Stream vs polling comparison in DynamoDB - Interactive Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to enable DynamoDB Streams on a table.

DynamoDB

aws dynamodb update-table --table-name MyTable --stream-specification StreamEnabled=[1],StreamViewType=NEW_IMAGE

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Atrue

Bfalse

Cenabled

Don

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'enabled' or 'on' instead of true.

Using uppercase True which is invalid in CLI.

To enable DynamoDB Streams, you set StreamEnabled to true.

2fill in blank

medium

Complete the code to poll DynamoDB for new records using the AWS SDK.

DynamoDB

const params = { StreamArn: 'MyStreamArn', [1]: 'LATEST' };

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AShardIteratorType

BStreamArn

CStreamViewType

DStreamLabel

Attempts:

3 left

💡 Hint

Common Mistakes

Using StreamViewType which defines what data is captured.

Using StreamArn which is the stream's identifier.

ShardIteratorType set to 'LATEST' tells the poller to start from the newest records.

3fill in blank

hard

Fix the error in this polling code snippet to correctly retrieve records from DynamoDB Streams.

DynamoDB

const records = await dynamodbstreams.getRecords({ ShardIterator: [1] }).promise();

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AshardIterator

BShardIterator

Csharditerator

DSharditerator

Attempts:

3 left

💡 Hint

Common Mistakes

Using lowercase or incorrect casing causes runtime errors.

Misspelling the parameter name.

The parameter name is case-sensitive and must be 'ShardIterator'.

4fill in blank

hard

Fill both blanks to create a DynamoDB Stream event handler that processes new records.

DynamoDB

exports.handler = async (event) => {
  for (const record of event.[1]) {
    if (record.eventName === '[2]') {
      console.log('New record:', record.dynamodb.NewImage);
    }
  }
};

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ARecords

BEvents

CINSERT

DMODIFY

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'Events' instead of 'Records'.

Checking for 'MODIFY' instead of 'INSERT' when looking for new records.

The event object has a 'Records' array. 'INSERT' is the eventName for new records.

5fill in blank

hard

Fill all three blanks to create a polling loop that fetches and processes DynamoDB Stream records.

DynamoDB

let shardIterator = await dynamodbstreams.getShardIterator({
  StreamArn: streamArn,
  ShardId: shardId,
  ShardIteratorType: '[1]'
}).promise().then(data => data.[2]);

while (shardIterator) {
  const data = await dynamodbstreams.getRecords({ ShardIterator: shardIterator }).promise();
  data.[3].forEach(record => {
    console.log('Record:', record);
  });
  shardIterator = data.NextShardIterator;
  await new Promise(resolve => setTimeout(resolve, 1000));
}

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ATRIM_HORIZON

BShardIterator

CRecords

DLATEST

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'TRIM_HORIZON' instead of 'LATEST' when wanting newest records.

Accessing wrong property name for iterator or records.

Not waiting between polls causing throttling.

ShardIteratorType 'LATEST' starts from newest records. The promise returns 'ShardIterator'. The data contains 'Records' array.