Why cost management prevents surprises in DynamoDB - See It in Action

Why cost management prevents surprises

📖 Scenario: You work for a small company that uses a cloud database service called DynamoDB. You want to keep track of how much each department spends on database usage every month. This helps avoid unexpected high bills and keeps the budget under control.

🎯 Goal: Build a simple DynamoDB table and queries to record and check monthly costs per department. This will help you manage costs and prevent surprises in billing.

📋 What You'll Learn

Create a DynamoDB table named DepartmentCosts with Department as the partition key and Month as the sort key.

Add a configuration variable cost_threshold to set the maximum allowed monthly cost.

Write a query to find all departments with costs exceeding the cost_threshold for a given month.

Add a final step to update the table with a new cost entry for a department and month.

💡 Why This Matters

🌍 Real World

Companies use cost management in cloud databases to avoid unexpected bills and keep budgets under control.

💼 Career

Database administrators and cloud engineers often create cost tracking systems to monitor and optimize cloud resource usage.

1

DATA SETUP: Create the DynamoDB table

Create a DynamoDB table named DepartmentCosts with Department as the partition key (string) and Month as the sort key (string).

DynamoDB

# Your code here to create the DynamoDB table DepartmentCosts with Department and Month keys

Need a hint?

Use dynamodb.create_table with KeySchema defining Department as HASH and Month as RANGE keys.

2

CONFIGURATION: Set the cost threshold

Create a variable called cost_threshold and set it to 1000 to represent the maximum allowed monthly cost in dollars.

DynamoDB

import boto3

dynamodb = boto3.resource('dynamodb')

DepartmentCosts = dynamodb.create_table(
    TableName='DepartmentCosts',
    KeySchema=[
        {'AttributeName': 'Department', 'KeyType': 'HASH'},  # Partition key
        {'AttributeName': 'Month', 'KeyType': 'RANGE'}       # Sort key
    ],
    AttributeDefinitions=[
        {'AttributeName': 'Department', 'AttributeType': 'S'},
        {'AttributeName': 'Month', 'AttributeType': 'S'}
    ],
    ProvisionedThroughput={
        'ReadCapacityUnits': 5,
        'WriteCapacityUnits': 5
    }
)

DepartmentCosts.wait_until_exists()

# Set the cost threshold
# Your code here

Need a hint?

Just create a variable named cost_threshold and assign it the value 1000.

3

CORE LOGIC: Query departments exceeding the cost threshold

Write a query using the DynamoDB Table resource DepartmentCosts to find all items where the Month is '2024-05' and the Cost attribute is greater than cost_threshold. Use the variable expensive_departments to store the query result.

DynamoDB

import boto3

dynamodb = boto3.resource('dynamodb')

DepartmentCosts = dynamodb.create_table(
    TableName='DepartmentCosts',
    KeySchema=[
        {'AttributeName': 'Department', 'KeyType': 'HASH'},  # Partition key
        {'AttributeName': 'Month', 'KeyType': 'RANGE'}       # Sort key
    ],
    AttributeDefinitions=[
        {'AttributeName': 'Department', 'AttributeType': 'S'},
        {'AttributeName': 'Month', 'AttributeType': 'S'}
    ],
    ProvisionedThroughput={
        'ReadCapacityUnits': 5,
        'WriteCapacityUnits': 5
    }
)

DepartmentCosts.wait_until_exists()

cost_threshold = 1000

# Query departments with cost > cost_threshold for month '2024-05'
# Your code here

Need a hint?

Use DepartmentCosts.scan with a FilterExpression combining Key('Month').eq('2024-05') and Attr('Cost').gt(cost_threshold).

4

COMPLETION: Add a new cost entry for a department

Add a new item to the DepartmentCosts table with Department set to 'Marketing', Month set to '2024-05', and Cost set to 1200.

DynamoDB

import boto3
from boto3.dynamodb.conditions import Key, Attr

dynamodb = boto3.resource('dynamodb')

DepartmentCosts = dynamodb.create_table(
    TableName='DepartmentCosts',
    KeySchema=[
        {'AttributeName': 'Department', 'KeyType': 'HASH'},  # Partition key
        {'AttributeName': 'Month', 'KeyType': 'RANGE'}       # Sort key
    ],
    AttributeDefinitions=[
        {'AttributeName': 'Department', 'AttributeType': 'S'},
        {'AttributeName': 'Month', 'AttributeType': 'S'}
    ],
    ProvisionedThroughput={
        'ReadCapacityUnits': 5,
        'WriteCapacityUnits': 5
    }
)

DepartmentCosts.wait_until_exists()

cost_threshold = 1000

expensive_departments = DepartmentCosts.scan(
    FilterExpression=Key('Month').eq('2024-05') & Attr('Cost').gt(cost_threshold)
)

# Add a new item for Marketing department for May 2024 with cost 1200
# Your code here

Need a hint?

Use DepartmentCosts.put_item with an Item dictionary containing the required keys and values.