AWS module 8.2 Amazon DynamoDB

Question 1

Q1

A company uses a relational database but struggles to handle rapidly changing data structures. Why is this happening and what type of database should they switch to?

Q2

A system requires flexible data where items can have different attributes in the same table. Why would a relational database fail here?

Q3

A database needs to handle massive scale with low latency globally. Why is DynamoDB more suitable than a relational database?

Answer 1

A1

Because relational databases require a fixed schema, making changes difficult. They should switch to a NoSQL database.

A2

Because relational databases enforce fixed schemas, meaning all rows must follow the same structure.

A3

Because DynamoDB supports horizontal scaling, low latency, and flexible schema, making it ideal for large-scale applications.

Question 2

Q4

A relational database scales vertically but still cannot handle increasing traffic. Why is this a limitation?

Q5

A NoSQL database scales horizontally. What does this mean and why is it beneficial?

Q6

Why are NoSQL databases better suited for semi-structured or unstructured data?

Answer 2

A4

Vertical scaling has limits (hardware constraints), making it unsuitable for very large workloads.

A5

It means adding more machines instead of upgrading one — improving scalability and performance.

A6

Because they do not require fixed schemas and can store flexible data formats like JSON.

Question 3

Q7

A developer needs to query data across multiple tables with relationships. Which database type should be used and why?

Q8

Why are joins difficult or inefficient in NoSQL databases?

Q9

A system requires strong relationships between datasets. Why is NoSQL not ideal here?

Answer 3

A7

Relational database — because it supports joins and structured relationships.

A8

Because NoSQL databases are not designed for relational queries and often store data in separate structures.

A9

Because NoSQL prioritises scalability and flexibility over structured relationships.

Question 4

Q10

What is DynamoDB and what type of database is it?

Q11

Why is DynamoDB considered serverless?

Q12

What is the main performance advantage of DynamoDB?

Answer 4

A10

A fully managed NoSQL database service.

A11

Because AWS manages infrastructure, scaling, and maintenance automatically.

A12

Low-latency, single-digit millisecond response times.

Question 5

Q13

What are the core components of DynamoDB?

Q14

What is an item in DynamoDB?

Q15

What is an attribute in DynamoDB?

Answer 5

A13

Tables, items, attributes

A14

A collection of attributes representing a record

A15

A key-value pair representing data

Question 6

Q16

Why must every DynamoDB item have a primary key?

Q17

What happens if two items have the same primary key?

Q18

What are the two types of primary keys in DynamoDB?

Answer 6

A16

To uniquely identify each item

A17

It is not allowed — primary keys must be unique

A18

• Partition key
• Composite key (partition + sort key)

Question 7

Q19

What is a partition key and how does it affect data distribution?

Q20

What is a sort key and when is it useful?

Q21

Why is choosing a good partition key critical in DynamoDB?

Answer 7

A19

It determines how data is distributed across storage — affects performance

A20

Used to sort and organise data within a partition

A21

Poor partition keys cause uneven data distribution and performance issues

Question 8

Q22

A DynamoDB table experiences uneven performance across partitions. What is the likely cause?

Q23

Why is DynamoDB better suited for applications with unpredictable workloads?

Q24

What is provisioned throughput in DynamoDB?

Answer 8

A22

Poor partition key design

A23

Because it supports automatic scaling and flexible throughput

A24

The amount of read/write capacity allocated

Question 9

Q25

What happens if you exceed provisioned throughput in DynamoDB?

Q26

How does auto scaling help DynamoDB performance?

Q27

Why is manual throughput configuration risky?

Answer 9

A25

Requests may be throttled

A26

It adjusts capacity automatically based on demand

A27

Because incorrect settings lead to throttling or wasted cost

Question 10

Q28

What is Time To Live (TTL) in DynamoDB?

Q29

Why is TTL useful for cost optimisation?

Q30

What happens when TTL expires on an item?

Answer 10

A28

A setting to automatically delete items after a set time

A29

It removes unused data, reducing storage cost

A30

The item is automatically deleted

Question 11

Q31

Why does DynamoDB not require schema migrations like relational databases?

Q32

What advantage does this give developers?

Q33

Why is schema flexibility important in modern applications?

Answer 11

A31

Because items can have different attributes

A32

Faster development and easier updates

A33

Because data structures change frequently