Transaction limits in DynamoDB - Practice Problems & Coding Challenges

Challenge - 5 Problems

🧠 Conceptual

intermediate

Maximum number of operations in a DynamoDB transaction

What is the maximum number of operations allowed in a single DynamoDB transaction?

A 10 operations

B 100 operations

C 50 operations

D 25 operations

💡 Hint

Think about the official AWS limits for transactional writes and reads.

DynamoDB transactions support up to 10 operations per transaction, including both reads and writes.

❓ query_result

intermediate

Result of exceeding transaction operation limit

What error will DynamoDB return if you try to execute a transaction with 12 operations?

A InternalServerError

B ValidationException with message 'Transaction size too large'

C TransactionCanceledException with reason 'Too many operations'

D ProvisionedThroughputExceededException

💡 Hint

Consider the error related to exceeding the allowed number of operations.

DynamoDB returns a ValidationException with message 'Transaction size too large' when the transaction exceeds the allowed number of operations.

📝 Syntax

advanced

Valid transaction request size in DynamoDB

Which of the following JSON snippets correctly respects the DynamoDB transaction limits for operations count and item size?

A { "TransactItems": [ { "Put": { "TableName": "Users", "Item": { "UserId": { "S": "123" }, "Name": { "S": "Alice" }, "Bio": { "S": "A very long string exceeding 400 KB..." } } } } ] }

B { "TransactItems": [ { "Put": { "TableName": "Users", "Item": { "UserId": { "S": "123" }, "Name": { "S": "Alice" } } } } ] }

C { "TransactItems": [ { "Put": { "TableName": "Users", "Item": { "UserId": { "S": "123" }, "Name": { "S": "Alice" } } } }, { "Put": { "TableName": "Users", "Item": { "UserId": { "S": "124" }, "Name": { "S": "Bob" } } } }, { "Put": { "TableName": "Users", "Item": { "UserId": { "S": "125" }, "Name": { "S": "Charlie" } } } }, { "Put": { "TableName": "Users", "Item": { "UserId": { "S": "126" }, "Name": { "S": "David" } } } }, { "Put": { "TableName": "Users", "Item": { "UserId": { "S": "127" }, "Name": { "S": "Eve" } } } }, { "Put": { "TableName": "Users", "Item": { "UserId": { "S": "128" }, "Name": { "S": "Frank" } } } }, { "Put": { "TableName": "Users", "Item": { "UserId": { "S": "129" }, "Name": { "S": "Grace" } } } }, { "Put": { "TableName": "Users", "Item": { "UserId": { "S": "130" }, "Name": { "S": "Hank" } } } }, { "Put": { "TableName": "Users", "Item": { "UserId": { "S": "131" }, "Name": { "S": "Ivy" } } } }, { "Put": { "TableName": "Users", "Item": { "UserId": { "S": "132" }, "Name": { "S": "Jack" } } } } ] }

D { "TransactItems": [] }

💡 Hint

Remember the max operations per transaction and item size limits.

Option C contains exactly 10 operations, each with a small item size, respecting DynamoDB transaction limits. Option C has only 1 operation (valid but less than max), C exceeds item size limit, D has zero operations which is invalid.

❓ optimization

advanced

Optimizing transaction usage under DynamoDB limits

You need to update 25 items atomically in DynamoDB. Given the transaction operation limit, what is the best approach?

A Split the updates into 3 transactions with 10, 10, and 5 operations each

B Use a single transaction with all 25 operations

C Update all items individually without transactions

D BatchWriteItem API with 25 items in one batch

💡 Hint

Consider the maximum operations per transaction and atomicity requirements.

DynamoDB transactions support up to 10 operations. To update 25 items atomically in groups, split into multiple transactions. BatchWriteItem does not guarantee atomicity.

🔧 Debug

expert

Diagnosing transaction failure due to size limits

A DynamoDB transaction with 8 operations fails with TransactionCanceledException. The items are small, but the transaction includes a condition expression on one item that is very large. What is the most likely cause?

A The provisioned throughput is exceeded

B The transaction has more than 10 operations

C The table does not exist

D The total size of all condition expressions exceeds the 4 MB transaction size limit

💡 Hint

Think about transaction size limits including condition expressions.

DynamoDB transactions have a 4 MB total size limit including items and condition expressions. Large condition expressions can cause failure even if item sizes are small.