Firebase - How to Delete Many Entries at Once

Firebase - How to delete many entries at once?

In order to delete multiple entries from your database, you need to know all those locations (refernces). So with other words, in the way you add data, you should also delete it.

Assuming your database looks like this:

Firebase-root
   |
   --- Users
   |     |
   |     --- userUid1
   |     |      |
   |     |      --- //user1 data
   |     |
   |     --- userUid2
   |            |
   |            --- //user2 data
   |
   --- Groups
         |
         --- groupId1
         |      |
         |      --- //group1 data
         |      |
         |      --- Users
         |            |
         |            --- userUid1: true
         |            |
         |            --- userUid3: true
         |
         --- groupId2
                |
                --- //group2 data

I suggest you using the method below:

private static void deleteUser(String userId, String groupId) {
    Map<String, Object> map = new HashMap<>();
    map.put("/Users/" + userId + "/", null);
    map.put("/Groups/" + groupId + "/Users/" + userId + "/", new HashMap<>().put(userId, null));
    //other locations
    databaseReference.updateChildren(map);
}

This method atomically deletes all those entries. Using these paths, you can perform simultaneous updates to multiple locations in the JSON tree with a single call to deleteUser() method. Simultaneous deletes made this way are atomic: either all updates succeed or all updates fail.

Hope it helps.

How to delete many of data in Realtime Database

There is support for deleting large nodes built into the Firebase CLI these days as explained in this blog How to Perform Large Deletes in the Realtime Database:

If you want to delete a large node, the new recommended approach is to use the Firebase CLI (> v6.4.0). The CLI automatically detects a large node and performs a chunked delete efficiently.

$ firebase database:remove /path/to/delete

---

My initial write-up is below. I'm pretty sure the CLI mentioned above implements precisely this approach, so that's likely a faster way to accomplish this, but I'm still leaving this explanation as it may be useful as background.

Deleting data is a write operation, so it's by definition going to put load on the database. Deleting a lot of data causes a lot of load, either as a spike in a short period or (if you spread it out) as a lifted load for a longer period. Spreading the load out is the best way to minimize impact for your regular users.

The best way to delete a long, flat list of keys (as you seem to have) is to:

1. Get a list of that keys, either from a backup of your database (which happens out of band), or by using the shallow parameter on the REST API.
2. Delete the data in reasonable batches, where reasonable depends on the amount of data you store per key. If each key is just a few properties, you could start deleting 100 keys per batch, and check how that impacts the load to determine if you can ramp up to more keys per batch.

Remove multiple records from Firebase Realtime database - Nodejs

You can remove multiple nodes in one go by using a multi-location update statement, and passing null for the values.

Something like:

const ref = firebase.database().reference();
ref.update({
  "/path/to/node/one": null,
  "/path/to/node/two": null,
  "/path/to/node/three": null
});

Delete millions of fields in Firebase Realtime Database

The common path for this is:

1. Enable automated backups for your database, and download the JSON from the Storage bucket.
2. Process the JSON locally, and determine the exact path of all nodes to remove.
3. Process the paths in reasonably sized chunks through the API, using multi-location updates.

Removing each chunk of nodes would be something like:

var nodesToRemove = ["/root/messages/messageid_1/field", "/root/messages/messageid_2/field"];

var updates = nodesToRemove.map(function(path) { 
  return { [path]: null };
});
firebase.database().ref().update(updates);

Firebase -- Bulk delete child nodes

You can delete all completed items in one go by using a multi-location update:

var updates = {};
for (var i in this.state.items) {
    var key = items[i]['.key'];
    if(items[i].done){
        updates[key] = null; // setting value to null deletes the key
    }
}
this.ref.update(updates);

How do I delete multiple document in firestore in flutter?

Obviously Firebase Firestore has no way to delete multiple documents, you can use for loop to achieve that.
You can make a list of the ids which you want to delete in Firestore
lets say

List _deletedIds = [6,2,7,4,5];
    for (var i = 0 ; i <= _deletedIds.length - 1 ; i++){
      FirebaseFirestore.instance.collection('Cart').doc(_deletedIds[i]).delete();
    }

Bulk-delete items from a firebase database in node.js

To determine the keys to delete, you'll need to attach a listener. Since that is needed, you might as well create a query that selects the correct children and deletes only those:

var ref = admin.database().ref('games');
var deleteAfterDate = ref.orderByChild('date').startAt('2017-04-05');

deleteAfterDate.once('value').then(function(snapshot) {
  var updates = {};
  snapshot.forEach(function(child) {
    updates[child.key] = null;
  });
  ref.update(updates);
});

How to delete multiple documents from Cloud Firestore using Batched writes in angular 5

It's so easy, try this!

private async deleteCollection(path: string) {
    const batch = db.batch();
    const qs = await db.collection(path).ref.get();
    qs.forEach(doc => batch.delete(doc.ref));
    return batch.commit();
}

---

Related Topics