Single-table design methodology in DynamoDB - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to define the primary key attribute name for a DynamoDB table.

DynamoDB

KeySchema: [{ AttributeName: '[1]', KeyType: 'HASH' }]

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

AUserId

BTimestamp

CEmail

DStatus

Attempts:

3 left

💡 Hint

Common Mistakes

Using an attribute that is not unique as the primary key.

Confusing sort key with partition key.

The primary key attribute name is usually a unique identifier like 'UserId' in single-table design.

2fill in blank

medium

Complete the code to add a sort key attribute name in the table schema.

DynamoDB

KeySchema: [ { AttributeName: 'UserId', KeyType: 'HASH' }, { AttributeName: '[1]', KeyType: 'RANGE' } ]

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

ACategory

BEmail

CStatus

DTimestamp

Attempts:

3 left

💡 Hint

Common Mistakes

Using a non-sortable attribute as the sort key.

Omitting the sort key when multiple items share the partition key.

The sort key often represents a time or sequence attribute like 'Timestamp' to order items.

3fill in blank

hard

Fix the error in the DynamoDB query to fetch items by partition key.

DynamoDB

Table.query({ KeyConditionExpression: 'UserId = :userId', ExpressionAttributeValues: { ':userId': [1] } })

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AuserId

B'12345'

C12345

D:userId

Attempts:

3 left

💡 Hint

Common Mistakes

Passing the variable name instead of its value.

Omitting quotes around string values.

The value for ExpressionAttributeValues must be a string or number wrapped correctly. Here, the user ID should be a string in quotes.

4fill in blank

hard

Fill both blanks to create a DynamoDB item with partition key and sort key attributes.

DynamoDB

Item: { 'UserId': [1], 'Timestamp': [2], 'Data': 'Sample' }

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A'user123'

B'2024-06-01T12:00:00Z'

C123456

D'dataValue'

Attempts:

3 left

💡 Hint

Common Mistakes

Using numbers instead of strings for keys.

Mixing up partition key and sort key values.

The partition key 'UserId' is a string like 'user123', and the sort key 'Timestamp' is a string timestamp in ISO format.

5fill in blank

hard

Fill all three blanks to write a DynamoDB update expression that sets a new attribute and increments a counter.

DynamoDB

UpdateExpression: 'SET [1] = :val, [2] = [3] + :inc', ExpressionAttributeValues: { ':val': 'active', ':inc': 1 }

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

AStatus

BCounter

CCount

DState

Attempts:

3 left

💡 Hint

Common Mistakes

Using different attribute names for increment operation.

Forgetting to repeat the attribute name in the increment expression.

'Status' is set to a new value, and 'Counter' is incremented by 1. The same attribute name 'Counter' is used twice in the update expression.