Diagnostics & Profiling

1. EF Core Logging Levels

// Program.cs — Development'ta SQL göster
builder.Services.AddDbContext<AppDbContext>(options =>
    options.UseSqlServer(connectionString)
           .LogTo(Console.WriteLine, LogLevel.Information)  // Sadece dev!
           .EnableSensitiveDataLogging()                     // Parametre değerlerini göster
           .EnableDetailedErrors());                         // Detaylı hata mesajları

// Production: sadece warning ve üstü
// appsettings.Production.json
// "Logging": { "LogLevel": { "Microsoft.EntityFrameworkCore": "Warning" } }

2. Query Tags — SQL'de İzlenebilirlik

var products = await context.Products
    .TagWith("GetActiveProducts - ProductController.Index")
    .TagWith($"UserId: {currentUser.Id}")
    .Where(p => p.IsActive)
    .ToListAsync();

-- SQL Server Profiler / pg_stat_activity'de görürsün:
-- GetActiveProducts - ProductController.Index
-- UserId: 42

SELECT [p].[Id], [p].[Name], [p].[Price]
FROM [Products] AS [p]
WHERE [p].[IsActive] = 1;

3. ToQueryString() — Debug Aracı

// Query'yi çalıştırmadan SQL'ini gör (debug sırasında)
var query = context.Products
    .Where(p => p.Price > 100)
    .OrderBy(p => p.Name);

Console.WriteLine(query.ToQueryString());
// Parametre değerleriyle birlikte tam SQL çıktısı verir

4. OpenTelemetry Entegrasyonu

// NuGet: OpenTelemetry.Instrumentation.EntityFrameworkCore
builder.Services.AddOpenTelemetry()
    .WithTracing(tracing => tracing
        .AddEntityFrameworkCoreInstrumentation(options =>
        {
            options.SetDbStatementForText = true;  // SQL'i span'a ekle
            options.SetDbStatementForStoredProcedure = true;
        })
        .AddSource("Microsoft.EntityFrameworkCore")
        .AddConsoleExporter());  // veya Jaeger, Zipkin, OTLP

5. N+1 Tespit — Interceptor ile

// N+1 tespiti için EF Core Interceptor (production-safe, derlenebilir)
public class QueryCountInterceptor : DbCommandInterceptor
{
    private static readonly AsyncLocal<int> _queryCount = new();

    public static int CurrentRequestQueryCount => _queryCount.Value;
    public static void Reset() => _queryCount.Value = 0;

    public override InterceptionResult<DbDataReader> ReaderExecuting(
        DbCommand command, CommandEventData eventData, InterceptionResult<DbDataReader> result)
    {
        _queryCount.Value++;
        return result;
    }

    public override ValueTask<InterceptionResult<DbDataReader>> ReaderExecutingAsync(
        DbCommand command, CommandEventData eventData, InterceptionResult<DbDataReader> result,
        CancellationToken cancellationToken = default)
    {
        _queryCount.Value++;
        return ValueTask.FromResult(result);
    }
}

// Kayıt:
builder.Services.AddDbContext<AppDbContext>(options =>
    options.UseSqlServer(connectionString)
           .AddInterceptors(new QueryCountInterceptor()));

// Middleware ile tespit:
app.Use(async (context, next) =>
{
    QueryCountInterceptor.Reset();
    await next();
    
    var count = QueryCountInterceptor.CurrentRequestQueryCount;
    if (count > 10)
        Log.Warning("⚠️ N+1 şüphesi: {Path} → {Count} sorgu",
            context.Request.Path, count);

    // Header olarak da eklenebilir (dev ortamda)
    context.Response.Headers["X-EF-Query-Count"] = count.ToString();
});

Diagnostics Araçları Özet