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DynamoDBquery~30 mins

Creating GSI in DynamoDB - Try It Yourself

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Creating a Global Secondary Index (GSI) in DynamoDB
📖 Scenario: You are managing a DynamoDB table for an online bookstore. The table stores information about books, including their BookID, Title, Author, and Genre. You want to create a Global Secondary Index (GSI) to efficiently query books by their Author.
🎯 Goal: Build a DynamoDB table schema with a Global Secondary Index (GSI) named AuthorIndex that uses Author as the partition key. This will allow quick lookups of books by author.
📋 What You'll Learn
Create a DynamoDB table named Books with BookID as the primary partition key.
Add a Global Secondary Index (GSI) named AuthorIndex with Author as the partition key.
Set the projection type of the GSI to ALL to include all attributes.
Specify the provisioned throughput for both the table and the GSI.
💡 Why This Matters
🌍 Real World
Global Secondary Indexes let you query DynamoDB tables efficiently using different keys than the primary key. This is common in real-world apps needing flexible search options.
💼 Career
Understanding how to create and configure GSIs is essential for backend developers and database administrators working with DynamoDB to optimize data access patterns.
Progress0 / 4 steps
1
Create the DynamoDB table schema
Create a DynamoDB table schema named Books with BookID as the primary partition key of type S (string). Define the attribute definitions for BookID, Title, Author, and Genre all as type S.
DynamoDB
Hint

Define the table name, attribute definitions for all attributes as strings, and set BookID as the partition key in the key schema.

2
Add Global Secondary Index (GSI) configuration
Add a GlobalSecondaryIndexes section to the table schema. Create a GSI named AuthorIndex with Author as the partition key (HASH). Set the projection type to ALL and provisioned throughput to 5 read and 5 write capacity units.
DynamoDB
Hint

Inside GlobalSecondaryIndexes, define the index name, key schema with Author as partition key, projection type as ALL, and provisioned throughput.

3
Verify attribute definitions include GSI key
Ensure the AttributeDefinitions section includes the Author attribute with type S because it is used as the partition key in the GSI.
DynamoDB
Hint

Make sure Author is listed in AttributeDefinitions with type S because it is the GSI partition key.

4
Complete the table creation JSON with all parts
Combine all parts to form the complete DynamoDB table creation JSON. It should include TableName, AttributeDefinitions, KeySchema, ProvisionedThroughput, and GlobalSecondaryIndexes with the AuthorIndex GSI.
DynamoDB
Hint

Make sure all parts are included together in one JSON object to create the table with the GSI.

Practice

(1/5)
1. What is the main purpose of creating a Global Secondary Index (GSI) in DynamoDB?
easy
A. To automatically backup the table data
B. To increase the storage capacity of the table
C. To allow querying the table using alternative key attributes
D. To encrypt the table data at rest

Solution

  1. Step 1: Understand what a GSI does

    A GSI lets you query a DynamoDB table using different key attributes than the primary key.

  2. Step 2: Compare options to GSI purpose

    Options A, B, and D describe backup, storage, and encryption, which are unrelated to GSI functionality.

  3. Final Answer:

    To allow querying the table using alternative key attributes -> Option C

  4. Quick Check:

    GSI = alternative query keys [OK]
Hint: GSIs let you query by new keys without changing the table [OK]
Common Mistakes:
  • Thinking GSI increases storage size
  • Confusing GSI with backup or encryption features
  • Assuming GSI changes the primary key
2. Which of the following is the correct syntax snippet to define a GSI named OrderDateIndex with OrderDate as the partition key in a DynamoDB table creation JSON?
easy
A. "GlobalSecondaryIndexes": [{"IndexName": "OrderDateIndex", "KeySchema": [{"AttributeName": "OrderDate", "KeyType": "HASH"}], "Projection": {"ProjectionType": "ALL"}}]
B. "GlobalSecondaryIndexes": [{"IndexName": "OrderDateIndex", "KeySchema": [{"AttributeName": "OrderDate", "KeyType": "RANGE"}], "Projection": {"ProjectionType": "ALL"}}]
C. "GlobalSecondaryIndexes": [{"IndexName": "OrderDateIndex", "KeySchema": [{"AttributeName": "OrderDate", "KeyType": "PRIMARY"}], "Projection": {"ProjectionType": "ALL"}}]
D. "GlobalSecondaryIndexes": [{"IndexName": "OrderDateIndex", "KeySchema": [{"AttributeName": "OrderDate", "KeyType": "PARTITION"}], "Projection": {"ProjectionType": "ALL"}}]

Solution

  1. Step 1: Identify correct KeyType for partition key in GSI

    The partition key in DynamoDB GSI uses KeyType "HASH".

  2. Step 2: Check options for correct KeyType and syntax

    "GlobalSecondaryIndexes": [{"IndexName": "OrderDateIndex", "KeySchema": [{"AttributeName": "OrderDate", "KeyType": "HASH"}], "Projection": {"ProjectionType": "ALL"}}] uses "HASH" correctly; B uses "RANGE" (wrong for partition key), C uses invalid "PRIMARY", D uses invalid "PARTITION".

  3. Final Answer:

    "GlobalSecondaryIndexes": [{"IndexName": "OrderDateIndex", "KeySchema": [{"AttributeName": "OrderDate", "KeyType": "HASH"}], "Projection": {"ProjectionType": "ALL"}}] -> Option A

  4. Quick Check:

    Partition key = HASH [OK]
Hint: Partition key in GSI always uses KeyType 'HASH' [OK]
Common Mistakes:
  • Using 'RANGE' instead of 'HASH' for partition key
  • Using invalid KeyType values like 'PRIMARY' or 'PARTITION'
  • Forgetting to define ProjectionType
3. Given a DynamoDB table with a GSI named UserEmailIndex where Email is the partition key, what will be the result of this query?
QueryInput = {
  TableName: "Users",
  IndexName: "UserEmailIndex",
  KeyConditionExpression: "Email = :email",
  ExpressionAttributeValues: {":email": "alice@example.com"}
}
medium
A. Returns all items where Email attribute equals 'alice@example.com' using the GSI
B. Returns all items where Email attribute equals 'alice@example.com' using the main table primary key
C. Returns an error because IndexName cannot be used in QueryInput
D. Returns all items regardless of Email attribute

Solution

  1. Step 1: Understand QueryInput with IndexName

    Specifying IndexName in QueryInput tells DynamoDB to query the GSI instead of the main table.

  2. Step 2: Analyze KeyConditionExpression

    The query filters items where Email equals 'alice@example.com' on the GSI partition key.

  3. Final Answer:

    Returns all items where Email attribute equals 'alice@example.com' using the GSI -> Option A

  4. Quick Check:

    Query with IndexName uses GSI keys [OK]
Hint: Use IndexName in query to search by GSI keys [OK]
Common Mistakes:
  • Assuming query uses main table keys when IndexName is set
  • Thinking IndexName causes error in QueryInput
  • Ignoring KeyConditionExpression filtering
4. You tried to create a GSI with this snippet but got an error:
"GlobalSecondaryIndexes": [{
  "IndexName": "StatusIndex",
  "KeySchema": [{"AttributeName": "Status", "KeyType": "HASH"}],
  "Projection": {"ProjectionType": "INCLUDE", "NonKeyAttributes": []}
}]

What is the likely cause of the error?
medium
A. IndexName cannot contain the word 'Index'
B. NonKeyAttributes must be a non-empty array when ProjectionType is INCLUDE
C. KeyType must be RANGE for GSIs
D. ProjectionType cannot be INCLUDE for GSIs

Solution

  1. Step 1: Check ProjectionType and NonKeyAttributes

    When ProjectionType is INCLUDE, NonKeyAttributes must be a non-empty array listing attributes to project.

  2. Step 2: Verify given snippet

    NonKeyAttributes is [], which is empty and invalid when ProjectionType is INCLUDE.

  3. Step 3: Eliminate other options

    ProjectionType INCLUDE is valid; KeyType HASH is valid for partition key; IndexName can contain 'Index'.

  4. Final Answer:

    NonKeyAttributes must be a non-empty array when ProjectionType is INCLUDE -> Option B

  5. Quick Check:

    INCLUDE projection requires NonKeyAttributes [OK]
Hint: INCLUDE projection needs NonKeyAttributes array [OK]
Common Mistakes:
  • Using empty or missing NonKeyAttributes with INCLUDE
  • Confusing KeyType HASH and RANGE for partition key
  • Thinking IndexName naming causes errors
5. You have a DynamoDB table with primary key UserID. You want to query users by their City and SignupDate. Which GSI definition allows efficient queries for all users in a city sorted by signup date?
hard
A. "GlobalSecondaryIndexes": [{"IndexName": "CitySignupIndex", "KeySchema": [{"AttributeName": "SignupDate", "KeyType": "RANGE"}], "Projection": {"ProjectionType": "ALL"}}]
B. "GlobalSecondaryIndexes": [{"IndexName": "CitySignupIndex", "KeySchema": [{"AttributeName": "SignupDate", "KeyType": "HASH"}, {"AttributeName": "City", "KeyType": "RANGE"}], "Projection": {"ProjectionType": "ALL"}}]
C. "GlobalSecondaryIndexes": [{"IndexName": "CitySignupIndex", "KeySchema": [{"AttributeName": "City", "KeyType": "RANGE"}, {"AttributeName": "SignupDate", "KeyType": "HASH"}], "Projection": {"ProjectionType": "ALL"}}]
D. "GlobalSecondaryIndexes": [{"IndexName": "CitySignupIndex", "KeySchema": [{"AttributeName": "City", "KeyType": "HASH"}, {"AttributeName": "SignupDate", "KeyType": "RANGE"}], "Projection": {"ProjectionType": "ALL"}}]

Solution

  1. Step 1: Identify partition and sort keys for query pattern

    To query all users in a city sorted by signup date, City should be the partition key (HASH) and SignupDate the sort key (RANGE).

  2. Step 2: Check options for correct KeySchema order

    "GlobalSecondaryIndexes": [{"IndexName": "CitySignupIndex", "KeySchema": [{"AttributeName": "City", "KeyType": "HASH"}, {"AttributeName": "SignupDate", "KeyType": "RANGE"}], "Projection": {"ProjectionType": "ALL"}}] correctly sets City as HASH and SignupDate as RANGE. Options B and C swap keys incorrectly. "GlobalSecondaryIndexes": [{"IndexName": "CitySignupIndex", "KeySchema": [{"AttributeName": "SignupDate", "KeyType": "RANGE"}], "Projection": {"ProjectionType": "ALL"}}] lacks partition key.

  3. Final Answer:

    "GlobalSecondaryIndexes": [{"IndexName": "CitySignupIndex", "KeySchema": [{"AttributeName": "City", "KeyType": "HASH"}, {"AttributeName": "SignupDate", "KeyType": "RANGE"}], "Projection": {"ProjectionType": "ALL"}}] -> Option D

  4. Quick Check:

    Partition key = City, Sort key = SignupDate [OK]
Hint: Partition key first (HASH), sort key second (RANGE) in KeySchema [OK]
Common Mistakes:
  • Swapping HASH and RANGE keys
  • Missing partition key in GSI
  • Using only one key when two are needed for sorting
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