Cost estimation for access patterns in DynamoDB - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is a key factor in estimating DynamoDB costs for access patterns?

The number of read and write capacity units consumed by your queries and operations is the key factor in estimating costs.

beginner

How does the size of an item affect DynamoDB cost estimation?

Larger items consume more capacity units because DynamoDB charges based on the size of data read or written, not just the number of items.

intermediate

What is the difference between strongly consistent and eventually consistent reads in cost?

Strongly consistent reads consume twice the read capacity units compared to eventually consistent reads for the same data size.

beginner

Why is it important to design efficient access patterns in DynamoDB?

Efficient access patterns reduce the number of capacity units consumed, lowering costs and improving performance.

intermediate

How do partition keys influence cost estimation in DynamoDB?

Good partition key design distributes workload evenly across partitions, preventing hot partitions that can increase costs and reduce performance.

Which factor directly affects the number of capacity units consumed in DynamoDB?

A Number of indexes defined

B Number of attributes in the table

C Number of tables in the database

D Size of the data item

DynamoDB charges capacity units based on the size of the data read or written, so item size directly affects cost.

How do strongly consistent reads affect read capacity units compared to eventually consistent reads?

A They consume the same read capacity units

B They consume twice the read capacity units

C They consume half the read capacity units

D They consume no read capacity units

Strongly consistent reads consume twice the read capacity units of eventually consistent reads for the same data size.

What happens if your partition key design causes hot partitions?

A Costs increase and performance may degrade

B No effect on cost or performance

C Costs decrease due to less data access

D DynamoDB automatically fixes hot partitions

Hot partitions cause uneven workload distribution, increasing costs and reducing performance.

Which access pattern helps reduce DynamoDB costs?

A Reading large amounts of unnecessary data

B Using inefficient queries that scan the whole table

C Designing queries to fetch only needed data

D Writing duplicate data multiple times

Fetching only needed data reduces capacity units consumed, lowering costs.

DynamoDB charges for write capacity units based on:

A Size of data written per request

B Number of indexes on the table

C Number of tables in the account

D Number of write requests only

Write capacity units depend on the size of data written, not just the number of requests.

Explain how read and write capacity units affect DynamoDB cost estimation for different access patterns.

Think about how much data you read or write and how often.

Describe why good partition key design is important for cost and performance in DynamoDB.

Imagine a busy road with traffic evenly spread versus all cars on one lane.