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Azure Cosmos Java

lingxling/azure-cosmos-java

Azure Cosmos DB SDK for Java. NoSQL database operations with global distribution, multi-model support, and reactive patterns.

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Install

one command, takes just this skill from the repository
npx skills add https://github.com/lingxling/awesome-skills-cn --skill azure-cosmos-java

The instruction itself

22 sections, as written by the author

Azure Cosmos DB SDK for Java

Client library for Azure Cosmos DB NoSQL API with global distribution and reactive patterns.

Installation

<dependency>
    <groupId>com.azure</groupId>
    <artifactId>azure-cosmos</artifactId>
    <version>LATEST</version>
</dependency>

Or use Azure SDK BOM:

<dependencyManagement>
    <dependencies>
        <dependency>
            <groupId>com.azure</groupId>
            <artifactId>azure-sdk-bom</artifactId>
            <version>{bom_version}</version>
            <type>pom</type>
            <scope>import</scope>
        </dependency>
    </dependencies>
</dependencyManagement>

<dependencies>
    <dependency>
        <groupId>com.azure</groupId>
        <artifactId>azure-cosmos</artifactId>
    </dependency>
</dependencies>

Environment Variables

COSMOS_ENDPOINT=https://<account>.documents.azure.com:443/
COSMOS_KEY=<your-primary-key>

Authentication

Key-based Authentication

import com.azure.cosmos.CosmosClient;
import com.azure.cosmos.CosmosClientBuilder;

CosmosClient client = new CosmosClientBuilder()
    .endpoint(System.getenv("COSMOS_ENDPOINT"))
    .key(System.getenv("COSMOS_KEY"))
    .buildClient();

Async Client

import com.azure.cosmos.CosmosAsyncClient;

CosmosAsyncClient asyncClient = new CosmosClientBuilder()
    .endpoint(serviceEndpoint)
    .key(key)
    .buildAsyncClient();

With Customizations

import com.azure.cosmos.ConsistencyLevel;
import java.util.Arrays;

CosmosClient client = new CosmosClientBuilder()
    .endpoint(serviceEndpoint)
    .key(key)
    .directMode(directConnectionConfig, gatewayConnectionConfig)
    .consistencyLevel(ConsistencyLevel.SESSION)
    .connectionSharingAcrossClientsEnabled(true)
    .contentResponseOnWriteEnabled(true)
    .userAgentSuffix("my-application")
    .preferredRegions(Arrays.asList("West US", "East US"))
    .buildClient();

Client Hierarchy

| Class | Purpose |

|-------|---------|

| CosmosClient / CosmosAsyncClient | Account-level operations |

| CosmosDatabase / CosmosAsyncDatabase | Database operations |

| CosmosContainer / CosmosAsyncContainer | Container/item operations |

Core Workflow

Create Database

// Sync
client.createDatabaseIfNotExists("myDatabase")
    .map(response -> client.getDatabase(response.getProperties().getId()));

// Async with chaining
asyncClient.createDatabaseIfNotExists("myDatabase")
    .map(response -> asyncClient.getDatabase(response.getProperties().getId()))
    .subscribe(database -> System.out.println("Created: " + database.getId()));

Create Container

asyncClient.createDatabaseIfNotExists("myDatabase")
    .flatMap(dbResponse -> {
        String databaseId = dbResponse.getProperties().getId();
        return asyncClient.getDatabase(databaseId)
            .createContainerIfNotExists("myContainer", "/partitionKey")
            .map(containerResponse -> asyncClient.getDatabase(databaseId)
                .getContainer(containerResponse.getProperties().getId()));
    })
    .subscribe(container -> System.out.println("Container: " + container.getId()));

CRUD Operations

import com.azure.cosmos.models.PartitionKey;

CosmosAsyncContainer container = asyncClient
    .getDatabase("myDatabase")
    .getContainer("myContainer");

// Create
container.createItem(new User("1", "John Doe", "[email protected]"))
    .flatMap(response -> {
        System.out.println("Created: " + response.getItem());
        // Read
        return container.readItem(
            response.getItem().getId(),
            new PartitionKey(response.getItem().getId()),
            User.class);
    })
    .flatMap(response -> {
        System.out.println("Read: " + response.getItem());
        // Update
        User user = response.getItem();
        user.setEmail("[email protected]");
        return container.replaceItem(
            user,
            user.getId(),
            new PartitionKey(user.getId()));
    })
    .flatMap(response -> {
        // Delete
        return container.deleteItem(
            response.getItem().getId(),
            new PartitionKey(response.getItem().getId()));
    })
    .block();

Query Documents

import com.azure.cosmos.models.CosmosQueryRequestOptions;
import com.azure.cosmos.util.CosmosPagedIterable;

CosmosContainer container = client.getDatabase("myDatabase").getContainer("myContainer");

String query = "SELECT * FROM c WHERE c.status = @status";
CosmosQueryRequestOptions options = new CosmosQueryRequestOptions();

CosmosPagedIterable<User> results = container.queryItems(
    query,
    options,
    User.class
);

results.forEach(user -> System.out.println("User: " + user.getName()));

Key Concepts

Partition Keys

Choose a partition key with:

  • High cardinality (many distinct values)
  • Even distribution of data and requests
  • Frequently used in queries

Consistency Levels

| Level | Guarantee |

|-------|-----------|

| Strong | Linearizability |

| Bounded Staleness | Consistent prefix with bounded lag |

| Session | Consistent prefix within session |

| Consistent Prefix | Reads never see out-of-order writes |

| Eventual | No ordering guarantee |

Request Units (RUs)

All operations consume RUs. Check response headers:

CosmosItemResponse<User> response = container.createItem(user);
System.out.println("RU charge: " + response.getRequestCharge());

Best Practices

  • Reuse CosmosClient — Create once, reuse throughout application
  • Use async client for high-throughput scenarios
  • Choose partition key carefully — Affects performance and scalability
  • Enable content response on write for immediate access to created items
  • Configure preferred regions for geo-distributed applications
  • Handle 429 errors with retry policies (built-in by default)
  • Use direct mode for lowest latency in production

Error Handling

import com.azure.cosmos.CosmosException;

try {
    container.createItem(item);
} catch (CosmosException e) {
    System.err.println("Status: " + e.getStatusCode());
    System.err.println("Message: " + e.getMessage());
    System.err.println("Request charge: " + e.getRequestCharge());
    
    if (e.getStatusCode() == 409) {
        System.err.println("Item already exists");
    } else if (e.getStatusCode() == 429) {
        System.err.println("Rate limited, retry after: " + e.getRetryAfterDuration());
    }
}

| Resource | URL |

|----------|-----|

| Maven Package | https://central.sonatype.com/artifact/com.azure/azure-cosmos |

| API Documentation | https://azuresdkdocs.z19.web.core.windows.net/java/azure-cosmos/latest/index.html |

| Product Docs | https://learn.microsoft.com/azure/cosmos-db/ |

| Samples | https://github.com/Azure-Samples/azure-cosmos-java-sql-api-samples |

| Performance Guide | https://learn.microsoft.com/azure/cosmos-db/performance-tips-java-sdk-v4-sql |

| Troubleshooting | https://learn.microsoft.com/azure/cosmos-db/troubleshoot-java-sdk-v4-sql |

When to Use

This skill is applicable to execute the workflow or actions described in the overview.

Limitations

  • Use this skill only when the task clearly matches the scope described above.
  • Do not treat the output as a substitute for environment-specific validation, testing, or expert review.
  • Stop and ask for clarification if required inputs, permissions, safety boundaries, or success criteria are missing.

Repackaged in 1 other repositories

same content, different owner
aiskillstore/marketplace open on GitHub →
lingxling/awesome-skills-cn open on GitHub →

How to use it

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