Unprocessed items handling in DynamoDB - Mini Project: Build & Apply

Handling Unprocessed Items in DynamoDB Batch Write

📖 Scenario: You are managing a DynamoDB table for an online bookstore. You want to batch write multiple book records at once. Sometimes, DynamoDB returns unprocessed items due to throttling or capacity limits. You need to handle these unprocessed items by retrying the batch write until all items are processed.

🎯 Goal: Build a DynamoDB batch write operation that retries unprocessed items until all are successfully written.

📋 What You'll Learn

Create a list of book items to write to DynamoDB

Set a maximum retry count for handling unprocessed items

Write a loop that performs batch write and retries unprocessed items

Complete the batch write operation ensuring no unprocessed items remain

💡 Why This Matters

🌍 Real World

Batch writing is common when inserting many records efficiently into DynamoDB. Handling unprocessed items ensures data consistency and reliability.

💼 Career

Understanding unprocessed items handling is essential for backend developers and cloud engineers working with AWS DynamoDB to build scalable and fault-tolerant applications.

1

Create the list of book items to write

Create a variable called book_items that is a list containing these exact dictionaries: {'PutRequest': {'Item': {'BookId': {'S': 'B001'}, 'Title': {'S': 'Learn DynamoDB'}}}}, {'PutRequest': {'Item': {'BookId': {'S': 'B002'}, 'Title': {'S': 'Master AWS'}}}}, and {'PutRequest': {'Item': {'BookId': {'S': 'B003'}, 'Title': {'S': 'Cloud Basics'}}}}.

DynamoDB

# Create the list of book items to write
# Your code here

Need a hint?

Use a list with dictionaries exactly as shown for each book item.

2

Set the maximum retry count

Create a variable called max_retries and set it to 5 to limit the number of retry attempts for unprocessed items.

DynamoDB

book_items = [
    {'PutRequest': {'Item': {'BookId': {'S': 'B001'}, 'Title': {'S': 'Learn DynamoDB'}}}},
    {'PutRequest': {'Item': {'BookId': {'S': 'B002'}, 'Title': {'S': 'Master AWS'}}}},
    {'PutRequest': {'Item': {'BookId': {'S': 'B003'}, 'Title': {'S': 'Cloud Basics'}}}}
]
# Set the maximum retry count
# Your code here

Need a hint?

Just assign the number 5 to max_retries.

3

Write the retry loop for batch write

Write a while loop that continues while book_items is not empty and max_retries is greater than 0. Inside the loop, call response = dynamodb.batch_write_item(RequestItems={'Books': book_items}). Then update book_items to response.get('UnprocessedItems', {}).get('Books', []). Decrease max_retries by 1 each loop.

DynamoDB

book_items = [
    {'PutRequest': {'Item': {'BookId': {'S': 'B001'}, 'Title': {'S': 'Learn DynamoDB'}}}},
    {'PutRequest': {'Item': {'BookId': {'S': 'B002'}, 'Title': {'S': 'Master AWS'}}}},
    {'PutRequest': {'Item': {'BookId': {'S': 'B003'}, 'Title': {'S': 'Cloud Basics'}}}}
]
max_retries = 5

# Write the retry loop for batch write
# Your code here

Need a hint?

Use a while loop with the conditions and update book_items and max_retries inside.

4

Complete the batch write operation

Add a final check after the loop: if book_items is not empty, set a variable failed_items to book_items. Otherwise, set failed_items to an empty list [].

DynamoDB

book_items = [
    {'PutRequest': {'Item': {'BookId': {'S': 'B001'}, 'Title': {'S': 'Learn DynamoDB'}}}},
    {'PutRequest': {'Item': {'BookId': {'S': 'B002'}, 'Title': {'S': 'Master AWS'}}}},
    {'PutRequest': {'Item': {'BookId': {'S': 'B003'}, 'Title': {'S': 'Cloud Basics'}}}}
]
max_retries = 5

while book_items and max_retries > 0:
    response = dynamodb.batch_write_item(RequestItems={'Books': book_items})
    book_items = response.get('UnprocessedItems', {}).get('Books', [])
    max_retries -= 1

# Add final check for failed items
# Your code here

Need a hint?

Use an if-else statement to assign failed_items based on whether book_items is empty.