Error handling and retries in DynamoDB - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to catch a DynamoDB exception.

DynamoDB

try {
  // some DynamoDB operation
} catch ([1] e) {
  console.log('Error:', e.message);
}

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

AError

BException

CDynamoDBError

DDynamoDBException

Attempts:

3 left

💡 Hint

Common Mistakes

Using a non-existent error class like DynamoDBException.

Using Exception which is not a JavaScript error type.

The standard error type to catch exceptions in JavaScript is Error. DynamoDB client errors are instances of Error.

2fill in blank

medium

Complete the code to retry a DynamoDB operation after catching a throttling error.

DynamoDB

if (error.code === [1]) {
  // retry logic here
}

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

A"InternalServerError"

B"ProvisionedThroughputExceededException"

C"ResourceNotFoundException"

D"ThrottlingException"

Attempts:

3 left

💡 Hint

Common Mistakes

Using ProvisionedThroughputExceededException which is older and less common.

Using unrelated error codes like ResourceNotFoundException.

The error code ThrottlingException indicates the request was throttled and can be retried.

3fill in blank

hard

Fix the error in the retry logic to wait before retrying.

DynamoDB

async function retryOperation() {
  try {
    await dynamoDbClient.send(command);
  } catch (error) {
    if (error.code === 'ThrottlingException') {
      await new Promise(resolve => setTimeout([1]));
      return retryOperation();
    }
    throw error;
  }
}

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

A() => resolve(), 1000

Bresolve, 1000

C() => resolve(), 1000)

Attempts:

3 left

💡 Hint

Common Mistakes

Passing resolve directly without wrapping in a function.

Missing parentheses or commas in setTimeout arguments.

The setTimeout function expects a callback and a delay in milliseconds. The correct syntax is setTimeout(() => resolve(), 1000).

4fill in blank

hard

Fill both blanks to implement exponential backoff in retry delay.

DynamoDB

async function retryWithBackoff(attempt) {
  try {
    await dynamoDbClient.send(command);
  } catch (error) {
    if (error.code === 'ThrottlingException' && attempt < 5) {
      const delay = [1] * Math.pow(2, [2]);
      await new Promise(resolve => setTimeout(() => resolve(), delay));
      return retryWithBackoff(attempt + 1);
    }
    throw error;
  }
}

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

A100

Battempt

C1000

Dattempt - 1

Attempts:

3 left

💡 Hint

Common Mistakes

Using too large base delay causing long waits.

Using attempt - 1 which delays less on retries.

Exponential backoff uses a base delay (e.g., 100 ms) multiplied by 2 to the power of the attempt number.

5fill in blank

hard

Fill all three blanks to log error details and retry with a max attempt limit.

DynamoDB

async function safeRetry(attempt) {
  try {
    await dynamoDbClient.send(command);
  } catch (error) {
    console.error('Error code:', [1]);
    console.error('Error message:', [2]);
    if (error.code === 'ThrottlingException' && [3] < 3) {
      await new Promise(resolve => setTimeout(() => resolve(), 200));
      return safeRetry(attempt + 1);
    }
    throw error;
  }
}

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

Aerror.code

Berror.message

Cattempt

Derror.statusCode

Attempts:

3 left

💡 Hint

Common Mistakes

Logging wrong error properties like statusCode.

Using a wrong variable for retry count.

Use error.code and error.message to log error details. The retry limit is controlled by the attempt variable.