Return values on write in DynamoDB - Cheat Sheet & Quick Revision

Recall & Review

beginner

What does the ReturnValues parameter do in a DynamoDB write operation?

It controls what data is returned after a write operation like PutItem, UpdateItem, or DeleteItem. You can get back the old item, the new item, or nothing.

intermediate

Name the possible values for ReturnValues in DynamoDB write operations.

• NONE: Returns nothing (default).
• ALL_OLD: Returns the item as it was before the write.
• UPDATED_OLD: Returns only the updated attributes before the write.
• ALL_NEW: Returns the item as it is after the write.
• UPDATED_NEW: Returns only the updated attributes after the write.

beginner

If you want to see the new values of an item after an update, which ReturnValues option should you use?

Use ALL_NEW to get the entire item as it looks after the update, or UPDATED_NEW to get only the attributes that changed.

beginner

What is the default behavior of ReturnValues if you don't specify it in a write operation?

By default, ReturnValues is set to NONE, so the write operation returns no data about the item.

intermediate

Why might you want to use ReturnValues in a real-world application?

It helps you confirm what changed or existed before the write without making a separate read request. For example, you can get the old item before deleting it or see updated fields after an update.

What does ReturnValues: ALL_OLD return after a DeleteItem operation?

A The item as it was before deletion

B The item as it is after deletion

C Only the updated attributes after deletion

D No data is returned

ALL_OLD returns the entire item as it was before the delete operation.

If you want no data returned after a write operation, which ReturnValues should you use?

A ALL_NEW

B NONE

C UPDATED_NEW

D ALL_OLD

NONE is the default and returns no data after the write.

Which ReturnValues option returns only the attributes that were updated, after an update?

A ALL_OLD

B ALL_NEW

C UPDATED_OLD

D UPDATED_NEW

UPDATED_NEW returns only the updated attributes after the update.

Can ReturnValues be used with PutItem to get the new item after insertion?

A Yes, use ALL_NEW

B No, it only works with UpdateItem

C Yes, use ALL_OLD

D No, PutItem never returns data

Using ALL_NEW with PutItem returns the item after insertion.

What is a practical benefit of using ReturnValues in a write operation?

A It speeds up the write operation

B It encrypts the data automatically

C It reduces the need for a separate read request

D It backs up the item to another table

Getting return values lets you see changes without an extra read call.

Explain the purpose of the ReturnValues parameter in DynamoDB write operations and list its main options.

Think about what you want to see after you change data.

Describe a scenario where using ReturnValues would help avoid an extra read request.

Imagine you want to confirm what changed immediately.

Practice

1. What does the ReturnValues parameter do in a DynamoDB write operation?

easy

A. It specifies what data should be returned after the write operation.

B. It controls the write capacity units consumed by the operation.

C. It sets the timeout duration for the write request.

D. It defines the table where data will be written.

Solution

1. Step 1: Understand the role of ReturnValues

   The ReturnValues parameter tells DynamoDB what data to send back after a write, such as old or new item attributes.

2. Step 2: Differentiate from other parameters

   ReturnValues does not affect capacity, timeout, or table selection; it only controls returned data.

3. Final Answer:

   It specifies what data should be returned after the write operation. -> Option A

4. Quick Check:

   ReturnValues controls returned data [OK]

Hint: ReturnValues returns data after write, not capacity or timeout [OK]

Common Mistakes:

• Confusing ReturnValues with capacity settings
• Thinking it sets request timeout
• Assuming it selects the table

2. Which of the following is the correct syntax to request the old item attributes after an update in DynamoDB using ReturnValues?

easy

A. "UPDATED_NEW"

B. "NONE"

C. "ALL_NEW"

D. "ALL_OLD"

Solution

1. Step 1: Recall ReturnValues options

   ReturnValues can be NONE, ALL_OLD, UPDATED_OLD, ALL_NEW, UPDATED_NEW.

2. Step 2: Identify option for old attributes after update

   "ALL_OLD" returns the entire item as it was before the update.

3. Final Answer:

   "ALL_OLD" -> Option D

4. Quick Check:

   Old attributes = ALL_OLD [OK]

Hint: Old data after update is ALL_OLD [OK]

Common Mistakes:

• Using ALL_NEW to get old data
• Confusing UPDATED_NEW with old data
• Setting NONE expecting data back

3. Given this DynamoDB update command snippet:

{
  TableName: "Users",
  Key: { "UserId": "123" },
  UpdateExpression: "SET Age = :newAge",
  ExpressionAttributeValues: { ":newAge": 30 },
  ReturnValues: "UPDATED_NEW"
}

What will the response contain?

medium

A. The entire item before the update.

B. Only the new Age attribute after the update.

C. No attributes, just success confirmation.

D. The entire item after the update.

Solution

1. Step 1: Understand ReturnValues "UPDATED_NEW" meaning

   This option returns only the attributes that were updated with their new values.

2. Step 2: Apply to given update

   The update changes Age to 30, so response includes only Age with value 30.

3. Final Answer:

   Only the new Age attribute after the update. -> Option B

4. Quick Check:

   UPDATED_NEW returns updated attributes [OK]

Hint: UPDATED_NEW returns only changed attributes with new values [OK]

Common Mistakes:

• Expecting full item back with UPDATED_NEW
• Confusing UPDATED_NEW with ALL_NEW
• Assuming no data returned with UPDATED_NEW

4. You wrote this DynamoDB PutItem request:

{
  TableName: "Products",
  Item: { "Id": "001", "Name": "Pen" },
  ReturnValues: "UPDATED_OLD"
}

But you get an error. What is wrong?

medium

A. ReturnValues must be set to "ALL_NEW" for PutItem.

B. The Item attribute is missing required keys.

C. "UPDATED_OLD" is invalid for PutItem operations.

D. TableName is incorrect.

Solution

1. Step 1: Check ReturnValues compatibility with PutItem

   PutItem supports only NONE or ALL_OLD for ReturnValues; UPDATED_OLD is invalid.

2. Step 2: Confirm other parameters

   Item and TableName are correct; error is due to invalid ReturnValues.

3. Final Answer:

   "UPDATED_OLD" is invalid for PutItem operations. -> Option C

4. Quick Check:

   PutItem supports NONE or ALL_OLD only [OK]

Hint: PutItem allows NONE or ALL_OLD only for ReturnValues [OK]

Common Mistakes:

• Using UPDATED_OLD with PutItem
• Assuming ALL_NEW required for PutItem
• Mistaking missing keys as cause

5. You want to update a user's email in DynamoDB and get back the entire updated item in one request. Which ReturnValues option should you use in your UpdateItem call?

hard

A. "ALL_NEW"

B. "UPDATED_OLD"

C. "NONE"

D. "ALL_OLD"

Solution

1. Step 1: Understand the goal

   You want the full updated item returned after the update.

2. Step 2: Match ReturnValues option

   "ALL_NEW" returns the entire item as it looks after the update.

3. Final Answer:

   "ALL_NEW" -> Option A

4. Quick Check:

   Full updated item = ALL_NEW [OK]

Hint: Use ALL_NEW to get full updated item after update [OK]

Common Mistakes:

• Choosing UPDATED_OLD which returns old updated attributes
• Using NONE expecting data back
• Selecting ALL_OLD which returns old full item