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DynamoDBquery~20 mins

Transaction error handling in DynamoDB - Practice Problems & Coding Challenges

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Challenge - 5 Problems
🎖️
Transaction Error Handling Master
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❓ query_result
intermediate
2:00remaining
What happens when a DynamoDB transaction fails due to a condition check?

Consider a DynamoDB transaction that includes a condition check on an item attribute. If the condition fails, what is the result of the transaction?

DynamoDB
TransactWriteItems with ConditionCheck failing
AThe entire transaction is rolled back and no changes are applied.
BOnly the condition check fails but other writes in the transaction succeed.
CThe transaction partially commits changes before the failure.
DThe transaction ignores the condition check and commits all writes.
Attempts:
2 left
💡 Hint

Think about atomicity in transactions.

🧠 Conceptual
intermediate
1:30remaining
Which error code indicates a transaction conflict in DynamoDB?

When two transactions try to modify the same item simultaneously, DynamoDB returns a specific error code. Which one is it?

AInternalServerError
BConditionalCheckFailedException
CProvisionedThroughputExceededException
DTransactionConflictException
Attempts:
2 left
💡 Hint

Look for the error related to transaction conflicts.

📝 Syntax
advanced
2:30remaining
Identify the syntax error in this DynamoDB transaction request snippet

Which option contains a syntax error in the TransactWriteItems request?

DynamoDB
TransactWriteItems({
  [
    {
      Put: {
        TableName: "Users",
        Item: { UserId: { S: "123" }, Name: { S: "Alice" } }
      }
    },
    {
      Update: {
        TableName: "Users",
        Key: { UserId: { S: "123" } },
        UpdateExpression: "SET Age = :age",
        ExpressionAttributeValues: { ":age": { N: "30" } }
      }
    }
  ]
})
ATransactWriteItems request is missing the required 'TransactItems' array.
BExpressionAttributeValues key ":age" is missing the colon.
CUpdateExpression uses SET but ExpressionAttributeValues is empty.
DMissing ConditionCheck in one of the TransactItems.
Attempts:
2 left
💡 Hint

Check the structure of the request object.

🔧 Debug
advanced
2:30remaining
Why does this DynamoDB transaction return a ConditionalCheckFailedException?

Given this transaction includes a ConditionCheck on an attribute that does not exist, why does it fail?

DynamoDB
TransactWriteItems({
  TransactItems: [
    {
      ConditionCheck: {
        TableName: "Orders",
        Key: { OrderId: { S: "order123" } },
        ConditionExpression: "attribute_exists(Status) AND Status = :val",
        ExpressionAttributeValues: { ":val": { S: "Pending" } }
      }
    },
    {
      Update: {
        TableName: "Orders",
        Key: { OrderId: { S: "order123" } },
        UpdateExpression: "SET Status = :newval",
        ExpressionAttributeValues: { ":newval": { S: "Processed" } }
      }
    }
  ]
})
AThe UpdateExpression syntax is invalid and causes the failure.
BThe attribute 'Status' does not exist on the item, so the condition fails.
CExpressionAttributeValues keys are duplicated causing a conflict.
DThe transaction is missing a required ReturnValuesOnConditionCheckFailure parameter.
Attempts:
2 left
💡 Hint

Check the condition expression and the item attributes.

❓ optimization
expert
3:00remaining
How to reduce transaction conflicts in high-concurrency DynamoDB applications?

You have a high-concurrency application using DynamoDB transactions that often fail with TransactionConflictException. Which approach best reduces conflicts?

AIncrease provisioned throughput to handle more transactions simultaneously.
BRemove condition checks to avoid transaction aborts.
CPartition data to minimize overlapping writes and use smaller transactions.
DUse batch writes instead of transactions to improve speed.
Attempts:
2 left
💡 Hint

Think about how to avoid multiple transactions modifying the same items.