LINQ Interview Question #117

What is the difference between server-side and client-side evaluation in LINQ?

LINQ Performance, EF Core LINQ, Expressions & Advanced Queries Senior Advanced

Quick Interview Answer

Server-side evaluation means the query provider translates operations so they run at the data source, such as a database. Client-side evaluation means data has reached the application and subsequent operations execute as .NET code.

Detailed Explanation

Server-side filtering and projection are usually preferred for large database sets because they reduce transferred data. Client-side processing is appropriate when the required logic cannot be translated and the data volume is intentionally bounded.

Code Example

var query = db.Products
    .Where(p => p.IsActive)       // Server-side
    .Select(p => new { p.Id, p.Name });

var result = query
    .AsEnumerable()
    .Where(x => CustomCheck(x.Name)) // Client-side
    .ToList();