Creating GSI in DynamoDB - Interactive Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to define a Global Secondary Index (GSI) with the partition key 'UserId'.

DynamoDB

"GlobalSecondaryIndexes": [{"IndexName": "UserIndex", "KeySchema": [{"AttributeName": [1], "KeyType": "HASH"}], "Projection": {"ProjectionType": "ALL"}}]

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

A"OrderId"

B"UserId"

C"Timestamp"

D"Status"

Attempts:

3 left

💡 Hint

Common Mistakes

Using the wrong attribute name for the partition key.

Confusing the sort key with the partition key.

The partition key for the GSI must be specified as 'UserId' to index by user.

2fill in blank

medium

Complete the code to add a sort key 'OrderDate' to the GSI.

DynamoDB

"KeySchema": [{"AttributeName": "UserId", "KeyType": "HASH"}, {"AttributeName": [1], "KeyType": "RANGE"}]

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

A"Timestamp"

B"OrderId"

C"OrderDate"

D"Status"

Attempts:

3 left

💡 Hint

Common Mistakes

Using the partition key attribute as the sort key.

Choosing an attribute that does not represent order date.

The sort key for the GSI is 'OrderDate' to sort orders by date.

3fill in blank

hard

Fix the error in the attribute definitions by selecting the correct attribute type for 'OrderDate'.

DynamoDB

"AttributeDefinitions": [{"AttributeName": "UserId", "AttributeType": "S"}, {"AttributeName": "OrderDate", "AttributeType": [1]]

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

A"N"

B"B"

C"BOOL"

D"S"

Attempts:

3 left

💡 Hint

Common Mistakes

Using number (N) type for date strings.

Using binary (B) type incorrectly.

'OrderDate' is stored as a string (S) in ISO 8601 format for sorting.

4fill in blank

hard

Fill both blanks to complete the GSI projection type and write capacity units.

DynamoDB

"ProvisionedThroughput": {"ReadCapacityUnits": 5, "WriteCapacityUnits": [1], "Projection": {"ProjectionType": [2]

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

A5

B10

C"ALL"

D"KEYS_ONLY"

Attempts:

3 left

💡 Hint

Common Mistakes

Setting write capacity units too low.

Choosing projection type 'KEYS_ONLY' when all attributes are needed.

Write capacity units are set to 10 and projection type is 'ALL' to include all attributes.

5fill in blank

hard

Fill all three blanks to complete the GSI definition with index name, partition key, and projection type.

DynamoDB

"GlobalSecondaryIndexes": [{"IndexName": [1], "KeySchema": [{"AttributeName": [2], "KeyType": "HASH"}], "Projection": {"ProjectionType": [3]]

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

A"UserDateIndex"

B"UserId"

C"INCLUDE"

D"OrderIndex"

Attempts:

3 left

💡 Hint

Common Mistakes

Using a generic index name.

Choosing wrong attribute for partition key.

Using projection type 'ALL' when only some attributes are needed.

The index is named 'UserDateIndex', partition key is 'UserId', and projection type is 'INCLUDE' to include specific attributes.

Practice

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": "[e-mail]"}
}

medium

A. Returns all items where Email attribute equals '[e-mail]' using the GSI

B. Returns all items where Email attribute equals '[e-mail]' 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 '[e-mail]' on the GSI partition key.

3. Final Answer:

   Returns all items where Email attribute equals '[e-mail]' 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