Cost estimation for access patterns in DynamoDB - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to specify the read capacity units for a DynamoDB table.

DynamoDB

ProvisionedThroughput={"ReadCapacityUnits": [1], "WriteCapacityUnits": 5}

Drag options to blanks, or click blank then click option'

A0

B10

C-5

D"five"

Attempts:

3 left

💡 Hint

Common Mistakes

Using zero or negative numbers for capacity units.

Using strings instead of numbers.

The ReadCapacityUnits must be a positive integer representing the number of strongly consistent reads per second.

2fill in blank

medium

Complete the code to calculate the total cost for 1000 read requests with a cost of $0.00013 per read unit.

DynamoDB

total_cost = 1000 * [1]

Drag options to blanks, or click blank then click option'

A0.013

B0.0013

C0.00013

D0.000013

Attempts:

3 left

💡 Hint

Common Mistakes

Using a wrong cost value like 0.0013 instead of 0.00013.

Confusing cost per write with cost per read.

The cost per read unit is $0.00013, so multiply by the number of requests to get total cost.

3fill in blank

hard

Fix the error in the code to correctly estimate the write capacity units needed for 500 writes per second with each write consuming 2 WCUs.

DynamoDB

required_wcu = 500 [1] 2

Drag options to blanks, or click blank then click option'

A/

B-

C+

D*

Attempts:

3 left

💡 Hint

Common Mistakes

Using addition instead of multiplication.

Dividing instead of multiplying.

Each write consumes 2 WCUs, so multiply the number of writes by 2 to get total WCUs needed.

4fill in blank

hard

Fill both blanks to create a DynamoDB query that filters items with attribute 'status' equal to 'active' and limits results to 10.

DynamoDB

response = table.query(KeyConditionExpression=[1], Limit=[2])

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AKey('status').eq('active')

BKey('status').ne('active')

C5

D10

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'ne' (not equal) instead of 'eq' (equal).

Setting limit to a wrong number.

The KeyConditionExpression must check for 'status' equal to 'active'. The Limit should be set to 10 to restrict results.

5fill in blank

hard

Fill all three blanks to create a DynamoDB update expression that sets 'score' to 100 only if the current 'score' is less than 100.

DynamoDB

response = table.update_item(Key=[1], UpdateExpression=[2], ConditionExpression=[3])

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A{"id": "123"}

B"SET score = :val"

C"score < :val"

D{"user": "123"}

Attempts:

3 left

💡 Hint

Common Mistakes

Using wrong key attribute name.

Missing 'SET' in update expression.

Using wrong condition expression.

The Key must identify the item by its primary key. The UpdateExpression sets the 'score' attribute. The ConditionExpression ensures the update only happens if the current score is less than 100.