; 
},

Basically, 'fetch()' allows me to deal with pure JSON objects, making it easier to iterate through them and alter them without performing 'update' commands.