title: Firebase cloud function trigger "onWrite" not called when array gets big
body: <p>I am using this</p>
  
  <pre><code>exports.countposts = functions.database.ref('/rooms/{roomId}/posts').onWrite((change, context) =&gt; {
  </code></pre>
  
  <p>It works! As soon as data is posted (in 99% of cases POSTed) onto the "array" <code>posts</code> (it is an array, I guess in the firebase database world no such exist), this function is called and all is well.</p>
  
  <p>However when the array <code>posts</code> get big, somewhere above 10000 (ten thousand), the function specified silently does not get called at all. I get no error logs. I am assuming/guessing this is a performance issue - when the number of children inside posts gets higher, the execution time of each function gets longer - more or less linearly.</p>
  
  <p>What is the problem here, how can I mitigate this?</p>