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Discover the reasons behind the record limit in EF Core 3.1 queries and learn how to overcome it effectively.
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Understanding the Limit on Data Size Returned from EF Core 3.1 Queries

In the world of web development, managing data efficiently is crucial for performance and user experience. If you're using Entity Framework Core (EF Core) 3.1 within a .NET Core 3.1 web application, you may have encountered a perplexing issue: your queries return far fewer records than expected. This blog aims to clarify the situation and provide a robust solution to overcome this limitation.

The Problem: Missing Records in Query Results

For instance, let’s imagine you have a web application connected to SQL Server 2017. You run a specific query through SQL Server Management Studio (SSMS) that successfully fetches around 630,000 records. However, when executing the same query through your application with EF Core, you only retrieve 50,479 records—despite the original query being expected to return many more. This fixed limit on returned records can be confusing and may lead to frustrating limitations in your application’s functionality.

Key Points to Consider:

Direct Query: The query works perfectly when run directly via SSMS.

Web App Query: The same query yields a fixed number of records every time it's executed through EF Core.

Record Count: If the expected results are below 50,479, the output matches the expectation, but anything beyond that results in a truncation of data.

The Solution: Expanding the List Capacity

Fortunately, after examining this issue more closely, the root cause was identified: the default capacity of the list that holds the output data from the query was limiting the number of records returned.

Adjusting the List Capacity

To resolve this problem, you simply need to modify your code to increase the capacity of the list that will hold the data you're retrieving. Here’s an example of how you can do this in your code:

[[See Video to Reveal this Text or Code Snippet]]

Explanation of the Code:

List Initialization: By creating a List with a specified capacity (in this case, 2,000,000), you ensure that the list can accommodate all possible returned records from your EF Core query.

Listing Records: You then proceed to fill this list through the asynchronous query call, ensuring that the output is correctly captured without hitting the default capacity limit.

Conclusion

By adjusting the list capacity in EF Core, you can bypass the frustrating limitation of receiving only a fraction of the expected record count. This solution not only optimizes your data handling but also enhances the overall performance of your .NET Core application. Always remember to tailor your collections according to your expected data load when working with large datasets.

Understanding and correcting these limitations can significantly improve your application’s efficiency and user satisfaction. Happy coding!