Configure client-side threading and parallelism options

Azure Cosmos DB is a globally distributed, multi-model database service provided by Microsoft. It offers various capabilities to enhance performance and scalability, including client-side threading and parallelism options. In this article, we will explore how to configure these options in your native applications using Azure Cosmos DB.

Client-side Threading

Azure Cosmos DB allows you to utilize client-side threading to parallelize and optimize requests sent to the database service. By default, each request made to Azure Cosmos DB is executed sequentially, meaning subsequent requests wait for the completion of the previous one. However, enabling client-side threading improves performance by allowing multiple requests to execute simultaneously.

To configure client-side threading, you need to set the EnableEndpointDiscovery property of the ConnectionPolicy class to true. This option enables automatic discovery of read endpoints, load balancing, and parallelization of requests across multiple replicas. Here’s an example of enabling client-side threading using C#:

using Microsoft.Azure.Documents.Client;

By enabling client-side threading, you allow Azure Cosmos DB to handle requests in a more efficient and parallelized manner, resulting in improved application performance and reduced latency.

Parallelism Options

Azure Cosmos DB provides parallel query and item feed handling options, which allow you to achieve maximum throughput and responsiveness in your applications.

Parallel Query

When querying the Azure Cosmos DB database, you can enable parallel query execution to process queries across multiple partitions simultaneously. This option is particularly useful when dealing with large volumes of data or complex queries.

To enable parallel query execution, set the MaxDegreeOfParallelism property of the FeedOptions class to the desired value. This property specifies the maximum degree of parallelism for a query. Here’s an example of enabling parallel query execution:

using Microsoft.Azure.Documents.Client;

// Execute query with FeedOptions
FeedResponse queryResultSet = await client.CreateDocumentQuery(collectionLink, queryDefinition, feedOptions).ToListAsync();


Setting -1 as the value for MaxDegreeOfParallelism allows Azure Cosmos DB to determine the optimal number of partitions to run the query across, depending on the data volume and available resources.

Parallel Item Feed Handling

When retrieving items from a feed, such as a change feed or query results, Azure Cosmos DB allows parallel item feed handling, which enhances performance by fetching items concurrently.

To enable parallel item feed handling, set the MaxItemCount property of the FeedOptions class to the desired value. This property defines the maximum number of items to be fetched from the feed in each request. Here’s an example:

using Microsoft.Azure.Documents.Client;

// Execute feed retrieval with FeedOptions
FeedResponse feedResultSet = await client.ReadDocumentFeedAsync(collectionLink, feedOptions);


By setting an appropriate value for MaxItemCount, you can control the number of items fetched per request, thereby achieving parallel item feed handling and improving the efficiency of your application.

Conclusion

In this article, we explored how to configure client-side threading and parallelism options in native applications using Azure Cosmos DB. By enabling client-side threading and optimizing parallelism options, such as parallel query execution and parallel item feed handling, you can significantly improve the performance and responsiveness of your applications.

Remember, optimizing performance in Azure Cosmos DB requires careful consideration of factors like data volume, complexity of queries, and available resources. Experimenting with different settings and monitoring the performance impact will help you fine-tune these configurations for your specific use cases.