Local Secondary Index (LSI) concept in DynamoDB - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to define a Local Secondary Index (LSI) with a sort key.

DynamoDB

LocalSecondaryIndexes: [{
  IndexName: 'LSI1',
  KeySchema: [
    { AttributeName: 'UserId', KeyType: 'HASH' },
    { AttributeName: [1], KeyType: 'RANGE' }
  ],
  Projection: { ProjectionType: 'ALL' }
}]

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AEmail

BUserId

CTimestamp

DStatus

Attempts:

3 left

💡 Hint

Common Mistakes

Using the same attribute 'UserId' for both partition and sort key.

Choosing an attribute not defined in the table schema.

The sort key for an LSI must be different from the partition key. 'Timestamp' is commonly used as a sort key.

2fill in blank

medium

Complete the query to use the LSI by specifying the index name.

DynamoDB

const params = {
  TableName: 'Orders',
  IndexName: [1],
  KeyConditionExpression: 'UserId = :uid and Timestamp > :ts',
  ExpressionAttributeValues: {
    ':uid': 'user123',
    ':ts': 1609459200
  }
};

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ADefaultIndex

BLSI1

CGSI1

DPrimaryIndex

Attempts:

3 left

💡 Hint

Common Mistakes

Using the primary index name or a Global Secondary Index name instead of the LSI name.

Omitting the 'IndexName' parameter.

To query using a Local Secondary Index, you specify its name in the 'IndexName' parameter. Here, 'LSI1' is the correct index name.

3fill in blank

hard

Fix the error in the LSI definition by choosing the correct attribute type for the sort key.

DynamoDB

AttributeDefinitions: [
  { AttributeName: 'UserId', AttributeType: 'S' },
  { AttributeName: 'Timestamp', AttributeType: [1] }
],

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AN

BB

CS

DBOOL

Attempts:

3 left

💡 Hint

Common Mistakes

Setting 'Timestamp' as a string when it is stored as a number.

Using unsupported attribute types like 'BOOL' for keys.

The 'Timestamp' attribute is usually a number, so its type should be 'N' (Number) in DynamoDB.

4fill in blank

hard

Fill both blanks to complete the LSI query with correct KeyConditionExpression and attribute values.

DynamoDB

const params = {
  TableName: 'Orders',
  IndexName: 'LSI1',
  KeyConditionExpression: 'UserId = :uid and [1] > :ts',
  ExpressionAttributeValues: {
    ':uid': 'user123',
    [2]: 1609459200
  }
};

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ATimestamp

B:ts

C:timestamp

D:time

Attempts:

3 left

💡 Hint

Common Mistakes

Using different placeholder names in the expression and values.

Using attribute names instead of placeholders in ExpressionAttributeValues.

The sort key attribute is 'Timestamp' and the placeholder in ExpressionAttributeValues must match ':ts' used in the KeyConditionExpression.

5fill in blank

hard

Fill all three blanks to define an LSI with correct attribute definitions, key schema, and projection type.

DynamoDB

AttributeDefinitions: [
  { AttributeName: 'UserId', AttributeType: 'S' },
  { AttributeName: [1], AttributeType: 'N' }
],
LocalSecondaryIndexes: [{
  IndexName: 'LSI1',
  KeySchema: [
    { AttributeName: 'UserId', KeyType: 'HASH' },
    { AttributeName: [2], KeyType: 'RANGE' }
  ],
  Projection: { ProjectionType: [3] }
}]

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ATimestamp

CALL

DUserId

Attempts:

3 left

💡 Hint

Common Mistakes

Mismatch between attribute definitions and key schema attribute names.

Using incorrect projection types.

The LSI uses 'Timestamp' as the sort key attribute with type 'N'. The projection type 'ALL' means all attributes are projected.