aggregate_sample.js

// @locus: server
if(Meteor.isServer){
Tracker.autorun(() => {
  CollectionObserved.find();
  collectAndSaveData();
});

function collectAndSaveData(){
  var aggregateData = CollectionObserved.aggregate(...);
  var aggregateDocId = ...;
  
  AggregateDataCollection.update(aggregateDocId, {
    $set: aggregateData
  });
}

// Publish

Meteor.publish('aggregateDataCol', function(){
  return AggregateDataCollection.find();
});
}