Firestore Bulk Writer Delete

index.js

const admin = require('firebase-admin');

// TODO(you): Change this to match your Project ID
admin.initializeApp({
  projectId: "YOUR-PROJECT-ID"
});

const READ_BATCH_SIZE = 250;
const db = admin.firestore();

async function main() {
  // TODO(you): Change this to be a query that matches your needs
  const baseQuery = db.collection('foo').where('bar', '==', 'baz');

  // Keep track of query pagination
  let startAfterDoc = undefined;
  let hasMore = true;

  // This new Bulk Writer API will help optimize your
  // delete batches for you.
  const writer = db.bulkWriter();

  // Keep track of stats
  let docsRead = 0;
  let docsDeleted = 0;

  writer.onWriteResult((ref) => {
    docsDeleted++;
    
    // Log a message every 1000 docs
    if (docsDeleted % 1000 === 0) {
      console.log(`[${new Date().toTimeString()}]: Read ${docsRead}, Deleted ${docsDeleted}`);
    }
  });

  while (hasMore) {
    let q = baseQuery.orderBy('__name__');
    if (startAfterDoc) {
      q = baseQuery.startAfter(startAfterDoc);
    }
    q = q.limit(READ_BATCH_SIZE);

    // Read a batch of docs
    const snap = await q.get();
    docsRead += snap.docs.length;

    // Tell BulkWriter to delete them all, but don't wait on it
    for (const d of snap.docs) {
      writer.delete(d.ref);
    }

    // If there are any results, read another page
    hasMore = snap.docs.length > 0;
    if (hasMore) {
      startAfterDoc = snap.docs[snap.docs.length - 1];
    }
  }

  // Wait for all of the deletes to finish now
  await writer.flush();
  await writer.close();
}

main();

package.json

{
  "name": "firestore-bulk-delete",
  "main": "index.js",
  "dependencies": {
    "firebase-admin": "^9.4.2"
  }
}