Agent skill

aws-sdk-java-v2-dynamodb

Provides Amazon DynamoDB patterns using AWS SDK for Java 2.x. Use when creating, querying, scanning, or performing CRUD operations on DynamoDB tables, working with indexes, batch operations, transactions, or integrating with Spring Boot applications.

View SKILL.md on GitHub Repository
Stars 192
Forks 20

Install this agent skill to your Project

npx add-skill https://github.com/giuseppe-trisciuoglio/developer-kit/tree/main/plugins/developer-kit-java/skills/aws-sdk-java-v2-dynamodb

SKILL.md

AWS SDK for Java 2.x - Amazon DynamoDB

Overview

Provides DynamoDB patterns using AWS SDK for Java 2.x with Enhanced Client for type-safe CRUD, queries, batch operations, transactions, and Spring Boot integration.

When to Use

  • CRUD operations on DynamoDB items
  • Querying tables with sort keys or GSI
  • Batch operations for multiple items
  • Atomic transactions across tables
  • Spring Boot integration with DynamoDB

Instructions

  1. Add AWS SDK DynamoDB dependencies to pom.xml
  2. Configure client setup (low-level or Enhanced Client)
  3. Define entity classes with @DynamoDbBean annotations
  4. Perform operations using DynamoDbTable (CRUD, query, scan, batch, transactions)
  5. Handle partial failures with retry logic and exponential backoff
  6. Use repository pattern for Spring Boot integration

Dependencies

Add to pom.xml:

xml
<!-- Low-level DynamoDB client -->
<dependency>
    <groupId>software.amazon.awssdk</groupId>
    <artifactId>dynamodb</artifactId>
</dependency>

<!-- Enhanced client (recommended) -->
<dependency>
    <groupId>software.amazon.awssdk</groupId>
    <artifactId>dynamodb-enhanced</artifactId>
</dependency>

Client Setup

Low-Level Client

java
import software.amazon.awssdk.regions.Region;
import software.amazon.awssdk.services.dynamodb.DynamoDbClient;

DynamoDbClient dynamoDb = DynamoDbClient.builder()
    .region(Region.US_EAST_1)
    .build();

Enhanced Client (Recommended)

java
import software.amazon.awssdk.enhanced.dynamodb.DynamoDbEnhancedClient;

DynamoDbEnhancedClient enhancedClient = DynamoDbEnhancedClient.builder()
    .dynamoDbClient(dynamoDb)
    .build();

Entity Mapping

java
@DynamoDbBean
public class Customer {

    @DynamoDbPartitionKey
    private String customerId;

    @DynamoDbAttribute("customer_name")
    private String name;

    private String email;

    @DynamoDbSortKey
    private String orderId;

    // Getters and setters
}

For complex entity mapping with GSIs and custom converters, see Entity Mapping Reference.

CRUD Operations

Basic Operations

java
// Create or update item
DynamoDbTable<Customer> table = enhancedClient.table("Customers", TableSchema.fromBean(Customer.class));
table.putItem(customer);

// Get item
Customer result = table.getItem(Key.builder().partitionValue(customerId).build());

// Update item
return table.updateItem(customer);

// Delete item
table.deleteItem(Key.builder().partitionValue(customerId).build());

Composite Key Operations

java
// Get item with composite key
Order order = table.getItem(Key.builder()
    .partitionValue(customerId)
    .sortValue(orderId)
    .build());

Query Operations

Basic Query

java
import software.amazon.awssdk.enhanced.dynamodb.model.QueryConditional;

QueryConditional queryConditional = QueryConditional
    .keyEqualTo(Key.builder()
        .partitionValue(customerId)
        .build());

List<Order> orders = table.query(queryConditional).items().stream()
    .collect(Collectors.toList());

Advanced Query with Filters

java
import software.amazon.awssdk.enhanced.dynamodb.Expression;

Expression filter = Expression.builder()
    .expression("status = :pending")
    .putExpressionValue(":pending", AttributeValue.builder().s("PENDING").build())
    .build();

List<Order> pendingOrders = table.query(r -> r
    .queryConditional(queryConditional)
    .filterExpression(filter))
    .items().stream()
    .collect(Collectors.toList());

For detailed query patterns, see Advanced Operations Reference.

Scan Operations

Warning: Scan reads entire table and consumes read capacity for all items. Prefer Query operations with partition keys or GSIs whenever possible.

Validation before scan:

  • Confirm query with partition key is not feasible for your access pattern
  • Verify table has sufficient provisioned read capacity or use on-demand mode
  • Consider using pagination with limit() to control capacity consumption
java
// Scan all items
List<Customer> allCustomers = table.scan().items().stream()
    .collect(Collectors.toList());

// Scan with filter
Expression filter = Expression.builder()
    .expression("points >= :minPoints")
    .putExpressionValue(":minPoints", AttributeValue.builder().n("1000").build())
    .build();

List<Customer> vipCustomers = table.scan(r -> r.filterExpression(filter))
    .items().stream()
    .collect(Collectors.toList());

Batch Operations

Batch Get

java
import software.amazon.awssdk.enhanced.dynamodb.model.*;

List<Key> keys = customerIds.stream()
    .map(id -> Key.builder().partitionValue(id).build())
    .collect(Collectors.toList());

ReadBatch.Builder<Customer> batchBuilder = ReadBatch.builder(Customer.class)
    .mappedTableResource(table);

keys.forEach(batchBuilder::addGetItem);

BatchGetResultPageIterable result = enhancedClient.batchGetItem(r ->
    r.addReadBatch(batchBuilder.build()));

List<Customer> customers = result.resultsForTable(table).stream()
    .collect(Collectors.toList());

Batch Write with Error Handling

java
WriteBatch.Builder<Customer> batchBuilder = WriteBatch.builder(Customer.class)
    .mappedTableResource(table);

customers.forEach(batchBuilder::addPutItem);

BatchWriteItemEnhancedRequest request = BatchWriteItemEnhancedRequest.builder()
    .addWriteBatch(batchBuilder.build())
    .build();

BatchWriteResult result = enhancedClient.batchWriteItem(request);

// Validate: check for unprocessed items
if (!result.writeResponsesForTable(table).isEmpty()) {
    // Retry unprocessed items with exponential backoff
    Map<String, AttributeValue> unprocessed = result.writeResponsesForTable(table).get(0)
        .unprocessedAttributes();
    if (unprocessed != null && !unprocessed.isEmpty()) {
        enhancedClient.batchWriteItem(r -> r
            .addWriteBatch(WriteBatch.builder(Customer.class)
                .mappedTableResource(table)
                .addPutItemFromItem(unprocessed)
                .build()));
    }
}

Transactions

Transactional Write with Retry

java
public void placeOrderWithRetry(Order order, Customer customer, int maxRetries) {
    int attempt = 0;
    while (attempt < maxRetries) {
        try {
            enhancedClient.transactWriteItems(r -> r
                .addPutItem(customerTable, customer)
                .addPutItem(orderTable, order));
            return;
        } catch (TransactionCanceledException e) {
            if (e.cancellationReasons().stream()
                .anyMatch(r -> r.code().equals("TransactionCanceledException")
                    && r.message().contains("throughput"))) {
                attempt++;
                if (attempt < maxRetries) {
                    try { Thread.sleep((long) Math.pow(2, attempt) * 100); }
                    catch (InterruptedException ie) { Thread.currentThread().interrupt(); }
                }
            } else {
                throw e; // Non-retryable error
            }
        }
    }
}

Transactional Read

java
TransactGetItemsEnhancedRequest request = TransactGetItemsEnhancedRequest.builder()
    .addGetItem(customerTable, customerKey)
    .addGetItem(orderTable, orderKey)
    .build();

List<Document> results = enhancedClient.transactGetItems(request);

Spring Boot Integration

Configuration

java
@Configuration
public class DynamoDbConfiguration {

    @Bean
    public DynamoDbClient dynamoDbClient() {
        return DynamoDbClient.builder()
            .region(Region.US_EAST_1)
            .build();
    }

    @Bean
    public DynamoDbEnhancedClient dynamoDbEnhancedClient(DynamoDbClient dynamoDbClient) {
        return DynamoDbEnhancedClient.builder()
            .dynamoDbClient(dynamoDbClient)
            .build();
    }
}

Repository Pattern

java
@Repository
public class CustomerRepository {

    private final DynamoDbTable<Customer> customerTable;

    public CustomerRepository(DynamoDbEnhancedClient enhancedClient) {
        this.customerTable = enhancedClient.table("Customers", TableSchema.fromBean(Customer.class));
    }

    public void save(Customer customer) {
        customerTable.putItem(customer);
    }

    public Optional<Customer> findById(String customerId) {
        Key key = Key.builder().partitionValue(customerId).build();
        return Optional.ofNullable(customerTable.getItem(key));
    }
}

For comprehensive Spring Boot integration patterns, see Spring Boot Integration Reference.

Testing

Unit Testing with Mocks

java
@ExtendWith(MockitoExtension.class)
class CustomerServiceTest {

    @Mock
    private DynamoDbClient dynamoDbClient;

    @Mock
    private DynamoDbEnhancedClient enhancedClient;

    @Mock
    private DynamoDbTable<Customer> customerTable;

    @InjectMocks
    private CustomerService customerService;

    @Test
    void saveCustomer_ShouldReturnSavedCustomer() {
        // Arrange
        when(enhancedClient.table(anyString(), any(TableSchema.class)))
            .thenReturn(customerTable);

        Customer customer = new Customer("123", "John Doe", "john@example.com");

        // Act
        Customer result = customerService.saveCustomer(customer);

        // Assert
        assertNotNull(result);
        verify(customerTable).putItem(customer);
    }
}

Integration Testing with LocalStack

java
@Testcontainers
@SpringBootTest
class DynamoDbIntegrationTest {

    @Container
    static LocalStackContainer localstack = new LocalStackContainer(
        DockerImageName.parse("localstack/localstack:3.0"))
        .withServices(LocalStackContainer.Service.DYNAMODB);

    @DynamicPropertySource
    static void configureProperties(DynamicPropertyRegistry registry) {
        registry.add("aws.endpoint",
            () -> localstack.getEndpointOverride(LocalStackContainer.Service.DYNAMODB).toString());
    }

    @Autowired
    private DynamoDbEnhancedClient enhancedClient;

    @Test
    void testCustomerCRUDOperations() {
        // Test implementation
    }
}

For detailed testing strategies, see Testing Strategies.

Best Practices

  • Use Enhanced Client: Type-safe operations with less boilerplate
  • Design partition keys for even distribution: Avoid hot partitions
  • Prefer queries over scans: Use GSIs for access patterns
  • Batch in chunks of 25/100: BatchGetItem limits to 100, BatchWriteItem to 25 per table
  • Handle partial failures: Implement retry with exponential backoff for ProvisionedThroughputExceeded
  • Use conditional writes: Prevent race conditions with attribute_not_exists(pk)

Examples

Complete CRUD Repository

java
@Repository
public class UserRepository {

    private final DynamoDbTable<User> userTable;

    public UserRepository(DynamoDbEnhancedClient enhancedClient) {
        this.userTable = enhancedClient.table("Users", TableSchema.fromBean(User.class));
    }

    public User save(User user) {
        userTable.putItem(user);
        return user;
    }

    public Optional<User> findById(String userId) {
        Key key = Key.builder().partitionValue(userId).build();
        return Optional.ofNullable(userTable.getItem(key));
    }

    public void deleteById(String userId) {
        userTable.deleteItem(Key.builder().partitionValue(userId).build());
    }
}

Conditional Write with Retry

java
public boolean createIfNotExists(User user) {
    PutItemEnhancedRequest<User> request = PutItemEnhancedRequest.builder(User.class)
        .item(user)
        .conditionExpression("attribute_not_exists(userId)")
        .build();

    try {
        userTable.putItemWithRequest(request);
        return true;
    } catch (ConditionalCheckFailedException e) {
        return false; // Item already exists
    }
}

Constraints and Warnings

  • Item Size Limit: DynamoDB items limited to 400KB
  • Partition Key Design: Poor design causes hot partitions
  • Batch Limits: BatchGetItem max 100, BatchWriteItem max 25 items per table
  • Transaction Costs: Transactions cost 2x read/write capacity units
  • Scan Operations: Scans consume large amounts of read capacity; use only when necessary

References

For detailed implementations, see the references folder:

  • Entity Mapping Reference
  • Advanced Operations Reference
  • Spring Boot Integration Reference
  • Testing Strategies

Recommended Agent Skills

Expand your agent's capabilities with these related and highly-rated skills.

giuseppe-trisciuoglio/developer-kit

aws-cli-beast

Provides advanced AWS CLI patterns for managing EC2, Lambda, S3, DynamoDB, RDS, VPC, IAM, and CloudWatch. Generates bulk operation scripts, automates cross-service workflows, validates security configurations, and executes JMESPath queries for complex filtering. Triggers on "aws cli help", "aws command line", "aws scripting", "aws automation", "aws batch operations", "aws bulk operations", "aws cli pagination", "aws multi-region", "aws profiles", "aws cli troubleshooting".

192 20
Explore
giuseppe-trisciuoglio/developer-kit

aws-cost-optimization

Provides structured AWS cost optimization guidance using five pillars (right-sizing, elasticity, pricing models, storage optimization, monitoring) and twelve actionable best practices with executable AWS CLI examples. Use when optimizing AWS costs, reviewing AWS spending, finding unused AWS resources, implementing FinOps practices, reducing EC2/EBS/S3 bills, configuring AWS Budgets, or performing AWS Well-Architected cost reviews.

192 20
Explore
giuseppe-trisciuoglio/developer-kit

aws-sam-bootstrap

Provides AWS SAM bootstrap patterns: generates `template.yaml` and `samconfig.toml` for new projects via `sam init`, creates SAM templates for existing Lambda/CloudFormation code migration, validates build/package/deploy workflows, and configures local testing with `sam local invoke`. Use when the user asks about SAM projects, `sam init`, `sam deploy`, serverless deployments, or needs to bootstrap/migrate Lambda functions with SAM templates.

192 20
Explore
giuseppe-trisciuoglio/developer-kit

aws-drawio-architecture-diagrams

Creates professional AWS architecture diagrams in draw.io XML format (.drawio files) using official AWS Architecture Icons (aws4 library). Use when the user asks for AWS diagrams, VPC layouts, multi-tier architectures, serverless designs, network topology, or draw.io exports involving Lambda, EC2, RDS, or other AWS services.

192 20
Explore
giuseppe-trisciuoglio/developer-kit

aws-cloudformation-bedrock

Provides AWS CloudFormation patterns for Amazon Bedrock resources including agents, knowledge bases, data sources, guardrails, prompts, flows, and inference profiles. Use when creating Bedrock agents with action groups, implementing RAG with knowledge bases, configuring vector stores, setting up content moderation guardrails, managing prompts, orchestrating workflows with flows, and configuring inference profiles for model optimization.

192 20
Explore
giuseppe-trisciuoglio/developer-kit

aws-cloudformation-s3

Provides AWS CloudFormation patterns for Amazon S3. Use when creating S3 buckets, policies, versioning, lifecycle rules, and implementing template structure with Parameters, Outputs, Mappings, Conditions, and cross-stack references.

192 20
Explore

Didn't find tool you were looking for?

Be as detailed as possible for better results