Update Multiple Items in DynamoDB Using Java (Guide w/ Code Examples)

DynamoDB does not provide a direct method to update multiple items at once, like a "batch update" operation. However, you can use the updateItem method in a loop to update multiple items one by one.

In the snippet shown below, a list of items to update is defined, and the updateItem method is called for each item in the list. The updateExpression and expressionAttributeValues are the same for all items, but the key of the item to update is taken from the current item in the loop. This enables a batch update.

However, you can also use a Transactional Update if you wish to update multiple updates as a single operation.

import com.amazonaws.services.dynamodbv2.AmazonDynamoDB;
import com.amazonaws.services.dynamodbv2.AmazonDynamoDBClientBuilder;
import com.amazonaws.services.dynamodbv2.model.AttributeValue.AttributeValue;
import com.amazonaws.services.dynamodbv2.model.UpdateItemRequest;

import java.util.List;
import java.util.Map;

public class MultipleUpdateExample {
    public static void main(String[] args) {
        // Create a new client
        AmazonDynamoDB client = AmazonDynamoDBClientBuilder.standard().build();

        // Define a list of items to update
        List<Map<String, AttributeValue>> itemsToUpdate = new ArrayList<Map<String, AttributeValue>>();
        itemsToUpdate.add(new HashMap<String, AttributeValue>() {{
            put("id", new AttributeValue().withS("123"));
        }});
        itemsToUpdate.add(new HashMap<String, AttributeValue>() {{
            put("id", new AttributeValue().withS("456"));
        }});
        itemsToUpdate.add(new HashMap<String, AttributeValue>() {{
            put("id", new AttributeValue().withS("789"));
        }});

        // Define the update expression
        String updateExpression = "SET price = :newPrice, quantity = :newQuantity";

        // Define the values for the update expression
        Map<String, AttributeValue> expressionAttributeValues = new HashMap<String, AttributeValue>();
        expressionAttributeValues.put(":newPrice", new AttributeValue().withN("999"));
        expressionAttributeValues.put(":newQuantity", new AttributeValue().withN("20"));

        for (Map<String, AttributeValue> item : itemsToUpdate) {
            // Create the update request
            UpdateItemRequest request = new UpdateItemRequest()
                .withTableName("Product")
                .withKey(item)
                .withUpdateExpression(updateExpression)
                .withExpressionAttributeValues(expressionAttributeValues);
    
            // Send the request to update the item
            client.updateItem(request);
        }
    }
}