Compiled queries in EF Core are precompiled versions of LINQ queries that can be executed multiple times with different parameters. By compiling queries, you can improve performance by reducing the overhead of query translation at runtime.
The following table summarizes the main benefits and use cases of compiled queries in EF Core:
| Benefit | Description | Use Case |
|---|---|---|
| Performance | Reduces runtime overhead by precompiling queries. | High-frequency queries and batch processing. |
| Reusability | Allows the same query to be reused with different parameters. | Queries with varying parameters but similar structure. |
| Scalability | Improves scalability by optimizing query execution. | Scalable applications with heavy data access. |
Compiled queries in EF Core optimize query execution by translating LINQ queries into SQL once and reusing the compiled query plan for subsequent executions. This approach reduces the translation overhead at runtime and improves performance.
// Define a compiled query
var compiledQuery = EF.CompileQuery((MyDbContext context, string status) =>
context.Orders.Where(o => o.Status == status).ToList());
This example introduces the concept of compiled queries and their importance in EF Core.
You can create compiled queries in EF Core using the `EF.CompileQuery` method. This method allows you to define a compiled query with parameters that can be executed multiple times.
// Create a compiled query
var getOrdersByStatus = EF.CompileQuery((MyDbContext context, string status) =>
context.Orders.Where(o => o.Status == status).ToList());
This example demonstrates how to create a compiled query in EF Core.
Once a query is compiled, you can execute it with different parameters, leveraging the precompiled plan to improve performance.
// Execute the compiled query with different parameters
var pendingOrders = getOrdersByStatus(myDbContext, "Pending");
var shippedOrders = getOrdersByStatus(myDbContext, "Shipped");
This example shows how to execute a compiled query with different parameters in EF Core.
Compiled queries can be used for complex query scenarios involving joins, groupings, and projections, allowing you to optimize performance for intricate data retrieval operations.
// Define a complex compiled query
var complexQuery = EF.CompileQuery((MyDbContext context, decimal minPrice) =>
context.Products
.Where(p => p.Price > minPrice)
.Include(p => p.Category)
.OrderBy(p => p.Name)
.ToList());
This example illustrates how to use compiled queries for complex scenarios in EF Core.
Comparing the performance of compiled queries with regular queries highlights the benefits of reduced translation overhead and faster execution times for repeated query executions.
var regularQuery = context.Orders.Where(o => o.Status == "Completed").ToList();
var compiledQuery = getOrdersByStatus(context, "Completed");
This example provides a performance comparison between compiled and regular queries in EF Core.
Caching compiled queries can further optimize performance by reusing the compiled query plan and minimizing the need for recompilation.
// Cache the compiled query
var cachedCompiledQuery = cache.GetOrCreate("CompiledQuery", entry =>
{
entry.AbsoluteExpirationRelativeToNow = TimeSpan.FromMinutes(10);
return EF.CompileQuery((MyDbContext context, string status) =>
context.Orders.Where(o => o.Status == status).ToList());
});
This example explains how to cache compiled queries in EF Core for optimal performance.
Following best practices for compiled queries ensures efficient and reliable performance. Consider the following guidelines:
Advanced techniques with compiled queries involve customizing query behavior and leveraging compiled queries for intricate data retrieval operations.
// Use compiled queries for advanced scenarios
var advancedQuery = EF.CompileQuery((MyDbContext context, string category) =>
context.Products
.Where(p => p.Category.Name == category)
.Select(p => new { p.Name, p.Price })
.ToList());
This example explores advanced techniques for using compiled queries in EF Core.
Handling parameter changes in compiled queries requires careful management to ensure that the query plan is reused effectively across different executions.
// Handle parameter changes in compiled queries
var ordersQuery = EF.CompileQuery((MyDbContext context, string status) =>
context.Orders.Where(o => o.Status == status).ToList());
var activeOrders = ordersQuery(myDbContext, "Active");
var cancelledOrders = ordersQuery(myDbContext, "Cancelled");
This example demonstrates how to handle parameter changes in compiled queries.
Testing and monitoring compiled query performance is crucial to ensure that the optimization benefits are realized. Use profiling tools to analyze query execution.
var stopwatch = Stopwatch.StartNew();
var result = getOrdersByStatus(myDbContext, "Pending");
stopwatch.Stop();
Console.WriteLine($"Execution time: {stopwatch.ElapsedMilliseconds} ms");
This example demonstrates how to test and monitor compiled query performance in EF Core.
EF Core 8 introduces new features and improvements that enhance the use of compiled queries, providing more options and flexibility for developers.
// EF Core 8 enhancements for compiled queries
var optimizedQuery = EF.CompileQuery((MyDbContext context, int pageSize, int pageNumber) =>
context.Customers
.OrderBy(c => c.Name)
.Skip(pageSize * (pageNumber - 1))
.Take(pageSize)
.ToList());
This example highlights the enhancements for compiled queries in EF Core 8.
Explore real-world scenarios where compiled queries can significantly improve performance, including use cases in e-commerce, data analytics, and high-frequency transaction processing.
// Real-world scenario: compiled query for high-frequency transactions
var transactionQuery = EF.CompileQuery((MyDbContext context, DateTime date) =>
context.Transactions
.Where(t => t.TransactionDate >= date)
.ToList());
This example provides real-world scenarios where compiled queries can be effectively applied in EF Core.
Combining compiled queries with caching strategies can further enhance performance by reusing query plans and minimizing database round-trips.
// Combine compiled queries with caching
var queryCacheKey = "OrdersByStatusQuery";
var compiledQueryWithCache = cache.GetOrCreate(queryCacheKey, entry =>
{
entry.AbsoluteExpirationRelativeToNow = TimeSpan.FromMinutes(10);
return EF.CompileQuery((MyDbContext context, string status) =>
context.Orders.Where(o => o.Status == status).ToList());
});
This example explores how to combine compiled queries with caching strategies in EF Core.
Be aware of common pitfalls when using compiled queries, such as excessive memory usage or unintended side effects. Understanding these pitfalls can help you avoid potential issues.
var customer = _context.Customers.AsNoTracking().FirstOrDefault(c => c.CustomerId == 1);
customer.Name = "New Name"; // Changes are not tracked
_context.SaveChanges(); // No update occurs
This example discusses common pitfalls and how to avoid them when using compiled queries in EF Core.
Handling complex query scenarios with compiled queries may require combining multiple query types and strategies to achieve the desired performance and functionality.
// Handle complex scenarios with compiled queries
var multiJoinQuery = EF.CompileQuery((MyDbContext context, string category) =>
context.Products
.Where(p => p.Category.Name == category)
.Join(context.Suppliers, p => p.SupplierId, s => s.Id, (p, s) => new { p, s })
.ToList());
This example explores how to handle complex query scenarios using compiled queries in EF Core.
Compiled queries in EF Core are powerful tools for optimizing query performance by reducing translation overhead and reusing query plans. By implementing compiled queries effectively, developers can build high-performance applications that efficiently manage data retrieval and provide a seamless user experience. Understanding and applying these optimization strategies will help you build robust, scalable applications that leverage the full potential of EF Core.