How can I update more than 500 docs in Firestore using Batch?

I'm trying to update a field timestamp with the Firestore admin timestamp in a collection with more than 500 docs.

const batch = db.batch();
const serverTimestamp = admin.firestore.FieldValue.serverTimestamp();

db
  .collection('My Collection')
  .get()
  .then((docs) => {
    serverTimestamp,
  }, {
    merge: true,
  })
  .then(() => res.send('All docs updated'))
  .catch(console.error);

This throws an error

{ Error: 3 INVALID_ARGUMENT: cannot write more than 500 entities in a single call
    at Object.exports.createStatusError (C:\Users\Growthfile\Desktop\cf-test\functions\node_modules\grpc\src\common.js:87:15)
    at Object.onReceiveStatus (C:\Users\Growthfile\Desktop\cf-test\functions\node_modules\grpc\src\client_interceptors.js:1188:28)
    at InterceptingListener._callNext (C:\Users\Growthfile\Desktop\cf-test\functions\node_modules\grpc\src\client_interceptors.js:564:42)
    at InterceptingListener.onReceiveStatus (C:\Users\Growthfile\Desktop\cf-test\functions\node_modules\grpc\src\client_interceptors.js:614:8)
    at callback (C:\Users\Growthfile\Desktop\cf-test\functions\node_modules\grpc\src\client_interceptors.js:841:24)
  code: 3,
  metadata: Metadata { _internal_repr: {} },
  details: 'cannot write more than 500 entities in a single call' }

Is there a way that I can write a recursive method which creates a batch object updating a batch of 500 docs one by one until all the docs are updated.

From the docs I know that delete operation is possible with the recursive approach as mentioned here:

https://firebase.google.com/docs/firestore/manage-data/delete-data#collections

But, for updating, I'm not sure how to end the execution since the docs are not being deleted.

Solution 1:

I also ran into the problem to update more than 500 documents inside a Firestore collection. And i would like to share how i solved this problem.

I use cloud functions to update my collection inside Firestore but this should also work on client side code.

The solution counts every operation which is made to the batch and after the limit is reached a new batch is created and pushed to the batchArray.

After all updates are completed the code loops through the batchArray and commits every batch which is inside the array.

It is important to count every operation set(), update(), delete() which is made to the batch because they all count to the 500 operation limit.

const documentSnapshotArray = await firestore.collection('my-collection').get();

const batchArray = [];
batchArray.push(firestore.batch());
let operationCounter = 0;
let batchIndex = 0;

documentSnapshotArray.forEach(documentSnapshot => {
    const documentData = documentSnapshot.data();

    // update document data here...

    batchArray[batchIndex].update(documentSnapshot.ref, documentData);
    operationCounter++;

    if (operationCounter === 499) {
      batchArray.push(firestore.batch());
      batchIndex++;
      operationCounter = 0;
    }
});

batchArray.forEach(async batch => await batch.commit());

return;

Solution 2:

I liked this simple solution:

const users = await db.collection('users').get()

const batches = _.chunk(users.docs, 500).map(userDocs => {
    const batch = db.batch()
    userDocs.forEach(doc => {
        batch.set(doc.ref, { field: 'myNewValue' }, { merge: true })
    })
    return batch.commit()
})

await Promise.all(batches)

Just remember to add import * as _ from "lodash" at the top. Based on this answer.