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This article mainly explains "EF Core how to improve query performance through explicit compilation". The content in the article is simple and clear, and it is easy to learn and understand. Please follow the editor's ideas to study and learn "how EF Core improves query performance through explicit compilation".

Before going into the details, it's important to note that EF Core already uses a cache for expression compilation; when your code needs to reuse a previously executed query, EF Core uses a hash to find and return the compiled query from the cache.

However, you may want to compile the query directly, skipping hash calculations and caching lookups. We can do this by using the following two methods in the EF static class:

EF.CompileQuery ()

EF.CompileAsyncQuery ()

These methods allow you to define a compiled query and then call it by calling a delegate.

In order to avoid differences in test results due to database queries, we use an in-memory database here, which costs less and avoids the problems caused by database optimization execution plans and caching.

Entity definition previous database DbContext

Define entity

Here we define a Category entity type, which is very simple and has only two attributes.

Public class Category {public Guid Id {get; set;} public string Name {get; set;}}

Database DbContext

In the FillCategories method, add three records to the in-memory database.

Public class TestDbContext: DbContext {public TestDbContext (DbContextOptions options): base (options) {} public DbSet Categories {get; set;} public void FillCategories () {var foodCategory = new Category {Id = Guid.NewGuid (), Name = "Food"} Categories.AddRange (foodCategory, new Category {Id = Guid.NewGuid (), Name = "Drinks"}, new Category {Id = Guid.NewGuid (), Name = "Clothing"}, new Category {Id = Guid.NewGuid () Name = "Electronis"}) SaveChanges (true);}} Test code public class CompileQueryTest {private Func _ getCategory = EF.CompileQuery ((TestDbContext context, Guid id) = > context.Categories.FirstOrDefault (c = > c.Id = = id)); private readonly TestDbContext _ dbContext; public CompileQueryTest () {var options = new DbContextOptionsBuilder (). UseInMemoryDatabase (Guid.NewGuid (). ToString ()). Options Var context = new TestDbContext (options); context.FillCategories (); _ dbContext = context;} private readonly Guid _ queryId = Guid.NewGuid (); [Benchmark] public void CompiledQuery () {_ = _ getCategory (_ dbContext, _ queryId) } [Benchmark] public void UnCompiledQuery () {_ = _ dbContext.Categories.FirstOrDefault (c = > c.Id = = _ queryId);}}

To get closer to the test results, we create TestDbContext objects in the constructor and populate the database.

Test result

We use Benchmark.Net for benchmark testing, and the test results are as follows:

MethodMeanErrorStdDevCompiledQuery10.59 us0.0580 us0.0543 usUnCompiledQuery79.55 us0.7860 us0.7353 us thank you for reading, the above is the content of "how EF Core improves query performance through explicit compilation". After the study of this article, I believe you have a deeper understanding of how EF Core can improve query performance through explicit compilation, and the specific use needs to be verified in practice. Here is, the editor will push for you more related knowledge points of the article, welcome to follow!

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