Burst capacity in DynamoDB - Practice Problems & Coding Challenges

Challenge - 5 Problems

🧠 Conceptual

intermediate

Understanding Burst Capacity in DynamoDB

What does burst capacity in DynamoDB allow your table to do?

A Temporarily exceed the provisioned throughput limits to handle sudden traffic spikes.

B Encrypt data at rest without affecting performance.

C Store data in multiple regions simultaneously for faster access.

D Automatically increase the table size beyond the maximum limit.

💡 Hint

Think about how DynamoDB handles sudden increases in read/write requests.

Burst capacity lets DynamoDB tables temporarily use unused capacity from previous periods to handle sudden spikes in traffic without throttling.

❓ query_result

intermediate

Effect of Burst Capacity on Throttling

Given a DynamoDB table with provisioned write capacity of 100 units, which scenario best describes when burst capacity will prevent throttling?

A The table has unused write capacity credits from previous minutes and suddenly receives 150 write requests in one second.

B The table receives 200 write requests per second consistently for several hours.

C The table receives 50 write requests per second, well below provisioned capacity.

D The table is idle for a day and then receives 1000 write requests in one second.

💡 Hint

Consider how burst capacity uses unused credits accumulated over time.

Burst capacity allows temporary exceeding of provisioned throughput using credits from unused capacity. Scenario C fits this because the spike is short and credits exist.

📝 Syntax

advanced

Identifying Incorrect Burst Capacity Usage Explanation

Which of the following statements about DynamoDB burst capacity is incorrect?

A Burst capacity credits accumulate when the table uses less than its provisioned throughput.

B Burst capacity is only available for tables with provisioned throughput mode.

C Burst capacity helps reduce throttling during sudden traffic spikes.

D Burst capacity can be used indefinitely to handle high traffic without any limits.

💡 Hint

Think about whether burst capacity has limits or can be used forever.

Burst capacity is limited by the amount of unused capacity credits accumulated; it cannot be used indefinitely.

❓ optimization

advanced

Optimizing Table Performance Using Burst Capacity

You have a DynamoDB table with variable traffic: low most of the day but occasional high spikes. Which strategy best uses burst capacity to optimize costs and performance?

A Use on-demand capacity mode to automatically handle spikes without provisioning.

B Provision throughput lower than peak traffic and rely on burst capacity for spikes.

C Provision throughput to match the highest expected traffic spike to avoid throttling.

D Disable burst capacity to prevent unpredictable performance.

💡 Hint

Consider cost savings and how burst capacity helps with spikes.

Provisioning lower throughput and relying on burst capacity for short spikes saves cost while handling traffic bursts effectively.

🔧 Debug

expert

Diagnosing Unexpected Throttling Despite Burst Capacity

A DynamoDB table with provisioned read capacity of 200 units is experiencing throttling during a sudden spike of 300 read requests per second. The table was idle before the spike. What is the most likely reason burst capacity did not prevent throttling?

A Burst capacity only applies to write operations, not read operations.

B The spike was too small to trigger burst capacity usage.

C The table had no accumulated burst capacity credits because it was idle before the spike.

D The table was using on-demand mode, so burst capacity is irrelevant.

💡 Hint

Think about how burst capacity credits accumulate and when they are available.

Burst capacity credits accumulate when the table uses less than provisioned throughput. If the table was idle, no credits were available to handle the spike.

Practice

1. What is the main purpose of burst capacity in DynamoDB?

easy

A. To backup data automatically

B. To permanently increase table throughput

C. To handle sudden spikes in traffic smoothly

D. To reduce storage costs

Solution

1. Step 1: Understand burst capacity concept

   Burst capacity allows DynamoDB to use unused capacity from earlier low traffic periods.

2. Step 2: Identify its main use

   This helps handle sudden traffic spikes smoothly without extra setup.

3. Final Answer:

   To handle sudden spikes in traffic smoothly -> Option C

4. Quick Check:

   Burst capacity = handle spikes [OK]

Hint: Burst capacity smooths sudden traffic spikes [OK]

Common Mistakes:

• Thinking burst capacity permanently increases throughput
• Confusing burst capacity with backup or storage features
• Assuming manual code is needed to use burst capacity

2. Which of the following statements about DynamoDB burst capacity is syntactically correct?

easy

A. BurstCapacity: enabled

B. ProvisionedThroughput: { ReadCapacityUnits: 5, WriteCapacityUnits: 5 }

C. EnableBurstCapacity = true

D. SetBurstCapacity(5)

Solution

1. Step 1: Check valid DynamoDB syntax

   ProvisionedThroughput with ReadCapacityUnits and WriteCapacityUnits is valid for table setup.

2. Step 2: Identify invalid options

   Options B, C, and D are not valid DynamoDB syntax or parameters.

3. Final Answer:

   <code>ProvisionedThroughput: { ReadCapacityUnits: 5, WriteCapacityUnits: 5 }</code> -> Option B

4. Quick Check:

   Valid syntax = ProvisionedThroughput: { ReadCapacityUnits: 5, WriteCapacityUnits: 5 } [OK]

Hint: Only ProvisionedThroughput syntax is valid here [OK]

Common Mistakes:

• Assuming burst capacity needs explicit enabling syntax
• Using incorrect parameter names
• Confusing configuration with method calls

3. Consider a DynamoDB table with provisioned read capacity of 10 units. The table has been idle for a while, accumulating unused capacity. Suddenly, a spike causes 15 read requests per second. What will happen?

medium

A. The table will reject all requests during the spike

B. The table will throttle all requests above 10 units immediately

C. The table will automatically increase provisioned capacity to 15 units

D. The table will use burst capacity to handle some requests above 10 units

Solution

1. Step 1: Understand idle capacity accumulation

   Unused capacity from idle periods accumulates as burst capacity credits.

2. Step 2: Apply burst capacity during spike

   When requests exceed provisioned units, DynamoDB uses burst capacity to handle some extra requests smoothly.

3. Final Answer:

   The table will use burst capacity to handle some requests above 10 units -> Option D

4. Quick Check:

   Burst capacity handles spikes above provisioned [OK]

Hint: Burst capacity covers temporary spikes above provisioned [OK]

Common Mistakes:

• Thinking DynamoDB instantly throttles above provisioned units
• Assuming automatic permanent capacity increase
• Believing all requests are rejected during spikes

4. You notice your DynamoDB table is throttling requests during a traffic spike, even though it was idle before. What is the most likely cause?

medium

A. Burst capacity credits were already used up before the spike

B. Provisioned throughput is set too high

C. Burst capacity must be manually enabled

D. The table is in on-demand mode

Solution

1. Step 1: Analyze burst capacity usage

   Burst capacity depends on unused capacity credits accumulated during idle times.

2. Step 2: Reason about throttling cause

   If credits are used up, the table cannot handle spikes beyond provisioned throughput, causing throttling.

3. Final Answer:

   Burst capacity credits were already used up before the spike -> Option A

4. Quick Check:

   Throttling = no burst credits left [OK]

Hint: No burst credits means throttling during spikes [OK]

Common Mistakes:

• Thinking burst capacity needs manual enabling
• Assuming high provisioned throughput causes throttling
• Confusing on-demand mode with provisioned burst capacity

5. A DynamoDB table has a provisioned write capacity of 20 units. It was idle for 10 minutes, then suddenly receives 50 write requests per second for 1 minute. How does burst capacity affect this scenario?

hard

A. Burst capacity allows some requests above 20 units to succeed temporarily

B. Burst capacity automatically increases provisioned capacity to 50 units

C. Burst capacity allows all 50 requests to succeed without throttling

D. Burst capacity does not apply to write requests

Solution

1. Step 1: Understand burst capacity accumulation

   Idle time accumulates unused write capacity credits that can be used in bursts.

2. Step 2: Apply burst capacity during spike

   During the spike, burst capacity allows handling some requests above provisioned 20 units temporarily, but not all 50.

3. Final Answer:

   Burst capacity allows some requests above 20 units to succeed temporarily -> Option A

4. Quick Check:

   Burst capacity = temporary extra writes above provisioned [OK]

Hint: Burst capacity helps some writes above provisioned temporarily [OK]

Common Mistakes:

• Assuming burst capacity handles all spike requests fully
• Thinking burst capacity increases provisioned throughput permanently
• Believing burst capacity applies only to reads