Scan vs query performance in AWS - Interactive Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to perform a fast data retrieval using a DynamoDB operation.

AWS

response = table.[1](KeyConditionExpression=key_expression)

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

Ascan

Bquery

Cget_item

Dput_item

Attempts:

3 left

💡 Hint

Common Mistakes

Using scan instead of query causes slower performance.

The query operation retrieves items efficiently by using the primary key, making it faster than scan.

2fill in blank

medium

Complete the code to retrieve all items from a DynamoDB table, which is slower but scans everything.

AWS

response = table.[1]()

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

Ascan

Bget_item

Cquery

Dupdate_item

Attempts:

3 left

💡 Hint

Common Mistakes

Using query when you want all items will not work without key conditions.

The scan operation reads every item in the table, which can be slow for large tables.

3fill in blank

hard

Fix the error in the code to improve performance by using the correct DynamoDB operation.

AWS

items = table.[1](KeyConditionExpression=key_expression)

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

Adelete_item

Bscan

Cquery

Dput_item

Attempts:

3 left

💡 Hint

Common Mistakes

Using scan with FilterExpression is slower than query with KeyConditionExpression.

Using query with a key condition is faster than scan with filter expressions.

4fill in blank

hard

Fill both blanks to create a dictionary comprehension that filters items with a condition and calculates a value.

AWS

result = {item['id']: item['value'] [1] 2 for item in items if item['value'] [2] 10}

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

A**

B>

C<

D+

Attempts:

3 left

💡 Hint

Common Mistakes

Using '+' instead of '**' changes the calculation.

The ** operator squares the value, and > filters values greater than 10.

5fill in blank

hard

Fill all three blanks to build a dictionary comprehension that transforms keys, selects values, and filters items.

AWS

filtered = [1]: [2] for [3], v in data.items() if v > 0}

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

Ak.upper()

Bv

Ck

Dv.lower()

Attempts:

3 left

💡 Hint

Common Mistakes

Using v.lower() for keys or wrong variable names causes errors.

Keys are converted to uppercase with k.upper(), values are kept as v, and iteration uses k.