Loading Techniques in EF Core

Working with Entity Framework Core? Knowing how data is loaded can drastically affect your app's performance. Here's a breakdown of the three key loading techniques:

Lazy Loading

• Loads related data only when the navigation property is first accessed.
• Reduces initial query load by delaying related data fetching.
• Requires navigation properties to be marked as virtual.
• Needs Microsoft.EntityFrameworkCore.Proxies and .UseLazyLoadingProxies() enabled.
• Can lead to N+1 query issues if overused.
• Improves performance when related data is rarely needed.
• Ideal for large datasets with optional relationships.
• Not supported in all scenarios like DTOs or projections.

Eager Loading

• Loads related data along with the main entity in a single query.
• Achieved using the .Include() and .ThenInclude() methods.
• Reduces round-trips by fetching all required data upfront.
• Useful when related data is always needed immediately.
• Can fetch multiple levels of related entities using chaining.
• Improves performance by avoiding lazy load triggers.
• May fetch unnecessary data if not carefully planned.
• Ideal for read-heavy scenarios with known data requirements.
• Simplifies the code logic by avoiding the need to manually load or loop for related collections later.

Explicit Loading

• Explicit loading loads related data only when you specifically request it using .Load() method.
• Useful when you don’t want automatic loading of navigation properties.
• Provides full control over when and what related data is fetched.
• Reduces unnecessary data transfer, ideal for fine-tuned performance.
• Use context.Entry(entity).Reference().Load() for single navigation properties.
• Use context.Entry(entity).Collection().Load() to load related collections manually.
• Works well in disconnected scenarios or with detached entities.
• Avoids N+1 issues common with lazy loading by controlling query execution.
• Helps load specific data after checking business logic or conditions.
• More verbose than eager loading but precise and performance-friendly when used right.

Coclusion

Choosing the right loading technique in EF Core—Lazy, Eager, or Explicit—can significantly impact your application’s performance and maintainability. Lazy is demand-based, Eager loads upfront, and Explicit gives precise control. Use them wisely based on data access patterns to ensure efficient, scalable, and clean data handling in your applications.