Why DynamoDB exists - Test Your Understanding

Practice - 5 Tasks

1fill in blank

easy

Complete the code to create a DynamoDB table with a primary key.

DynamoDB

aws dynamodb create-table --table-name Music --attribute-definitions AttributeName=Artist,AttributeType=S --key-schema AttributeName=[1],KeyType=HASH --provisioned-throughput ReadCapacityUnits=5,WriteCapacityUnits=5

Drag options to blanks, or click blank then click option'

AArtist

BSongTitle

CAlbum

DYear

Attempts:

3 left

💡 Hint

Common Mistakes

Using an attribute name not defined in attribute-definitions.

Confusing HASH and RANGE key types.

The primary key must match the attribute defined. Here, 'Artist' is the primary key.

2fill in blank

medium

Complete the code to put an item into the DynamoDB table.

DynamoDB

aws dynamodb put-item --table-name Music --item '{"Artist": {"S": "No One You Know"}, "SongTitle": {"S": [1]'

Drag options to blanks, or click blank then click option'

A"Hello World"

B"Call Me Today"

C"Goodbye"

D"New Song"

Attempts:

3 left

💡 Hint

Common Mistakes

Forgetting quotes around the string value.

Using a wrong attribute name.

The SongTitle value must be a string in quotes. "Call Me Today" is the example song title.

3fill in blank

hard

Fix the error in the query to get an item by primary key.

DynamoDB

aws dynamodb get-item --table-name Music --key '{"Artist": {"S": [1]'

Drag options to blanks, or click blank then click option'

ANo One You Know

BNoOneYouKnow

C"No One You Know"

D'No One You Know'

Attempts:

3 left

💡 Hint

Common Mistakes

Using single quotes instead of double quotes.

Not quoting the string value at all.

The string value must be enclosed in double quotes inside the JSON string.

4fill in blank

hard

Fill both blanks to create a DynamoDB table with a composite primary key.

DynamoDB

aws dynamodb create-table --table-name Music --attribute-definitions AttributeName=[1],AttributeType=S AttributeName=[2],AttributeType=S --key-schema AttributeName=Artist,KeyType=HASH AttributeName=SongTitle,KeyType=RANGE --provisioned-throughput ReadCapacityUnits=5,WriteCapacityUnits=5

Drag options to blanks, or click blank then click option'

AArtist

BYear

CSongTitle

DAlbum

Attempts:

3 left

💡 Hint

Common Mistakes

Defining attributes not used in key-schema.

Mixing up HASH and RANGE key attribute names.

The composite key uses 'Artist' as HASH and 'SongTitle' as RANGE key, so both must be defined as attributes.

5fill in blank

hard

Fill all three blanks to write a query that scans the table for items where Year is greater than 2010.

DynamoDB

aws dynamodb scan --table-name Music --filter-expression "[1] [2] :yearVal" --expression-attribute-names '{"#yr": "[3]"}' --expression-attribute-values '{":yearVal": {"N": "2010"}}'

Drag options to blanks, or click blank then click option'

AYear

B>

C#yr

DArtist

Attempts:

3 left

💡 Hint

Common Mistakes

Using attribute name directly without placeholder in filter expression.

Using wrong comparison operator.

Mismatching placeholder names.

The filter expression uses the placeholder '#yr' for the attribute name 'Year' and the operator '>' to compare with 2010.

Practice

1. Why was DynamoDB created by Amazon?
DynamoDB is designed to:

easy

A. Require manual scaling and hardware setup

B. Replace all traditional relational databases immediately

C. Provide fast and reliable data storage without managing servers

D. Only store data temporarily for caching purposes

Solution

1. Step 1: Understand DynamoDB's purpose

   DynamoDB was built to offer a fast, reliable database service that does not require users to manage servers or infrastructure.

2. Step 2: Compare options with DynamoDB features

   Options A, B, and C contradict DynamoDB's key features like automatic scaling and persistent storage.

3. Final Answer:

   Provide fast and reliable data storage without managing servers -> Option C

4. Quick Check:

   DynamoDB = fast, reliable, serverless storage [OK]

Hint: Remember: DynamoDB is serverless and scales automatically [OK]

Common Mistakes:

• Thinking DynamoDB replaces all databases immediately
• Assuming DynamoDB only caches data temporarily
• Believing manual server management is needed

2. Which of the following is the correct way to describe DynamoDB's scaling feature?

easy

A. DynamoDB automatically adjusts capacity based on traffic

B. DynamoDB requires manual intervention to add more capacity

C. DynamoDB cannot scale beyond 1 million items

D. DynamoDB scales only when you restart the service

Solution

1. Step 1: Recall DynamoDB's scaling capability

   DynamoDB is designed to automatically scale up or down depending on the workload without user action.

2. Step 2: Eliminate incorrect options

   Options B, C, and D contradict this automatic scaling feature.

3. Final Answer:

   DynamoDB automatically adjusts capacity based on traffic -> Option A

4. Quick Check:

   Scaling = automatic adjustment [OK]

Hint: DynamoDB scales automatically with traffic changes [OK]

Common Mistakes:

• Thinking manual scaling is needed
• Believing there is a fixed item limit
• Assuming restart is required to scale

3. Consider this DynamoDB feature description:

"DynamoDB automatically handles hardware provisioning, setup, and configuration."

What is the main benefit of this feature?

medium

A. Users must manually configure servers

B. Users can focus on application logic, not infrastructure

C. Users need to monitor hardware health constantly

D. Users must install database software themselves

Solution

1. Step 1: Understand automatic management in DynamoDB

   DynamoDB removes the need for users to manage hardware or software setup.

2. Step 2: Identify the benefit

   This allows users to focus on building their applications instead of managing infrastructure.

3. Final Answer:

   Users can focus on application logic, not infrastructure -> Option B

4. Quick Check:

   Automatic management = focus on app logic [OK]

Hint: Automatic setup means less infrastructure work for users [OK]

Common Mistakes:

• Assuming users still configure servers
• Thinking users must monitor hardware
• Believing manual software installation is needed

4. You wrote: "DynamoDB requires you to manually add servers to handle more data."
What is wrong with this statement?

medium

A. DynamoDB does not store data persistently

B. DynamoDB requires manual software installation

C. DynamoDB only works with SQL queries

D. DynamoDB automatically scales without manual server addition

Solution

1. Step 1: Identify the incorrect claim

   The statement says manual server addition is needed, which contradicts DynamoDB's automatic scaling.

2. Step 2: Confirm DynamoDB's actual behavior

   DynamoDB manages servers and capacity automatically, so users do not add servers manually.

3. Final Answer:

   DynamoDB automatically scales without manual server addition -> Option D

4. Quick Check:

   Manual server addition = false for DynamoDB [OK]

Hint: DynamoDB auto-scales; no manual server adding needed [OK]

Common Mistakes:

• Believing manual server management is required
• Confusing DynamoDB with traditional databases
• Assuming DynamoDB needs software installation

5. A company expects its data to grow rapidly and unpredictably. Why should they choose DynamoDB over a traditional database?

hard

A. Because DynamoDB automatically scales and requires no server management

B. Because DynamoDB only supports small datasets efficiently

C. Because DynamoDB needs manual capacity planning for growth

D. Because DynamoDB requires frequent software updates by users

Solution

1. Step 1: Analyze the company's needs

   The company needs a database that can handle rapid and unpredictable growth easily.

2. Step 2: Match DynamoDB features to needs

   DynamoDB automatically scales and removes server management, fitting the company's requirements perfectly.

3. Step 3: Eliminate wrong options

   Options B, C, and D contradict DynamoDB's automatic scaling and serverless nature.

4. Final Answer:

   Because DynamoDB automatically scales and requires no server management -> Option A

5. Quick Check:

   Rapid growth needs auto-scaling = DynamoDB [OK]

Hint: Auto-scaling and no server management fit rapid growth [OK]

Common Mistakes:

• Thinking DynamoDB only works for small data
• Assuming manual capacity planning is needed
• Believing users must update software often