Batch limits and best practices in Firebase - Mini Project: Build & Apply

Batch Limits and Best Practices with Firebase

📖 Scenario: You are managing a Firebase Firestore database for a small online store. You want to update multiple product prices at once using batch writes. However, Firestore limits batch writes to 500 operations per batch. You need to handle this limit properly to avoid errors.

🎯 Goal: Build a Firebase batch write process that updates product prices in batches of 500 or less, following best practices to handle batch limits.

📋 What You'll Learn

Create a list of 600 product IDs with their new prices.

Set a batch size limit variable to 500.

Write a loop that processes the product updates in batches of 500 or less.

Commit each batch properly to Firestore.

💡 Why This Matters

🌍 Real World

Batch writes are essential when updating many documents in Firestore efficiently and within limits.

💼 Career

Understanding batch limits and best practices is important for backend developers and cloud engineers working with Firebase.

1

Create the product updates list

Create a list called productUpdates containing 600 objects. Each object should have id as a string from "product1" to "product600" and newPrice as a number starting from 10 and increasing by 1 for each product.

Firebase

# Create the productUpdates list with 600 products
# Your code here

Need a hint?

Use a list comprehension with range(1, 601) to create 600 products.

2

Set the batch size limit

Create a variable called batchSize and set it to 500 to represent the Firestore batch write limit.

Firebase

productUpdates = [{"id": f"product{i}", "newPrice": 10 + i - 1} for i in range(1, 601)]
# Set the batchSize variable to 500
# Your code here

Need a hint?

Just assign 500 to batchSize.

3

Write the batch processing loop

Write a for loop using range with variables start and end to process productUpdates in slices of size batchSize. Inside the loop, create a new batch with db.batch() and add update operations for each product in the current slice using batch.update(). Use db.collection('products').doc(product['id']) as the document reference and update the price field with product['newPrice']. Do not commit the batch yet.

Firebase

productUpdates = [{"id": f"product{i}", "newPrice": 10 + i - 1} for i in range(1, 601)]
batchSize = 500
# Write a for loop to process productUpdates in batches
# Your code here

Need a hint?

Use range(0, len(productUpdates), batchSize) to loop in steps of 500.

4

Commit each batch

Inside the for loop after adding all updates, commit the batch by calling batch.commit().

Firebase

productUpdates = [{"id": f"product{i}", "newPrice": 10 + i - 1} for i in range(1, 601)]
batchSize = 500
for start in range(0, len(productUpdates), batchSize):
    end = start + batchSize
    batch = db.batch()
    for product in productUpdates[start:end]:
        docRef = db.collection('products').doc(product['id'])
        batch.update(docRef, {"price": product['newPrice']})
    # Commit the batch here
    # Your code here

Need a hint?

Call batch.commit() after adding all updates in the batch.