Return values on write in DynamoDB - Step-by-Step Execution

Concept Flow - Return values on write

Start Write Operation

↓

Perform Write (Put/Update/Delete)

↓

Check ReturnValues Parameter

↓

NONE

↓

Return No

↓

Attributes

↓

End Write Operation

When you write data, you can choose what old or new attribute values to get back by setting ReturnValues.

Execution Sample

DynamoDB

UpdateItem {
  Key: {id: 1},
  UpdateExpression: 'SET age = :newAge',
  ExpressionAttributeValues: {':newAge': 30},
  ReturnValues: 'UPDATED_OLD'
}

This updates the age attribute and returns the old age value before update.

Execution Table

Step	Action	ReturnValues	Returned Data
1	Start UpdateItem	N/A	No data returned yet
2	Apply UpdateExpression	UPDATED_OLD	Old attribute values before update
3	Return response	UPDATED_OLD	{"age": 25}
4	End operation	N/A	Update complete, returned old age

💡 Update applied and old attribute values returned as per ReturnValues = UPDATED_OLD

Variable Tracker

Variable	Start	After Step 2	After Step 3	Final
age	25	30 (updated)	25 (returned)	30 (stored)
ReturnValues	N/A	UPDATED_OLD	UPDATED_OLD	UPDATED_OLD

Key Moments - 2 Insights

Why do we get old attribute values back instead of new ones?

Because ReturnValues is set to UPDATED_OLD, DynamoDB returns the attribute values before the update, as shown in execution_table step 3.

What happens if ReturnValues is NONE?

No attribute values are returned after the write, so the response contains no data, unlike the UPDATED_OLD case in step 3.

Visual Quiz - 3 Questions

Look at the execution_table, what is returned at step 3?

A The new attribute values after update

B The old attribute values before update

C No attribute values

D An error message

💡 Hint

Check the 'Returned Data' column at step 3 in execution_table

At which step is the update applied to the attribute 'age'?

A Step 2

B Step 1

C Step 3

D Step 4

💡 Hint

Look at the 'Action' column in execution_table where update happens

If ReturnValues was set to NONE, what would change in the execution_table?

A Returned Data at step 3 would show old values

B Returned Data at step 3 would show new values

C Returned Data at step 3 would be empty

D The update would not happen

💡 Hint

ReturnValues NONE means no data returned after write

Concept Snapshot

ReturnValues controls what data DynamoDB returns after a write.
Options include NONE (no data), ALL_OLD (all old attributes), UPDATED_OLD (only updated old attributes), ALL_NEW (all new attributes), UPDATED_NEW (only updated new attributes).
Set ReturnValues in your write request to get desired feedback.
Useful for confirming changes or retrieving previous data.

Full Transcript

When you perform a write operation in DynamoDB, such as UpdateItem, you can specify the ReturnValues parameter to control what attribute data is returned. The options include NONE, ALL_OLD, UPDATED_OLD, ALL_NEW, and UPDATED_NEW. For example, if you set ReturnValues to UPDATED_OLD, DynamoDB returns only the attribute values that were updated, but before the update. The execution flow starts with the write request, applies the update, checks the ReturnValues setting, and returns the requested data. This helps you confirm what changed or retrieve previous values without a separate read. If ReturnValues is NONE, no attribute data is returned. Understanding this helps you write efficient and clear DynamoDB operations.