title: Firestore offline data: Merging writes, maximum time of offline persistence
body: <p><a href="https://firebase.google.com/docs/firestore/manage-data/enable-offline" rel="noreferrer">https://firebase.google.com/docs/firestore/manage-data/enable-offline</a></p>
  
  <p>How does Firestore work with offline data?</p>
  
  <ol>
  <li><p>How are writes merged by many clients editing the same data offline, that then come online at the same time?</p></li>
  <li><p>How long is offline data persisted? If my user uses my app for 5 years offline, then comes back online, will this be an issue? Do offline changes persist after device restarts?</p></li>
  <li><p>Does query performance of offline data degrade as the data set gets larger?</p></li>
  </ol>
  
  <p>Im specifically interested in the web Firestore client.</p>
  
  <p>Do all the language clients implement the above in the same manner?</p>
  
  <p>Thanks.</p>