Creating a DynamoDB table in AWS - Quick Revision & Summary

Recall & Review

beginner

What is Amazon DynamoDB?

Amazon DynamoDB is a fully managed NoSQL database service that provides fast and predictable performance with seamless scalability.

beginner

What is a primary key in a DynamoDB table?

A primary key uniquely identifies each item in a DynamoDB table. It can be a simple primary key (partition key) or a composite primary key (partition key and sort key).

intermediate

Why do you need to specify read and write capacity units when creating a DynamoDB table?

Read and write capacity units define the throughput capacity for the table, controlling how many reads and writes per second the table can handle. This helps manage performance and cost.

intermediate

What is the difference between on-demand and provisioned capacity modes in DynamoDB?

On-demand capacity automatically adjusts to your workload and charges per request, while provisioned capacity requires you to specify read/write units and is better for predictable workloads.

advanced

What is a Global Secondary Index (GSI) in DynamoDB?

A Global Secondary Index is an index with a partition key and optional sort key that can be different from the base table's primary key, allowing efficient queries on different attributes.

Which of the following is required when creating a DynamoDB table?

A Primary key definition

B VPC configuration

C Subnet group

D IAM user password

Every DynamoDB table must have a primary key defined to uniquely identify items.

What does a partition key in DynamoDB do?

A Encrypts data

B Defines table backup schedule

C Distributes data across partitions

D Limits table size

The partition key determines how data is distributed across storage partitions for scalability.

Which capacity mode charges you based on the number of reads and writes you perform?

A Burst capacity

B Provisioned capacity

C Reserved capacity

D On-demand capacity

On-demand capacity mode charges per request and automatically scales with your workload.

What is the purpose of a sort key in a DynamoDB table?

A To sort items with the same partition key

B To set read capacity

C To define table region

D To encrypt data

The sort key allows multiple items with the same partition key to be stored and sorted.

Which feature allows querying a DynamoDB table using an alternate key?

A Local Secondary Index

B Global Secondary Index

C Primary Key

D Backup and Restore

Global Secondary Indexes let you query the table using different keys than the primary key.

Explain the steps to create a DynamoDB table with a simple primary key.

Think about what you need to uniquely identify items and how you want to handle capacity.

Describe the difference between provisioned and on-demand capacity modes in DynamoDB and when to use each.

Consider workload predictability and cost management.

Practice

1. What is the main purpose of the primary key when creating a DynamoDB table?

easy

A. To define the table's read capacity

B. To store the table's name

C. To specify the AWS region

D. To uniquely identify each item in the table

Solution

1. Step 1: Understand the role of the primary key

   The primary key uniquely identifies each item in a DynamoDB table, ensuring no duplicates.

2. Step 2: Differentiate from other table properties

   Table name, capacity, and region do not serve as unique identifiers for items.

3. Final Answer:

   To uniquely identify each item in the table -> Option D

4. Quick Check:

   Primary key = unique item ID [OK]

Hint: Primary key means unique ID for each item [OK]

Common Mistakes:

• Confusing primary key with table name
• Thinking capacity defines uniqueness
• Mixing region with key attributes

2. Which AWS CLI command correctly creates a DynamoDB table named Users with a primary key UserId of type string?

easy

A. aws dynamodb create-table --table-name Users --attribute-definitions AttributeName=UserId,AttributeType=S --key-schema AttributeName=UserId,KeyType=HASH --provisioned-throughput ReadCapacityUnits=5,WriteCapacityUnits=5

B. aws dynamodb create-table --name Users --key UserId --type String

C. aws dynamodb make-table --table Users --key UserId --type S

D. aws dynamodb create-table --table Users --attribute UserId String --key UserId HASH

Solution

1. Step 1: Identify correct AWS CLI syntax for creating a table

   The correct command uses create-table with --table-name, --attribute-definitions, --key-schema, and --provisioned-throughput.

2. Step 2: Verify attribute and key schema details

   AttributeName=UserId with AttributeType=S (string) and KeyType=HASH for primary key is correct.

3. Final Answer:

   aws dynamodb create-table --table-name Users --attribute-definitions AttributeName=UserId,AttributeType=S --key-schema AttributeName=UserId,KeyType=HASH --provisioned-throughput ReadCapacityUnits=5,WriteCapacityUnits=5 -> Option A

4. Quick Check:

   Correct CLI syntax = aws dynamodb create-table --table-name Users --attribute-definitions AttributeName=UserId,AttributeType=S --key-schema AttributeName=UserId,KeyType=HASH --provisioned-throughput ReadCapacityUnits=5,WriteCapacityUnits=5 [OK]

Hint: Use --attribute-definitions and --key-schema for keys [OK]

Common Mistakes:

• Using wrong command like make-table
• Missing provisioned throughput
• Incorrect flags like --name instead of --table-name

3. Given this AWS CLI command:

aws dynamodb create-table --table-name Products --attribute-definitions AttributeName=ProductId,AttributeType=S AttributeName=Category,AttributeType=S --key-schema AttributeName=ProductId,KeyType=HASH AttributeName=Category,KeyType=RANGE --provisioned-throughput ReadCapacityUnits=10,WriteCapacityUnits=5

What is the primary key type of the Products table?

medium

A. No primary key defined

B. Simple primary key with only a HASH key

C. Composite primary key with HASH and RANGE keys

D. Primary key with only a RANGE key

Solution

1. Step 1: Analyze the key schema in the command

   The command defines two keys: ProductId as HASH and Category as RANGE.

2. Step 2: Understand primary key types in DynamoDB

   A primary key with both HASH and RANGE keys is called a composite primary key.

3. Final Answer:

   Composite primary key with HASH and RANGE keys -> Option C

4. Quick Check:

   HASH + RANGE = composite key [OK]

Hint: HASH + RANGE keys mean composite primary key [OK]

Common Mistakes:

• Thinking two attributes mean no key
• Confusing RANGE key as standalone primary key
• Ignoring key-schema details

4. You run this command to create a DynamoDB table:

aws dynamodb create-table --table-name Orders --attribute-definitions AttributeName=Id,AttributeType=N --key-schema AttributeName=OrderId,KeyType=HASH --provisioned-throughput ReadCapacityUnits=5,WriteCapacityUnits=5

But you get an error. What is the most likely cause?

medium

A. The attribute definition and key schema attribute names do not match

B. Provisioned throughput values are missing

C. The key schema is missing a RANGE key

D. AttributeType should be 'S' for string, not 'N' for number

Solution

1. Step 1: Check attribute definitions and key schema names

   The attribute definitions specify AttributeName=Id, but the key schema specifies AttributeName=OrderId. The names do not match, causing the error.

2. Step 2: Verify other potential issues

   Provisioned throughput values are present (not B), a simple primary key with only HASH is allowed (not C), AttributeType=N is valid for numeric IDs (not D).

3. Final Answer:

   The attribute definition and key schema attribute names do not match -> Option A

4. Quick Check:

   Attribute names must match exactly [OK]

Hint: Match attribute names exactly in definitions and key schema [OK]

Common Mistakes:

• Assuming 'N' type is invalid
• Expecting RANGE key for all tables
• Missing provisioned throughput

5. You want to create a DynamoDB table named Sessions with a composite primary key: UserId (string) as HASH and SessionId (string) as RANGE. You also want to set autoscaling for read and write capacity. Which of the following is the best approach?

hard

A. Create the table without specifying key schema and add keys later

B. Use aws dynamodb create-table with attribute definitions and key schema, then configure autoscaling via Application Auto Scaling service

C. Use aws dynamodb create-table with only HASH key and enable autoscaling in the same command

D. Create the table with fixed provisioned throughput and manually update capacity when needed

Solution

1. Step 1: Define table with composite primary key

   Use create-table with attribute definitions for UserId and SessionId, and key schema with HASH and RANGE keys.

2. Step 2: Configure autoscaling separately

   DynamoDB autoscaling is set up via Application Auto Scaling service after table creation; it cannot be enabled directly in create-table command.

3. Final Answer:

   Use aws dynamodb create-table with attribute definitions and key schema, then configure autoscaling via Application Auto Scaling service -> Option B

4. Quick Check:

   Composite key + separate autoscaling setup = Use aws dynamodb create-table with attribute definitions and key schema, then configure autoscaling via Application Auto Scaling service [OK]

Hint: Create table first, then set autoscaling separately [OK]

Common Mistakes:

• Trying to enable autoscaling in create-table command
• Skipping RANGE key for composite key
• Creating table without key schema