In the fast-paced world of modern enterprises, real-time applications are essential for processing and responding to data the moment it’s generated. These high-traffic systems require instant updates, where even a brief delay can result in substantial financial losses. The key challenge in such scenarios is ensuring dataset changes are immediately reflected where relevant. Unfortunately, depending solely on traditional databases for these updates can lead to significant inefficiencies and scalability hurdles.
Limitations of Traditional Databases for Real-Time Applications
Traditional databases fall short when it comes to handling the rapid data updates that real-time applications require. They are built to query static data, meaning that to access the latest information, the same query must be executed repeatedly. This periodic polling introduces delays in data retrieval and overwhelms the database with redundant queries, mostly even when there are no changes in the dataset, resulting in significant performance and scalability challenges.
SqlDependency And Its Shortcomings
SqlDependency, available in Microsoft SQL Server, allows you to monitor a dataset for changes, such as additions, updates, or deletions by specifying a SQL statement and notifying you about the change. But the problem with SqlDependency is that once fired, it gets unregistered from the database, leaving your dataset out of sync. Additionally, SqlDependency doesn’t specify which record was modified. So, to find the change in your dataset, you have to fetch the complete dataset again instead of directly fetching only the specific record, which is inefficient.
In addition to the limitations of SqlDependency, traditional databases are unable to meet the high transactional demands of real-time applications. When tens of thousands of queries are executed every second, the database quickly becomes a scalability bottleneck. This is because although you can linearly scale your application tier by adding more application servers, you cannot do the same with your database server.
NCache’s Continuous Query: An Efficient Solution
This is where a distributed cache like NCache comes into play. NCache enables you to cache data, significantly reducing the frequency of expensive database trips and alleviating scalability bottlenecks. Its powerful Continuous Query feature offers a robust solution for real-time applications, allowing you to register SQL-like queries with the cache cluster. These queries remain active and notify your application of any changes in the dataset, without the need for repeated database polling. Here is a sample code for the NCache Continuous Query:
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// Query for required operation string query = "SELECT $VALUE$ FROM Alachisoft.NCache.Samples.Data.Product WHERE Category = ?"; // Create query command and add parameters var queryCommand = new QueryCommand(query); queryCommand.Parameters.Add("Category", "Beverages"); // Create Continuous Query var cQuery = new ContinuousQuery(queryCommand); // Item add, update, remove notification // EventDataFilter.DataWithMetadata returns the cache keys added cQuery.RegisterNotification(new QueryDataNotificationCallback(OnChangeInQueryResultSet), EventType.ItemAdded | EventType.ItemUpdated | EventType.ItemRemoved, EventDataFilter.DataWithMetadata); // Register continuousQuery on server cache.MessagingService.RegisterCQ(cQuery); |
Unlike SqlDependency, NCache’s Continuous Query remains active and doesn’t unregister after each change notification. This ensures that your high-traffic, real-time applications continue to receive updates across multiple changes, providing consistent and uninterrupted data monitoring.
Benefits of Continuous Query in Real-Time Applications
NCache Continuous Query also provides you with the flexibility to receive notifications separately for ADD, UPDATE, and DELETE events, allowing you to tailor your response to specific data changes effectively. Additionally, you can specify and adjust these events at runtime, which is not possible with SqlDependency. This capability helps minimize the volume of event traffic between the cache cluster and your application, enhancing overall efficiency.
Conclusion
In conclusion, NCache’s Continuous Query feature stands out as a powerful, event-driven solution unmatched by other databases. Its ability to deliver real-time notifications and its linear scalability make it ideal for handling high-traffic, real-time applications effectively. Experience the advantages of NCache firsthand by downloading NCache Enterprise today!
